Femoral Cortical Thickness Index in a Population of Dogs Undergoing Total Hip Arthroplast

Introduction: Femoral cortical thickness is a known factor for assessing fracture risk in humans undergoing Total Hip Arthroplasty (THA) yet has not been defined in dogs. The primary objective is to establish a femoral cortical thickness index (fCTI) for dogs undergoing THA, while secondary objectives include comparing fCTI in dogs with fractures/fissures and assessing measurement reproducibility. The authors hypothesize that lower fCTI indicates a higher fracture risk and that measurements will demonstrate high precision between observers.

Materials and Methods: A retrospective review of medical records for dogs undergoing THA was conducted, analysing only the first side in bilateral cases. Three measuring points were defined on preoperative mediolateral radiographs: Immediately distal to the lesser trochanter, quarter-, and midway down the femur. The average of these points calculated the fCTI. Ten cases with varying fCTI scores were selected for interobserver comparisons, and statistical analyses were performed.

Results: The analysis of 224 cases revealed a significant association between lower fCTI and the incidence of perioperative fractures (p < 0.0001). The mean fCTI for all dogs was 0.409, while it was statistically lower at 0.334 for dogs that sustained fissures/fractures. Deviations in body condition score also correlated with increased fracture risk. Interobserver and pre-and postoperative measurement comparisons showed near-perfect correlation.

Discussion/Conclusion: This study is the first to quantitatively assess femoral cortical thickness in dogs undergoing THA. Findings confirm that lower fCTI is associated with a higher risk of perioperative fractures and that measurements can be reliably reproduced between observers. These results may guide future clinical decision-making.

Acknowledgment

K.L.W., DVM, DACVS, owns the patent for the BFX lateral bolt and receives royalties from BioMedtrix.

Publication History

Article published online:
15 July 2025