Failure Patterns Leading to Revision After Distal Humerus Fracture Fixation: A Multicenter Study.

BACKGROUND: Distal humerus fractures are associated with substantial complication and revision rates following operative fixation. Although overall complication frequencies are well documented, the specific mechanisms leading to revision surgery and their associated risk factors remain insufficiently characterized.

PURPOSE: To analyze mechanism-specific patterns and determinants of revision surgery after operative treatment of distal humerus fractures, focusing on infectious, mechanical, and functional failure pathways.

METHODS: This multicenter retrospective cohort study included 491 adult patients undergoing revision surgery after distal humerus fracture fixation across 11 specialized centers. The full cohort was used for descriptive characterization of all recorded revision causes, allowing overlapping complication categories. For the primary inferential analysis, 411 patients were included in a three-category outcome variable comprising infectious, mechanical, and functional leading revision pathways. Biological and degenerative complications were retained for descriptive characterization. Univariate and multivariable multinomial logistic regression analyses were performed to identify patient-, injury-, and treatment-related factors associated with specific revision mechanisms, using mechanical complications as the reference category. Time to revision was compared between groups.

RESULTS: Mechanical complications occurred in 177 patients (43.1%), functional complications in 170 (41.4%), and infectious complications in 64 (15.6%). In the complete descriptive cohort (n = 491), functional complications represented the most frequently recorded indication for revision surgery overall. The combined category of implant malposition/secondary implant dislocation accounted for the majority of mechanical failure mechanisms. Open fractures were independently associated with infectious complications (OR 5.88, 95% CI 2.19-15.80; p < 0.001). Revision surgery for functional impairment showed a statistically significant but weak association with younger patient age (OR 0.96 per year, 95% CI 0.94-0.98; p < 0.001), whereas fracture morphology and treatment-related variables were not independently associated with functional revision pathways after adjustment. Median time to revision differed significantly between groups, occurring earliest in infectious complications (3.5 months), followed by mechanical (6.0 months) and functional complications (10.0 months).

CONCLUSIONS: Revision surgery after distal humerus fracture fixation follows distinct mechanism-specific pathways rather than a uniform pattern of failure. Open fractures are strongly associated with infectious complications, whereas younger age showed only a weak association with functional revision pathways. Mechanical complications are predominantly characterized by implant malposition and secondary implant dislocation. These findings support a differentiated approach to postoperative surveillance, patient counselling, and mechanism-specific assessment.