Factors associated with pre-clinical disability and recovery of muscle and physical function following total knee arthroplasty
Petrella, John Kenneth
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Physical functional performance reflects the cumulative abilities of multiple physiological systems including joint and muscle function. Aging, inactivity, and disease can slowly degrade peak capacities and abilities of older adults necessary for living independently. In the first study, high functioning individuals (HIGH) were compared to individuals living independently but exhibiting lower levels of physical function (LOW). Group membership was determined by a threshold score of 57 on the Continuous scale Physical Functional Performance Test. Groups were compared on ability to perform tasks with or without difficulty or modification and mobility factors including gait speed, stride length, and steps/day. Our results indicate that older adults with high function had 27% greater gait speed, 18% greater stride length, 47% greater steps/day, and reported one less task requiring modification compared to those with low function. In the second study, individuals with osteoarthritis (OA) scheduled for total knee arthroplasty (TKA) were examined. The purpose of this study was to examine 1) decrements in joint, muscle, and physical function associated with OA, and 2) the time course of three months recovery in joint, muscle, and physical function after TKA. Prior to surgery, individuals with OA had significantly more use-related pain and reduced muscle and physical function compared to controls. TKA reduced use-related pain 83% by 1 month post surgery. From 1 month to 3 months, the surgical limb of TKA patients increased knee range of motion by 13%, quadriceps strength by 16%, muscle quality by 13%, extensor power by 55%, and steps/day by 46% while physical function increased 19% to a level predictive of independent living. Range of motion was a significant predictor of physical function. These results indicate that older adults living independently but with lower levels of function modify more mobility-related tasks and take fewer steps/day. Individuals recovering from TKA surgery can expect significant pain relief in one month followed by improved joint, muscle, and physical function by three months.