A RANDOMIZED CONTROLLED TRIAL COMPARING OPERATIVE AND NONOPERATIVE TREATMENT OF ULNAR DIAPHYSEAL FRACTURES

Isolated ulnar diaphyseal fractures are relatively uncommon, with an incidence of 0.02 to 0.04 per 1,000. Despite being uncommon, complications surrounding this injury are frequent, including high non-union rates, decreased forearm pronation and supination, decreased elbow range of motion, radioulnar synostosis, and prolonged pain. Research investigating the best treatment option for this injury is scarce, and there is no consensus on optimal treatment methods. Therefore, this large randomized controlled trial (RCT) aims to compare clinical, radiographic, and functional outcomes between open reduction and internal fixation (ORIF) and non-operative treatment in patients with isolated ulnar diaphyseal fractures. This is a multi-centre, open-label, parallel RCT of patients with isolated, closed AO/OTA type 22-A and 22-B injuries, without extension into the proximal or distal radio-ulnar joints. Patients were excluded if the fracture was displaced 30-degrees of angulation. Eligible patients were randomized to one of the two treatment arms: non-operative treatment with closed reduction and below-elbow casting, or surgical treatment with ORIF with a limited contact dynamic compression plate and screw construct. Randomization was conducted electronically with a 1:1 ratio using variable block sizes and stratification by recruiting site. The primary outcome measure is the Disability Shoulder, Arm, Hand (DASH) score at 12 weeks post-injury. In addition, the Short Form 36 (SF-36) and Pain Visual Analogue Scale (VAS) are used to compare functional outcomes between groups. The secondary outcome measures include clinical (range of motion, grip strength), radiologic (time to union), and economic outcomes, assessed throughout patient follow-up until 12 months post-injury. Descriptive statistics will be used to characterize the study population. Intention-to-treat analysis will be performed with independent samples t-tests to compare the mean DASH, SF-36, and VAS questionnaire scores and for time to return to work. For secondary analysis, analysis of variance (ANOVA) and pairwise comparisons will be completed for the DASH, SF-36, and ROM data at each follow-up time interval. Independent samples t-test will be used for time to union data. Exploratory subgroup analyses are planned to examine treatment effects for covariates including age, sex, site, handedness, and injury classification. A total of 100 participants were enrolled and randomized (49 ORIF and 51 non-operative) across 11 participating sites (Table 1). The mean age of the overall cohort is 40.0 (± 18.0) years, with 72% being male. The final follow-up for this large, multi-centre RCT will be completed in March 2023; therefore, the study final results will be available for the 2023 COA meeting. This will be the largest RCT of operative compared with non-operative management of isolated ulnar diaphyseal fractures. This is a multi-centre study with a large loss to follow-up rate included in the sample size calculation, in order to ensure appropriate statistical power, given historical difficulty in following this patient population. Patients were enrolled at 11 participating sites to maximize generalizability of the study findings. For any figures or tables, please contact the authors directly.