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The Failing Knee Replacement for FRCS
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The Failing Knee Replacement for FRCS
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Segment:0 .
Uh, good evening, everyone. Failing knee arthroplasty, this is a common topic in Vegas and can come up in the clinical section too. I got one in as my short case, the patient was a middle aged lady.
With a painful, totally arthroplasty done two years back. There was no scope for much examination because of pain, and I was squeezed mainly on the approach and the thought process. When you come across a scenario. Feeling totally arthroplasty can be classified into three groups.
Structural biology and kind of according to the more failure. Structural failure includes loosening of the components, prosthetic and periprosthetic fracture. Biologic failure represents prosthetic joint infection. Paint emphatic failure is the failure in motion. It can occur in of ephemeral and glenohumoral joint.
Of femoral join kinematic failure includes a spectrum of conditions with stiff knee at one end where components are put in excessive tightness. To instability at the other end where there is a loose joint. Of magic failure of the pattullo film rejoin include better alignment and extensive insufficiency.
Of the more than 100,000 pictures done in UK annually, the revision risk following primary TCA at 10 years follow up is 5. This 4% to 5% range of failure is reported in most of the NGOs around the world. When we look at the poll registry data of the average US.
Aseptic loosening at 29.8 is the most common indication for revision surgery, followed by infection at 14.8% There is a tendency for increasing incidence of infection in the recent literature. When you look at the cause of failure. When you look at this graph. Of all that, out of anger around the world, you can clearly see that still two years in fiction, which is represented by the red line, is the most common indication for remission.
But after two years as a loosening in the Trem is the most common indication for overall course of revision in total capacity. This is a diagnostic algorithm for the evaluation of failed totally arthroplasty proposed by Kelly wins, published in PJ in 2014. Eight modes of failure are listed in the column on the left.
And the data points to be collected in each is given the right. Each eight bolts of failure should be considered one after the other. In all cases of failed totally arthroplasty in a sequential fashion. This is because. Symptoms can overlap in different types of failure. And different types of failure can also coexist.
The first four more of media that is from 1 to 4. The differential diagnosis can be reached by simple history and clinical examination Allen and the last 4 from 5 to eight. The differential diagnosis can be reached by standard X-ray evaluation. Infection is number one.
It is put on the top of the list as it has to be ruled out in all cases of painful, totally arthroplasty. With high index of clinical suspicion by history and physical examination. Let's raise Israel's yuppie demands. Join aspiration to be performed. Extensor insufficiency is suspected when there is extensive lag on examination.
Stiffness is quantified by the passive and the active range of motion. TBO patellofemoral instability is suspected if there is dynamic instability on gait and instability in any three planes of motion on examination. But man tracking is apparent on the axilo view radiograph. Loosening is diagnosed when the component is subsided. Or when there is circumferential lines at present on radiographs.
Very periprosthetic fracture is suspected by history of trauma and is confirmed by radiographs. Breakage of the implant may be difficult to diagnose, but may be picked up by basic radiographs. Revision, totally arthroplasty must not be in the water until the cause of failure is well defined. There is a nine group in this algorithm where history, examination and basic radiological investigations are normal.
In these cases, it is important to rule out neuropathic. Extra articular or psychosomatic costs of paid. Neuropathic pain is estimated to have a prevalence of 30, 13% following total arthroplasty. Diabetic neuropathy, fibromyalgia, complex regional pain syndrome and stuffiness neuralgia are potential causes of neuropathic pain.
Extra articular causes of pain could be referred pain from the lumbar spine and the hip and extra articular knee causes like bursitis or tendinitis. Spain with. Patient with chronic pain for more than six months, with no diagnosis, with adequate workup. Or with a discrepancy of clinical findings and symptoms should undergo a psychological exploration.
Depression should be ruled out. As it can be a cause or the result of chronic pain. Do a chronological evaluations of live events leading to the arthroplasty failure. Leaked details of total knee arthroplasty operation, including indications, perioperative wound problems and the need of usage of perioperative antibiotics.
Operation record of the patient should be made available if possible. Conform the type of implant used intraoperatively findings. Any difficulties or intraoperatively complications. The surgeon fees during the index operation should be solved. On examination. Look at the overall alignment of the lower limb. And also of the spine to a 360 degree inspection of the knee in standing.
Gate is the best way to diagnose diagnostic instability. Assess the patient ability or stays. Sitting an active knee extension can reveal flexion instability extends the power and leg and dynamic Butler tracking. Evaluate the need for localizing the exact area of readiness. Quantify the deformity in all three planes, including recover and flexion contracture, coronal deformities of bankers and parasites and its correct ability.
Assess the medial lateral laxity in zero, 30 degrees and 90 degrees of flexion and Andrew posterior stability in neutral and 90 degrees of flexion. Always screen the spine and the hip and the it is still neurovascular check. Radiological evaluation, radiological evaluation of the failed totally arthroplasty all needs get a standard lower extremity, weight bearing AP and lateral and skyline view radiographs.
