Femoral and acetabular features explain acetabular contact pressure sensitivity to hip internal rotation in persons with cam morphology: A finite element analysis

Jordan Cannon; Jeffery W Rankin; Kristi L Lewton; Jia Liu; Christopher M Powers

doi:10.1016/j.clinbiomech.2023.106025

Femoral and acetabular features explain acetabular contact pressure sensitivity to hip internal rotation in persons with cam morphology: A finite element analysis

Clin Biomech (Bristol). 2023 Jul:107:106025. doi: 10.1016/j.clinbiomech.2023.106025. Epub 2023 Jun 2.

Authors

Jordan Cannon¹, Jeffery W Rankin², Kristi L Lewton¹, Jia Liu³, Christopher M Powers⁴

Affiliations

¹ Jacquelin Perry Musculoskeletal Biomechanics Research Laboratory, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA; Department of Integrative Anatomical Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
² Rancho Research Institute, Rehabilitation Engineering Program, Downey, CA, USA.
³ Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
⁴ Jacquelin Perry Musculoskeletal Biomechanics Research Laboratory, Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA. Electronic address: powers@pt.usc.edu.

PMID: 37302302
DOI: 10.1016/j.clinbiomech.2023.106025

Abstract

Background: Femoroacetabular impingement is characterized by premature contact between the proximal femur and acetabulum. The loss of femoral head-neck concavity associated with cam morphology leads to mechanical impingement during hip flexion and internal rotation. Other femoral and acetabular features have been linked with mechanical impingement but have not been comprehensively investigated. This study sought to determine which bony features are most influential in contributing to mechanical impingement in persons with a cam morphology.

Methods: Twenty individuals (10 female, 10 male) with a cam morphology participated. Finite element analyses incorporating subject-specific bony geometry derived from computed tomography scans were used to determine which femoral (alpha angle and femoral neck-shaft angle) and acetabular (anteversion angle, inclination angle, depth, and lateral center-edge angle) features accentuate acetabular contact pressure with increasing degrees of hip internal rotation with the hip flexed to 90°. To determine the best predictors of acetabular contact pressure sensitivity to internal rotation, all morphological variables were included in a stepwise regression with the final model subjected to a bootstrapping procedure.

Findings: The stepwise regression revealed that femoral neck-shaft angle, acetabular anteversion angle, acetabular inclination angle, and acetabular depth were the best combination of variables to predict contact pressure sensitivity to internal rotation, explaining 55% of the variance. Results of the bootstrap analysis revealed that a median value of 65% [37%, 89%] variance in sensitivity could be explained by these morphological variables.

Interpretation: Mechanical impingement and the concomitant acetabular contact pressure are modulated by multiple femoral and acetabular features in persons with a cam morphology.

Keywords: Cam morphology; Femoral and acetabular morphology; Femoroacetabular impingement; Finite element analysis; Hip internal rotation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acetabulum* / diagnostic imaging
Female
Femoracetabular Impingement* / diagnostic imaging
Femur / diagnostic imaging
Finite Element Analysis
Hip Joint / diagnostic imaging
Humans
Male
Range of Motion, Articular