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Hip joint torsional loading before and after cam femoroacetabular impingement surgery

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Title: Hip joint torsional loading before and after cam femoroacetabular impingement surgery
Authors: Ng, KCG
El Daou, H
Bankes, M
Rodriguez y Baena, F
Jeffers, J
Item Type: Journal Article
Abstract: Background: Surgical management of cam femoroacetabular impingement (FAI) aims to preserve the native hip and restore joint function, though it is unclear how the capsulotomy, cam deformity, and capsular repair influence joint mechanics to balance functional mobility. Purpose: The purpose was to examine the contributions of the capsule and cam deformity to hip joint mechanics. Using in vitro, cadaveric methods, we examined the individual effects of the surgical capsulotomy, cam resection, and capsular repair towards passive range of motion and resistance of applied torque. Study Design: Descriptive laboratory study. Methods: Twelve cadaveric hips with cam deformities (n = 12) were skeletonized to the capsule and mounted onto a robotic testing platform. The robot positioned each intact hip in multiple testing positions: 1) Extension, 2) Neutral 0°, 3) Flexion 30°, 4) Flexion 90°, 5) flexion-adduction and internal rotation (FADIR), 6) flexion-abduction and external rotation (FABER); and performed applicable internal and external rotations, recording the neutral path of motion until a 5-Nm torque was reached in each rotational direction. Each hip then underwent a series of surgical stages (T-capsulotomy, cam resection, capsular repair) and was retested to reach 5 Nm internal and external torque again after each stage. In addition, during the capsulotomy and cam resection stages, the initial intact hip’s recorded path of motion was replayed to measure changes in resisted torque. Results: Examining changes in motion, external rotation increased substantially after capsulotomies, but internal rotation only further increased at Flexion 90° (change = +32%, P = .001, d = .58) and FADIR (change = +33%, P < .001, d = .51) after cam resections. Capsular repair provided marginal restraint for internal rotation, but restrained the external rotation compared to the capsulotomy stage. Examining changes in torque, both internal and external torque resistance decreased after capsulotomy. Compared to the capsulotomy stage, cam resection further reduced internal torque resistance during Flexion 90° (change = –45%, P < .001, d = .98) and FADIR (change = –37%, P = .003, d = 1.0), where the cam deformity accounted for 21% in Flexion 90° and 27% in FADIR of the intact hip’s torsional resistance. Conclusion: Although the capsule played a predominant role in joint constraint, the cam deformity provided 21–27% of the intact hip’s resistance to torsional load in flexion and internal rotation. Resecting the cam deformity would reduce this loading on the chondrolabral junction. Clinical Relevance: These findings are the first to quantify the contribution of the cam deformity to resisting hip joint torsional loads and thus quantify the reduced loading on the chondrolabral complex that can be achieved after cam resection.
Issue Date: 1-Feb-2019
Date of Acceptance: 19-Sep-2018
URI: http://hdl.handle.net/10044/1/64960
DOI: 10.1177/0363546518815159
ISSN: 0363-5465
Publisher: SAGE Publications
Start Page: 420
End Page: 430
Journal / Book Title: American Journal of Sports Medicine
Volume: 47
Issue: 2
Copyright Statement: © 2018 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://www.creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (E
Funder's Grant Number: EP/K027549/1
EP/N006267/1
Keywords: Science & Technology
Life Sciences & Biomedicine
Orthopedics
Sport Sciences
cam
femoroacetabular impingement
capsule
robot
in vitro
CAPSULAR REPAIR
ARTHROSCOPIC TREATMENT
PROSPECTIVE COHORT
T-CAPSULOTOMY
PART 1
DEFORMITY
OUTCOMES
OSTEOARTHRITIS
MOTION
RECONSTRUCTION
cam
capsule
femoroacetabular impingement
in vitro
robot
Biomechanical Phenomena
Cadaver
Femoracetabular Impingement
Hip Joint
Humans
Joint Capsule
Male
Middle Aged
Movement
Range of Motion, Articular
Robotics
Rotation
Torque
Hip Joint
Joint Capsule
Humans
Cadaver
Range of Motion, Articular
Movement
Robotics
Torque
Rotation
Middle Aged
Male
Femoracetabular Impingement
Biomechanical Phenomena
0903 Biomedical Engineering
0913 Mechanical Engineering
1106 Human Movement and Sports Sciences
Orthopedics
Publication Status: Published
Online Publication Date: 2018-12-31
Appears in Collections:Mechanical Engineering
Department of Surgery and Cancer
Faculty of Medicine
Institute of Global Health Innovation
Faculty of Engineering