Insist for good quality radiographs with adequate exposure and at least showing 15 centimeters of distal femur and proximal tibia of on the knee. AP and lateral radiographs. In the long axis film says the mechanical axis. And the coronal positioning of the femoral and the tibial implants.
On weight bearing AP and lateral views know the type of prosthesis component sizing medial, lateral and posterior overhead radial loosen lines at the cement bone in the face of both the components. Look at areas of osteoporosis lysis in the femoral condyles and in the tibial condyles. Only Italy, where which is shown as joint space asymmetric.
All filling of the joint restoration of the join line. Austria femoral of Gondola offset femoral component infection and the posterior tibial slope. Continuity of the soft tissue shadow of the tendon and the presence of patella alter and bahaa. Oblique views.
Identify who lost your license in the posterior femoral quantile, which is otherwise hidden by the box of the femoral component. The above images clearly demonstrate massive osteoporosis, both in the lateral and in the medial epicondyle in the oblique view, which is not conspicuous on the lateral radiograph. From the pain plane, stress radiographs at 10 degrees and 90 degrees of flexion are helpful to document mental instability and asymmetry of the extension and flexion gaps.
Radiographs about so lateral space opening at 10 degrees and 90 degrees of opening on various rescue and invalid stress fields, there is no opening on the medial joint space. Andrew bas status, Chris radiographs can diagnose instability in the sagittal plane in 90 degrees of flexion. Ct scan are useful in every revision surgery to quantify the rotation alignment of the femoral and the tibial components.
It is also useful in detecting austere light, especially under the female component and in detecting subtle perioperative periprosthetic fractures not visible on radiographs. Rotation alignment of the components of the tibia can be defined by two methods in the first method. The trans epicondyle axis is transport, but transposed onto the slice through the tibial base plate and the ankle.
That trans epicondyle, or axis that is formed by the posterior tangential base plate line that is cd, gives the rotational position of the tibial plate. About three degrees of rotation on either side is acceptable in this middle. In the second matter, the anchor formed by the TBL component axis DCA.
With the line, that is the line from the center of the tibia to the tibial tubercle is the position of the tibial component. The normal rotation using this method is 18 degrees plus or minus 2.5 degrees of internal rotation. Potential alignment of the femoral component is measured by the angle formed by the trans epicondyle access to the tangential line to the posterior femoral component.
You may just choose postulating lesions of the femoral contain medial femur, epicondyle and lateral tibial plateau. Use of bone scan in diagnosing component loosening and infection in tick is controversial. The most commonly used scans in the scenario is the triple face technician, 99 bone scan. Indium, one one, leukocytes can.
For colloid, bone marrow scan. These are the three scans that can be useful. People face bone scans are highly sensitive, but not very specific. A negative scan is highly predictive of absence of significant component loosening or infection. But you should remember that bone scan remains positive for up to one year post totally out of plastic.
A negative Indian one leukocytes can is a strong predictor of the absence of infection. For colloid, bone marrow scan has a role in detecting infection, sulfur colloid accumulates throughout the reticuloendothelial system and the bone marrow. A hypoplastic bone marrow normally encounter surrounding joint replacements will give rise to increased uptake.
However, in infection, this uptake is suppressed. So when used in combination with the Indian scan, if positive Indian scan with a negative sulfur colloid scan is suggestive of infection. Let us come to aseptic, loosening the pathogenesis of aseptic loosening is either a mechanical failure or osteolysis beneath the implants.
Bone cement works well in well balanced need, because the primary force is compression, which is equally distributed throughout the bone cement in the face. This is not the case in Allen. The image above shows stress distribution in the coronal plane. The variously. That is compressive forces on the medial component and tensile forces on the lateral component.
Bone cement buy properties is strong in compression and weaken tension. If the subchondral goal is structurally strong. With good cement technique, the compressive load on the middle component is resisted and prevents implant subsidies. If this resistance is weak, the implant will subside immediately into virus, leading to increased tensile forces on the lateral component, resulting in semen bonding at the semen implant in the face, leading to loosening.
The second course of aseptic loosening these austere laces beneath the components will stabilize this. You see macrophage activated inflammatory reaction to slap micron polyethylene red Ripley's. Factors that increases the wear rate in polyethylene in DKA can be divided into patient factors that is increased activity level and obesity. Polyethylene factors sterilization of by gamma radiation in air when compared to vacuum or inert gas.
Conventional when compared to crosslink, poorly manufacturing by mentioning was a data compression molding and increased shelf life. Backside where between the pulley and the tibial plate can result in only where this can be reduced by better locking mechanism between and the base plate and polishing the tibial base plate. Political factors, including third body, where soft tissue imbalance and component alignment can increase.
Polly, where? Coming to instability. Stability in any joint is provided by the articular geometry, the static stabilizers, that is the ligaments and the dynamic stabilizers. That is the muscles. In total, knee arthroplasty, we put a metal and polyethylene articulation with different levels of constraint in an envelope of soft tissues.
Key to maintaining stability in total, knee arthroplasty depends on the tension at which the static stabilizes. That is, the ligaments works throughout the range of motion of the knee. To understanding the needs stability, we need to understand the stress strain curve of the ligament. To maintain the stability of the total knee arthroplasty, the strain of the knee ligaments needs to be maintained in the toe region, just enough stress to straighten the crimped collides and fibrous.
