Long-Term Outcomes of Pedicled Gastrocnemius Flaps in Total Knee Arthroplasty

Background: Deficient soft tissue following total knee arthroplasty (TKA) can jeopardize outcome. The gastrocnemius flap is an important means of providing coverage of a knee with deficient soft tissue. There is a paucity of long-term studies on the use of the gastrocnemi us flap in the setting of TKA. The purpose of this study was to review the outcomes after the use of pedicled gastrocnemius flaps for coverage of a soft-tissue defect at the time of TKA. Methods: Eighty-three patients in whom a gastrocnemius flap had been used to cover the site of a primary (n = 18) or revision (n = 65) TKA over a 25-year period were identified. There were 48 women (58%) and 35 men (42%) with a mean age and body mass index (BMI) of 65 years and 32.6 kg/m(2). The mean wound size was 49 cm(2), and the wound was most commonly located over the anterior aspect of the knee/patellar tendon (n = 33). Patients were followed to the time of implant or flap revision, amputation, or death or for a minimum of 2 years (mean, 8 years). Clinical outcomes were assessed using the Knee Society Score (KSS) for pain and the KSS for function. The Kaplan-Meier method was used to assess revision and amputation-free survival. Risk factors for amputation and revision were identified with Cox regression. Results: The 10-year revision and amputation-free survival rates following gastrocnemius flap coverage were 68% and 79%, respectively. The risk of implant failure was increased by morbid obesity (BMI of 40 kg/m(2)) (hazard ratio [HR] = 2.82, 95% confidence interval [CI] =1.09 to 7.32, p = 0.03) and >= 5 prior surgical procedures on the knee (HR = 2.68, 95% CI = 1.04 to 6.88, p = 0.04). The risk of amputation was increased in patients with >= 5 prior surgical procedures (HR = 10.76, 95% CI = 2.38 to 48.58, p = 0.002), an age of 65 years (HR = 4.94, 95% CI = 1.10 to 22.09, p = 0.03), and a wound size of 50 cm(2) (HR = 3.29, 95% CI = 1.14 to 9.53, p = 0.02). Preoperatively the mean KSSs for pain and function were 46 and 28, and these scores significantly (p < 0.05) improved to 78 and 43, respectively, at the time of follow-up. Conclusions: The gastrocnemius flap reliably provides coverage of components used in complex knee reconstruction. A history of multiple surgical procedures on the knee and larger soft-tissue defects increase the risk of revision TKA and of amputation.