Surgical options for chronic patellar tendon rupture in total knee arthroplasty.

PURPOSE: The purpose of this study was to compare mid-term results of three different reconstructive techniques for chronic patellar tendon disruption after total knee arthroplasty (TKA). Several surgical techniques have been proposed, but to date it is still unclear which is the best solution. The hypothesis was that allografts provide better functional results than autografts in restoring a correct joint function. METHODS: Twenty-one reconstructions were performed in twenty-one patients (three groups of seven patients) with chronic patellar tendon lesion following TKA. Group I underwent reconstruction with an Achilles tendon allograft with a calcaneal block, Group II with an autograft of the quadriceps tendon reinforced by the semitendinosus tendon and Group III with a full extensor mechanism allograft consisting of the tibial tubercle, patellar tendon, patella, and quadriceps tendon. Preoperatively and at each follow-up, the value of the extensor lag and the Knee Score (KS) were recorded. RESULTS: The mean extensor lag decreased from 50° ± 19.4° to 3° ± 1.6°. The KSS improved from 44.7 ± 20.5 to 78.9 ± 13.6 points. The comparison between the groups showed statistically significant differences in the mean postoperative KS between Groups I (average score of 87.7 ± 14.3 points) and II (average score of 70 ± 4.1 points), but not between Groups I and III (average score of 78.9 ± 14.6 points) or between Groups II and III. Differences in the postoperative extensor lag were not significant between the three groups. CONCLUSIONS: The present study may serve surgeons in choosing the best reconstructive strategy for a chronic patellar tendon lesion in TKA. According to the reported results, an Achilles tendon allograft should be considered the gold standard repair. The autograft technique is suitable when the host tissue is competent, particularly when dealing with younger patients or post-infection. A full extensor mechanism allograft may represent a reliable solution when the defect involves the patellar bone or the quadriceps tendon. LEVEL OF EVIDENCE: IV.