If we put the implants in more tension in the tight elastic zone of deformation of the ligaments, the patient might have pain and is likely to have a stiff knee. He furthermore, attention to the plastic sort of information there is either a sequential failure or a catastrophic ligament failure when the strain exceeds the yield point, leading to instability. Compromised stability due to inadequate ligament sprains should be managed going higher in the implant constrain ladder.
So the components used in well-balanced needs. Bias is used in when the PCL is nonfunctional, whereas whereas constrained implants are used when there is a continuation of the collateral ligaments. And full hinge or a complete hinge is used in case of global instability. Going higher in the employment ladder increases the stress transferred to the bone implant in the face and usually requires a stem augmentation to redistribute the stresses when they can spend the implant is used.
Well, coming onto the prosthetic joint infection, which is the most common cause of early tortellini arthroplasty failure. Morbidity associated with revision. For prosthetic joint infection is 5-fold when compared to its aseptic counterparts. One should be aware about the risk factors of prosthetic joint infection to have a high degree of suspicion of diagnosis when it is present.
These risk factors include immunosuppressant drugs, immunosuppressive conditions, including poorly controlled diabetes with HBA 1c, more than nine chronic renal failure, acute liver failure, malnutrition with albumin less than 3.5 HIV with CD4 counts less than 400. Three units of blood transfusion, three units or more a blood transfusion during the perioperative period. Inflammatory property as in rheumatoid arthritis, psoriasis or ankylosing spondylitis.
Lifestyle factors like morbid obesity, smoking, intravenous drug use and poor oral hygiene. Any concurrent systemic infection or fold2 also increases the infection rate. This is the new definition of PGA proposed by the International consensus meeting in 2018, which has been validated by several military centric studies.
It has several additions when compared to the rs 2003 criteria for a diagnosis. In this criteria, definite infection, if one of the major criteria is present, that is one of two positive cultures or presence of a communicating sinus tract. There are six minor criteria in which the serum d-dimer. The serum leukocyte trace, synovial alpha defensin and sino will CRP are additional factors that are included in the new system.
Points 1 to 3 is given for each criteria, and that addition of points more than six. The joint is considered infected between two and 5 possible infection and less than two. Not infected. If the diagnosis of BGA is inconclusive in the preoperative assessment, there is an extension scoring intra or. Which also take into consideration the score, plus points given to positive histology on frozen section positive, purulent and single positive culture and adding up the points, a decision on whether the joint is infected or knot is taken.
McPherson proposed a staging system for prosthetic joint infection where there are three categories the infection type, the systemic host and local factors. Infection type is classified from 1 to 3 with early post-operative infection, acute hemorrhaging infection and late chronic infection. They also consider the host factors 8 to see and local factors 1 to 3.
This is an interesting diagnostic algorithm for prosthetic joint infection. Ba ba, the pilot of this algorithm, is they make an active effort to search for the source of infection by active investigation and going down the table when the infection is inconclusive. The authors suggest arthroscopic or open biopsy for diagnosis of the.
But let complications in arthroplasty, as we mentioned earlier, type of kinematics are dependent on static stabilizers, that is the ligaments. But the key to pattullo femoral kinematic is the dynamic stabilizers that is the quadriceps muscle for an efficient extensor mechanism for components that are important. One is the muscle.
Next is the continuity of the mechanism. Third is the liberal and fourth is the fulcrum. The muscle should be innovative and it should be highly functional in polio and in spinal stenosis or disability speak. There is relative weakness in obesity and in any cases of pain, there is reflex inhibition of the quadriceps. In all these conditions, patients assumes a quadriceps avoidance gait where they lock the knee in relative hyperextension in stance.
This lead to increased stresses in the replaced knee and could lead to failure. Continuity of the quadriceps muscle from its insertion in the tibial tubercle through the patella and the tendon should be maintained if this continuously is breached as in peel-back tendon ruptures and patella fractures. The total knee arthroplasty can be Lebanon should be maintained by preserving the patella, which is lost in battle like to me.
The Falcons should be maintained when the Butler is well centered in the group without ball tracking, subluxation and dislocation. The risk factors of complication in decay is increased in patient factors, which is a welcome sign of more than 10 degrees. Obesity and in particular surgery related factors are asymmetrical but lateral release you less, resulting in interruption of blood supply and femoral and tibial component rotational alignment.
Implant factors with the femoral implant with increased cochlear high metal back and central patella have a failure rate. The goals of revision, totally arthroplasty is different from primary total arthroplasty. Goals include extraction of components with minimal bone loss, restoration of joint line, balance of ligaments, restoration of bone deficiencies, stable fixation of the implants and adequate soft tissue cover.
Good exposure is a prerequisite for a successful revision surgery. Most remission can be done by a medial approach. Exposure is facilitated by a complete sign of economy, of the sine of you, which is always present in recent cases. Further exposure can be. Can be achieved by either a chorus of smith, which is the most common procedure or the only procedure that is needed in most of the cases where an oblique incision of the quadriceps at 45 degrees from the superior extent of the medial incision, it is close by side to side.
