Association of Trapezium Morphology With Primary Treatment Failure in Acute Traumatic Thumb Carpometacarpal Joint Dislocation.

BACKGROUND

This study aimed to determine whether trapezium morphology, specifically trapezial inclination, is a risk factor for the failure of primary conservative or minimally invasive treatment for acute traumatic thumb carpometacarpal (CMC) joint dislocations in the relatively early period. We hypothesized that an elevated trapezial inclination would be associated with a higher rate of treatment failure.

METHODS

We retrospectively reviewed patients treated for acute thumb CMC joint dislocations between 1976 and 2025 with closed reduction and subsequent immobilization or percutaneous pinning. Patients were classified into "failure" (recurrent dislocation or subsequent symptomatic subluxation) or "non-failure" groups. Trapezial inclination, measured on oblique hand radiographs, was compared between the groups using the Mann-Whitney U test.

RESULTS

Fourteen patients met the inclusion criteria (7 failure, 7 non-failure). While demographics were not significantly different, the failure group demonstrated a significantly higher mean trapezial inclination (19.1° vs 8.7°; P = .0012). This significant difference persisted in a subgroup analysis that excluded associated Gedda type 3 Bennett fracture (P = .0318)

Conclusions

Elevated trapezial inclination may predict the failure of primary conservative or minimally invasive treatment in the relatively early period for acute thumb CMC joint dislocation. Our findings suggest that patients with this steep trapezium may be poor candidates for conservative or minimally invasive management and should be considered for primary definitive surgery.