To Angulate or Not to Angulate the Ulna during the Progressive Distraction Period Performed with a Monolateral External Fixator in Paediatric Patients with a Chronic Monteggia Fracture?

Background and Objectives: The purpose of this study was to compare the clinical and radiographic evolution of chronic Monteggia fractures (CMFs) treated by ulnar osteotomy and monolateral external fixators (MEFs) with or without angulation of the ulna during the distraction period. Materials and Methods: This retrospective study evaluated 20 children (14 boys and 6 girls) with CMFs. According to the strategy of ulnar lengthening, two groups of patients were identified: patients undergoing gradual lengthening with (Group A, n = 11) or without ulna angulation (Group B, n = 9). The mean age at the time of surgery was 7.7 years old (range, 5.4−12.9). The mean time from initial trauma to surgery was 26.3 months (range, 1−96), and the mean follow-up was 24.6 months (range, 5.5−45.4). Clinical outcomes were evaluated by Kim et al.’s Elbow Performance Score, while radiographic outcomes were assessed on plain radiographs. Results: Age at surgery, sex, laterality, time between trauma and surgery, and time of follow up in the two groups of patients showed no significant differences. The radial head was successfully reduced in 9 of 9 and 10 of 11 patients in Groups B and A, respectively (p = 1.00). The mean time to achieve radial head reduction was shorter in Group B (18.1 ± 5.3 days) than in Group A (39.2 ± 18.7 days; p = 0.004). The mean angulation of the ulna at the end of treatment was significantly lower in Group B (0.6° ± 1.1°) than in Group A (25.9° ± 6.3°; p < 0.0001). The average ulnar lengthening at the end of treatment in Group B (14.1 ± 5.8 mm) was, on average, 7.7 mm less than that in Group A (21.8 ± 9.7 mm; p = 0.05). The Kim et al. Elbow Performance Score at the last follow-up visit was comparable between the two groups of patients (p = 1.00). Conclusions: A shorter time to achieve radial head reduction and less deformity of the ulna can be expected in paediatric patients with CMFs undergoing intraoperative restoration of ulnar alignment and gradual lengthening without angulation postoperatively.