Aims: The purpose of this study was to objectively evaluate isokinetic strength, clinical, and radiographical outcome of 22 patients with bilateral TKA using the same prosthesis with and without patella resurfacing. Methods: Bilateral TKA, one with, one without patella resurfacing was performed in 22 osteoarthritic patients, mean age was 68 years (58 to 79) using the Low-Contact-Stress prosthesis. Minimum Follow-up was one year at time of investigation. Evaluation included clinical investigation, speciþc patella scores, radiographic analysis and isokinetic strength measurement of both knee ßexion and extension at 60 degrees per second (Biodex). Results: There was no signiþcant difference in the clinical scores (mean: 26 out of 30 points), but mean iso-kinetic strength of knee extension was signiþcantly stronger (p< 0.0001) in the non-resurfaced TKA (40.5 Nm) compared with the resurfaced TKA (38,5 Nm). Flexion was also signiþcantly stronger in the patella non-resurfaced group with 22.4 Nm versus 19.5 Nm in the resurfaced group. Mean lateral deviation was significantly (p< 0.001) less optimal in the resurfaced group as was postoperative patello-femoral congruent contact (p< 0.001). However, there was no correlation between lateral patella deviation or congruent contact and iso-kinetic strength. Conclusions: The results of this prospective and randomized study indicate that mean isokinetic strength of both knee ßexion and extension was signiþcantly stronger in the non-resurfaced TKA. This study provides encouraging data for patella non-resurfacing.

Aims Patellectomized knees perform poorly with respect to extensor mechanism function and anterior knee pain. Methods: In the period of 1990 to 1995, nine previously patellectomized patients with a mean age of 55 years (range: 38 to 67) underwent cementless Low-Contact-Stress TKA with autologous reconstruction of a new patella. One patient deceased 5 years post surgery. Mean follow-up was 8.0 years (range: 6 to 12) The autograft was taken in five cases from the iliac crest, in two cases from the posterior femoral condyle and in another two cases from the opposite patella at time of simultaneous bilateral TKA surgery. Evaluation included clinical investigation, specific patella score, radiographic analysis and isokinetic strength measurement at 60 degrees per second (Biodex). Results: Clinical scores had a mean of 27 out of 30 points (range: 19 to 30) and mean isokinetic strength of knee extension reached 71Nm (81%) compared with the opposite site. One patient with bilateral patellectomy and unilateral TKA showed an increase of 50% strength (51Nm versus 77Nm) in the kne with TKA and neo-patella. Radiographs in three planes showed minor signs of neo-patella bone resorption in three cases, but evidence of retrabeculation and bone remodelling in all neo-patellae. Conclusions: Reconstruction of a neo-patella in TKA using autograft provides near to normal isokinetic strength, no evidence of considerable autograft resorption, excellent or good clinical outcome and high patients satisfaction after a mean of 8 years. The study provides encouraging data for reconstructing a new patella in patellectomized knees during TKA.