Leg press power best indicator of function after knee arthroplasty

By Helen Albert, Senior medwireNews Reporter

Leg press power is a better indicator of performance-based and self-reported functionality after total knee arthroplasty (TKA) than knee extension strength, show study findings.

From these results it may be speculated that closed kinetic chain exercises, where the foot is held in one position, are superior to open kinetic chain exercises, where the foot is free to move, for rehabilitation after TKA, say Thomas Bandholm (Copenhagen University Hospital, Hvidovre, Denmark) and colleagues.

However, writing in the Archives of Physical Medicine and Rehabilitation, they emphasize that "this hypothesis awaits future experimental verification."

Bandholm and colleagues recruited 44 individuals with osteoarthritis to take part in their cross-sectional study. All the participants had unilateral TKA a mean of 28 days previously and were aged 65.5 years on average.

Exclusion criteria included musculoskeletal disease other than osteoarthritis, neuromuscular disease, postoperative complications, limited postoperative movement, and excessive postoperative pain. Five patients were excluded, four due to excessive pain and one due to limited postoperative movement, leaving 39 for final analysis.

The participants' self-reported functionality at 28 days, and the 10-meter fast speed walking and 30-second chair stand tests were used to test performance-based functionality. Maximal isometric knee extensions and dynamic leg presses were also completed to measure their body-mass normalized knee extension strength and leg press power for the operated leg.

Both muscle impairment measures were significantly associated with self- and performance-related functionality, but normalized leg press power had the closest and most significant association with post-operative function after TKA.

These findings "may be explained by the fact that performance-based measures of function are typically closed kinetic-chain tasks, such as walking or rising from a chair, and self-reported measures of function typically include questions that address perceived difficulty with performing these same tasks," suggest Bandholm and co-workers.

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