For the past 5 years various implant manufactures and surgeons were flogging high flexion as the next best thing in TKR. The only proven study to date suggests that highflexion ie more 135 degrees is acheivable in patients who has high preop flexion. The implants at best protect the patient who get high flexion by increasing the contact area. Looking at the video above it is clear that the contact surface decreases as the flexion increases to the extent it could cause serious wear problems in time. Patellofemoral pressures are another cause for concern. If the patient consistently squat, one could possibly predict wear and earlier revision.
Different manufactures use different methods to achieve this. Some increase the posterior condyle width( meaning remove more posterior bone which could be a problem in revision).Some change the poly curvature to achieve this. Few make the femoral box trapezoidal meaning wider box posteriorly to allow for more rotation in flexion to achieve this
Surgically one's options include
removal of posterior femoral and tibial osteophytes
maintaining the femoral offset with the replaced implant
Fractional lengthening of quads if quads contracture exists
increasing the flexion gap by 2 mm- potentially dangerous - could cause flexion instabilty
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