The closure and literature shows that it doesn't affect the body's function. Full stop. Other methods have also turned out. And tibial osteotomy. A Swift bone cancer and ligament preserving removal of implants is essential for the timely progression of surgery, sequential removal of components progressively create more space to facilitate exposure.
After adequate surgical exposure, the first component to be removed is the polyethylene insert, which creates space for the femoral component, followed by the tibial component followed by the cement in the middle of the canal. The last component to be removed is the patellar component to protect the remaining thin Kessler bone. The three steps implantation technique of revision, totally arthroplasty.
The first step is to re-establish. It trial platform with a STEM extension in neutral in paranal and sagittal plane. And the rotation of the airplane oriented to the people to buckle in step two, which is done or steps done in 90 degrees of flexion. The step is divided. The step 2 is divided into a, B and C in step two a, establish the femoral rotation parallel to the trans epicondyle axis.
Select the femoral component size. Select the largest femoral component, avoiding medial lateral overhang. In to see. Maintain the join line with the type of nimble articulation within 1.5 centimeters of the inferior Butler. In step three, the knee is brought in the neutral extension, avoiding flexion and recovery time and the proximal distal position of the femoral component and the necessity of femoral augments are assessed.
Egawa message. Consider all modes of failure in failing totally arthroplasty do a systematic and a comprehensive evaluation. Always rule out infection. Do not proceed with revision surgery if you are not able to identify the cause. A revision surgery in revision surgery, correct? The reasons for failure. Thank you.
Leon, thank you very much. Thank you. So I hope I find that very useful, interesting talks and very key things there. Are there any questions that people like to ask with regards to the talk? And obviously, I'm conscious that it is now nearly 3 o'clock in the morning or gone by 4 o'clock in the morning in Singapore.
So the first question from Villa's joint line, 1.5 centimeter from interior ball of Patel. Do you check in flexion or extension of the knee? OK, so in flexion of the knee, it is. It is 1.5 centimeter. Once it is an extension, it is much lesser than that. It is around 0.5 to once intimidate. The patella comes down in extension, so 1.5 centimeter is infliction of pain.
OK and any degree of friction or 30 degrees or that is in step two, so the join lane is assessed in step 2 and the 3 step implantation technique so that all the steps, all the three steps in the step two is done in 90 degrees of flexion. So OK, so it is 90 degrees. OK another question, you would you explain the election instability, please? Yes, so instability can be divided mainly into three types.
The first is the extension instability, election instability and global instability. These are the three main forms of instability. Extension instability is the instability in full extension in the egawa test virus plain and also in also going to extension flexion flexion instability is the andro postural instability in 90 degrees of flexion. Global instability is the instability both in flexion and in extension, and also has got like other causes, like when the patient that is implants obsidian's and loosening associated implants obsidian's in loosening.
So the knee is losing or plates. Midfield instability is an instability, which is described in Lee's recent literature, where the army is unstable between full extension and 90 degrees of flexion. Usually it is caused by medial collateral, ligament or release and posterior capsular over released. So there is an asymmetry Kessler Kessler over release will result in like hyperextension of the knee and medial collateral.
Ligament instability will lead to Vallecas instability of the knee. So when the knee passes from, say, around 30 to 60 degrees of flexion as in stair climbing, the patient experiences instability. So this is a relatively new concept note which is not like, you know, well described in the literature. What what exactly caused this is not well described, but this is the current understanding.
OK so, Uh, a new rule for respect in painful typekit or with normal radiographs and no apparent kind of medical errors. Yeah so it can be used in infected totally arthroplasty. But like, you know, it's not a standard procedure that we follow, which can be mentioned in the exam, but the exact role is not well defined, according to at least according to my practice.
I don't routinely use suspect in the diagnosis of infection in PGA. OK, so it doesn't dictate if you are going to do a revision or no. It doesn't give you any clue for the decision for revision of painfully without infections not mentioned as like clear indication whether the joint is infected or not. Even in prosthetic joint infection, it is mainly high index of suspicion with the basic serological markers and joined aspiration, which is the key in the diagnosis.
And now there is more trend towards getting a histopathologic diagnosis by making either a small incision and taking the sign over or by an arthroscopic biopsy, or if all the other criterias are inconclusive. OK would you say that? I will discuss a case in the MDT for a replacement. I hate to get that. Can you repeat the question?
OK, so in just a case of you are going to do a revision knee replacement or you should say like, I will discuss that with the MDT or yeah, of course, in the example, in the future, definitely any complex scenario in the exam revision is not a standard problem that we face, even in arthroplasty surgeon. We definitely discuss it among our colleagues, so we should definitely say that we will be discussing the case with the senior plastic surgeon like, you know, to get, get, get, get the opinion.
Definitely, you should consider. Yeah I think that is also the last question. Thank you very much for fantastic traject. Thank you very much. Thanks Thanks. Thanks, everyone for listening. Thank you very much, and have a good rest. A busy day tomorrow. I hope we'll give thanks.
