Corrective derotation osteotomy of the proximal phalanx using intraoperative Mixed Reality guidance.

Introduction: Malunion of phalangeal or metacarpal fractures can significantly impair the function and alignment of adjacent joints, leading to long-term disability. Corrective osteotomy is a pivotal surgical intervention designed to realign deformity and restore optimal function in such cases. Different approaches to assess the angle of correction have been used in the past; traditionally it has been just visual control or sterile protractor. A more recent approach has been by the introduction of patient-specific instrumentation or navigation. However, another promising one is the application of Mixed Reality (MR) support for precise planning and angle correction. Presentation of case: This report discusses the case of a 27-year-old male patient with malunion of the proximal phalanx with 14° rotation deformity leading to finger overlapping on flexion, impairing his function and alignment of the IV digit. In such a case where relatively minimal correction is vital and required, precision becomes paramount. Therefore, to achieve the desired result, we used MR for both surgical osteotomy planning and intraoperative guidance. After surgery, the patient regained adequate union, alignment and normal function. Clinical discussion: In our case, MR technology enabled us to perform a precise corrective osteotomy of the phalanx, which required a minor degree of correction. Accurate correction without the use of this technology would be challenging. Conclusion: MR can be effectively utilized in the surgical correction of phalanx malunion. This technology contributes to improved alignment and functional outcome.