Do Amputation Characteristics Predict Outcomes Measures and Infections After Osseointegration Surgery?

Abstract

To determine which patient characteristics are associated with patient-reported outcomes (PROs) and infection outcomes after transfemoral Osseointegration (OI) surgery. Single-center retrospective study. Walter Reed National Military Medical Center, Bethesda, MD. Patients who underwent unilateral or bilateral transfemoral OI surgery and completed 2-year follow-up. Baseline patient characteristics (age at primary amputation, time living with limb loss, residual femur length, age at OI surgery, and limb-loss-adjusted body mass index [BMI]) were evaluated as predictors of change in PROs from baseline to 2-year follow-up (Questionnaire for Persons with a Transfemoral Amputation (Q-TFA) domains, patient-reported outcomes measurement information system (PROMIS) domains, and patient-reported prosthesis use) and of infection outcomes (any infection and number of infections), using generalized linear models with Akaike information criteria-guided backward elimination and adjustment for amputation laterality (unilateral vs. bilateral). There were 54 patients included (37 unilateral and 17 bilateral) who completed 2-year follow-up. The unilateral cohort had a mean age of 41.1 years (range, 24-72 years) and was predominantly male (33 men and 4 women), whereas the bilateral cohort had a mean age of 33.6 years (range, 26-41 years) and consisted entirely of male patients. Adjusted BMI best predicted changes in Q-TFA Global (R 2 = 0.06, F(1,48) = 3.8, P = 0.05) and problem scores (R 2 = 0.07, F(1,48) = 4.7, P = 0.03), as well as PROMIS Pain Interference (R 2 = 0.25, F(1,50) = 17.8, P < 0.001) and Pain Behavior scores (R 2 = 0.26, F(1,50) = 18.7, P < 0.001) between baseline and 2-year follow-up. Adjusted BMI also best predicted changes in Q-TFA Prosthetic Use, PROMIS Physical Function, and prosthesis use time. Adjusted BMI was the strongest predictor of the number of infections. Among unilateral and bilateral transfemoral amputees undergoing OI surgery with 2-year follow-up, lower adjusted BMI was associated with improved PROs and fewer infection events. Differences between unilateral and bilateral amputees suggest that amputation laterality may modify postoperative outcomes. Prognostic, Level III. See Instructions for Authors for a complete description of levels of evidence.