Re-displacement of a pediatric diaphyseal forearm fracture can lead to a malunion with symptomatic impairment in forearm rotation, which may require a corrective osteotomy. Corrective osteotomy with two-dimensional (2D) radiographic planning for malunited pediatric forearm fractures can be a complex procedure due to multiplanar deformities. Three-dimensional (3D) corrective osteotomy can aid the surgeon in planning and obtaining a more accurate correction and better forearm rotation. This prospective study aimed to assess the accuracy of correction after 3D corrective osteotomy for pediatric forearm malunion and if anatomic correction influences the functional outcome. Our primary outcome measures were the residual maximum deformity angle (MDA) and malrotation after 3D corrective osteotomy. Post-operative MDA > 5° or residual malrotation > 15° were defined as non-anatomic corrections. Our secondary outcome measure was the gain in pro-supination. Between 2016–2018, fifteen patients underwent 3D corrective osteotomies for pediatric malunited diaphyseal both-bone fractures. Three-dimensional corrective osteotomies provided anatomic correction in 10 out of 15 patients. Anatomic corrections resulted in a greater gain in pro-supination than non-anatomic corrections: 70° versus 46° (p = 0.04, ANOVA). Residual malrotation of the radius was associated with inferior gain in pro-supination (p = 0.03, multi-variate linear regression). Three-dimensional corrective osteotomy for pediatric forearm malunion reliably provided an accurate correction, which led to a close-to-normal forearm rotation. Non-anatomic correction, especially residual malrotation of the radius, leads to inferior functional outcomes.

An unstable distal ulnar stump after Darrach resection, alongside pathology of the radiocarpal joint, is difficult to manage without fusion of at least one joint. Currently, no standard 2-in-1 arthroplasty is available. We report the case of a 72-year-old woman with loosening of the radial stem of a Universal 2 total wrist prosthesis combined with radioulnar impingement after a Darrach procedure. Because of poor radial bone stock, the standard fixation technique of a semi-constrained distal radioulnar joint prosthesis (Aptis) was not possible. We present a technique to fix the semi-constrained distal radioulnar joint prosthesis as well as a total wrist prosthesis by a custom 3-dimensional printed flange prosthesis to the ulnar border of the radius. Three years after surgery, the patient remained pain-free, with 60° flexion, 75° extension, 80° pronation, and 80° supination.