Morphological Survey of Ideal Femoral Head and Neck Ostectomy Angle

Introduction: Femoral head and neck ostectomy (FHO) is routinely performed via craniolateral and ventral approaches. The ideal FHO angle (iFHOA) to guide the osteotomy is poorly defined. The goal of this study was to document iFHOA for canine and feline femurs of varied morphology. We hypothesized that iFHOA would be different than the previously accepted 45 degrees and that iFHOA would be different for canine and feline femurs of varied morphology.

Materials and Methods: A sample size calculation was performed, and patients were divided into four categories: normal canine, canine with hip dysplasia, chondrodystrophic canine, and feline. iFHOA was independently measured by three reviewers as previously described. Agreement between the observers was evaluated using Bland–Altman Analysis. Data was evaluated for normality assumption. Linear Mixed regression analysis was used to compare groups. A p-value of 0.05 was used as a criterion to determine statistical significance.

Results: Four hundred radiographs were reviewed (100 per group). The average iFHOA for all groups was significantly less than 45 degrees (p < 0.0001). Chondrodystrophic dogs and cats had a statistically significantly lower iFHOA compared with normal dogs (36.3 and 33.4 degrees, respectively).

Discussion/Conclusion: All patient groups had an average iFHOA less than the previously recommended 45 degrees. Based on the findings in this study, preoperative iFHOA measurement is advised for all cases, particularly when taking a ventral approach and with chondrodystrophic patients.

Acknowledgment

None.

Publication History

Article published online:
15 July 2025