102. RESTORATION OF PATELLAR BONE STOCK DURING PROSTHETIC KNEE SURGERY

Abstract

Purpose of the study: Insufficient patellar bone can raise problems for revision total knee arthroplasty and for certain cases of lateral patellofemoral degeneration. Several options are proposed: non-resurfacing, resurfacing on an asymmetrical bone cut, patellar thinning possibly leading to fracture, or patellar bone graft to obtain a regular thick bone.

Material and methods: We report a series of 26 patellar reconstructions among 19 primary osteoarthritis cases with lateral patellofemoral degeneration and five revisions. The patellar reconstruction involved the entire patellar surface in five cases and the lateral facet in 19. For only two cases, a bank graft was used. For the others, the graft was shaped from the tibial resection. Stabilisation used screw fixation in only one case. For the others, two cemented patellar anchor buttons were used to stabilise the graft. All patients were reviewed clinically and radiographically at minimum 12 months. Mean follow-up was 54 months (12–95).

Results: Patellar thickness measured during surgery was improved from 18.1 mm (10–25) to 24.5 mm (21–31). The DMS and function scores improved respectively: 45.5 and 40.7 preoperatively and 89.1 and 72.8 at last follow-up. Seven patients were noted C in the Charnley classification at last follow-up and five used one or two crutches for walking. Twelve patients used the hand rail when climbing stairs and seven needed to use their hands to get up from a chair. All grafts except the allograft fused and all patellar buttons remained stable. There was one lucency at last follow-up. Among the 13 patella exhibited a shift preoperatively, only one remained at last follow-up. There were no subluxations at last follow-up (15 preoperatively).

Discussion: This work shows the pertinence of patellar bone grafts to restore bone stock and avoid complications related to resurfacing asymmetry: pain and patellar shift. Fixation by osteosynthesis does not appear to be necessary. Autographs can be used without risk. Allografts still have to prove their efficacy in this indication.