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Name:
Subvastus Approach Total Knee Replacement
Description:
Subvastus Approach Total Knee Replacement
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https://cadmoremediastorage.blob.core.windows.net/e3390e75-522c-4cdd-b615-21a40aa9ced1/videoscrubberimages/Scrubber_1.jpg
Duration:
T00H12M24S
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https://cadmoreoriginalmedia.blob.core.windows.net/e3390e75-522c-4cdd-b615-21a40aa9ced1/Subvastus Approach Total Knee Replacement.mp4?sv=2019-02-02&sr=c&sig=HnNu%2F5yxZ6kejs4a0ughYuXUIQot9WMRyH%2FQbfo5IWc%3D&st=2024-11-23T09%3A40%3A12Z&se=2024-11-23T11%3A45%3A12Z&sp=r
Upload Date:
2024-05-31T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
ANOOP JHURANI: This video demonstrates the exposure of knee through the subvastus approach and pearls, tips, and tricks of exposure through the subvastus approach. So we are doing the left knee first, which has lateral compartment arthritis and has about 5 degrees of valgus and the right knee has varus, and you can see the lateral view of the left knee, which has lateral compartment arthritis.
ANOOP JHURANI: That's the overall alignment measured from the hip knee to the ankle. And the left knee has lateral compartment arthritis primarily. And we'll expose this knee through the subvastus approach and then do perform the knee replacement through with the Biomet Vanguard knee. And the tips of subvastus approach are to dissect a medial flap and do a blunt dissection with finger of the vastus medialis muscle of the medial intramuscular septum.
ANOOP JHURANI: And the tendon of the vastus medialis comes quite low down on the patella until about the midpoint of the patella, and we should not make the mistake of cutting the tendon. So the trick is to start proximally, dissect the muscle medially of the medial intermuscular septum, keep the fascia intact so that the blood supply to the skin is not disrupted, and come down really on till the midpoint of the patella and then have come down to the tubercle and that's the genicular artery we should always protect, and the best way to dissect the muscle of the vessel and the intermuscular septum is through finger dissection.
ANOOP JHURANI: And once we do that, the vastus medialis surprisingly comes off very nicely along with the patella to the lateral side. Now we approach the femur first and the white side line is marked and the insertion point is at the junction of the patellofemoral and the tibiofemoral articulation, should pause the intermedullary guide always very gradually and not force it to prevent perforation of the anterior femoral shaft, and keep our head hand up so that we are not perforating.
ANOOP JHURANI: Take off 9 millimetres from the distal femoral condyles and always do this cut with the new saw blade and come down and measure it that we have really cut 9. In case there is a fixed flexion deformity, we can take 2 millimetres more. In case there is a recurvatum deformity, we can take 2 millimetres less. So we should always come down and see that we have really cut, especially from the posterior sides, absolutely flush, otherwise our femoral component will not be in perpendicular in the sagittal plane.
ANOOP JHURANI: Next, we mark the inter epicondylar line and feel properly the lateral epicondyle and the medial epicondyle. We can make this small right angle instrument to mark this line again, perpendicular to the whiteside line, and our femur component rotation should be perpendicular to the whiteside line. Next is to use a posterior referencing system, and this system is excellent because we can rotate our femoral component to 1 degree from 0 to 9.
ANOOP JHURANI: So it's not three, five or 7 as in other sets, but this you can rotate three, four, five, six, anything you want being parallel to the intra epicondylar axis. And we have 10 sizes in this particular Vanguard system, which ensures that your posterior offset is correct and your sizing is correct and you are not juggling between what size to take. Mostly it is an accurate size because the sizing is at two millimetres, starting from 55 to 75.
ANOOP JHURANI: And so here we can see that we have sized it and we have rotated it about four degrees, which is parallel to the intra epicondylar axis. In valgus we got to be careful of those, otherwise because of hypoplasia of the lateral femoral condyle, we may put our femoral component in internal rotation. So if we are using this jig we should increase our rotation, so that we are parallel to the fixed bony landmarks.
ANOOP JHURANI: We should always recheck that we are not notching and we are flush with the anterior cortex, so just a finger check and then we take off the anterior condyles and the insole boot should show us that we are in proper external rotation. So the medial condyle cut anteriorly should be half that of lateral side, and that will tell us that we are incorrect external rotation.
