Salvage of composite soft tissue and extensor mechanism defects of the knee using free anterolateral thigh flaps with vascularized fascia lata.

Composite soft tissue reconstruction of the knee poses a great challenge. At our institution, we have employed free anterolateral thigh (ALT) flaps with vascularized fascia lata (vFL) for reinforcing or reconstructing extensor mechanism. Herein, we evaluated complications and outcomes in these patients. A retrospective chart review was performed, including individuals who underwent soft tissue free flap reconstruction of the knee from 01/01/2015 to 12/31/2022 at our institution. We analyzed each patient's clinical history, peri-, and postoperative details. Analysis was performed using Excel. Twenty-three patients were included: 82.6% men, median age 62 years, median BMI 31.4 kg/m2. Defects were caused by trauma (30.4%), tumor (30.4%), and infection (39.1%). Notably, 52.2% of patients had previous extensor mechanism injury with attempted repair. Moreover, 52.2% failed a prior soft tissue reconstruction, most commonly a pedicled gastrocnemius flap (91.7%). Course was commonly complicated by deep soft tissue or joint infection (69.2%). Patients underwent free ALT flaps; in 17 patients vFL was used for reinforcement of an attenuated extensor mechanism, and in 6 patients, the vFL component was used to bridge an extensor mechanism gap. One patient experienced full flap loss owing to venous thrombosis. Treatable complications were common: 26.1% major wound complications, 26.1% minor wound complications, and 17.4% donor site complications. Notably, 95.7% of patients were ambulatory following reconstruction with 91.7° of mean active range of knee flexion and extensor lag of 14.4°. Free ALT flap with vFL is an effective limb salvage reconstruction option for large, composite soft tissue defects of the knee and extensor mechanism, often in the setting of chronic infection. Although complications are common, total flap loss is rare, and it can be expected to restore functional range of motion and ambulation.