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Finger Extensor Tendon Mechanism: Anatomy and Pathology
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Finger Extensor Tendon Mechanism: Anatomy and Pathology
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Language: EN.
Segment:0 .
MARTIN POSNER: The title of my presentation is Finger Extensor Tendon Mechanism, Anatomy and Pathology. The impetus for this presentation was based on a response I often received from first and second year residents when I asked them an anatomy question pertaining to the hand.
MARTIN POSNER: They would often tell me it's the intrinsics. Well, in fact, that rarely was the correct answer. This presentation I'm going to cover anatomy, intrinsic paralysis, intrinsic contractures, and Boutonniere deformity. Regarding the anatomy, we've probably all seen this diagram that has been reproduced many times of 15 soft tissue structures involving a finger. When I first looked at it, I had a sinking feeling that I would never be able to understand this mechanism when actually the extensor tendon mechanism is not that difficult and I hope my presentation simplifies it.
MARTIN POSNER: The tendon mechanism has contributions from both extrinsic and intrinsic muscles. If we just look at the anatomy of finger motions regarding the extrinsics, there's an FDP or profundus tendon that inserts on the volar base of the distal phalanx, an FDS or flexor digitorum superficialis tendon that inserts on the volar, middle of the middle phalanx and EDC tendons that extend the fingers. For the index and little fingers,
MARTIN POSNER: there's also a proprius tendon, for the index it's the extensor indicis proprius and for the little finger, the extensor digiti quinti proprius. Both proprius tendons are sent to the ulnar side of the EDC. When the extrinsic muscles contract with no other forces acting on the finger, this result is what we call clawing. The MP joints will often hyperextend and the interphalangeal joints.
MARTIN POSNER: Clawing is due to an absence of intrinsics also referred to as the intrinsic minus or intrinsic negative hand. The primary pathology is usually neurogenic due to a nerve injury and also nerve neuropathies of various types. Clawing of all fingers is due to median and ulnar nerve pathology. There are some patients whose intrinsics are all ulnar nerve innervated due to a riche-cannieu nerve connection in the palm.
MARTIN POSNER: It is a nerve connection and not a nerve anastomosis since nerves do not have stomas and can't anastomose. Clawing requires intact profundi. Clawing is always worse with a low ulnar nerve lesion because the profundi in such a lesion are intact. Clawing also requires supple joints, MP joints that passively hyperextend. In tight jointed individuals who have little passive hyperextension,
MARTIN POSNER: they will have little or sometimes no clawing. Normally the MP and IP joints flex together with only the extrinsics, there's no primary flexor of the MP joint. The MP joints will flex only after the IP joints and the fingers roll into the palm. The problem is often a great disability because the fingers can't grasp around large objects. If this diagram shows the extrinsic function of the finger, what's missing and what's missing are the intrinsics.
MARTIN POSNER: They are the primary flexors of the MP joints and they also extend the interphalangeal joints. However, they are not the only extensors of those joints. The intrinsics provide a link that courses volar to the, to the MP joint and dorsal to the PIP joint. With only intrinsic function as can occur with a Volkmann's ischemic contracture of the intrinsic muscles, has in this patient who is a hemophiliac who developed a compartment syndrome that was not properly treated.
MARTIN POSNER: He developed intrinsic contractures of all the intrinsics to the fingers and thumb. He developed flexion contractures of the MP joints and extension contractures to the interphalangeal joints. You will also note from the photograph that the thumb is in an adducted position. A Volkmann's ischemic contracture of the intrinsic muscles is very different from a Volkmann's ischemic contracture of the extrinsic flexor muscles.
MARTIN POSNER: The latter results in typically clawing of the fingers with hyperextension of the MP joints and flexion of the interphalangeal joints. As I stated, the intrinsics extend the interphalangeal joints. Can the extrinsics also extend them? And the answer is definitely yes via the central tendons, also commonly referred to as the central slips. The extrinsic contribution consists of sagittal fibers and the central tendon.
MARTIN POSNER: The intrinsic contribution consists of transverse and oblique fibers and lateral bands. Let's look at sagittal fibers and transverse fibers. They are contiguous with each other, but they have entirely different functions. The sagittal fibers go from dorsal to volar and insert on the volar plates and extend the MP joints. They are part of the extrinsic system.
MARTIN POSNER: The transverse fibers run the opposite direction. They go from volar to dorsal and flex the MP joints. They are part of the intrinsic system. The orientation of sagittal fibers varies with positions of the MP joint. With the MP joint extended in neutral position, the fibers are perpendicular to the axis of the joint. With hyperextension of the MP joint, the fibers are almost horizontal.
MARTIN POSNER: The extension force is only at the MP joint, the central tendon is lax and when the extrinsic extensors contract, they are unable to pull through to the central tendon that is, that that is lax and the PIP joint cannot extend. However, with MP flexion, the sagittal fibers are oblique and distal to the axis of joint motions. Therefore, when the extrinsic extensor tendon contracts, it is capable of pulling through to the central tendon and extend the PIP joint.
MARTIN POSNER: The extrinsics are the only extensors of the MP joints and they are the only active flexors flexors of the IP joints. The intrinsics are the primary flexors of the MP joint, and they extend the interphalangeal joints. However, the extrinsics can also extend these joints provided they do not hyperextend the MP joints. Therefore, when asked what extends the interphalangeal joints, if they respond only the intrinsics and extrinsics that is not completely true.
MARTIN POSNER: The response regarding the extrinsics must add the following statement provided they do not hyperextend the MP joints. Let's look at intrinsic paralysis and treatment. Treatment depends on an important clinical test that by blocking MP extension, it permits the extrinsic extensors to pull through to the central tendons and extend the PIP joints. See, a question that I commonly ask residents is at what position should the MP joints be blocked to permit the extrinsics to pull through to the central tendons and extend the PIP joints?
MARTIN POSNER: The correct answer is not in terms of degree, the correct answer is just enough to achieve full PIP extension and it can be as little as zero degrees as in this patient. The Bouvier maneuver is not effective when the central tendon becomes attenuated, and that is a common complication of chronic severe clawing. Therefore, clawing should not be ignored after nerve injury.
MARTIN POSNER: The clawing should be immediately splinted and that splinting should continue after the nerve repair until the intrinsics are re-innervated, or if the nerve repair is unsuccessful, until intrinsic function can be restored by a reconstructive procedure that I will discuss. The splint that is necessary for a maneuver is referred to as a lumbrical Bar splint, and the Bouvier maneuver is the basis for the splint.
MARTIN POSNER: The splint will be effective, provided the central tendons are not attenuated and the splint is fabricated in sufficient flexion to permit the extrinsics to pull through to the central tendons and extend the PIP joints. The operative procedures for intrinsic paralysis depend on if the Bouvier maneuver is effective and can extend the PIP joints or is no longer effective because the central tendons are attenuated.
MARTIN POSNER: Historically, a bone block was inserted into the dorsum of a metacarpal head to create a absolute block to extension of the MP joint. This is no longer used and is only of historical interest. A common procedure that is used is a volar capsulodesis of the MP joint or of multiple MP joints, and a less commonly procedure is using a flexor digitorum superficialis tendon that is looped around the A1 or A2 pulley or is inserted directly into the proximal phalanx.
MARTIN POSNER: None of these procedures will increase grip force. When the Bouvier maneuver is not effective, the only procedures are tenodesis or more commonly, tendon transfers. Let's look at the operative procedures when the Bouvier maneuver is effective. A common procedure is a volar capsulodeses that was described by Eduardo Zancolli of Argentina. This procedure has a high likelihood of success.
