gms | German Medical Science

Objectives/Interrogation: Malunions of forearm bones can result in reduced pronosupination and/or in instability of the distal radioulnar joint. Despite several studies investigating the outcome of soft tissue repairs, limited data exists for stability restoration by isolated corrective osteotomies.

Although a precise preoperative plan is of paramount importance to restore forearm bone alignment in corrective osteotomies, conventional deformity analyses are imprecise; especially rotational deformities are poorly assessed compared to analysis in 3D bone models.

So far, preoperative 3D analysis of the forearm bones deformities and distal radioulnar joint incongruence has not been evaluated in patients with joint instability. Consecutively, we hereby present the outcome of corrective osteotomies performed by 3D printed patient-specific instruments.

Methods: Ten patients (age: 17.2 - 43.1 years) were included, treated at our institution between 2013 and 2018, with corrective osteotomies of the forearm bones by patient-specific instruments. Simultaneous corrective osteotomy of ulna and radius was performed in 6 cases and in the remaining 4 cases a corrective osteotomy only of the radius.

Bone deformity analysis was performed by superimposing the malunion to the contralateral healthy bone models with the realignment of distal radioulnar joint congruency. The preoperative plan was executed by 3D printed patient-specific cutting and reduction instruments. Intraoperative length adaption along the long bone axis was ensured by an adaptable reduction guide to intraoperatively adjust the distal radioulnar joint congruity during pronosupination of the forearm.

Results and Conclusions: A volar instability was addressed in 8 patients and a dorsal instability/radioulnar impaction in the remaining 2 patients. In total, 7 out of 10 patients were clinically stable following a corrective osteotomy of the forearm.

The residual error between the 3D preoperative plan and the postoperative result was similar to previously published results of navigation by patient-specific instruments (translational error +/-1 mm, rotational error +/- 5°).

In the majority of the cases (7 out of 10), isolated corrective osteotomies of the forearm bones fully addressed distal radioulnar joint instability. Accurate execution of the preoperative plan considering three-dimensional analyses of bone deformities and joint incongruences was facilitated by patient-specific instruments.