Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis

Introduction: Patients with osteoarthritis (OA) of the knee have quadriceps weakness and arthrogenous muscle inhibition (AMI). While total knee arthroplasty (TKA) reliably reduces pain and improves function in patients with knee OA, quadriceps weakness persists after surgery. The purpose of this investigation was to assess contributions of AMI to quadriceps weakness before and after TKA and to assess the effect of pain on AMI. Methods: Twenty-eight patients with unilateral, end-stage, primary knee OA 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 voluntary contraction. Knee pain during contraction was measured using a numeric rating scale. Results: The involved quadriceps were significantly weaker than the uninvolved prior to TKA ( p