Open, combat-related loss, or disruption of the knee extensor mechanism: Treatment strategies, classification, and outcomes

Objective: To report the outcomes of repair or reconstruction of high-energy, open knee extensor disruption or loss due to combatrelated injuries.

Design: Retrospective review.

Setting: Tertiary (Level/Role V) Military Treatment Facility.

Patients: Fourteen consecutive patients who sustained 17 complex, open knee extensor mechanism injuries during combat operations between March 2003 and May 2012.

Intervention: Primary repair or staged allograft extensor reconstruction after serial debridement and closure or soft tissue coverage.

Main Outcome Measures: Final knee range of motion, extensor lag, ambulatory ability and assist devices, and complications requiring reoperation or salvage procedure.

Results: The open knee extensor mechanism injuries required a mean of 11 procedures per injury. At a mean final follow-up of 39 months (range, 12-89 months), all patients achieved regular community ambulation, with 36% requiring assist devices due to con-comitant or bilateral injuries. Average knee flexion was 92 degrees, and 35% of extremities had an extensor lag >10 degrees; however, 6 of 9 extremities with allograft reconstructions had extensor lags of <10 degrees, and 5 had no extensor lag. The presence of a major periarticular or patellar fracture was significantly associated with the knee requiring a subsequent extensor mechanism allograft reconstruction procedure. One extremity each underwent knee arthrodesis or transfemoral amputation due to severe infection.

Conclusions: High-energy, open knee extensor mechanism injuries are severe and rarely occur in isolation, but limb salvage is generally successful after multiple procedures. Patients who required staged allograft reconstruction, despite high complication rates, generally had favorable results.