Biomechanics of Cam Femoroacetabular Impingement: A Systematic Review.

Purpose: To assess how biomechanical gait parameters (kinematics, kinetics, and muscle force estimations) differ between patients with cam-type femoroacetabular impingement (FAI) and healthy controls, through a systematic search.
Methods: A systematic review of the literature from PubMed, Scopus, and Medline and EMBASE via OVID SP was undertaken from inception to April 2020 using PRISMA guidelines. Studies that described kinematics, kinetics, and/or estimated muscle forces in cam-type FAI were identified and reviewed.
Results: The search strategy identified 404 articles for evaluation. Removal of duplicates and screening of titles and abstracts resulted in full-text review of 37 articles, with 12 meeting inclusion criteria. The 12 studies reported biomechanical data on a total of 173 cam-FAI (151 cam-specific, 22 mixed-type) patients and 177 healthy age-, sex-, and body mass index-matched controls. Patients with cam FAI had reduced hip sagittal plane range of motion (mean difference -3.00° [-4.10, -1.90], P < .001), reduced hip peak extension angles (mean difference -2.05° [-3.58, -0.53] , P = .008), reduced abduction angles in the terminal phase of stance, and reduced iliacus and psoas muscle force production in the terminal phase of stance compared to the control groups. Cam FAI cohorts walked at a slower speed compared with controls.
Conclusions: In conclusion, patients with cam-type FAI exhibit altered sagittal and frontal plane kinematics as well as altered muscle force production during level gait compared to controls. These findings will help guide future research into gait alterations in FAI and how such alterations may contribute to pathologic progression and furthermore, how such alterations can be modified for therapeutic benefit.
Level of Evidence: Systematic review of Level III studies.
(Copyright © 2021 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)