Bone substitute in distal radius osteotomy: a prospective randomized double-blinded study on micromotion and outcomes in 42 patients up to one year.

Introduction: Symptomatic malunion following a distal radius fracture (DRF) is commonly treated with a corrective osteotomy. Such osteotomy is traditionally fixed with a palmar plate in combination with autogenous bone graft in the osteotomy gap. However, bone grafting prolongs surgery and may result in comorbidity. Recent studies suggest that filling the osteotomy gap may not be necessary. An alternative is to fill the gap with an injectable bone substitute (IBS). However, there is limited data on inter-fragmentary micromotion in osteotomies utilizing IBS. This study aims to assess micromotion and outcomes in patients undergoing corrective osteotomy for malunited DRFs, comparing outcomes between those treated with and without IBS.

Materials And Methods: Patients undergoing distal radius osteotomy for symptomatic malunion were randomized to either an IBS (hydroxyapatite, HA) group or control group (where the osteotomy gap was left unfilled) in combination with palmar plate fixation. Radiostereometric Analysis (RSA) markers were placed in the radius, and RSA assessments were conducted immediately postoperatively and at 6 weeks, 3, 6, and 12 months. The primary outcome of the study was dorsal/palmar tilt, while the secondary outcomes were radial shortening, radial inclination, radial shift, as well as clinical and Patient Reported Outcomes (PROMs).

Results: 42 patients (24 control, 18 HA-group) were included in the analysis. Significantly less micromotions were noted in the HA-group at multiple follow-ups (p ≤ 0.05) in X-axis rotation and Y-axis translation, however they were in the subclinical scale. Both groups showed functional improvements over time, but there were no differences between the groups in clinical outcomes or PROMs.

Conclusions: Hydroxyapatite bone substitute does not offer additional benefits in terms of stability or outcomes in extra-articular corrective osteotomy for malunited DRFs when a palmar plate is used for fixation and palmar cortical bone contact is maintained.