Bilateral sensory effects of unilateral passive accessory mobilization in patients with thumb carpometacarpal osteoarthritis

Objective: The purpose of this study was to investigate changes in pressure sensitivity and pinch grip force in the nonsymptomatic side in patients with thumb carpometacarpal (CMC) osteoarthritis (OA) after the application of a unilateral passive accessory mobilization to the symptomatic hand.

Methods: Secondary analysis of data from a randomized trial with concealed allocation, blinded assessor, and intention-to-treat analysis was performed. Twenty-eight patients (72% females), with unilateral CMC OA and mean age ± SD of 82 ± 6 years, met all the inclusion criteria and agreed to participate. The experimental group received passive accessory mobilization to the CMC OA, and the control group received a nontherapeutic dose of intermittent ultrasound on the affected side for 4 sessions over 2 weeks. Outcome measures including pressure pain thresholds (PPTs) at the lateral epicondyle, thumb CMC joint, tubercle of the scaphoid bone, and the unciform apophysis of the hamate bone and tip and tripod pinch and grip strength of the contralateral/unaffected hand were assessed at baseline as well as 1 and 2 weeks after treatment by an assessor blinded to the group allocation. A repeated measures analysis of variance was used to determine changes in PPT and pinch and grip strength.

Results: No important baseline differences were observed between groups. At the end of the follow-up period, the experimental group exhibited a significant increase in PPT at the CMC joint as compared with the control group 0.6 kg/cm(2) (95% confidence interval, 0.3-1.0; F3.0 = 4.89; P = .009). Although PPT changes in the experimental group were higher than the control group at the remaining sites, differences did not reach statistically significance. Similarly, tip, tripod pinch, and grip strength remained unchanged after the intervention.

Conclusion: This secondary analysis found that the application of a unilateral passive accessory mobilization targeted to the symptomatic CMC joint induced an increase of PPT levels 2 weeks after treatment; however, differences were small and likely of limited clinical value. No contralateral motor effects were observed. Future studies including larger sample sizes are needed to examine the effects of joint mobilization on motor and sensory effects.