Precision of the Wilson corrective osteotomy of the first metacarpal base using specific planning and instruments for treatment of basal thumb arthritis

INTRODUCTION: Arthritis of the basal thumb is a relatively common condition also affecting younger patients. Wilson et al. described a 20°–30° closing wedge osteotomy of the first metacarpal bone to unload the trapeziometacarpal joint. It was the purpose of this study to analyze the clinical and radiographic outcome of patients who underwent proximal extension osteotomy of the first metacarpal bone using patient-specific planning and instruments (PSI). METHODS: All patients who underwent proximal metacarpal osteotomy for basal thumb arthritis at our tertiary referral center were retrospectively included. The patients underwent preoperative planning using computed tomography and 3D segmentation to build patient-specific guides and instruments for the operative treatment. Stable fixation of the osteotomy was achieved by internal plating. The inclusion criterion was a minimum follow-up of 1 year with clinical examination, including the Michigan Hand Outcomes Questionnaire (MHQ), and computed tomography to validate the correction. Complications and reinterventions were recorded. RESULTS: A total of eight Wilson osteotomies in six patients could be included at a mean follow-up duration of 33±16 months (range, 12 to 55 months). The patients were 49±8 years (range, 36 to 58 years) at the surgery and 88% were female. The postoperative MHQ for general hand function was 77±8 (range, 45 to 100) and the MHQ for satisfaction was 77±28 (range, 17 to 100). The working status was unchanged in 7/8 hands (6/7 patients). Radiographic analysis revealed successful correction in all cases with unchanged Eaton–Littler stage in 7/8 hands. No complications were recorded. CONCLUSION: The combined extending and ulnar adducting osteotomy using patient-specific guides and instrumentation provides an accurate treatment for early-stage thumb arthritis. LEVEL OF EVIDENCE: Type IV—retrospective, therapeutic study. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00402-022-04430-4.