Bilateral disruption of soft tissue extensor mechanism of knee: functional outcome and comparison to unilateral...

Bilateral ruptures of the extensor mechanism are rare.

The purpose of this study was to compare the clinical outcomes of operatively treated unilateral and bilateral knee soft tissue extensor mechanism injuries and to identify risk factors for bilateral disruption.

All patients operatively treated for a knee extensor mechanism injury were entered into a database and prospectively followed. Postoperative protocol was standardized for all patients. Demographic data, baseline characteristics, range of motion, complications, pain, and functional status were assessed. The main patient-reported outcome measures used in this study were the SF-36 Health Survey and the Lysholm Scale.

Patients who sustained bilateral injuries were more likely to have one or more systemic medical conditions. There was no statistical difference between the groups with regard to mechanism of injury or body mass index. The average follow-up was 29 months (range 6-60 months). Patient-reported outcomes, in the form of the SF-36 Health Survey and Lysholm scores, were not significantly different between the two groups at final follow-up. Range of motion and quadriceps strength was also similar between the two cohorts. At latest follow-up, 88% of patients with unilateral injuries and 83% of patients with bilateral disruption were able to return to their pre-injury employment.

Operatively treated bilateral knee extensor mechanism disruptions fare similar to unilateral injuries with regard to ultimate functional outcome. The presence of one of more preexisting medical conditions was identified as a risk factor for bilateral tendinous disruption.