MARTIN POSNER: The MP joints are flexed to positions that permit PIP extension via the intrinsics. Actually, flexion contractions aren't produced of these joints. The volar plate is then advanced more proximally and sutured into a slot in the neck of the metacarpal or sutured into a roughened area at that surface. This is preferable than simply excising an ellipse of the volar plate because that can later stretch out. By attaching the volar plate directly to the metacarpal,
MARTIN POSNER: the repair is stable and permanent. Here's an example of an 18-year-old with Charcot-Marie-Tooth, who has severe clawing, and the Bouvier maneuver shows complete correction of that clawing by positioning the MP joints in slight flexion. The degree of flexion is determined, determined by measuring the angle using a goniometer and at surgery a goniometer is used at the MP joints are first pinned in those positions that were determined by preoperative evaluation.
MARTIN POSNER: Each joint is then pinned with a medium thickness k-wire. The membranous portion is then moved proximally and sutured into the metacarpal neck using a suture anchor. And if proper planning is done and the joint is stabilized in the proper degree of flexion, an excellent result can be expected. Regarding the option of using a superficialis tendon that is looped around either the A or A2 pulley or actually inserted into the proximal phalanx, the tendon actually becomes a primary flexor of the MP joint and PIP extension is still via the extrinsics and the Bouvier maneuver must therefore still be effective.
MARTIN POSNER: The potential benefit of inserting the FDS tendon into the phalanx is to improve muscle force, however, that improvement is minimal. I use the term muscle force because that is the correct terminology. Muscle strength that is commonly used is incorrect. Muscle strength is ambiguous terminology that describes different measures of muscle function. Muscle force is the pressure contracting muscle exerts at its insertion.
MARTIN POSNER: It's related to the cross section of the muscle, regardless of the length of its fibers. The cross sectional areas of the profunda muscles and the interosseous to the fingers are similar, even though the profunda muscle fibers are much longer in length, both muscle groups have similar muscle forces. That is the reason that with paralysis of the interosseous, grip strength is decreased generally more than 50%. Muscle work capacity is the ability of a muscle to exert a force over a distance.
MARTIN POSNER: Its force times distance and muscle power is work per unit of time. It's important in muscle physiology, but it's not important for considering tendon transfer. As I stated, it's impossible to replace the total loss of muscle force of paralyzed intrinsics to the fingers using tendon transfers. The procedures that I mentioned of using the FDS tendon require precise tensioning
MARTIN POSNER: and that's a problem with the procedure. Volar plate capsule indices are far more predictable and therefore preferred. Remember, it's muscle force, not muscle strength. When the Bouvier maneuver is not effective, the options are either tenodeses or tendon transfers. Tenodeses are essentially static procedures and not particularly effective. Both tenodeses and tendon transfers must follow the course of the intrinsics; volar to the MP joint and dorsal to the interphalangeal joint.
MARTIN POSNER: Several tenodeses, tenodeses have been recommended. The Fowler, Fowler tenodesis uses a free graft around the extensor retinaculum. Each slip is sutured volar to the deep transverse metacarpal ligament to make certain that its volar to the axis of motion of the MP joint and then each is sutured into a lateral band. With wrist extension, the tenodesis will tighten slightly.
MARTIN POSNER: The Riordan tenodesis used half of the ECRL and half of the ECU. Each of those tendons was split into two slips and each routed and attached similar to the Fowler tenodesis. Since both the ECRL and ECU insert distal to the wrist joint, they are not affected by wrist motions and this tenodesis is is entirely static. The ulnar tenodesis involved a tendon graft from the volar plate of the MP joint to the extensor extensor tendon, which was also a totally static procedure.
MARTIN POSNER: Riordan and Omer tenodeses tended to produce fixed flexion contractures of MP joints and significantly restricted PIP flexion. A preferred procedure is a tendon transfer, and tendon transfers are required when the Bouvier maneuver can no longer achieve PIP extension by blocking MP extension or when that MP extension must be blocked to a significant degree, approximately more than 35 or 40 degrees.
MARTIN POSNER: To do a capsulodesis when the Bouvier maneuver requires it blocking the MP joint more than 35 or 40 degrees is generally not a good idea because you would be producing a flexion contracture of the MP joints which may itself be disabling. Tendon transfers are sometimes indicated when there is a grip weak force that causes a disability. However, as I stated, it's impossible to restore normal grip force.
MARTIN POSNER: It's also important to emphasize and re emphasize that all intrinsic transfers must pass volar to the axis of motion of the MP joints and then sutured into one lateral band. A commonly performed procedure is to use a superficialis tendon of 1 or 2 fingers if four fingers are involved. This was the Bunnell transfer.
MARTIN POSNER: An FDS tendon was split and since the tendon is already volar to the axis of motion of the MP joint, each slip was simply passed down the lumbrical canal and sutured into the radial lateral band of each finger. All the transfers are volar to the axis of motion of the MP joint because that's where they began volar to the axis of motion. A clinical example of a Bunnell intrinsic transfer was in this 25-year-old with an ulnar nerve laceration.
MARTIN POSNER: The Bouvier maneuver was not effective because the central slips had attenuated because the clawing had not been splinted. A superficialis tendon of the ring finger was split and a slip of each of the tendons was passed down the lumbar canal and sutured into the radial lateral band of the ring finger and the little finger with the MP joint of the finger flexed and the interphalangeal joints extended
MARTIN POSNER: in this so-called intrinsic positive. Post-operatively, the patient clawing was eliminated and they regained excellent digital mobility. The transfer was truly working as an active transfer because the patient was able to position the ring and little fingers in intrinsic plus positions. The Fowler transfer uses an extensor, uses the extensor indicis proprius and or the extensor digiti Quinti proprius in this 55-year-old diabetic with ulnar neuropathy and clawing.
MARTIN POSNER: The main complaint was inability to adduct her little finger, and there was also a positive Wartenberg sign that is commonly a presenting symptom in patients with ulnar neuropathies. The Bouvier maneuver produced almost complete PIP extension because it was incomplete, a tendon transfer was used. Question I often ask is when using the EDQP as a transfer, what must be determined and why?
MARTIN POSNER: And the answer is it's critically important to determine that the EDC tendon to that finger effectively extends the MP joint. Of the two extensor tendons to a little finger, The EDQP tendon is far more constant than the EDC. The only way to determine if an EDC tendon is present and is effective in extending the MP joint is by a surgical incision. If the EDC tendon is functioning well, then the proprius tendon to the little finger can be used as an intrinsic transfer.
MARTIN POSNER: The tendon is passed volar to the axis of motion of the MP joint, and this is done by passing the tendon deep to the deep transverse metacarpal ligament. Since it is passing deep to that ligament, the tendon is sutured into the radial lateral band of the little finger. Post-operatively the clawing was corrected, the patient was able to place the ring of little fingers in intrinsic plus positions, and the Wartenberg's sign was also decreased.
MARTIN POSNER: Brand also described a tendon transfer using a wrist extensor and attached to a four tailed graft that he then first passed through the carpal canal. He used either the ECRL or the ECRP. When using one wrist extensor for a tendon transfer, it's always important to use the central wrist extensor, the CRB. If two wrist extensors have to be used for tendon transfers, then the ECRB is retained and the ECRL and the ECU are used. In the brand transfer with a motor and grafts were passed through the carpal canal.
MARTIN POSNER: The tendons were already volar to the axis of motion and then the slips could then be passed through the lumbrical canals. When he did this in his patients, none of them developed carpal tunnel syndrome and the reason for that is that his patients all had leprosy and therefore had insensate hands both in the median and ulnar nerve distributions. The Brand type II transfer was then developed with the motor remains dorsal and the grafts have to be passed volar to the axis of motion of the MP joints, and they have to be passed deep to the deep transverse metacarpal.
MARTIN POSNER: In this clinical case of a 35-year-old who had a post op repair of flexor tendon lacerations and median and ulnar nerve lacerations, he regained good digital flexion but regained no intrinsic function to either his intrinsics or his thumb. For the purpose of the fingers, the ECRL tendon was used as a motor attached to a four tailed graft. The ECRL was used as the motor for because the ECU tendon was used for opposition.
