Aspiration and Corticosteroid Injections Improve Gait Biomechanics in Knee OA

Effusion aspiration and ultrasound-guided corticosteroid injections improve isokinetic knee strength and sagittal plane moments in patients with knee osteoarthritis (OA) and synovitis, according to study findings published in Arthritis Care & Research (Hoboken).

Researchers in Canada conducted a prospective cohort study using data from patients with symptomatic knee OA and synovitis who were registered in the Western Ontario Registry for Early Osteoarthritis (WOREO) Knee study.

The researchers evaluated inflammatory features of knee OA, specifically joint effusion, and factors determining synovitis score, according to the Outcome Measures in Rheumatology (OMERACT) system, using musculoskeletal ultrasound scans performed by a trained sonographer. Muscle strength and gait were assessed using isokinetic knee extension and flexion strength tests and 3D gait analysis, respectively.

Researchers also collected subjective data on knee pain using the patient-reported Knee Osteoarthritis Outcome Score (KOOS) pain subscales.

Between 3 to 4 weeks after aspiration of knee effusion followed by ultrasound-guided injection of 40 mg of triamcinolone combined with 1% lidocaine, the researchers noted changes in average:

• effusion depth, which decreased by -1.05 mm
• regional synovitis score, which decreased by -0.55 of a total of 9
• walking speed, which increased
• knee extension and flexion strength, which increased by 4.70 Nm and 3.91 Nm, respectively,
• peak external knee flexion moment and peak external knee extension moment, which increased by 3.33 Nm and decreased by -2.99 Nm, respectively, and
• KOOS pain scores, which increased by 5.91 of a total of 100.

Following the procedure, the researchers assessed for changes in gait waveforms using the 3D gait analysis over 100% of the stance compared with preinjection assessments. They observed that peak external knee flexion moment improved during 13% to 38% of stance and peak external knee extension moment improved during 76% to 89% of stance.

Greater synovitis was associated with lower knee extension strength, and lower pain was associated with increased knee extension and flexion strength.

Study limitations included the inability to determine the mechanisms involved in mediating changes in inflammation, strength, and gait; the lack of a comparator group; the lack of blinding during grading of the musculoskeletal ultrasound findings; potential placebo effect of the injections; and the possibility of changes in 1 knee affecting changes in the contralateral knee in patients who received bilateral injections.

“We believe that the present results are important in providing some steps in determining clinically important changes in patients with symptomatic knee OA and synovitis, and suggest that clinical management of knee OA should address biomechanics, inflammation, and pain,” the study authors said.