The Effect of Simulated Total Distal Interphalangeal Joint Stiffness on Grip Strength

Purpose:Production of a functional grip pattern requires the concerted action of numerous structures within the hand. This study quantifies the effect of total distal interphalangeal joint (DIPJ) stiffness to grip strength.Methods:Fifty (25 men, 25 women, 100 hands) individuals with a mean age of 38 years (range: 17-69 years) were recruited. Exclusion criteria included history of previous upper limb injury, neuropathies, or systemic disease. Custom thermoplastic orthoses were used to splint participants’ DIPJ in full extension simulating stiffness. Grip strength before and after splinting was measured using a calibrated Jamar dynamometer. Data were analyzed using paired and independent sample t tests and 2 × 2 repeated-measures analysis of variance with hand dominance and configuration (splinted or unsplinted) as within-subject factors.Results:Restriction of DIPJ flexion led to a 20% decrease in grip strength (P < .001). There was no significant difference in this decrease between dominant and non-dominan...