Computer-Aided Design Planning and 3D-printed Patient-specific Guide to Address an Oblique Plane Antebrachial Deformity in a Dog

Computer-aided design (CAD) and patient-specific 3D-printed guides have been demonstrated to improve the accuracy of antebrachial deformity correction in dogs (1,2). This report describes a successful application of CAD and a patient-specific 3D-printed guide to correct a complex antebrachial deformity in a 6-month-old Maltese dog presented with left forelimb lameness. Radiographs of the affected limb showed elbow incongruity, a short ulna, and a long curve radius. A multiplanar antebrachial deformity was diagnosed based on CT scans. Employing CAD (Grasshopper algorithmic modeling tool integrated into Rhinoceros software), the center of rotation of angulation was identified in the distal radius. An oblique plane deformity was diagnosed, characterized by 21° valgus, 30°excessive procurvatum, and 42° external torsion. Using CAD, the surgery was simulated virtually, and an osteotomy guide with high-profile features was custom-designed for the radius. Intra-operative models and surgical guides were 3D-printed in polylactic acid. The surgery involved a bi-oblique ulnar osteotomy and an oblique-plane closing-wedge ostectomy of the radius. The guide was perfectly positioned and stabilized with K-wires to the bone. After the ostectomy, a mini-series Fixin plate was placed dorsally on the radius. Postoperative radiographs showed resolution of deformity and elbow incongruity. Radiographical union of the osteotomy site was observed 60 days post-op. After seven months, radiographs showed a decrease in radial bone density underneath the plate, indicative of stress protection ascribed to the plate's rigidity. Staged plate dynamization was performed at 7 and 9 months, followed by complete plate removal at 11 months. This case report highlights the benefits of using CAD planning and patient-specific 3D guides in an antebrachial corrective osteotomy; as well as the importance of long-term follow-ups for early diagnosis and management of stress protection. Future research should focus on objective assessments of CAD and 3D technologies in corrective procedures, comparing them to free-hand surgeries (2,3).