Functional and radiological outcomes of Bennett's fractures treated by Iselin's technique: About 29 cases with 6-year (2-14) follow-up.

Introduction: The percutaneous pinning method described by Iselin is one of the techniques used for treating Bennett fractures at the base of the thumb metacarpal. There is little published data on the medium- and long-term outcomes of this treatment, with most studies having a mean follow-up of 4 years. The primary objective of this study was to evaluate the functional and radiological outcomes of percutaneous pinning by Iselin's method with a mean follow-up of 6 years. The secondary objective was to look for evidence of radiographic carpometacarpal (CMC) arthritis.

Hypotheses: 1) The functional outcomes are good, and the clinical outcomes are comparable to the contralateral side. 2) While radiographic CMC arthritis may be present in the medium term, it will not interfere with work and recreational activities.

Methods: This was a single-center, multiple-surgeon, retrospective case series. Twenty-nine patients were included who had a mean and median follow-up of 6 years (min 2, max 14). The functional outcomes (satisfaction, pain, subjective strength deficit, DASH), clinical outcomes (tip pinch, key pinch and grip strength compared to contralateral side) and the thumb's mobility (abduction angle, Kapandji score) were determined. Return to work and recreational activities were documented. CMC arthritis was assessed on lateral radiographs of the thumb in neutral position based on the Eaton-Littler classification.

Results: The average patient satisfaction score was 87% (20; 100). The mean pain level was 0.7/10 (0-8) at rest and 2/10 (0-10) during effort. The subjective strength deficit was 12% ± 16. The mean DASH score was 8.8/100 (0-43). The mean tip-pinch strength in the operated thumb was significantly lower than the contralateral side (-9.3% ± 16.5), as was the mean key-pinch (-6.3% ± 16.9). Thumb abduction was significantly reduced relative to the contralateral side (-4.1° ± 5.24) as was the Kapandji score (-0.5 ± 0.81). CMC arthritis was visible on 100% of radiographs (96% were stage 1 or 2).

Discussion: The surgical treatment of Bennett fractures by percutaneous pinning using the Iselin method produces satisfactory functional outcomes in the medium term, although there was a moderate loss of strength and mobility in the thumb.

Level of evidence: IV; retrospective, single-center case series.