MARTIN POSNER: The four tails were then passed deep to the deep transverse metacarpal ligament and for the index finger, the tendon was attached to the ulnar lateral band for the little finger to the radial lateral band and for the middle and ring fingers it really did not matter. Post-operatively, the clawing was eliminated, the patient regained excellent flexion,
MARTIN POSNER: he also regained excellent function following the opposition transfer, using the ECU tendon as the motor. Intrinsic contractures of the fingers are often referred to as intrinsic plus deformities. This is tested using the Bunnell test, which is a passive two part test to evaluate intrinsic tightness. It's critically important that the patient's hand is relaxed.
MARTIN POSNER: Part one: the intrinsic muscles of position in maximum stretch. It's important not just to extend the MP joints, but to hyper extend them and then the PIP joints are flexed by placing downward pressure on the dorsum of the middle segments. Part two is the intrinsic muscles are positioned in a relaxed position. The MP joints are flexed and the PIP joints also flexed. In this position,
MARTIN POSNER: the lateral bands are relaxed with MP flexed. PIP motions that are unchanged with MP extension and MP flexion can be due to intrinsic contractures or joint contractures or both. These photographs show that pressure is being placed over the distal segments, but as I previously stated, it's far preferable to place the pressure over the dorsum of the middle segment. With MP flexion,
MARTIN POSNER: PIP flexion remains absent and this is due to a contracture of the PIP joint. Or, as I recently said, it could also be due to an intrinsic contracture as well. It's important that the radial and ulnar intrinsics are evaluated in each finger. It's important that not just with hyperextension of the MP joint, it's important that the proximal phalanx be deviated first to one side, ulnar or radial, and then to the other side.
MARTIN POSNER: As an example, when evaluating the index finger, the first dorsal interosseous is tested by maximally hyperextending the MP joint and then deviating the finger in an ulnar direction. When testing the first volar interosseous. The MP joint is maximally extended and the finger is then deviated radially, which puts more tension on the first volar than on the first dorsal.
MARTIN POSNER: And as seen here, the first volar interosseous is tighter than the first dorsal interosseous. Generally contractures of the first volar interosseous have a greater effect on PIP joints than contractures of the first dorsal interosseous. And the reason for that is that the first volar interosseous is a, has a much more well-developed lateral band than the lateral band of the first dorsal interosseous whose muscle inserts primarily into the proximal phalanx.
MARTIN POSNER: Intrinsic tightness should always be considered when PIP flexion is limited, and this is common in chronic trigger fingers, and it's a diagnosis that's often missed. Early in my career, I've missed this diagnosis and I surgically released the A1 pulley in patients who had trigger fingers or as I generally prefer to do, to excise the A1 pulley and post-operatively the patient no longer had any triggering or locking, but still was very symptomatic.
MARTIN POSNER: Active flexion can often be completed in these patients because their profunda tendons are strong enough to overcome mild to moderate intrinsic tightness. But a clue to the diagnosis is the patient complains of tightness with finger flexion. Therefore, when evaluating patients with chronic trigger fingers or any trigger fingers, it's important to also evaluate if they have any intrinsic tightness and if they do, the intrinsic should be released at the same time that the proximal A1 pulley of the tendon sheath is released or excised. Intrinsic contractures may not always be demonstrated preoperatively, but they should be anticipated at surgery, particularly when surgery is necessary for extension contractions of PIP joints.
MARTIN POSNER: In this case of a PIP dislocation of a of the middle finger after reduction, the middle and ring fingers were splinted.
MARTIN POSNER: That splinting continued for 4 to 5 weeks and the patient developed extensive contractures of both fingers. I've often advised Residents Fellows, never immobilize uninjured fingers for acute injuries. The Bunnell test was negative preoperatively, but intrinsic contractures in this finger were likely and were ?.
MARTIN POSNER: To release intrinsic contractures, there are just two types; a proximal release which simply means proximal to the MP joint, which eliminates all intrinsic function on the, on that finger and is indicated when MP extension and PIP flexion are both limited. This was commonly seen in patients with rheumatoid arthritis. A distal release is one that's simply distal to the MP joint.
MARTIN POSNER: It's performed when MP extension is normal, but PIP flexion is limited. At surgery, the lateral band and oblique fibers are excised, but the transverse fibers are retained. Surgery is first performed to release the intrinsic on the tight side, and this is determined by preoperative evaluation when the intrinsics on both the radial and ulnar sides of the fingers are evaluated.
MARTIN POSNER: When both sides are equally tight, it's dealer's choice. A distal intrinsic release is performed by a longitudinal incision over the proximal segment, and through that incision, the transverse and oblique fibers can be exposed on both sides of the finger if necessary. The operation is to excise that triangular tissue comprising the lateral band and oblique fibers on that side of the finger where the intrinsics are notably tight.
MARTIN POSNER: If necessary, it's also excised on the opposite side of the finger as well. In the patient with PIP extension, contractures to the middle and ring fingers. Capsulectomies fully restored passive flexion of the PIP joints but at surgery, the intrinsics were tested again and they were still contracted. Therefore another incision was made dorsally and through that incision, a distal intrinsic release was performed completely correcting the contracture.
MARTIN POSNER: The final part of the operation was to make an incision in the palm and at the level of the A1 pulley or slightly proximally, traction was placed on the flexor tendons to make certain that they would produce complete flexion of the finger and the tendons themselves were not scarred within the finger. Finally, I'd like to discuss the Boutonniere deformity, which curiously is only referred to that in English speaking countries.
MARTIN POSNER: In French speaking countries, the deformity is commonly referred to as the deformite buttonhole. It is called a buttonhole deformity because the sides are comprised of the radial and ulnar lateral bands that have subluxed volar to the axis of motion of the PIP joint. Normally when the PIP joint is flexed on the 90 degrees, we are unable to actively extend the DIP joints.
MARTIN POSNER: The reason being is that the central tendon insertion is pulled distally with the PIP fully flexed and the lateral bands become lax. However, in an acute boutonniere deformity, there is often a positive Elson test where the DIP joints are extended, the central tendon ruptures, the lateral bands are pulled proximally, they are no longer lax. Also, the DIP joint extends due to the subluxated lateral bands that are volar to the PIP axis.
MARTIN POSNER: The retinacular ligament often contracts and the retinacular ligament limits active DIP flexion or it can actually cause an extension contracture of the DIP joint. The retinacular ligament has two components; a transverse and oblique component similar to an intrinsic. When a PIP joint goes into flexion, the oblique retinacular ligament is in a relaxed position and when ligaments are in relaxed positions, they often undergo contractures.
MARTIN POSNER: It's important not to permit the oblique retinacular ligament to become contracted. In normal individuals, the oblique retinacular ligament is normally tight and this can easily be evaluated and is sometimes referred to as the intrinsic, intrinsic plus finger. In the diagram I showed you earlier, the intrinsics are the leakage that pass volar to the MP joint and dorsal to the PIP joint.
MARTIN POSNER: The retinacular ligament is actually a second linkage, just one joint distal to the intrinsic linkage. The oblique retinacular ligament passes from volar to the PIP joint and dorsal to the DIP joint. It's actually a series of overlapping linkage systems. First the intrinsics and then the oblique retinacular ligament.
MARTIN POSNER: With an acute boutonniere deformity, it's important to split the PIP joint in full extension, not to splint the DIP joint. Bunnell originally used the safety pin of a horse blanket, and it was commonly referred to as a safety pin splint. In more modern times, more effective splints can be fabricated by hand therapists that will only limit mobility of the PIP joint. The TIP joint is left free for active as well as passive exercises.
