PURPOSE: Hardware irritation is a common complication following ulnar shortening osteotomy (USO) and often requires secondary plate removal. Although plate surface location and distal plate positioning have been proposed as contributing factors, their independent effects remain poorly defined. This study evaluated the influence of plate location and distal plate position on hardware irritation in patients treated with specialized USO plates.
METHODS: We retrospectively reviewed 145 patients who underwent USO with specialized ulnar shortening plates between 2016 and 2025. Plate location was classified as dorsal, ulnar, or palmar. The distance from the ulnar styloid tip to the distal edge of the plate was measured on postoperative radiographs. Multivariable logistic regression was used to identify independent predictors of hardware irritation, and receiver operating characteristic (ROC) curve analysis was performed in each subgroup to determine an optimal distance cutoff.
RESULTS: Hardware irritation occurred in 37 patients (26%). Plate location (dorsal, ulnar, or palmar) was not independently associated with irritation (P = .238). On multivariable logistic regression, a shorter distance from the ulnar styloid tip to the distal plate edge was the only significant independent predictor of hardware irritation (odds ratio [OR], 0.63; 95% confidence interval [CI], 0.54-0.75; P < .001). ROC curve analysis identified location-specific optimal cutoffs: 31 mm for dorsal (area under the curve [AUC], 0.882), 33 mm for ulnar (AUC, 0.927), and 31 mm for palmar placement (AUC, 0.977). In each subgroup, plates positioned below the respective cutoff had a significantly higher irritation rate (dorsal: 53% vs 8%, P = .001; ulnar: 55% vs 3%, P < .001; palmar: 85% vs 9%, P < .001). To facilitate clinical application, a uniform 30-mm threshold applied across all locations also demonstrated strong discriminatory performance (overall AUC, 0.918; 67% vs 9% irritation rate; P < .001).
CONCLUSIONS: Plate surface location does not independently predict hardware irritation after USO with specialized plates. The distance from the ulnar styloid tip to the distal plate edge was the only significant independent predictor, and positioning the distal plate edge at least approximately 30 mm from the ulnar styloid tip-regardless of plate surface-may serve as a practical clinical reference to reduce the risk of hardware irritation and the need for secondary plate removal.
TYPE OF STUDY/LEVEL OF EVIDENCE: Retrospective cohort study, IV.
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