Evaluation of Radiographic Outcomes in Dogs with BFx-Lateral Bolt Stems

Introduction: This study evaluates short-term radiographic and clinical outcomes in dogs implanted with BFx-lateral bolt (BFx-LB) stems in total hip replacement (THR). We hypothesize that BFx-LB stems would suit a wide range of femoral morphologies.

Materials and Methods: Medical and radiographic records of dogs undergoing THR with BFx-LB stems at three institutions were reviewed. Inclusion criteria required complete medical records and radiographs from preoperative, immediate postoperative, and 8 to 12 weeks postoperative. A single reviewer evaluated all radiographs and on the postoperative and follow-up radiographs: canal flare index (CFI), stem femoral canal fill (FCF), stem subsidence, and frontal and sagittal plane stem alignment were measured.

Results: The study included 104 cases from 95 dogs, with each hip treated as a separate case for bilateral THRs. The complication rate was 12.5%, with none of those complications being attributed to the stem. The mean (SD) CFI was 1.82 (0.27). The mean (SD) FCF was 68 (7.5%). The mean (SD) stem subsidence was 0.99 mm (1.2 mm). Varus and caudal deviations were the most common stem misalignments. Follow-up radiographs showed that in the coronal plane, the mean (SD) varus drift was 0.42 degrees (1.20 degrees). In the sagittal plane, the mean (SD) caudal drift was 0.26 degrees (1 degree).

Discussion/Conclusion: Despite our FCF being well below the recommended 85% for BFx stems, the low complication rate suggests this older guideline may not apply to BFx-LB stems. The low subsidence likely contributed to low stem-related complications. This study supports our hypothesis and corroborates the existing literature on BFx-LB.

Acknowledgment

None.

Publication History

Article published online:
15 July 2025