MARTIN POSNER: Regarding the boutonniere and pseudo boutonniere deformity, a pseudo boutonniere deformity is a flexion contracture of a PIP joint. There is no primary injury to the extensor tendon. The injury is on the volar surface of the joint, not the dorsal surface. In a boutonniere deformity, not only is extension of the PIP joint effective, but there is limited or no active flexion at the DIP joint.
MARTIN POSNER: While in a pseudo boutonniere deformity, there is no adverse effect on flexion of the DIP joint. Therefore, in making the diagnosis between a boutonniere and pseudo boutonniere deformity, don't look at the PIP joint, look at the DIP joint. It's important to remember that a severe pseudo boutonniere deformity can become a true boutonniere deformity when the central tendon isn't attenuated,
MARTIN POSNER: and that is likely in a very severe PIP contracture, as in this patient who had a 90 degree contracture of his PIP joint. The classification of boutonniere deformities is acute, subacute and chronic. An acute boutonniere deformity requires an index of suspicion when evaluating an acute injury because there may be just swelling and tenderness over the dorsum of a PIP joint.
MARTIN POSNER: Active extension of the PIP joint could be complete or near-complete. If this injury is limited just to the central tendon, such as a small laceration and there is no damage to the triangular ligaments, it's possible that those ligaments will not shift fully to the axis of motion. If in doubt about the diagnosis, the PIP joint should be splinted in extension and the patient re-evaluated within a week.
MARTIN POSNER: The PIP joint is splinted in full extension and as I previously stated, the DIP joint should not be splinted to permit both active and passive exercises, and these exercises are most effective if they are done frequently each hour, but for brief periods of time. 10 repetitions is more than sufficient. Surgery is generally unnecessary for the acute closed boutonniere deformity, except for a central slip avulsion with a bony fragment.
MARTIN POSNER: My preference is to treat these rare injuries with a cerclage wire that is passed through a hole in the dorsal part of the middle phalanx, and then the wire is passed under the lateral bands and then just superficial to the central tendon and brings the bony fragment back into anatomical position. The subacute boutonniere deformity is one where there is joint swelling, a loss of active extension, and often there is some restriction of PIP extension as well.
MARTIN POSNER: In these situations, non-operative measures can be tried using a static splint that prevents PIP flexion. Again, as previously noted, the patient is encouraged to both actively and passively flex the DIP joint. The subacute boutonniere deformity where passive PIP extension is more restricted, serial casts are used that are changed weekly. Similar to clubfoot casts, padding is placed over the dorsum of the PIP joint and on the volar surface of the fingertip.
MARTIN POSNER: In this patient, six serial casts were used over six weeks, followed by therapy, and he regained good mobility with only slight loss of PIP. A cooperative patient is crucial to a successful treatment. This patient was seen six weeks after his injury where his PIP joint was almost 90 degrees. Serial casts were used, after the fourth cast there was improvement. After the sixth cast, there was significantly more improvement, and I was becoming optimistic that this would be an effective treatment.
MARTIN POSNER: However, he then removed the cast, disappeared and returned two months later with his contracture even more severe than when it was when I first examined him. He went on to a PIP joint. The chronic boutonniere deformity, the criteria for surgery are supple tissues and excellent passive mobility. As with any tendon repairs or tendon reconstructions, you cannot restore active joint motions when passive motions are restricted.
MARTIN POSNER: A cooperative patient is critically important. There are numerous surgical techniques that have been described and all relocate the lateral bands dorsal to the axis of the PIP joint. I generally adhere to the acronym of KISS. Keep it simple, stupid. A curved incision is made over the dorsum of the PIP joint, a curved incision is superior than a bayonet incision because it it avoids any suture line directly over the tendon repair.
MARTIN POSNER: The lateral bands are brought dorsal to the axis of motion and sutured together with 1 or 2 fine, 5-0 6 or 6-0 nylon sutures. And they are sutured together in the area where the triangular ligament would be. If possible, the central tendon is advanced and sutured to the site. It's critically important not to place any sutures at or proximal to the PIP joint because that will likely result in an extension contracture of the joint.
MARTIN POSNER: Postoperatively, this patient made an excellent recovery. Here's an unusual case where reconstruction of the central tendon and lateral bands was required. He had sustained obvious partial amputations of the middle and ring fingers and had sustained a complete avulsion of the soft tissues and tendons over the PIP joint that had been previously treated at another hospital with a pedicle flap. He had good passive extension of the PIP joint
MARTIN POSNER: and the technique to reconstruct intrinsic function was simply to follow the course of the anatomy, which means that there should be a tendon that is dorsal to the PIP joint and then goes volar to the MP joint. A tendon graft using the plantaris was passed through a hole through the middle phalanx, crossed over the PIP joint in order to keep it dorsal to the axis of motion. Each limb of the graft was then passed volar to the MP joint axis.
MARTIN POSNER: One limb of the graft was sutured to the first volar interosseous tendon and the other to the first dorsal interosseous tendon with the finger in the intrinsic plus position. Very satisfactory, active motions were restored to the finger. Fowler described a similar technique. With regard to the chronic stiff boutonniere deformity, this is due to two problems.
MARTIN POSNER: The first is the incompetent extensor tendon mechanism and the second is joint stiffness. It is important not to reconstruct extensor tendon when the PIP and DIP joints are stiff. A capsulectomy and an extensive tendon reconstruction at the same operation will change a stiff flexed finger into a stiff extended finger. These are difficult problems.
MARTIN POSNER: The attempt should be made to reduce the two problems to one. Treat the secondary joint stiffness by non-operative procedures and if successful, then surgery to reconstruct the central tendon. The techniques to treat the secondary joint stiffness, dynamic or elastic splints are usually not effective because they do not provide a sufficient force. Static progressive extension splints with a ratchet mechanism can be effective if the joints are not yet rigid,
MARTIN POSNER: and similarly, serial casts that are changed weekly can also be effective if the joints are not rigid. If non-operative measures are ineffectively, are ineffective, then perhaps you can consider surgery. Surgery would require two stages; capsulectomies of the PIP and DIP joints plus release of the contracture of the oblique retinacular ligament and stage two would require reconstruction of the central tendon. The prerequisite for such a two stage procedure would require an incredibly well motivated patient who is willing to maintain passive PIP mobility after stage one and prior to stage two.
MARTIN POSNER: This would require the use of dynamic flexion and extension splints as well as static splints and other measures as well. This is rarely indicated and rarely accomplished. The interval between stages one and two is usually six months or more, and the overall recovery is more than a year. Again, it would require an incredibly well motivated patient willing to expend the time and effort to regain active PIP extension and not lose flexion of the PIP.
MARTIN POSNER: Is there ever an indication for PIP capsulotomy and extensive tendon reconstruction at the same operation? The only condition I can think of is a chronic volar dislocation of a PIP joint because the only alternative is a PIP arthrodesis. Years ago, I encountered this 72-year-old female who had a chronic volar dislocation of a PIP joint of five weeks duration.
MARTIN POSNER: I told her preoperatively that perhaps I would make an effort to restore some active motions of the joint with the realization that if I regained only 10 or 20 degrees of active motions, it would be 10 or 20 degrees more than a joint fusion. At surgery, both radial and ulnar lateral bands were completely dislocated volar to the axis of motion of the PIP joint.
MARTIN POSNER: The volar plate was contracted and scarred, and in order to reduce the dislocation had to be excised. The volar plate after excision, it was possible to reduce the dislocation. The joint was then pinned, the extensor tendon reconstruction reconstructed and sutures were only placed distal to the PIP joint, and post-operatively, she regained a remarkable degree of active motions that I thought was very surprising.
MARTIN POSNER: After this patient, I had six other patients who had a similar problem and were treated in a similar fashion. Each patient was informed that attempting to restore any active motions could fail and they might require PIP fusions. Post-operatively, their motions averaged 57 degrees and none required additional surgery. And this was written up in the Journal of Hand Surgery in 1986.
