Evaluation of Locking Screw-Intramedullary Pin System for Supracondylar Fracture Repair in Dogs

Objective To biomechanically and clinically compare a novel locking screw–intramedullary pin system with dynamic cross pinning for stabilization of supracondylar femur fractures in dogs. Materials and Methods Thirty-six canine cadaveric femora were randomly allocated into two groups (n = 18 each). Group I was stabilized using dynamic cross pinning, and Group II using the novel locking screw–intramedullary pin system. A standardized transverse supracondylar osteotomy was created. Constructs were subjected to axial compression and three-point bending until failure. Ultimate load to failure and displacement at failure were recorded. Torsional testing was attempted; however, rotational slippage prevented meaningful torque analysis. Clinically, twelve client-owned dogs (< 20 kg) with supracondylar femoral fractures were randomly assigned (n = 6/group). Primary clinical outcome was weight-bearing score at 60 days. Secondary outcomes included pain score, inflammation score, joint range of motion, implant stability, and radiographic callus formation. Results Group II constructs demonstrated significantly higher ultimate load to failure under axial compression and three-point bending compared with Group I (p < 0.05). In the clinical cohort, dogs treated with the locking screw–intramedullary pin system showed significantly improved weight-bearing, earlier restoration of joint motion, fewer implant-related complications, and more consistent radiographic healing at 60 days (p < 0.05). Conclusion The locking screw–intramedullary pin system demonstrated greater resistance to axial and bending loads in vitro and was associated with improved short-term functional outcomes compared with dynamic cross pinning in growing dogs. Further studies with larger sample sizes and validated torsional testing are warranted.