Effect of knee aspiration and intra-articular corticosteroid injection on gait biomechanics, strength, and patient-reported outcomes in patients with knee osteoarthritis

Abstract

Purpose: Synovial inflammation is associated with pain and disease progression in knee OA and may adversely affect joint biomechanics. The presence of knee inflammation is associated with quadriceps avoidance gait (decreased external knee flexion moment) and decreased quadriceps and hamstring strength. The effect of decreasing knee inflammation on gait biomechanics and strength is unknown. Here, we investigate the effects of inflammation on gait biomechanics in patients with knee OA and inflammation on ultrasound (US), testing the effects of knee aspiration and intra-articular corticosteroid injection on gait, strength, and clinical outcomes. Methods: Forty-five patients with knee OA, synovitis and effusion underwent US, gait biomechanics and strength assessments, and completed the Knee Injury and Osteoarthritis Outcome Score (KOOS), before and 3 weeks after receiving a knee aspiration and 40 mg triamcinolone injection under US guidance (Table 1). Ultrasound assessments were performed by a Canadian Rheumatology Ultrasound Society (CRUS) trained examiner using a 12 Hz linear probe. The suprapatellar recess was scanned in the long axis view medially, laterally and in the midline with the knee flexed to 30o. All US exams were graded using previously validated OMERACT grading criteria for synovitis, synovial hyperplasia, effusion, and power Doppler (6-point scale). Three-dimensional quantitative gait analysis was completed using a 12-camera motion capture system and floor mounted force plate and used to calculate knee angles and moments during walking. Strength testing was completed using an isokinetic dynamometer. Patients completed three maximal knee extension and flexion trials at 90 degrees per second. US, gait and strength tests were completed by the same examiner. Paired t-tests were used to assess mean differences in gait, strength and KOOS scores. Results: There was a significant (p < 0.05) increase in external knee flexion moment [mean change (95%CI)]: 0.32 %BW*ht (0.07, 0.57), peak quadriceps strength [5.95 Nm (0.99, 10.91)], and peak hamstring strength [4.03 Nm (0.56, 7.51)] 3 weeks after injection. There were significant (p < 0.05) improvements in US composite scores [-0.86 (-1.30, -0.42)], and KOOS Subscales for Symptoms [6.16 (1.63, 10.69)], Pain [6.43 (1.17, 11.69)], Function in Daily Living [5.61 (0.80, 10.42)] and Function in Sport and Recreation [9.37 (0.56, 18.18)]. There were no other significant changes in gait (Table 2). Conclusions: Patients undergoing aspiration and injection for knee synovitis and effusion experience increased knee flexion moments during walking and increased maximal quadriceps and hamstring strength. These results suggest a link between inflammation and joint biomechanics in patients with knee OA; interventions that induce changes in knee inflammation detectable by US can improve knee biomechanics during walking.View Large Image Figure ViewerDownload Hi-res image Download (PPT)