Blinded, Prospective, Randomized Clinical Trial Comparing Volar, Dorsal, and Custom Thermoplastic Splinting in Treatment of Acute Mallet Finger

Purpose To compare volar, dorsal, and custom splinting techniques in acute Doyle I mallet finger injuries. Methods We developed a radiographic lag measurement using the contralateral normal digit as an internal control for establishing the approximate preinjury maximal extension of the mallet finger. The difference in maximal distal interphalangeal joint extension between the injured and contralateral normal digit was defined as the radiographic lag difference. We randomized 87 subjects meeting the inclusion criteria to one of 3 splint types: volar padded aluminum splint, dorsal padded aluminum splint, and custom thermoplastic. Splints were continued for 6 weeks full-time. A total of 77 subjects were available for measurement of the primary outcome measure: radiographic lag difference at week 12. Secondary outcome measures were recorded at weeks 7 and 24. Results No lag difference was demonstrated at week 12 (p = .12), although a trend suggesting superiority (closest value to 0 difference) of the custom thermoplastic splint was observed. The mean radiographic lag differences were −16.2° (95% confidence interval [CI], −21.3° to −11.0°) for the dorsal padded aluminum splint, −13.6° (95% CI, −18.0° to −9.2°) for the volar padded aluminum splint, and −9.0° (95% CI, −14.5° to 3.4°) for the custom thermoplastic splint. Secondary between-group analyses showed no differences for radiographic or clinical lag, Michigan Hand Outcome Questionnaire scores, or complications. Secondary analyses of the whole cohort suggested that clinical measurement overestimates true lag, increased lag occurs after discontinuation of splinting, and clinically measured improvement in lag is noted at week 24. Conclusions No lag difference was demonstrated between custom thermoplastic, dorsal padded aluminum splint, and volar padded aluminum splinting for Doyle I acute mallet fingers. Clinical measurement overestimates true lag in mallet injuries. Increased lag occurs after discontinuation of splinting. Increased age and complications correlate with worse radiographic lag. Type of study/level of evidence Therapeutic II.