(1) To measure objectively the subjective improvement in joint stiffness following intra-articular injections of corticosteroids, and (2) to record changes in joint stiffness in the first 24 hours after injection to look for changes in the physical properties of the joint that would be consistent with a crystal synovitis.
The study population consisted of 15 patients having 17 metacarpophalangeal joints injected as part of their routine care. Measurements were taken before injection, at 24 hours, and after one week. Outcome variables included articular stiffness, strength, joint range of movement, and subjective scores.
At 24 hours, mean values for stiffness had increased (mean slope from 0.0085 to 0.0123 Nm degree-1; curve area from 0.1003 to 0.1555 units), but the increase was not significant. After one week a significant decrease in "elastic stiffness" had occurred (mean slope from 0.0085 to 0.0065 Nm degree-1; P = 0.025). Significant changes in grip, range of movement, and subjective scores were also found after one week (maximum grip from 75.3 to 85.9 N; flexion/extension range from 87.0 to 102.4 degrees; pain visual analogue scale (VAS) from 50 mm to 12 mm; stiffness VAS from 65 mm to 27 mm).
An early increase in joint stiffness in some patients following intra-articular corticosteroids is consistent with a transient synovitis. Symptoms of joint stiffness generally correlate with mechanical measures which provide a useful objective index of acute changes in joint pathophysiology.