Metal backed patellar component failure is a new complication of TKR and will be seen in increasing numbers. A type of failure was a separation of the polyethyene from metal backing and this dissociation is followed by wearing of the metal
backing
against the femoral component.
From February 1991 to June 1994, the revision was done in 18 knees in 15 patients(2 males, 13 females) who had metal backed patellar component at Kyung Hee University Hospital. The authors reviewed clinical and radiological findings. The initial
diagnosis was OA in 13 cases, and RA in 5 cases. The average body weight was 66.7kg (54kg to 84kg). The average age was 62 years (41 years to 74 years). The initial prosthesis of TKR included PCA in 8 cases, MGI in 5 cases, PFC in 2 cases,
Microloc
in 2
cases, and TC IV in 1 cases. In 15 cases, cemented TKR was done. All patients had swelling and pain. Six cases had the click sound and the dislocation of patella was found in 3 cases. Lateral tilting of patella(more than 160 congruence angle) in
skyline
view was observed in 6 cases. The femorotibial angle before the revision was average valgus 3.80(varus 150-valgus 150), and range of motion was average 1060(800-1350)
The averge time from initial TKR to the revision was revised in one tibial insert and patellar components were revised in three cases. All three components were revised in remaining cases. Lateral releases were performed in 2 cases. The average
duration
of follow-up score was 88. We concluded that failure was failure was associated with metal backing, surgical technique, patient activity.
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