Thanks thanks, David. All the best. Thank you. Once again.
Segment:0 .
Uh, good evening, everyone. Failing knee arthroplasty, this is a common topic in Vegas and can come up in the clinical section too. I got one in as my short case, the patient was a middle aged lady.
With a painful, totally arthroplasty done two years back. There was no scope for much examination because of pain, and I was squeezed mainly on the approach and the thought process. When you come across a scenario. Feeling totally arthroplasty can be classified into three groups.
Structural biology and kind of according to the more failure. Structural failure includes loosening of the components, prosthetic and periprosthetic fracture. Biologic failure represents prosthetic joint infection. Paint emphatic failure is the failure in motion. It can occur in of ephemeral and glenohumoral joint.
Of femoral join kinematic failure includes a spectrum of conditions with stiff knee at one end where components are put in excessive tightness. To instability at the other end where there is a loose joint. Of magic failure of the pattullo film rejoin include better alignment and extensive insufficiency.
Of the more than 100,000 pictures done in UK annually, the revision risk following primary TCA at 10 years follow up is 5. This 4% to 5% range of failure is reported in most of the NGOs around the world. When we look at the poll registry data of the average US.
Aseptic loosening at 29.8 is the most common indication for revision surgery, followed by infection at 14.8% There is a tendency for increasing incidence of infection in the recent literature. When you look at the cause of failure. When you look at this graph. Of all that, out of anger around the world, you can clearly see that still two years in fiction, which is represented by the red line, is the most common indication for remission.
But after two years as a loosening in the Trem is the most common indication for overall course of revision in total capacity. This is a diagnostic algorithm for the evaluation of failed totally arthroplasty proposed by Kelly wins, published in PJ in 2014. Eight modes of failure are listed in the column on the left.
And the data points to be collected in each is given the right. Each eight bolts of failure should be considered one after the other. In all cases of failed totally arthroplasty in a sequential fashion. This is because. Symptoms can overlap in different types of failure. And different types of failure can also coexist.
The first four more of media that is from 1 to 4. The differential diagnosis can be reached by simple history and clinical examination Allen and the last 4 from 5 to eight. The differential diagnosis can be reached by standard X-ray evaluation. Infection is number one.
It is put on the top of the list as it has to be ruled out in all cases of painful, totally arthroplasty. With high index of clinical suspicion by history and physical examination. Let's raise Israel's yuppie demands. Join aspiration to be performed. Extensor insufficiency is suspected when there is extensive lag on examination.
Stiffness is quantified by the passive and the active range of motion. TBO patellofemoral instability is suspected if there is dynamic instability on gait and instability in any three planes of motion on examination. But man tracking is apparent on the axilo view radiograph. Loosening is diagnosed when the component is subsided. Or when there is circumferential lines at present on radiographs.
Very periprosthetic fracture is suspected by history of trauma and is confirmed by radiographs. Breakage of the implant may be difficult to diagnose, but may be picked up by basic radiographs. Revision, totally arthroplasty must not be in the water until the cause of failure is well defined. There is a nine group in this algorithm where history, examination and basic radiological investigations are normal.
In these cases, it is important to rule out neuropathic. Extra articular or psychosomatic costs of paid. Neuropathic pain is estimated to have a prevalence of 30, 13% following total arthroplasty. Diabetic neuropathy, fibromyalgia, complex regional pain syndrome and stuffiness neuralgia are potential causes of neuropathic pain.
Extra articular causes of pain could be referred pain from the lumbar spine and the hip and extra articular knee causes like bursitis or tendinitis. Spain with. Patient with chronic pain for more than six months, with no diagnosis, with adequate workup. Or with a discrepancy of clinical findings and symptoms should undergo a psychological exploration.
Depression should be ruled out. As it can be a cause or the result of chronic pain. Do a chronological evaluations of live events leading to the arthroplasty failure. Leaked details of total knee arthroplasty operation, including indications, perioperative wound problems and the need of usage of perioperative antibiotics.
Operation record of the patient should be made available if possible. Conform the type of implant used intraoperatively findings. Any difficulties or intraoperatively complications. The surgeon fees during the index operation should be solved. On examination. Look at the overall alignment of the lower limb. And also of the spine to a 360 degree inspection of the knee in standing.
Gate is the best way to diagnose diagnostic instability. Assess the patient ability or stays. Sitting an active knee extension can reveal flexion instability extends the power and leg and dynamic Butler tracking. Evaluate the need for localizing the exact area of readiness. Quantify the deformity in all three planes, including recover and flexion contracture, coronal deformities of bankers and parasites and its correct ability.
Assess the medial lateral laxity in zero, 30 degrees and 90 degrees of flexion and Andrew posterior stability in neutral and 90 degrees of flexion. Always screen the spine and the hip and the it is still neurovascular check. Radiological evaluation, radiological evaluation of the failed totally arthroplasty all needs get a standard lower extremity, weight bearing AP and lateral and skyline view radiographs.
Insist for good quality radiographs with adequate exposure and at least showing 15 centimeters of distal femur and proximal tibia of on the knee. AP and lateral radiographs. In the long axis film says the mechanical axis. And the coronal positioning of the femoral and the tibial implants.
