Long-term results of extensor mechanism reconstruction using Achilles tendon allograft after total knee arthroplasty

Disruption of the extensor mechanism after total knee arthroplasty (TKA) is an infrequent but devastating complication. Presently, limited data exists regarding the optimal treatment and long-term outcomes.

Patients who underwent reconstruction of their knee extensor mechanism using Achilles tendon allograft following TKA between January 2003 and January 2012 were identified. Sixteen patients with 17 reconstructions (10 patellar tendons, 7 quadriceps tendons) were studied. All patients underwent evaluation at an average of 45.7 months. Ten of the patients were followed to an average of 65.4 months.

After reconstruction, the average extensor lag was 6.6° and average knee flexion was 105.1°. Of the patients with a minimum follow-up of two years and an average follow-up of 65.4 months, the average extensor lag and knee flexion was 8.4° and 107.9°, respectively, with quadriceps strength maintained at an average of 4/5. The quadriceps tendon reconstructions had an average extensor lag and flexion of 2.9° and 103°, respectively. The patellar tendon reconstructions, excluding one re-rupture, had an average extensor lag and flexion of 9.6° and 105.1°, respectively. Four patients died during the follow-up period. All but one of the patients were below the mean for age-matched controls on the SF-36.

Achilles tendon allograft reconstruction is a reliable and durable treatment for patients who sustain not only patellar tendon ruptures, but also quadriceps tendon ruptures following TKA. Despite the success of this technique, the injury and procedure have a profound impact on overall function.