Objective Assessment of Function in a Two-Digit Hand - A Comparison of the Functional Outcome between the Little Finger and the Index Finger as the Ulnar Post.

Background: In mutilated hand reconstruction, the choice between index or little finger as the sole ulnar post to oppose a functional thumb remains controversial. This study objectively compares functional outcomes between these two configurations in basic two-digit hand. Methods: This retrospective study (2013-2020) evaluated 11 patients with a functional two-digit hand. Inclusion criteria included an uninjured thumb and the presence of only one uninjured digit serving as an ulnar post, either little finger (group 1) or index (group 2), characterised by good web space, sensate perception, painlessness and the ability to oppose each other in movement. Assessments included pinch and grip strength measurements, Jebsen-Taylor Hand Function Test (JHFT) and disabilities of arm, shoulder and hand (DASH) score. Non-parametric tests (Mann-Whitney U) compared continuous variables with significance at p < 0.05. Results: Objective testing revealed superior function in group 2 patients (index finger ulnar post) patients versus group 1 patients (JHFT: 1.39 vs. 1.91 minutes; grip: 4 vs. 1.2 kg; pinch: 2.5 vs. 0.4 kg). DASH scores favoured group 2 patients (25.2 vs. 37.4), though not statistically significant (p = 0.144). Conclusions: Our findings challenge traditional ulnar-digit preference, demonstrating the index finger provides significantly better strength and functional outcomes as the ulnar post in basic two-digit hands. These results support prioritising radial-digit reconstruction when the first web space is uncompromised, though individual patient factors and occupational demands should be considered. Level of Evidence: Level III (Therapeutic).