Below-elbow or above-elbow cast for conservative treatment of extra-articular distal radius fractures with dorsal displacement: a prospective randomized trial

Background: Distal radial fractures are common traumatic injuries, but their management remains controversial also in case of conservative treatment regarding the type of immobilisation. Hence, we conducted a two-arm, parallel-group, prospective randomised trial to compare the capacity of long casts (above-elbow) and short casts (below-elbow) to maintain the reduction of extra-articular distal radius fractures with dorsal displacement (AO/OTA classification: 2R3A2.2). Methods: Seventy-four eligible patients with AO/OTA 2R3A2.2 fractures treated with closed reduction and cast immobilisation were randomised to the long cast group (n°= 37) or to the short cast group (n°= 37). Baseline radiological parameters, radial inclination (RI), radial height (RH), ulnar variance (UV) and palmar tilt (PT) were taken, and compared with clinical (DASH, Mayo Wrist and Mayo Elbow) and radiological scores taken at 7-10 days, 4 weeks and 12 weeks. Furthermore, to evaluate correlations between radiological parameters and functional outcomes, patients were divided into two groups according to whether or not their radiological parameters at Follow-ups 2 and 3 were acceptable, i.e. within the range 11-12 mm for RH, 16°-28° for RI, - 4-+ 2 mm for UV and 0°-22° for PT. Results: Patient demographic and baseline radiological parameters were similar between groups. At follow-up, there were no statistically significant differences between the two types of cast in terms of RI, RH, UV or PT, or Mayo wrist or DASH scores. Short cast group patients displayed better Mayo elbow score at follow-up 2 (4 weeks), but this difference was no longer statistically significant at follow-up 3 (12 weeks). No statistically significant differences in clinical outcomes were found between patients who presented acceptable radiographic parameters at follow-up and those who did not. Conclusion: As there were no significant differences between short casts and long casts in terms of fracture reduction maintenance or clinical outcomes, short casts are an effective method of post-reduction immobilisation in AO/OTA 2R3A2.2 fracture of the radius. Radiological parameters outside the range conventionally considered acceptable do not preclude a satisfactory clinical outcome. Trial registration: ClinicalTrials.gov PRS, NCT04062110. Registred 20 August 2019.