MARTIN POSNER: Thank you for your attention.
Segment:0 .
MARTIN POSNER: The title of my presentation is Finger Extensor Tendon Mechanism, Anatomy and Pathology. The impetus for this presentation was based on a response I often received from first and second year residents when I asked them an anatomy question pertaining to the hand.
MARTIN POSNER: They would often tell me it's the intrinsics. Well, in fact, that rarely was the correct answer. This presentation I'm going to cover anatomy, intrinsic paralysis, intrinsic contractures, and Boutonniere deformity. Regarding the anatomy, we've probably all seen this diagram that has been reproduced many times of 15 soft tissue structures involving a finger. When I first looked at it, I had a sinking feeling that I would never be able to understand this mechanism when actually the extensor tendon mechanism is not that difficult and I hope my presentation simplifies it.
MARTIN POSNER: The tendon mechanism has contributions from both extrinsic and intrinsic muscles. If we just look at the anatomy of finger motions regarding the extrinsics, there's an FDP or profundus tendon that inserts on the volar base of the distal phalanx, an FDS or flexor digitorum superficialis tendon that inserts on the volar, middle of the middle phalanx and EDC tendons that extend the fingers. For the index and little fingers,
MARTIN POSNER: there's also a proprius tendon, for the index it's the extensor indicis proprius and for the little finger, the extensor digiti quinti proprius. Both proprius tendons are sent to the ulnar side of the EDC. When the extrinsic muscles contract with no other forces acting on the finger, this result is what we call clawing. The MP joints will often hyperextend and the interphalangeal joints.
MARTIN POSNER: Clawing is due to an absence of intrinsics also referred to as the intrinsic minus or intrinsic negative hand. The primary pathology is usually neurogenic due to a nerve injury and also nerve neuropathies of various types. Clawing of all fingers is due to median and ulnar nerve pathology. There are some patients whose intrinsics are all ulnar nerve innervated due to a riche-cannieu nerve connection in the palm.
MARTIN POSNER: It is a nerve connection and not a nerve anastomosis since nerves do not have stomas and can't anastomose. Clawing requires intact profundi. Clawing is always worse with a low ulnar nerve lesion because the profundi in such a lesion are intact. Clawing also requires supple joints, MP joints that passively hyperextend. In tight jointed individuals who have little passive hyperextension,
MARTIN POSNER: they will have little or sometimes no clawing. Normally the MP and IP joints flex together with only the extrinsics, there's no primary flexor of the MP joint. The MP joints will flex only after the IP joints and the fingers roll into the palm. The problem is often a great disability because the fingers can't grasp around large objects. If this diagram shows the extrinsic function of the finger, what's missing and what's missing are the intrinsics.
MARTIN POSNER: They are the primary flexors of the MP joints and they also extend the interphalangeal joints. However, they are not the only extensors of those joints. The intrinsics provide a link that courses volar to the, to the MP joint and dorsal to the PIP joint. With only intrinsic function as can occur with a Volkmann's ischemic contracture of the intrinsic muscles, has in this patient who is a hemophiliac who developed a compartment syndrome that was not properly treated.
MARTIN POSNER: He developed intrinsic contractures of all the intrinsics to the fingers and thumb. He developed flexion contractures of the MP joints and extension contractures to the interphalangeal joints. You will also note from the photograph that the thumb is in an adducted position. A Volkmann's ischemic contracture of the intrinsic muscles is very different from a Volkmann's ischemic contracture of the extrinsic flexor muscles.
MARTIN POSNER: The latter results in typically clawing of the fingers with hyperextension of the MP joints and flexion of the interphalangeal joints. As I stated, the intrinsics extend the interphalangeal joints. Can the extrinsics also extend them? And the answer is definitely yes via the central tendons, also commonly referred to as the central slips. The extrinsic contribution consists of sagittal fibers and the central tendon.
MARTIN POSNER: The intrinsic contribution consists of transverse and oblique fibers and lateral bands. Let's look at sagittal fibers and transverse fibers. They are contiguous with each other, but they have entirely different functions. The sagittal fibers go from dorsal to volar and insert on the volar plates and extend the MP joints. They are part of the extrinsic system.
MARTIN POSNER: The transverse fibers run the opposite direction. They go from volar to dorsal and flex the MP joints. They are part of the intrinsic system. The orientation of sagittal fibers varies with positions of the MP joint. With the MP joint extended in neutral position, the fibers are perpendicular to the axis of the joint. With hyperextension of the MP joint, the fibers are almost horizontal.
MARTIN POSNER: The extension force is only at the MP joint, the central tendon is lax and when the extrinsic extensors contract, they are unable to pull through to the central tendon that is, that that is lax and the PIP joint cannot extend. However, with MP flexion, the sagittal fibers are oblique and distal to the axis of joint motions. Therefore, when the extrinsic extensor tendon contracts, it is capable of pulling through to the central tendon and extend the PIP joint.
MARTIN POSNER: The extrinsics are the only extensors of the MP joints and they are the only active flexors flexors of the IP joints. The intrinsics are the primary flexors of the MP joint, and they extend the interphalangeal joints. However, the extrinsics can also extend these joints provided they do not hyperextend the MP joints. Therefore, when asked what extends the interphalangeal joints, if they respond only the intrinsics and extrinsics that is not completely true.
MARTIN POSNER: The response regarding the extrinsics must add the following statement provided they do not hyperextend the MP joints. Let's look at intrinsic paralysis and treatment. Treatment depends on an important clinical test that by blocking MP extension, it permits the extrinsic extensors to pull through to the central tendons and extend the PIP joints. See, a question that I commonly ask residents is at what position should the MP joints be blocked to permit the extrinsics to pull through to the central tendons and extend the PIP joints?
MARTIN POSNER: The correct answer is not in terms of degree, the correct answer is just enough to achieve full PIP extension and it can be as little as zero degrees as in this patient. The Bouvier maneuver is not effective when the central tendon becomes attenuated, and that is a common complication of chronic severe clawing. Therefore, clawing should not be ignored after nerve injury.
MARTIN POSNER: The clawing should be immediately splinted and that splinting should continue after the nerve repair until the intrinsics are re-innervated, or if the nerve repair is unsuccessful, until intrinsic function can be restored by a reconstructive procedure that I will discuss. The splint that is necessary for a maneuver is referred to as a lumbrical Bar splint, and the Bouvier maneuver is the basis for the splint.
MARTIN POSNER: The splint will be effective, provided the central tendons are not attenuated and the splint is fabricated in sufficient flexion to permit the extrinsics to pull through to the central tendons and extend the PIP joints. The operative procedures for intrinsic paralysis depend on if the Bouvier maneuver is effective and can extend the PIP joints or is no longer effective because the central tendons are attenuated.
MARTIN POSNER: Historically, a bone block was inserted into the dorsum of a metacarpal head to create a absolute block to extension of the MP joint. This is no longer used and is only of historical interest. A common procedure that is used is a volar capsulodesis of the MP joint or of multiple MP joints, and a less commonly procedure is using a flexor digitorum superficialis tendon that is looped around the A1 or A2 pulley or is inserted directly into the proximal phalanx.
MARTIN POSNER: None of these procedures will increase grip force. When the Bouvier maneuver is not effective, the only procedures are tenodesis or more commonly, tendon transfers. Let's look at the operative procedures when the Bouvier maneuver is effective. A common procedure is a volar capsulodeses that was described by Eduardo Zancolli of Argentina. This procedure has a high likelihood of success.
