Concomitant capitellum fractures in patients with radial head fractures: incidence, risk factors and primary outcomes.

purposeThis study aimed to determine the incidence of combined radial head and capitellum fractures (CRHCF), identify risk factors for concomitant capitellum fractures (CCF) in patients with radial head fractures (RHF), and evaluate the primary outcomes of CRHCF.

methodsPatients with isolated RHF or CRHCF were retrospectively studied using our institutional fracture registry data from January 2013 to December 2022. Demographic data, injury mechanisms, fracture features, clinical outcomes, and postoperative complications were collected. Patients with isolated RHF were stratified into Group 1, while those with CRHCF were categorized into Group 2. Univariate and multivariate analyses were performed to identify risk factors for CCF incidence. Elbow range of motion (ROM) was evaluated across different classification subgroups, and functional outcomes were quantified using the Disabilities of the Arm, Shoulder and Hand (DASH) score and the Mayo Elbow Performance Index (MEPI).

resultsA total of 161 patients with RHF were enrolled, with a mean age of 45.2 ± 13.9 years. Of these, 28 cases (17.4%) were diagnosed as CRHCF. According to the Bryan-Morrey classification, CRHCF cases included 11 type I (46.4% of CRHCF), 14 type II (39.3% of CRHCF), and 3 type III (14.3% of CRHCF). Multivariate analysis identified five independent risk factors for CCF in RHF patients: ≥2 RHF fragments (2 fragments: adjusted odds ratio [aOR] = 2.39, P = 0.049; ≥3 fragments: aOR = 3.75, P = 0.007), high injury energy (aOR = 3.78, P = 0.008), elbow valgus deformity (≥ 15°, aOR = 3.12, P = 0.023), narrowed radial-capitellar joint space (aOR = 2.81, P = 0.036), and preoperative visual analog scale (VAS) score ≥ 7 points (aOR = 3.59, P = 0.008). Additionally, the severity of RHF (per Hm-Mason classification) was significantly higher in Group 2 than in Group 1 (p = 0.027). All patients completed follow-up, with a mean duration of 18.2 ± 6.5 months. During follow-up, all fractures achieved union without significant complications. Correlation analysis showed that the Bryan-Morrey classification was associated with functional scores: patients with type II, I, and III CRHCF exhibited sequentially poorer functional outcomes, characterized by higher DASH scores and lower MEPI scores (p < 0.0001).

conclusionsThis study shows CRHCF incidence is higher than clinically assumed, with five independent risk factors identified. Bryan-Morrey type II fractures had the most favorable DASH and MEPS scores. Additional case series are needed to validate these findings.