ANOOP JHURANI: So you can see that on the lateral side, we have cut almost 2 times the medial side. Once we have done that we go off the posterior condyles. Prevention with two hormones is important to prevent any injury to the collateral ligaments. And once we have cut the posterior condyles we should ensure if we sized it correctly, the posterior medial cut should be roughly 8-9 millimetres. So the distal cut is 9 and the posterior cut is 9, then we have balanced our flexion and extension gap, and when we cut the tibia, the tibia influences both the gaps equally.
ANOOP JHURANI: So the gap balancing is not a problem, especially with femur components which have 10 sizes or more. The gap balancing is never a problem because we are cutting 9 millimeters both of the distal condyles and the posterior condyle, which makes both the gaps equal. And then we cut the tibia, which will affect both the gaps equally. So we are pretty much balanced.
ANOOP JHURANI: The advantage of doing the femur first is that we do not have to dislocate the tibia forcefully anteriorly, especially in fused stiff tough cases or bulky patients, where subluxation of the tibia is the first step, may be a little challenging, or may demand a release medially significantly to sublux the tibia out and cause laxity medially. So now we've cut the box and we've prepared the femur completely, the next step is to lift the femur and see what the flexion gap is, and then see what the extension gap is.
ANOOP JHURANI: Then we cut on the tibia and about 8 to 10 millimeters of the medial epicondyle in this case, because this is a valgus knee. And we can check with the navigation if we want that we should not be more than 1, 1.5 degrees of varus/valgus. The slope in this particular case is 7 degrees because the poly does not have a slope.
ANOOP JHURANI: So this is verifying the tibial resection, and then we take off the tibia and you can see that this is a valgus arthritis as there is raw bone on the lateral side and some residual cartilage on the medial side. And in valgus knee, we should cut a little less bone because usually we cut 8 and put in a 10 poly. The other advantage of this system is that any femur can go on any tibia, so there is virtually a complete modularity between the tibia and the femur, and we don't have to think as to what femur will go on what tibia.
ANOOP JHURANI: Also we can use raw to see that our tibial cut is absolutely perpendicular to the mechanical axis, even after verifying with navigation. So there you can see that the tibia cut is nicely sloped and perpendicular to the mechanical axis. If this if the cut points towards the medial side, then the cut is in valgus.
ANOOP JHURANI: If the cut points towards the lateral side, {INAUDIBLE}, then it is in varus. We have to be perpendicular to the mechanical axis, that's the femur component. It has two lug holes and it's a beautiful component because the medial lateral sizing is very good, especially for Asian patients, which are smaller, and the medial lateral overhang is problem with most of the components.
ANOOP JHURANI: But this component is very nicely sized for our Indian patients. And we can use a PS or a PS+ option. This is a 10 poly and you can see we have got complete extension, we open about 2 to 3 millimeters laterally, about 2 millimeters medially. So we should get complete extension. And the patella comes down very nicely with the subvastus approach and we not actually cut the tendons, so patellar tracking is never truly a problem, and the whole muscle, along with the patellar extensor mechanism, comes very nicely.
ANOOP JHURANI: It's very stable in flexion and it should be stable in mid flexion flexion and should get good movement up to 130 degrees. We mark the external rotation when the femur component meets with the tibia component in extension, and that is where our tibial component should be placed. We take off the osteophytes from the patella, we can resurface if we want. If the cartilage damage is more than 50%, I would definitely resurface the patella.
ANOOP JHURANI: If it is less than 50%, especially on the medial articular facet, I would generally not resurface the patella, but the choice is that we can always resurface. And this system has got a milling system of the patella, which is very nice and two patellas are available, one thin and one standard. That is a tibial perforation and we have rotated our tibial component not to the tibial tuberosity, but to the anterior medial border of the tibia 1, and 2 when it meets the femur component.
ANOOP JHURANI: And that's the correct external rotation in a PS knee. There is the preparation of a modular tibia. The cementing is crucial and we should cement the posterior aspect of the femur condyles very meticulously.
ANOOP JHURANI: So if alignment and balance is good, the third variant of long term success of knee arthroplasty is cementing. And we should really pressurize this cement both on the anterior posterior condyles, the distal surface, and the chamfer cuts very nicely into the lug holes as well. There goes the PS Vanguard femur component. It's got an open box and we had to take out the cement from the box.