MARTIN POSNER: The MP joints are flexed to positions that permit PIP extension via the intrinsics. Actually, flexion contractions aren't produced of these joints. The volar plate is then advanced more proximally and sutured into a slot in the neck of the metacarpal or sutured into a roughened area at that surface. This is preferable than simply excising an ellipse of the volar plate because that can later stretch out. By attaching the volar plate directly to the metacarpal,
MARTIN POSNER: the repair is stable and permanent. Here's an example of an 18-year-old with Charcot-Marie-Tooth, who has severe clawing, and the Bouvier maneuver shows complete correction of that clawing by positioning the MP joints in slight flexion. The degree of flexion is determined, determined by measuring the angle using a goniometer and at surgery a goniometer is used at the MP joints are first pinned in those positions that were determined by preoperative evaluation.
MARTIN POSNER: Each joint is then pinned with a medium thickness k-wire. The membranous portion is then moved proximally and sutured into the metacarpal neck using a suture anchor. And if proper planning is done and the joint is stabilized in the proper degree of flexion, an excellent result can be expected. Regarding the option of using a superficialis tendon that is looped around either the A or A2 pulley or actually inserted into the proximal phalanx, the tendon actually becomes a primary flexor of the MP joint and PIP extension is still via the extrinsics and the Bouvier maneuver must therefore still be effective.
MARTIN POSNER: The potential benefit of inserting the FDS tendon into the phalanx is to improve muscle force, however, that improvement is minimal. I use the term muscle force because that is the correct terminology. Muscle strength that is commonly used is incorrect. Muscle strength is ambiguous terminology that describes different measures of muscle function. Muscle force is the pressure contracting muscle exerts at its insertion.
MARTIN POSNER: It's related to the cross section of the muscle, regardless of the length of its fibers. The cross sectional areas of the profunda muscles and the interosseous to the fingers are similar, even though the profunda muscle fibers are much longer in length, both muscle groups have similar muscle forces. That is the reason that with paralysis of the interosseous, grip strength is decreased generally more than 50%. Muscle work capacity is the ability of a muscle to exert a force over a distance.
MARTIN POSNER: Its force times distance and muscle power is work per unit of time. It's important in muscle physiology, but it's not important for considering tendon transfer. As I stated, it's impossible to replace the total loss of muscle force of paralyzed intrinsics to the fingers using tendon transfers. The procedures that I mentioned of using the FDS tendon require precise tensioning
MARTIN POSNER: and that's a problem with the procedure. Volar plate capsule indices are far more predictable and therefore preferred. Remember, it's muscle force, not muscle strength. When the Bouvier maneuver is not effective, the options are either tenodeses or tendon transfers. Tenodeses are essentially static procedures and not particularly effective. Both tenodeses and tendon transfers must follow the course of the intrinsics; volar to the MP joint and dorsal to the interphalangeal joint.
MARTIN POSNER: Several tenodeses, tenodeses have been recommended. The Fowler, Fowler tenodesis uses a free graft around the extensor retinaculum. Each slip is sutured volar to the deep transverse metacarpal ligament to make certain that its volar to the axis of motion of the MP joint and then each is sutured into a lateral band. With wrist extension, the tenodesis will tighten slightly.
MARTIN POSNER: The Riordan tenodesis used half of the ECRL and half of the ECU. Each of those tendons was split into two slips and each routed and attached similar to the Fowler tenodesis. Since both the ECRL and ECU insert distal to the wrist joint, they are not affected by wrist motions and this tenodesis is is entirely static. The ulnar tenodesis involved a tendon graft from the volar plate of the MP joint to the extensor extensor tendon, which was also a totally static procedure.
MARTIN POSNER: Riordan and Omer tenodeses tended to produce fixed flexion contractures of MP joints and significantly restricted PIP flexion. A preferred procedure is a tendon transfer, and tendon transfers are required when the Bouvier maneuver can no longer achieve PIP extension by blocking MP extension or when that MP extension must be blocked to a significant degree, approximately more than 35 or 40 degrees.
MARTIN POSNER: To do a capsulodesis when the Bouvier maneuver requires it blocking the MP joint more than 35 or 40 degrees is generally not a good idea because you would be producing a flexion contracture of the MP joints which may itself be disabling. Tendon transfers are sometimes indicated when there is a grip weak force that causes a disability. However, as I stated, it's impossible to restore normal grip force.
MARTIN POSNER: It's also important to emphasize and re emphasize that all intrinsic transfers must pass volar to the axis of motion of the MP joints and then sutured into one lateral band. A commonly performed procedure is to use a superficialis tendon of 1 or 2 fingers if four fingers are involved. This was the Bunnell transfer.
MARTIN POSNER: An FDS tendon was split and since the tendon is already volar to the axis of motion of the MP joint, each slip was simply passed down the lumbrical canal and sutured into the radial lateral band of each finger. All the transfers are volar to the axis of motion of the MP joint because that's where they began volar to the axis of motion. A clinical example of a Bunnell intrinsic transfer was in this 25-year-old with an ulnar nerve laceration.
MARTIN POSNER: The Bouvier maneuver was not effective because the central slips had attenuated because the clawing had not been splinted. A superficialis tendon of the ring finger was split and a slip of each of the tendons was passed down the lumbar canal and sutured into the radial lateral band of the ring finger and the little finger with the MP joint of the finger flexed and the interphalangeal joints extended
MARTIN POSNER: in this so-called intrinsic positive. Post-operatively, the patient clawing was eliminated and they regained excellent digital mobility. The transfer was truly working as an active transfer because the patient was able to position the ring and little fingers in intrinsic plus positions. The Fowler transfer uses an extensor, uses the extensor indicis proprius and or the extensor digiti Quinti proprius in this 55-year-old diabetic with ulnar neuropathy and clawing.
MARTIN POSNER: The main complaint was inability to adduct her little finger, and there was also a positive Wartenberg sign that is commonly a presenting symptom in patients with ulnar neuropathies. The Bouvier maneuver produced almost complete PIP extension because it was incomplete, a tendon transfer was used. Question I often ask is when using the EDQP as a transfer, what must be determined and why?
MARTIN POSNER: And the answer is it's critically important to determine that the EDC tendon to that finger effectively extends the MP joint. Of the two extensor tendons to a little finger, The EDQP tendon is far more constant than the EDC. The only way to determine if an EDC tendon is present and is effective in extending the MP joint is by a surgical incision. If the EDC tendon is functioning well, then the proprius tendon to the little finger can be used as an intrinsic transfer.
MARTIN POSNER: The tendon is passed volar to the axis of motion of the MP joint, and this is done by passing the tendon deep to the deep transverse metacarpal ligament. Since it is passing deep to that ligament, the tendon is sutured into the radial lateral band of the little finger. Post-operatively the clawing was corrected, the patient was able to place the ring of little fingers in intrinsic plus positions, and the Wartenberg's sign was also decreased.
MARTIN POSNER: Brand also described a tendon transfer using a wrist extensor and attached to a four tailed graft that he then first passed through the carpal canal. He used either the ECRL or the ECRP. When using one wrist extensor for a tendon transfer, it's always important to use the central wrist extensor, the CRB. If two wrist extensors have to be used for tendon transfers, then the ECRB is retained and the ECRL and the ECU are used. In the brand transfer with a motor and grafts were passed through the carpal canal.
MARTIN POSNER: The tendons were already volar to the axis of motion and then the slips could then be passed through the lumbrical canals. When he did this in his patients, none of them developed carpal tunnel syndrome and the reason for that is that his patients all had leprosy and therefore had insensate hands both in the median and ulnar nerve distributions. The Brand type II transfer was then developed with the motor remains dorsal and the grafts have to be passed volar to the axis of motion of the MP joints, and they have to be passed deep to the deep transverse metacarpal.
MARTIN POSNER: In this clinical case of a 35-year-old who had a post op repair of flexor tendon lacerations and median and ulnar nerve lacerations, he regained good digital flexion but regained no intrinsic function to either his intrinsics or his thumb. For the purpose of the fingers, the ECRL tendon was used as a motor attached to a four tailed graft. The ECRL was used as the motor for because the ECU tendon was used for opposition.
