The Effect of Ring Finger Distal Interphalangeal Joint Stiffness on Grip Strength: A Simulated Study in Normal Participants.

Background

Pain of the hand distal interphalangeal joints may result from trauma, osteoarthritis or inflammatory arthritis. When symptoms are not controlled by non-operative means, surgical arthrodesis may be performed, resulting in complete stiffness of the joint and possible weakening of grip strength. This study aims to quantify the effect of a stiff ring finger distal interphalangeal joint on overall grip strength.

Methods

One hundred participants were screened to exclude upper limb pathology. A Jamar dynamometer was used to assess overall hand grip strength. A splint was used to prevent distal interphalangeal joint flexion, thus replicating a fused distal interphalangeal joint. Participants were tested with and without the splint and the results compared. The mean of three grip strength tests was taken.

Results

The participants included 55 females. Mean age was 31 (18-60 years). 76 participants had a reduction in grip strength with splinting, with a significant difference seen (p < 0.05) on Wilcoxon signed rank test. The median reduction in grip strength with splinting was 1.67 kg. However only 10 participants (10%) had a grip strength loss of greater than 6.5 kg, which is the minimal clinically important difference.

Conclusions

This study found a significant loss in overall hand grip strength when the ring finger distal interphalangeal joint was stiffened. However, despite this significant change, only 10 (10%) participants experienced a reduction of greater than 6.5 kg. This is the level of weakness felt to be required to reduce function. Thus our results suggest that 90% of patients with a stiff ring finger distal interphalangeal joint are unlikely to have a clinically identifiable functional reduction in grip strength as a result.