On weight bearing AP and lateral views know the type of prosthesis component sizing medial, lateral and posterior overhead radial loosen lines at the cement bone in the face of both the components. Look at areas of osteoporosis lysis in the femoral condyles and in the tibial condyles. Only Italy, where which is shown as joint space asymmetric.
All filling of the joint restoration of the join line. Austria femoral of Gondola offset femoral component infection and the posterior tibial slope. Continuity of the soft tissue shadow of the tendon and the presence of patella alter and bahaa. Oblique views.
Identify who lost your license in the posterior femoral quantile, which is otherwise hidden by the box of the femoral component. The above images clearly demonstrate massive osteoporosis, both in the lateral and in the medial epicondyle in the oblique view, which is not conspicuous on the lateral radiograph. From the pain plane, stress radiographs at 10 degrees and 90 degrees of flexion are helpful to document mental instability and asymmetry of the extension and flexion gaps.
Radiographs about so lateral space opening at 10 degrees and 90 degrees of opening on various rescue and invalid stress fields, there is no opening on the medial joint space. Andrew bas status, Chris radiographs can diagnose instability in the sagittal plane in 90 degrees of flexion. Ct scan are useful in every revision surgery to quantify the rotation alignment of the femoral and the tibial components.
It is also useful in detecting austere light, especially under the female component and in detecting subtle perioperative periprosthetic fractures not visible on radiographs. Rotation alignment of the components of the tibia can be defined by two methods in the first method. The trans epicondyle axis is transport, but transposed onto the slice through the tibial base plate and the ankle.
That trans epicondyle, or axis that is formed by the posterior tangential base plate line that is cd, gives the rotational position of the tibial plate. About three degrees of rotation on either side is acceptable in this middle. In the second matter, the anchor formed by the TBL component axis DCA.
With the line, that is the line from the center of the tibia to the tibial tubercle is the position of the tibial component. The normal rotation using this method is 18 degrees plus or minus 2.5 degrees of internal rotation. Potential alignment of the femoral component is measured by the angle formed by the trans epicondyle access to the tangential line to the posterior femoral component.
You may just choose postulating lesions of the femoral contain medial femur, epicondyle and lateral tibial plateau. Use of bone scan in diagnosing component loosening and infection in tick is controversial. The most commonly used scans in the scenario is the triple face technician, 99 bone scan. Indium, one one, leukocytes can.
For colloid, bone marrow scan. These are the three scans that can be useful. People face bone scans are highly sensitive, but not very specific. A negative scan is highly predictive of absence of significant component loosening or infection. But you should remember that bone scan remains positive for up to one year post totally out of plastic.
A negative Indian one leukocytes can is a strong predictor of the absence of infection. For colloid, bone marrow scan has a role in detecting infection, sulfur colloid accumulates throughout the reticuloendothelial system and the bone marrow. A hypoplastic bone marrow normally encounter surrounding joint replacements will give rise to increased uptake.
However, in infection, this uptake is suppressed. So when used in combination with the Indian scan, if positive Indian scan with a negative sulfur colloid scan is suggestive of infection. Let us come to aseptic, loosening the pathogenesis of aseptic loosening is either a mechanical failure or osteolysis beneath the implants.
Bone cement works well in well balanced need, because the primary force is compression, which is equally distributed throughout the bone cement in the face. This is not the case in Allen. The image above shows stress distribution in the coronal plane. The variously. That is compressive forces on the medial component and tensile forces on the lateral component.
Bone cement buy properties is strong in compression and weaken tension. If the subchondral goal is structurally strong. With good cement technique, the compressive load on the middle component is resisted and prevents implant subsidies. If this resistance is weak, the implant will subside immediately into virus, leading to increased tensile forces on the lateral component, resulting in semen bonding at the semen implant in the face, leading to loosening.
The second course of aseptic loosening these austere laces beneath the components will stabilize this. You see macrophage activated inflammatory reaction to slap micron polyethylene red Ripley's. Factors that increases the wear rate in polyethylene in DKA can be divided into patient factors that is increased activity level and obesity. Polyethylene factors sterilization of by gamma radiation in air when compared to vacuum or inert gas.
Conventional when compared to crosslink, poorly manufacturing by mentioning was a data compression molding and increased shelf life. Backside where between the pulley and the tibial plate can result in only where this can be reduced by better locking mechanism between and the base plate and polishing the tibial base plate. Political factors, including third body, where soft tissue imbalance and component alignment can increase.
Polly, where? Coming to instability. Stability in any joint is provided by the articular geometry, the static stabilizers, that is the ligaments and the dynamic stabilizers. That is the muscles. In total, knee arthroplasty, we put a metal and polyethylene articulation with different levels of constraint in an envelope of soft tissues.
Key to maintaining stability in total, knee arthroplasty depends on the tension at which the static stabilizes. That is, the ligaments works throughout the range of motion of the knee. To understanding the needs stability, we need to understand the stress strain curve of the ligament. To maintain the stability of the total knee arthroplasty, the strain of the knee ligaments needs to be maintained in the toe region, just enough stress to straighten the crimped collides and fibrous.