MARTIN POSNER: The four tails were then passed deep to the deep transverse metacarpal ligament and for the index finger, the tendon was attached to the ulnar lateral band for the little finger to the radial lateral band and for the middle and ring fingers it really did not matter. Post-operatively, the clawing was eliminated, the patient regained excellent flexion,
MARTIN POSNER: he also regained excellent function following the opposition transfer, using the ECU tendon as the motor. Intrinsic contractures of the fingers are often referred to as intrinsic plus deformities. This is tested using the Bunnell test, which is a passive two part test to evaluate intrinsic tightness. It's critically important that the patient's hand is relaxed.
MARTIN POSNER: Part one: the intrinsic muscles of position in maximum stretch. It's important not just to extend the MP joints, but to hyper extend them and then the PIP joints are flexed by placing downward pressure on the dorsum of the middle segments. Part two is the intrinsic muscles are positioned in a relaxed position. The MP joints are flexed and the PIP joints also flexed. In this position,
MARTIN POSNER: the lateral bands are relaxed with MP flexed. PIP motions that are unchanged with MP extension and MP flexion can be due to intrinsic contractures or joint contractures or both. These photographs show that pressure is being placed over the distal segments, but as I previously stated, it's far preferable to place the pressure over the dorsum of the middle segment. With MP flexion,
MARTIN POSNER: PIP flexion remains absent and this is due to a contracture of the PIP joint. Or, as I recently said, it could also be due to an intrinsic contracture as well. It's important that the radial and ulnar intrinsics are evaluated in each finger. It's important that not just with hyperextension of the MP joint, it's important that the proximal phalanx be deviated first to one side, ulnar or radial, and then to the other side.
MARTIN POSNER: As an example, when evaluating the index finger, the first dorsal interosseous is tested by maximally hyperextending the MP joint and then deviating the finger in an ulnar direction. When testing the first volar interosseous. The MP joint is maximally extended and the finger is then deviated radially, which puts more tension on the first volar than on the first dorsal.
MARTIN POSNER: And as seen here, the first volar interosseous is tighter than the first dorsal interosseous. Generally contractures of the first volar interosseous have a greater effect on PIP joints than contractures of the first dorsal interosseous. And the reason for that is that the first volar interosseous is a, has a much more well-developed lateral band than the lateral band of the first dorsal interosseous whose muscle inserts primarily into the proximal phalanx.
MARTIN POSNER: Intrinsic tightness should always be considered when PIP flexion is limited, and this is common in chronic trigger fingers, and it's a diagnosis that's often missed. Early in my career, I've missed this diagnosis and I surgically released the A1 pulley in patients who had trigger fingers or as I generally prefer to do, to excise the A1 pulley and post-operatively the patient no longer had any triggering or locking, but still was very symptomatic.
MARTIN POSNER: Active flexion can often be completed in these patients because their profunda tendons are strong enough to overcome mild to moderate intrinsic tightness. But a clue to the diagnosis is the patient complains of tightness with finger flexion. Therefore, when evaluating patients with chronic trigger fingers or any trigger fingers, it's important to also evaluate if they have any intrinsic tightness and if they do, the intrinsic should be released at the same time that the proximal A1 pulley of the tendon sheath is released or excised. Intrinsic contractures may not always be demonstrated preoperatively, but they should be anticipated at surgery, particularly when surgery is necessary for extension contractions of PIP joints.
MARTIN POSNER: In this case of a PIP dislocation of a of the middle finger after reduction, the middle and ring fingers were splinted.
MARTIN POSNER: That splinting continued for 4 to 5 weeks and the patient developed extensive contractures of both fingers. I've often advised Residents Fellows, never immobilize uninjured fingers for acute injuries. The Bunnell test was negative preoperatively, but intrinsic contractures in this finger were likely and were ?.
MARTIN POSNER: To release intrinsic contractures, there are just two types; a proximal release which simply means proximal to the MP joint, which eliminates all intrinsic function on the, on that finger and is indicated when MP extension and PIP flexion are both limited. This was commonly seen in patients with rheumatoid arthritis. A distal release is one that's simply distal to the MP joint.
MARTIN POSNER: It's performed when MP extension is normal, but PIP flexion is limited. At surgery, the lateral band and oblique fibers are excised, but the transverse fibers are retained. Surgery is first performed to release the intrinsic on the tight side, and this is determined by preoperative evaluation when the intrinsics on both the radial and ulnar sides of the fingers are evaluated.
MARTIN POSNER: When both sides are equally tight, it's dealer's choice. A distal intrinsic release is performed by a longitudinal incision over the proximal segment, and through that incision, the transverse and oblique fibers can be exposed on both sides of the finger if necessary. The operation is to excise that triangular tissue comprising the lateral band and oblique fibers on that side of the finger where the intrinsics are notably tight.
MARTIN POSNER: If necessary, it's also excised on the opposite side of the finger as well. In the patient with PIP extension, contractures to the middle and ring fingers. Capsulectomies fully restored passive flexion of the PIP joints but at surgery, the intrinsics were tested again and they were still contracted. Therefore another incision was made dorsally and through that incision, a distal intrinsic release was performed completely correcting the contracture.
MARTIN POSNER: The final part of the operation was to make an incision in the palm and at the level of the A1 pulley or slightly proximally, traction was placed on the flexor tendons to make certain that they would produce complete flexion of the finger and the tendons themselves were not scarred within the finger. Finally, I'd like to discuss the Boutonniere deformity, which curiously is only referred to that in English speaking countries.
MARTIN POSNER: In French speaking countries, the deformity is commonly referred to as the deformite buttonhole. It is called a buttonhole deformity because the sides are comprised of the radial and ulnar lateral bands that have subluxed volar to the axis of motion of the PIP joint. Normally when the PIP joint is flexed on the 90 degrees, we are unable to actively extend the DIP joints.
MARTIN POSNER: The reason being is that the central tendon insertion is pulled distally with the PIP fully flexed and the lateral bands become lax. However, in an acute boutonniere deformity, there is often a positive Elson test where the DIP joints are extended, the central tendon ruptures, the lateral bands are pulled proximally, they are no longer lax. Also, the DIP joint extends due to the subluxated lateral bands that are volar to the PIP axis.
MARTIN POSNER: The retinacular ligament often contracts and the retinacular ligament limits active DIP flexion or it can actually cause an extension contracture of the DIP joint. The retinacular ligament has two components; a transverse and oblique component similar to an intrinsic. When a PIP joint goes into flexion, the oblique retinacular ligament is in a relaxed position and when ligaments are in relaxed positions, they often undergo contractures.
MARTIN POSNER: It's important not to permit the oblique retinacular ligament to become contracted. In normal individuals, the oblique retinacular ligament is normally tight and this can easily be evaluated and is sometimes referred to as the intrinsic, intrinsic plus finger. In the diagram I showed you earlier, the intrinsics are the leakage that pass volar to the MP joint and dorsal to the PIP joint.
MARTIN POSNER: The retinacular ligament is actually a second linkage, just one joint distal to the intrinsic linkage. The oblique retinacular ligament passes from volar to the PIP joint and dorsal to the DIP joint. It's actually a series of overlapping linkage systems. First the intrinsics and then the oblique retinacular ligament.
MARTIN POSNER: With an acute boutonniere deformity, it's important to split the PIP joint in full extension, not to splint the DIP joint. Bunnell originally used the safety pin of a horse blanket, and it was commonly referred to as a safety pin splint. In more modern times, more effective splints can be fabricated by hand therapists that will only limit mobility of the PIP joint. The TIP joint is left free for active as well as passive exercises.
MARTIN POSNER: Regarding the boutonniere and pseudo boutonniere deformity, a pseudo boutonniere deformity is a flexion contracture of a PIP joint. There is no primary injury to the extensor tendon. The injury is on the volar surface of the joint, not the dorsal surface. In a boutonniere deformity, not only is extension of the PIP joint effective, but there is limited or no active flexion at the DIP joint.
