Quadriceps strength and volitional activation before and after total knee arthroplasty for XXXX .

@entity1 @entity571 @entity425 @entity158 @entity121 @entity2472
INTRODUCTION: @entity1 with @entity571 ( @entity571 ) of the knee have @entity425 and @entity121 ( @entity121 ). While total knee arthroplasty (TKA) reliably reduces @entity158 and improves function in @entity1 with knee @entity571 , @entity425 persists after surgery. The purpose of this investigation was to assess contributions of @entity121 to @entity425 before and after TKA and to assess the effect of @entity158 on @entity121 . METHODS: Twenty-eight @entity1 with unilateral, end-stage, primary knee @entity571 were tested an average of 10 days before and 26 days after TKA. The mean age at time of operation was 63 years (range 49-82 years). Measurements on the involved and uninvolved knees were performed using the burst-superimposition technique, where supramaximal electrical stimulation is superimposed on a @entity2472 . Knee @entity158 during contraction was measured using a numeric rating scale. RESULTS: The involved quadriceps were significantly weaker than the uninvolved prior to TKA (p<0.05). Quadriceps strength decreased by 60% (p<0.001) and activation decreased 17% (p<0.001) after TKA. Changes in muscle activation accounted for 65% of the variability in the change in quadriceps strength (r(2)=0.65) (p<0.001). Knee @entity158 during muscle contraction accounted for a small, but significant portion of the change in voluntary activation (r(2)=0.22) (p=0.006). DISCUSSION: Exercise regimens that emphasize strong muscle contraction and clinical tools that facilitate muscle activation like biofeedback and neuromuscular electrical stimulation may be necessary to reverse the quadriceps activation failure and weakness in the @entity1 with knee @entity571 that worsens after TKA. The failure of current rehabilitation regimens to directly address activation deficits within the first months after surgery may explain the persistent @entity425 in @entity1 after TKA.