If we put the implants in more tension in the tight elastic zone of deformation of the ligaments, the patient might have pain and is likely to have a stiff knee. He furthermore, attention to the plastic sort of information there is either a sequential failure or a catastrophic ligament failure when the strain exceeds the yield point, leading to instability. Compromised stability due to inadequate ligament sprains should be managed going higher in the implant constrain ladder.
So the components used in well-balanced needs. Bias is used in when the PCL is nonfunctional, whereas whereas constrained implants are used when there is a continuation of the collateral ligaments. And full hinge or a complete hinge is used in case of global instability. Going higher in the employment ladder increases the stress transferred to the bone implant in the face and usually requires a stem augmentation to redistribute the stresses when they can spend the implant is used.
Well, coming onto the prosthetic joint infection, which is the most common cause of early tortellini arthroplasty failure. Morbidity associated with revision. For prosthetic joint infection is 5-fold when compared to its aseptic counterparts. One should be aware about the risk factors of prosthetic joint infection to have a high degree of suspicion of diagnosis when it is present.
These risk factors include immunosuppressant drugs, immunosuppressive conditions, including poorly controlled diabetes with HBA 1c, more than nine chronic renal failure, acute liver failure, malnutrition with albumin less than 3.5 HIV with CD4 counts less than 400. Three units of blood transfusion, three units or more a blood transfusion during the perioperative period. Inflammatory property as in rheumatoid arthritis, psoriasis or ankylosing spondylitis.
Lifestyle factors like morbid obesity, smoking, intravenous drug use and poor oral hygiene. Any concurrent systemic infection or fold2 also increases the infection rate. This is the new definition of PGA proposed by the International consensus meeting in 2018, which has been validated by several military centric studies.
It has several additions when compared to the rs 2003 criteria for a diagnosis. In this criteria, definite infection, if one of the major criteria is present, that is one of two positive cultures or presence of a communicating sinus tract. There are six minor criteria in which the serum d-dimer. The serum leukocyte trace, synovial alpha defensin and sino will CRP are additional factors that are included in the new system.
Points 1 to 3 is given for each criteria, and that addition of points more than six. The joint is considered infected between two and 5 possible infection and less than two. Not infected. If the diagnosis of BGA is inconclusive in the preoperative assessment, there is an extension scoring intra or. Which also take into consideration the score, plus points given to positive histology on frozen section positive, purulent and single positive culture and adding up the points, a decision on whether the joint is infected or knot is taken.
McPherson proposed a staging system for prosthetic joint infection where there are three categories the infection type, the systemic host and local factors. Infection type is classified from 1 to 3 with early post-operative infection, acute hemorrhaging infection and late chronic infection. They also consider the host factors 8 to see and local factors 1 to 3.
This is an interesting diagnostic algorithm for prosthetic joint infection. Ba ba, the pilot of this algorithm, is they make an active effort to search for the source of infection by active investigation and going down the table when the infection is inconclusive. The authors suggest arthroscopic or open biopsy for diagnosis of the.
But let complications in arthroplasty, as we mentioned earlier, type of kinematics are dependent on static stabilizers, that is the ligaments. But the key to pattullo femoral kinematic is the dynamic stabilizers that is the quadriceps muscle for an efficient extensor mechanism for components that are important. One is the muscle.
Next is the continuity of the mechanism. Third is the liberal and fourth is the fulcrum. The muscle should be innovative and it should be highly functional in polio and in spinal stenosis or disability speak. There is relative weakness in obesity and in any cases of pain, there is reflex inhibition of the quadriceps. In all these conditions, patients assumes a quadriceps avoidance gait where they lock the knee in relative hyperextension in stance.
This lead to increased stresses in the replaced knee and could lead to failure. Continuity of the quadriceps muscle from its insertion in the tibial tubercle through the patella and the tendon should be maintained if this continuously is breached as in peel-back tendon ruptures and patella fractures. The total knee arthroplasty can be Lebanon should be maintained by preserving the patella, which is lost in battle like to me.
The Falcons should be maintained when the Butler is well centered in the group without ball tracking, subluxation and dislocation. The risk factors of complication in decay is increased in patient factors, which is a welcome sign of more than 10 degrees. Obesity and in particular surgery related factors are asymmetrical but lateral release you less, resulting in interruption of blood supply and femoral and tibial component rotational alignment.
Implant factors with the femoral implant with increased cochlear high metal back and central patella have a failure rate. The goals of revision, totally arthroplasty is different from primary total arthroplasty. Goals include extraction of components with minimal bone loss, restoration of joint line, balance of ligaments, restoration of bone deficiencies, stable fixation of the implants and adequate soft tissue cover.
Good exposure is a prerequisite for a successful revision surgery. Most remission can be done by a medial approach. Exposure is facilitated by a complete sign of economy, of the sine of you, which is always present in recent cases. Further exposure can be. Can be achieved by either a chorus of smith, which is the most common procedure or the only procedure that is needed in most of the cases where an oblique incision of the quadriceps at 45 degrees from the superior extent of the medial incision, it is close by side to side.