MARTIN POSNER: While in a pseudo boutonniere deformity, there is no adverse effect on flexion of the DIP joint. Therefore, in making the diagnosis between a boutonniere and pseudo boutonniere deformity, don't look at the PIP joint, look at the DIP joint. It's important to remember that a severe pseudo boutonniere deformity can become a true boutonniere deformity when the central tendon isn't attenuated,
MARTIN POSNER: and that is likely in a very severe PIP contracture, as in this patient who had a 90 degree contracture of his PIP joint. The classification of boutonniere deformities is acute, subacute and chronic. An acute boutonniere deformity requires an index of suspicion when evaluating an acute injury because there may be just swelling and tenderness over the dorsum of a PIP joint.
MARTIN POSNER: Active extension of the PIP joint could be complete or near-complete. If this injury is limited just to the central tendon, such as a small laceration and there is no damage to the triangular ligaments, it's possible that those ligaments will not shift fully to the axis of motion. If in doubt about the diagnosis, the PIP joint should be splinted in extension and the patient re-evaluated within a week.
MARTIN POSNER: The PIP joint is splinted in full extension and as I previously stated, the DIP joint should not be splinted to permit both active and passive exercises, and these exercises are most effective if they are done frequently each hour, but for brief periods of time. 10 repetitions is more than sufficient. Surgery is generally unnecessary for the acute closed boutonniere deformity, except for a central slip avulsion with a bony fragment.
MARTIN POSNER: My preference is to treat these rare injuries with a cerclage wire that is passed through a hole in the dorsal part of the middle phalanx, and then the wire is passed under the lateral bands and then just superficial to the central tendon and brings the bony fragment back into anatomical position. The subacute boutonniere deformity is one where there is joint swelling, a loss of active extension, and often there is some restriction of PIP extension as well.
MARTIN POSNER: In these situations, non-operative measures can be tried using a static splint that prevents PIP flexion. Again, as previously noted, the patient is encouraged to both actively and passively flex the DIP joint. The subacute boutonniere deformity where passive PIP extension is more restricted, serial casts are used that are changed weekly. Similar to clubfoot casts, padding is placed over the dorsum of the PIP joint and on the volar surface of the fingertip.
MARTIN POSNER: In this patient, six serial casts were used over six weeks, followed by therapy, and he regained good mobility with only slight loss of PIP. A cooperative patient is crucial to a successful treatment. This patient was seen six weeks after his injury where his PIP joint was almost 90 degrees. Serial casts were used, after the fourth cast there was improvement. After the sixth cast, there was significantly more improvement, and I was becoming optimistic that this would be an effective treatment.
MARTIN POSNER: However, he then removed the cast, disappeared and returned two months later with his contracture even more severe than when it was when I first examined him. He went on to a PIP joint. The chronic boutonniere deformity, the criteria for surgery are supple tissues and excellent passive mobility. As with any tendon repairs or tendon reconstructions, you cannot restore active joint motions when passive motions are restricted.
MARTIN POSNER: A cooperative patient is critically important. There are numerous surgical techniques that have been described and all relocate the lateral bands dorsal to the axis of the PIP joint. I generally adhere to the acronym of KISS. Keep it simple, stupid. A curved incision is made over the dorsum of the PIP joint, a curved incision is superior than a bayonet incision because it it avoids any suture line directly over the tendon repair.
MARTIN POSNER: The lateral bands are brought dorsal to the axis of motion and sutured together with 1 or 2 fine, 5-0 6 or 6-0 nylon sutures. And they are sutured together in the area where the triangular ligament would be. If possible, the central tendon is advanced and sutured to the site. It's critically important not to place any sutures at or proximal to the PIP joint because that will likely result in an extension contracture of the joint.
MARTIN POSNER: Postoperatively, this patient made an excellent recovery. Here's an unusual case where reconstruction of the central tendon and lateral bands was required. He had sustained obvious partial amputations of the middle and ring fingers and had sustained a complete avulsion of the soft tissues and tendons over the PIP joint that had been previously treated at another hospital with a pedicle flap. He had good passive extension of the PIP joint
MARTIN POSNER: and the technique to reconstruct intrinsic function was simply to follow the course of the anatomy, which means that there should be a tendon that is dorsal to the PIP joint and then goes volar to the MP joint. A tendon graft using the plantaris was passed through a hole through the middle phalanx, crossed over the PIP joint in order to keep it dorsal to the axis of motion. Each limb of the graft was then passed volar to the MP joint axis.
MARTIN POSNER: One limb of the graft was sutured to the first volar interosseous tendon and the other to the first dorsal interosseous tendon with the finger in the intrinsic plus position. Very satisfactory, active motions were restored to the finger. Fowler described a similar technique. With regard to the chronic stiff boutonniere deformity, this is due to two problems.
MARTIN POSNER: The first is the incompetent extensor tendon mechanism and the second is joint stiffness. It is important not to reconstruct extensor tendon when the PIP and DIP joints are stiff. A capsulectomy and an extensive tendon reconstruction at the same operation will change a stiff flexed finger into a stiff extended finger. These are difficult problems.
MARTIN POSNER: The attempt should be made to reduce the two problems to one. Treat the secondary joint stiffness by non-operative procedures and if successful, then surgery to reconstruct the central tendon. The techniques to treat the secondary joint stiffness, dynamic or elastic splints are usually not effective because they do not provide a sufficient force. Static progressive extension splints with a ratchet mechanism can be effective if the joints are not yet rigid,
MARTIN POSNER: and similarly, serial casts that are changed weekly can also be effective if the joints are not rigid. If non-operative measures are ineffectively, are ineffective, then perhaps you can consider surgery. Surgery would require two stages; capsulectomies of the PIP and DIP joints plus release of the contracture of the oblique retinacular ligament and stage two would require reconstruction of the central tendon. The prerequisite for such a two stage procedure would require an incredibly well motivated patient who is willing to maintain passive PIP mobility after stage one and prior to stage two.
MARTIN POSNER: This would require the use of dynamic flexion and extension splints as well as static splints and other measures as well. This is rarely indicated and rarely accomplished. The interval between stages one and two is usually six months or more, and the overall recovery is more than a year. Again, it would require an incredibly well motivated patient willing to expend the time and effort to regain active PIP extension and not lose flexion of the PIP.
MARTIN POSNER: Is there ever an indication for PIP capsulotomy and extensive tendon reconstruction at the same operation? The only condition I can think of is a chronic volar dislocation of a PIP joint because the only alternative is a PIP arthrodesis. Years ago, I encountered this 72-year-old female who had a chronic volar dislocation of a PIP joint of five weeks duration.
MARTIN POSNER: I told her preoperatively that perhaps I would make an effort to restore some active motions of the joint with the realization that if I regained only 10 or 20 degrees of active motions, it would be 10 or 20 degrees more than a joint fusion. At surgery, both radial and ulnar lateral bands were completely dislocated volar to the axis of motion of the PIP joint.
MARTIN POSNER: The volar plate was contracted and scarred, and in order to reduce the dislocation had to be excised. The volar plate after excision, it was possible to reduce the dislocation. The joint was then pinned, the extensor tendon reconstruction reconstructed and sutures were only placed distal to the PIP joint, and post-operatively, she regained a remarkable degree of active motions that I thought was very surprising.
MARTIN POSNER: After this patient, I had six other patients who had a similar problem and were treated in a similar fashion. Each patient was informed that attempting to restore any active motions could fail and they might require PIP fusions. Post-operatively, their motions averaged 57 degrees and none required additional surgery. And this was written up in the Journal of Hand Surgery in 1986.
MARTIN POSNER: Thank you for your attention.
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