Background: Ulnar shortening osteotomy (USO) is a well-established procedure for ulnar impaction syndrome. Various types of osteotomies have been described. Methods: A retrospective cohort study was conducted to compare the results of transverse osteotomy (TO) fixed with a small fragment dynamic compression plate (Synthes, Pennsylvania, USA), to oblique osteotomy (OO) fixed with a procedure specific plate and instrumentation system (Acumed LLC, Oregon, USA). A total of 39 patients underwent TO and 62 patients underwent OO between 2007 and 2016. The main outcomes compared were rate of union, duration of radiological healing, implant removal rate and other complications. Results: The two groups were comparable with regards to demographics, side operated and smoking status (p > 0.05). Amongst the TO group; 36 out of 39 patients (92.3%) achieved union, 3 patients (7.7%) developed non-union. Six out of the 36 healed TO (16.6%) required removal of hardware due to implant-related pain. No other complications were recorded amongst TO group needing surgical intervention. Amongst the OO group, 2 of the early cohort of 62 patients (3.2%) sustained acute failure of the metalwork due to technical error. One of the remaining 60 patients (1.6%) developed non-union giving an overall union rate of 95.2%. Two patients out of 59 healed OO (3.3%) required removal of hardware. Conclusions: Although there were 2 early failures, there was a trend towards improved union rate with OO, but this did not reach statistical significance (p > 0.05). There was a significantly higher hardware removal rate recorded in TO group (p = 0.023). The OO showed shorter duration for radiological healing than TO (p < 0.05). USO performed with an OO and fixed with procedure specific plate has lower implant removal rate, a shorter duration for radiological healing and comparable union rate to TO fixed with DCP, but needs careful attention to detail.
Keywords: Oblique osteotomy; Transverse osteotomy; Ulnar shortening.