Biomechanical evaluation of a cemented femoral stem for canine total hip replacement across two breeds

Cemented total hip replacement (THR) remains an established procedure for restoring hip joint function in dogs with degenerative or traumatic coxofemoral disease; however, limited evidence exists regarding the mechanical integrity and load-transfer characteristics of cemented femoral stem constructs within native canine femora. This study critically evaluated the biomechanical performance of a novel modular cemented femoral stem using cadaveric femora from German Shepherd Dogs (GSDs) and Labrador Retrievers (LABs), emphasizing axial, bending, and torsional behaviors in correlation with radiographic and morphometric parameters. Eighteen pairs of adult canine femora were harvested postmortem, with one side implanted following standardized second-generation cementation protocols and the contralateral side retained intact. Following radiographic and CT-based templating, specimens underwent displacement-controlled axial compression, three-point bending, and torsion tests. Cemented implantation significantly reduced ultimate compressive, bending, and torsional strengths compared to intact femora (p < 0.05), though stiffness remained unaffected, suggesting preservation of elastic response despite altered failure thresholds. GSD femora consistently exhibited greater load-bearing capacity, yield strength, and energy absorption than LABs, reflecting breed-specific variations in cortical geometry and canal morphology. Radiographs confirmed precise stem alignment, uniform cement mantles averaging 5 mm, and consistent canal fill exceeding 60 %, indicative of optimized cementation. Failure patterns transitioned from brittle cortical fractures in intact specimens to ductile interfacial shear at the bone-cement interface in implanted constructs, demonstrating efficient load redistribution through the composite system. Collectively, these findings highlight the mechanical reliability and breed-dependent adaptability of the cemented THR system, supporting its translational potential for achieving durable fixation and functional load transfer in canine clinical applications while offering valuable insights relevant to comparative orthopedic biomechanics.