ANOOP JHURANI: Always go from posterior to anterior to prevent the femur component going into flexion. And that's the tibial cementing again pressurizing on both the surfaces into the keel as well, and on the surface of the tibia. {INAUDIBLE} gently, ensure that it's solidly sitting and pressurize in extension and hold it still so that the cement sets and there is no movement of the components while the cement is setting.
ANOOP JHURANI: So the advantage of subvastus approach truly is that we are not cutting the tendon {INAUDIBLE} It has shown to enhance patellar tracking, virtually eliminate release of any lateral release, and...
Segment:0 .
ANOOP JHURANI: This video demonstrates the exposure of knee through the subvastus approach and pearls, tips, and tricks of exposure through the subvastus approach. So we are doing the left knee first, which has lateral compartment arthritis and has about 5 degrees of valgus and the right knee has varus, and you can see the lateral view of the left knee, which has lateral compartment arthritis.
ANOOP JHURANI: That's the overall alignment measured from the hip knee to the ankle. And the left knee has lateral compartment arthritis primarily. And we'll expose this knee through the subvastus approach and then do perform the knee replacement through with the Biomet Vanguard knee. And the tips of subvastus approach are to dissect a medial flap and do a blunt dissection with finger of the vastus medialis muscle of the medial intramuscular septum.
ANOOP JHURANI: And the tendon of the vastus medialis comes quite low down on the patella until about the midpoint of the patella, and we should not make the mistake of cutting the tendon. So the trick is to start proximally, dissect the muscle medially of the medial intermuscular septum, keep the fascia intact so that the blood supply to the skin is not disrupted, and come down really on till the midpoint of the patella and then have come down to the tubercle and that's the genicular artery we should always protect, and the best way to dissect the muscle of the vessel and the intermuscular septum is through finger dissection.
ANOOP JHURANI: And once we do that, the vastus medialis surprisingly comes off very nicely along with the patella to the lateral side. Now we approach the femur first and the white side line is marked and the insertion point is at the junction of the patellofemoral and the tibiofemoral articulation, should pause the intermedullary guide always very gradually and not force it to prevent perforation of the anterior femoral shaft, and keep our head hand up so that we are not perforating.
ANOOP JHURANI: Take off 9 millimetres from the distal femoral condyles and always do this cut with the new saw blade and come down and measure it that we have really cut 9. In case there is a fixed flexion deformity, we can take 2 millimetres more. In case there is a recurvatum deformity, we can take 2 millimetres less. So we should always come down and see that we have really cut, especially from the posterior sides, absolutely flush, otherwise our femoral component will not be in perpendicular in the sagittal plane.
ANOOP JHURANI: Next, we mark the inter epicondylar line and feel properly the lateral epicondyle and the medial epicondyle. We can make this small right angle instrument to mark this line again, perpendicular to the whiteside line, and our femur component rotation should be perpendicular to the whiteside line. Next is to use a posterior referencing system, and this system is excellent because we can rotate our femoral component to 1 degree from 0 to 9.
ANOOP JHURANI: So it's not three, five or 7 as in other sets, but this you can rotate three, four, five, six, anything you want being parallel to the intra epicondylar axis. And we have 10 sizes in this particular Vanguard system, which ensures that your posterior offset is correct and your sizing is correct and you are not juggling between what size to take. Mostly it is an accurate size because the sizing is at two millimetres, starting from 55 to 75.
ANOOP JHURANI: And so here we can see that we have sized it and we have rotated it about four degrees, which is parallel to the intra epicondylar axis. In valgus we got to be careful of those, otherwise because of hypoplasia of the lateral femoral condyle, we may put our femoral component in internal rotation. So if we are using this jig we should increase our rotation, so that we are parallel to the fixed bony landmarks.
ANOOP JHURANI: We should always recheck that we are not notching and we are flush with the anterior cortex, so just a finger check and then we take off the anterior condyles and the insole boot should show us that we are in proper external rotation. So the medial condyle cut anteriorly should be half that of lateral side, and that will tell us that we are incorrect external rotation.
ANOOP JHURANI: So you can see that on the lateral side, we have cut almost 2 times the medial side. Once we have done that we go off the posterior condyles. Prevention with two hormones is important to prevent any injury to the collateral ligaments. And once we have cut the posterior condyles we should ensure if we sized it correctly, the posterior medial cut should be roughly 8-9 millimetres. So the distal cut is 9 and the posterior cut is 9, then we have balanced our flexion and extension gap, and when we cut the tibia, the tibia influences both the gaps equally.
