Acetabular Conformation in Dogs

Kenneth A. Johnson, MVSc, PhD, FACVSc, DACVS, DECVS

Radiographic images of acetabular morphology and pathology in dogs suffering from hip dysplasia have been extensively studied. However, measurements made of acetabular conformation and orientation from two-dimensional radiographic images can be highly inaccurate. The canine acetabulum is not perfectly spherical, and it is angled both laterally and caudally; together these two angles resolve into a compound angle of orientation. This makes the preoperative planning of acetabular component orientation in total hip arthroplasty approximate at best. The guidelines for canine total hip arthroplasty suggest that angles of lateral opening of 35 to 45 degrees and version of 15 to 25 degrees should be achieved to reduce the risk of postoperative luxation. But, for the inexperienced surgeon, consistently achieving this degree of accuracy can be very difficult in every total hip arthroplasty surgery.

In this issue of VCOT, Fracka and colleagues report a new method of measuring the orientation of normal canine acetabulum relative to pelvic reference points, using modelling of CT images.[1] They found “that although the mean values for acetabular alignment were generally consistent with clinical guidelines, some dogs in their (sic) study had more extreme values, and there was a wide range of angles across different breeds. Using a standard set of recommended angles across all breeds of dogs may lead to incorrect cup placement and an increased risk of postoperative complications such as luxation.”[1]

This study is important because it lays important methodological foundations for using precise patient-specific measurements of the native acetabular orientation to allow computer-navigated or robot-assisted orientation of the acetabular component in total hip arthroplasty, as being performed in humans.[2]

Publication History

Article published online:
17 July 2023

• References

• 1 Fracka AB, Zindl C, Allen MJ. Three-dimensional morphometry of the canine pelvis: implications for total hip replacement surgery. Vet Comp Orthop Traumatol 2023; 36 (04) 175-183
• 2 Buchan GBJ, Hecht II CJ, Liu D, Mokete L, Kendoff D, Kamath AF. Improved accuracy of a novel fluoroscopy-based robotically assisted THA system compared to manual THA. J Robot Surg 2023; (e-pub ahead of print) DOI: 10.1007/s11701-023-01623-w.