PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY

Geoffrey Ng; Marcus Bankes; George Grammatopoulos; Jonathan Jeffers; Justin Cobb

doi:10.1302/1358-992X.2021.2.018

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PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY

The British Orthopaedic Research Society (BORS) Annual Meeting 2020, held online, 7–8 September 2020.

Geoffrey Ng
Marcus Bankes
George Grammatopoulos
Jonathan Jeffers
Justin Cobb

PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY

Ng G, Bankes M, Grammatopoulos G, Jeffers J, Cobb J. PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY. Orthop Procs. 2021;103-B(SUPP_2):18-18. doi:10.1302/1358-992X.2021.2.018

Ng, Geoffrey, et al. “PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY.” Orthopaedic Proceedings, vol. 103-B, no. SUPP_2, 2021, pp. 18-18., https://doi.org/10.1302/1358-992X.2021.2.018

Ng, G., Bankes, M., Grammatopoulos, G., Jeffers, J., & Cobb, J. (2021). PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY. Orthopaedic Proceedings, 103-B(SUPP_2), 18-18. https://doi.org/10.1302/1358-992X.2021.2.018

Ng, G., Bankes, M., Grammatopoulos, G., Jeffers, J. and Cobb, J. (2021) “PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY.” Orthopaedic Proceedings, 103-B(SUPP_2), pp. 18-18. Available at: https://doi.org/10.1302/1358-992X.2021.2.018

Ng, Geoffrey, Marcus Bankes, George Grammatopoulos, Jonathan Jeffers, and Justin Cobb. “PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY.” Orthopaedic Proceedings 103-B, no. SUPP_2 (2021): 18-18. https://doi.org/10.1302/1358-992X.2021.2.018

Ng G, Bankes M, Grammatopoulos G, Jeffers J, Cobb J. PELVIC INCIDENCE IS A MAJOR PREDICTOR OF HIP IMPINGEMENT AND DYSPLASIA MOBILITY. Orthop Procs. 2021 Mar 1;103-B(SUPP_2):18-18. https://doi.org/10.1302/1358-992X.2021.2.018

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Abstract

OBJECTIVES

Cam femoroacetabular impingement (FAI – femoral head-neck deformity) and developmental dysplasia of the hip (DDH – insufficient acetabular coverage) constitute a large portion of adverse hip loading and early degeneration. Spinopelvic anatomy may play a role in hip stability thus we examined which anatomical relationships can best predict range of motion (ROM).

METHODS

Twenty-four cadaveric hips with cam FAI or DDH (12:12) were CT imaged and measured for multiple femoral (alpha angles, head-neck offset, neck angles, version), acetabular (centre-edge angle, inclination, version), and spinopelvic features (pelvic incidence). The hips were denuded to the capsule and mounted onto a robotic tester. The robot positioned each hip in multiple flexion angles (Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°); and performed internal-external rotations to 5 Nm in each position. Independent t-tests compared the anatomical parameters and ROM between FAI and DDH (CI = 95%). Multiple linear regressions determined which anatomical parameters could predict ROM.

RESULTS

The FAI group demonstrated restricted ROM in deep hip flexion, with DDH showing higher ROM in Flexion 30° (+20%, p = 0.03), 60° (+31%, p = 0.001), and 90° (+36%, p = 0.001). In Neutral 0° and Flexion 30°, femoral neck and version angles together predicted ROM (R² = 60%, 58% respectively); whereas in Flexion 60°, pelvic incidence and femoral neck angle predicted ROM (R² = 77%). In Flexion 90°, pelvic incidence and radial alpha angle together predicted ROM (R² = 81%), where pelvic incidence alone accounted for 63% of this variance.

CONCLUSIONS

Pelvic incidence is essential to predict hip ROM. Although a cam deformity or acetabular undercoverage can elevate risks of labral tears and progressive joint degeneration, they may not be primary indicators of restrictive hip impingement or dysplastic instability. Better delineating additional spinopelvic characteristics can formulate early diagnostic tools and improve opportunities for nonsurgical management.

Declaration of Interest

(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.