The closure and literature shows that it doesn't affect the body's function. Full stop. Other methods have also turned out. And tibial osteotomy. A Swift bone cancer and ligament preserving removal of implants is essential for the timely progression of surgery, sequential removal of components progressively create more space to facilitate exposure.
After adequate surgical exposure, the first component to be removed is the polyethylene insert, which creates space for the femoral component, followed by the tibial component followed by the cement in the middle of the canal. The last component to be removed is the patellar component to protect the remaining thin Kessler bone. The three steps implantation technique of revision, totally arthroplasty.
The first step is to re-establish. It trial platform with a STEM extension in neutral in paranal and sagittal plane. And the rotation of the airplane oriented to the people to buckle in step two, which is done or steps done in 90 degrees of flexion. The step is divided. The step 2 is divided into a, B and C in step two a, establish the femoral rotation parallel to the trans epicondyle axis.
Select the femoral component size. Select the largest femoral component, avoiding medial lateral overhang. In to see. Maintain the join line with the type of nimble articulation within 1.5 centimeters of the inferior Butler. In step three, the knee is brought in the neutral extension, avoiding flexion and recovery time and the proximal distal position of the femoral component and the necessity of femoral augments are assessed.
Egawa message. Consider all modes of failure in failing totally arthroplasty do a systematic and a comprehensive evaluation. Always rule out infection. Do not proceed with revision surgery if you are not able to identify the cause. A revision surgery in revision surgery, correct? The reasons for failure. Thank you.
Leon, thank you very much. Thank you. So I hope I find that very useful, interesting talks and very key things there. Are there any questions that people like to ask with regards to the talk? And obviously, I'm conscious that it is now nearly 3 o'clock in the morning or gone by 4 o'clock in the morning in Singapore.
So the first question from Villa's joint line, 1.5 centimeter from interior ball of Patel. Do you check in flexion or extension of the knee? OK, so in flexion of the knee, it is. It is 1.5 centimeter. Once it is an extension, it is much lesser than that. It is around 0.5 to once intimidate. The patella comes down in extension, so 1.5 centimeter is infliction of pain.
OK and any degree of friction or 30 degrees or that is in step two, so the join lane is assessed in step 2 and the 3 step implantation technique so that all the steps, all the three steps in the step two is done in 90 degrees of flexion. So OK, so it is 90 degrees. OK another question, you would you explain the election instability, please? Yes, so instability can be divided mainly into three types.
The first is the extension instability, election instability and global instability. These are the three main forms of instability. Extension instability is the instability in full extension in the egawa test virus plain and also in also going to extension flexion flexion instability is the andro postural instability in 90 degrees of flexion. Global instability is the instability both in flexion and in extension, and also has got like other causes, like when the patient that is implants obsidian's and loosening associated implants obsidian's in loosening.
So the knee is losing or plates. Midfield instability is an instability, which is described in Lee's recent literature, where the army is unstable between full extension and 90 degrees of flexion. Usually it is caused by medial collateral, ligament or release and posterior capsular over released. So there is an asymmetry Kessler Kessler over release will result in like hyperextension of the knee and medial collateral.
Ligament instability will lead to Vallecas instability of the knee. So when the knee passes from, say, around 30 to 60 degrees of flexion as in stair climbing, the patient experiences instability. So this is a relatively new concept note which is not like, you know, well described in the literature. What what exactly caused this is not well described, but this is the current understanding.
OK so, Uh, a new rule for respect in painful typekit or with normal radiographs and no apparent kind of medical errors. Yeah so it can be used in infected totally arthroplasty. But like, you know, it's not a standard procedure that we follow, which can be mentioned in the exam, but the exact role is not well defined, according to at least according to my practice.
I don't routinely use suspect in the diagnosis of infection in PGA. OK, so it doesn't dictate if you are going to do a revision or no. It doesn't give you any clue for the decision for revision of painfully without infections not mentioned as like clear indication whether the joint is infected or not. Even in prosthetic joint infection, it is mainly high index of suspicion with the basic serological markers and joined aspiration, which is the key in the diagnosis.
And now there is more trend towards getting a histopathologic diagnosis by making either a small incision and taking the sign over or by an arthroscopic biopsy, or if all the other criterias are inconclusive. OK would you say that? I will discuss a case in the MDT for a replacement. I hate to get that. Can you repeat the question?
OK, so in just a case of you are going to do a revision knee replacement or you should say like, I will discuss that with the MDT or yeah, of course, in the example, in the future, definitely any complex scenario in the exam revision is not a standard problem that we face, even in arthroplasty surgeon. We definitely discuss it among our colleagues, so we should definitely say that we will be discussing the case with the senior plastic surgeon like, you know, to get, get, get, get the opinion.
Definitely, you should consider. Yeah I think that is also the last question. Thank you very much for fantastic traject. Thank you very much. Thanks Thanks. Thanks, everyone for listening. Thank you very much, and have a good rest. A busy day tomorrow. I hope we'll give thanks.
Thanks thanks, David. All the best. Thank you. Once again.
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