Simulated distal interphalangeal joint fusion of the index and middle fingers in 0° and 20° of flexion: a comparison of grip strength and dexterity.

Purpose To evaluate dexterity and grip strength after simulated distal interphalangeal (DIP) joint fusion of the index and middle fingers in varying degrees of flexion. Methods Forty-six right-handed subjects performed grip and dexterity testing using the Grooved Pegboard Test in positions of index finger 20° flexion or full extension, middle finger 20° flexion or full extension, and unrestricted index and middle finger DIP joint motion (control). Simulated fusion was performed with the use of custom-molded thermoplastic orthoses. Results Index finger dexterity scores were improved when the DIP joint was splinted in 20° compared with full extension. There was no significant difference in the middle finger dexterity when comparing 20° flexion with full extension. In either position, dexterity scores were higher (lower performance) for the index finger than for the middle finger, showing a greater interference to dexterity with splinting the index finger DIP joint. Mean grip strength was unaffected by middle finger DIP joint position, whereas splinting of the index finger in full extension resulted in reduced grip strength. Conclusions Because positioning the middle finger DIP joint in either extension or 20° of flexion did not significantly affect grip strength or dexterity, other considerations such as appearance can be given priority. For the index finger, however, positioning the DIP joint in 20° of flexion may improve grip strength and dexterity over positioning it in neutral. Type of study/level of evidence Prognostic I.