[Malunion of the distal radius: 3D planning and performance of intra- and extra-articular corrective osteotomy].

Objective: Restoration of the original anatomy with reduction of both current symptoms and risk of posttraumatic osteoarthritis.

Indications: Symptomatic intra- or extra-articular malunion due to limitation of movement and/or painful function, intra-articular step of > 1 mm, instability of the distal radioulnar joint.

Contraindications: Minimal deformity. Pre-existing osteoarthritis Knirk and Jupiter II or higher. Simpler surgical alternative, e.g., ulna shortening osteotomy. Smoking or advanced age are not contraindications.

Surgical technique: Preoperative assessment and performance of a bilateral computed tomography (CT). Three-dimensional (3D) malposition analysis and calculation of the correction. Planning of the corrective osteotomy on the 3D model and creation of patient-specific drilling and sawing guides. Performing the 3D-guided osteotomy.

Postoperative management: Early functional unloaded mobilization with the splint for 8 weeks until consolidation control with CT.

Results: Significant reduction of the step to < 1 mm (p ≤ 0.05) can be achieved with intra-articular corrections. In extra-articular corrective osteotomies, a mean residual rotational malalignment error of 2.0° (± 2.2°) and a translational malalignment error of 0.6 mm (± 0.2 mm) is achieved. Single-cut osteotomies in the shaft region can be performed to within a few degrees for rotation (e.g., pronation/supination 4.9°) and for translation (e.g., proximal/distal, 0.8 mm). After surgery, a mean residual 3D angle of 5.8° (SD 3.6°) was measured. Furthermore, surgical time for 3D-assisted surgery is significantly reduced compared to the conventional technique (140 ± 37 vs 108 ± 26 min; p < 0.05). Thus, the progression of osteoarthritis can be reduced in the medium term and improved mobility and grip strength are achieved. The clinical outcome parameters based on patient-rated wrist evaluation (PRWE) and the disabilities of the arm, shoulder and hand (DASH) scores are roughly comparable.