ANOOP JHURANI: So the gap balancing is not a problem, especially with femur components which have 10 sizes or more. The gap balancing is never a problem because we are cutting 9 millimeters both of the distal condyles and the posterior condyle, which makes both the gaps equal. And then we cut the tibia, which will affect both the gaps equally. So we are pretty much balanced.
ANOOP JHURANI: The advantage of doing the femur first is that we do not have to dislocate the tibia forcefully anteriorly, especially in fused stiff tough cases or bulky patients, where subluxation of the tibia is the first step, may be a little challenging, or may demand a release medially significantly to sublux the tibia out and cause laxity medially. So now we've cut the box and we've prepared the femur completely, the next step is to lift the femur and see what the flexion gap is, and then see what the extension gap is.
ANOOP JHURANI: Then we cut on the tibia and about 8 to 10 millimeters of the medial epicondyle in this case, because this is a valgus knee. And we can check with the navigation if we want that we should not be more than 1, 1.5 degrees of varus/valgus. The slope in this particular case is 7 degrees because the poly does not have a slope.
ANOOP JHURANI: So this is verifying the tibial resection, and then we take off the tibia and you can see that this is a valgus arthritis as there is raw bone on the lateral side and some residual cartilage on the medial side. And in valgus knee, we should cut a little less bone because usually we cut 8 and put in a 10 poly. The other advantage of this system is that any femur can go on any tibia, so there is virtually a complete modularity between the tibia and the femur, and we don't have to think as to what femur will go on what tibia.
ANOOP JHURANI: Also we can use raw to see that our tibial cut is absolutely perpendicular to the mechanical axis, even after verifying with navigation. So there you can see that the tibia cut is nicely sloped and perpendicular to the mechanical axis. If this if the cut points towards the medial side, then the cut is in valgus.
ANOOP JHURANI: If the cut points towards the lateral side, {INAUDIBLE}, then it is in varus. We have to be perpendicular to the mechanical axis, that's the femur component. It has two lug holes and it's a beautiful component because the medial lateral sizing is very good, especially for Asian patients, which are smaller, and the medial lateral overhang is problem with most of the components.
ANOOP JHURANI: But this component is very nicely sized for our Indian patients. And we can use a PS or a PS+ option. This is a 10 poly and you can see we have got complete extension, we open about 2 to 3 millimeters laterally, about 2 millimeters medially. So we should get complete extension. And the patella comes down very nicely with the subvastus approach and we not actually cut the tendons, so patellar tracking is never truly a problem, and the whole muscle, along with the patellar extensor mechanism, comes very nicely.
ANOOP JHURANI: It's very stable in flexion and it should be stable in mid flexion flexion and should get good movement up to 130 degrees. We mark the external rotation when the femur component meets with the tibia component in extension, and that is where our tibial component should be placed. We take off the osteophytes from the patella, we can resurface if we want. If the cartilage damage is more than 50%, I would definitely resurface the patella.
ANOOP JHURANI: If it is less than 50%, especially on the medial articular facet, I would generally not resurface the patella, but the choice is that we can always resurface. And this system has got a milling system of the patella, which is very nice and two patellas are available, one thin and one standard. That is a tibial perforation and we have rotated our tibial component not to the tibial tuberosity, but to the anterior medial border of the tibia 1, and 2 when it meets the femur component.
ANOOP JHURANI: And that's the correct external rotation in a PS knee. There is the preparation of a modular tibia. The cementing is crucial and we should cement the posterior aspect of the femur condyles very meticulously.
ANOOP JHURANI: So if alignment and balance is good, the third variant of long term success of knee arthroplasty is cementing. And we should really pressurize this cement both on the anterior posterior condyles, the distal surface, and the chamfer cuts very nicely into the lug holes as well. There goes the PS Vanguard femur component. It's got an open box and we had to take out the cement from the box.
ANOOP JHURANI: Always go from posterior to anterior to prevent the femur component going into flexion. And that's the tibial cementing again pressurizing on both the surfaces into the keel as well, and on the surface of the tibia. {INAUDIBLE} gently, ensure that it's solidly sitting and pressurize in extension and hold it still so that the cement sets and there is no movement of the components while the cement is setting.
ANOOP JHURANI: So the advantage of subvastus approach truly is that we are not cutting the tendon {INAUDIBLE} It has shown to enhance patellar tracking, virtually eliminate release of any lateral release, and...
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