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Morphometric geometrical analysis to determine the centre of the acetabular component placement in Crowe type IV hips undergoing total hip arthroplasty.
Yoshitani, J.; Kabata, T.; Kajino, Y.; Ueno, T.; Ueoka, K.; Nakamura, T.; Tsuchiya, H.
[Miscellaneous Article] The Bone & Joint Journal. 101B(2):189-197, February 2019.

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Aims: We analyzed the acetabular morphology of Crowe type IV hips using CT data to identify a landmark for the ideal placement of the centre of the acetabular component, as assessed by morphometric geometrical analysis, and its reliability.

Patients and Methods: A total of 52 Crowe IV hips (42 patients; seven male, 35 female; mean age 68.5 years (32 to 82)) and 50 normal hips (50 patients; eight male, 42 female; mean age 60.7 years (34 to 86)) undergoing total hip arthroplasty were retrospectively identified. In this CT-based simulation study, the acetabular component was positioned at the true acetabulum with a radiological inclination of 40[degrees] and anteversion of 20[degrees]. Acetabular shape and the position of the centre of the acetabular component were analyzed by morphometric geometrical analysis using the generalized Procrustes analysis.

Results: The acetabular shapes of Crowe IV hips were distinctively triangular; the ideal position of the centre of the acetabular component was superior on the posterior bony wall. The first and second relative warps explained 34.2% and 18.4% of the variance, respectively, compared with that of 28.6% and 18.0% in normal hips. We defined the landmark as one-third the distance from top on the posterior bony wall in Crowe IV hips. The average distance from the centre of the acetabular component was 5.6 mm.

Conclusion: Crowe IV hips are distinctively triangular; the point one-third from the top on the posterior bony wall was a useful landmark for placing the acetabular component.