Predicting Patellar Failure After Total Knee Arthroplasty

Abstract

Level IV, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Ten-year Results of an Inset Biconvex Patella Prosthesis in Primary Knee Arthroplasty

“…With knee flexion we suppose a superiorly directed shear force is applied to the component, which can lead to failure of the implant, although there are no biomechanical studies to confirm or refute this. Although we could not correlate other factors to failure of this implant, a recent study of an onlay all-polyethylene patella component involving large numbers (8531) reported lateral release, BMI greater than 30 kg/m 2 , flexion greater than 100°, preoperative valgus alignment of 10°or greater, medial patella component position, and a tibial component greater than 12 mm were associated with aseptic loosening of the patella component [30]. The rate of fracture in our study was low, and most fractures occurred in relation to osteonecrosis.…”

The Anatomical Graduated Component total knee replacement

“…The relationship of time on the development of these lines gave (Table VI). 22 The survival of the prosthesis at 20 years with the endpoint of aseptic loosening of the tibial, femoral or patellar components was 94.58% (95% CI 0.9073 to 0.9686) (Table VII) and at the same interval with the addition of infection as a cause of failure, was 93.11% (95% CI 0.8935 to 0.9558) (Table VIII). Of the 13 failures associated with an infection, nine were successfully treated with a two-stage revision procedure, but two required a repeat two-stage exchange with delayed reimplantation.…”

“…The effect of these modifications during the course of the study remains unknown, although the reduction in the requirement for a lateral release in the presence of some external rotation of the femoral component has been recognised. 22 The use of a cruciate-retaining nonmodular cemented AGC TKR in the absence of a preoperative valgus deformity, implanted over the age of 70 years, gives a survival rate over 20 years of 98%.…”

The effect of femoral component rotation on the extensor retinaculum of the knee

“…This may be related to lateral retinacular release after TKR, which may have an incidence as high as 50% 33 and has been related to loosening of the patellar component. 34 This effect was larger in the MPFL than in the deep transverse fibers of the lateral retinaculum, contrary to popular understanding. These length changes may be related to the tensile behavior of the retinacula: the MPFL stretches 26 AE 7 mm to failure, 24 the deep transverse fibers of the lateral retinaculum 11 AE 4 mm.…”