Effects of total knee arthroplasty on skeletal muscle morphology and gene expression 2 hours after surgery

Abstract

Osteoarthritis (OA) is the leading cause of hospitalization for older adults and total knee arthroplasty (TKA) is one of the most effective surgical remediations of long standing OA. During TKA, a tourniquet is used to maintain a clear operating field and reduce intra‐operative blood flow. As a result, ischemia‐reperfusion (IR) occurs after tourniquet pressure is released, which may negatively impact muscle metabolism. Our prior reports on the acute effects of IR during TKA suggest decreased protein synthesis, increased protein degradation and activation of the endoplasmic reticulum stress response in skeletal muscle. The purpose of this experiment was to determine if skeletal muscle morphology and skeletal muscle gene expression were altered two hours after TKA. Muscle biopsies were obtained immediately before tourniquet was applied, at maximal ischemia, and two hours post‐surgery (reperfusion). There were 12 subjects (n= 8 female, 4 male; age = 68±5.8) and tourniquet time was 43±10 minutes and post‐surgery biopsy time was 138±32 minutes. Histological analysis of skeletal muscle cross sections was performed to examine cross sectional area (CSA) in all fiber types. There was a 20% increase in Type I fiber CSA, 18% in IIa and 22% in IIx 2 hours post‐surgery (p<0.05). These preliminary results suggest that IR during TKA induces changes in muscle morphology and gene expression that persist two hours post‐surgery. Clinically, these data may support our hypothesis that anoxia occurring during tourniquet application followed by reperfusion may negatively impact muscle cell metabolism and potentially contribute to muscle atrophy and reduced functional mobility in these older adults