Application of Novel Biomaterials to Enhance Bone Regeneration in a Canine Non-Union Olecranon Fracture

A six-year-old, neutered male Pomeranian weighing 4.25 kg was presented with a two-year history of non-weight-bearing lameness of the left thoracic limb following an untreated traumatic olecranon fracture. Orthopedic examination revealed markedly reduced elbow joint range of motion and muscle atrophy. Radiographs demonstrated a distinct fracture line with proximolateral displacement of the olecranon fragment. Preoperative computed tomography (CT) and three-dimensional (3D) reconstruction were used to establish the surgical plan and to pre-contour a locking plate. Surgical treatment was performed in sequential steps, including removal of scar tissue, reopening of the bone marrow channel, and internal fixation. Considering the compromised biological environment of a chronic non-union, a bioactive graft composed of porous leaf-stacked structure (LSS) polycaprolactone particles incorporating recombinant human bone morphogenetic protein-2 (rhBMP-2) and mesenchymal stem cells (MSCs) was applied in combination with plate-screw fixation. The patient showed progressive improvement after surgery, achieving full weight-bearing and restoration of elbow joint motion comparable to the contralateral side. Follow-up radiographs and CT confirmed fracture union, and the radiolucency of the LSS scaffold enabled precise monitoring of bone healing. This case highlights the potential utility of combining patient-specific surgical planning with sustained delivery of rhBMP-2 and MSCs using LSS particles for the management of chronic non-union fractures in small animals.