Total knee arthroplasty (TKA) is the most common and cost effective surgery used to mitigate painful end-stage knee osteoarthritis. Projections suggest that by 2030 over 3.5 million older adults will undergo primary TKA annually in the U.S. It is estimated that a tourniquet is used by 95% of orthopedic surgeons during TKA to create a bloodless field and to ensure proper bone implant cementing. Prior studies by our lab suggest that tourniquet use may be detrimental, potentially leading to ischemia-reperfusion injury and cell swelling acutely following surgery; however, these studies focused on the vastus lateralis muscle. To our knowledge, less is known about how tourniquet use during TKA may impact the tibialis anterior (TA) muscle, which in older adults provides greater postural control support relative to younger individuals. PURPOSE: Determine if tourniquet use during TKA alters pH and oxidative capacity in the tibialis anterior (TA) 2 weeks after surgery. METHODS: Non-invasive in-vivo 31-phosphorous magnetic resonance spectroscopy was used to assess muscle metabolism in both the operative and non-operative TA 2 weeks ±4 days after surgery in two groups: those who had tourniquet (T) during surgery and those who did not (NT). RESULTS: Average resting pH in the NT group operative leg (n=2) was 7.025 and non-operative leg was 7.02. Average resting pH in the T group operative leg (n=3) was 7.01 and non-operative leg was 7.027. Oxidative capacity in the NT group operative leg (n=1) was .0177 and non-operative leg (n=1) was .0303. Oxidative capacity in the T group operative leg (n=2) was .0406 while the non-operative leg (n=1) was .0238. CONCLUSIONS: Our preliminary results suggest that tourniquet use during TKA alters muscle metabolism in the TA, which may be significant because older adults rely on the TA for balance control and ambulation more than younger individuals. Alterations in TA metabolism following TKA surgery using tourniquet may impact recovery of strength and function in this population of older adults. Further analysis is required in order to determine if TKA with tourniquet alters metabolism 2 weeks post-surgery.

Supported by NIH grant: R01AG046401

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