OBJECTIVE FUNCTION, LEAN MASS, AND ASSOCIATED GENETIC ADAPTATIONS OF THE OPERATED LEG FOLLOWING TOTAL HIP ARTHROPLASTY

Abstract

Purpose: To characterize muscle recovery following total hip arthroplasty (THA) combining genetic adaptations in the affected leg with objective function and body composition assessment. Methods: Preoperatively and at six weeks postoperatively, objective function was assessed by: maximal voluntary contraction of the operated leg quadriceps (MVCOLQ) in Newtons (N), 30[Formula: see text]s chair sit-to-stand (ST), and six-minute walk test (6MWT), with lean mass of the operated leg estimated by dual energy X-ray absorptiometry (DEXA). Genetic adaptations were assessed from vastus lateralis (VL) biopsies by quantitative polymerase chain reaction (qPCR) analysis of markers of hypertrophy (FOS, calpain2 (CAPN2)), atrophy (20[Formula: see text]s proteasome alpha subunit 7 (PSMA7), cathepsin L2 (CTSL2), inflammation (Tumour necrosis factor alpha (TNF-[Formula: see text]), Interleukin-6 (IL-6)) and lipid metabolism (lipoprotein lipase, LPL and peroxisome proliferated activated receptor gamma (PPARAG). Results: 14 patients were recruited. At six weeks, no significant differences, relative to preoperative values, were noted in either objective function or leg lean mass. Markers for hypertrophy were increased (FOS [Formula: see text]1463%, [Formula: see text]), with atrophy (PSMA7 [Formula: see text]44.8%, [Formula: see text]; CTSL2 [Formula: see text]42.5%, [Formula: see text]), inflammation (TNF [Formula: see text]29.6%, [Formula: see text]) and lipid metabolism markers showing a decreasing trend (LPL [Formula: see text]42.45%, [Formula: see text]). Conclusion: The initial post-THA intramuscular environment appears supportive of anabolism. However, this is not reflected in objective function or lean mass measures at six weeks, suggesting longer duration may be required for physiological adaptation to occur.