Through-knee amputation is a feasible alternative to above-knee amputation

Abstract

Objective: Through-knee amputation (TKA) is a rare amputation performed in <2% of all major lower extremity amputations in the United States. Despite biomechanical benefits and improved rehabilitation compared with above-knee amputation (AKA), TKA has largely been abandoned by vascular surgeons because of concerns for poor wound healing. The purpose of this study was to evaluate surgical outcomes of TKA.

Methods: The American College of Surgeons National Surgical Quality Improvement Program between 2005 and 2012 was queried using Current Procedural Terminology codes indicating AKA and TKA. Baseline characteristics were reviewed, and logistic regression analysis was performed to identify predictors of 30-day mortality. Propensity score matching was used to balance comorbidities between AKA and TKA. Operative variables and postoperative complications were compared between the groups.

Results: A total of 7469 AKA and 251 TKA patients were identified among 15,932 major lower extremity amputations. Baseline characteristics were examined. White race, chronic obstructive pulmonary disease, dyspnea, emergent operation, steroid use, myocardial infarction, congestive heart failure, high American Society of Anesthesiologists score, old age, preoperative sepsis or septic shock, and dialysis dependency were associated with increased 30-day mortality. Independent lifestyle and smoking (within 1 year) were protective against early death. Baseline comorbidities were not statistically significant after 1:1 propensity score matching. Operative outcomes were similar in both groups (AKA vs TKA). Wound infection (7.2% vs 11.2%; P = .16), dehiscence rate (1.2% vs 0.8%; P = 1.0), and 30-day mortality (9.6% vs 11.2%; P = .66) were comparable. Other outcome parameters, including cardiopulmonary and genitourinary complications, were similar except for a higher likelihood of return to the operating room in the TKA group (27.9% vs 12.4%; P < .01). Postoperative mortality was not associated with TKA (P = .77) or reoperation (P = .42), but it was associated with the patients' physiologic conditions (dyspnea, sepsis, emergent operation, high American Society of Anesthesiologists score, and dependent lifestyle). Predictors of reoperation were contaminated wound (hazard ratio [HR], 2.19; confidence interval [CI], 1.17-3.23; P = .015), sepsis or septic shock (HR, 2.63; CI, 1.37-5.05; P = .004), chronic obstructive pulmonary disease (HR, 2.81; CI, 1.23-6.42; P = .014), and wound infection (HR, 4.91; CI, 2.06-11.70; P < .001). Presence of peripheral vascular disease was not associated with post-TKA reoperation (P = .073).

Conclusions: TKA demonstrated similar postoperative morbidity and mortality compared with AKA. Wound infection and risk of dehiscence were equivalent. TKA did demonstrate a higher rate of reoperation; however, neither TKA nor reoperation predicted postoperative mortality. Patients in stable physiologic condition without active infection can safely undergo elective TKA to maximize rehabilitation potential.