Capsular ligament function after total hip arthroplasty
File(s)
Published version
Author(s)
van Arkel, R
Ng, KCG
Muirhead-Allwood, S
Jeffers, J
Type
Journal Article
Abstract
Background: The hip joint capsule passively restrains extreme range of motion, protecting the native hip against impingement, dislocation, and edge-loading. We hypothesized that following total hip arthroplasty (THA), the reduced femoral head size impairs this protective biomechanical function.
Methods: In cadavers, THA was performed through the acetabular medial wall, preserving the entire capsule, and avoiding the targeting of a particular surgical approach. Eight hips were examined. Capsular function was measured by rotating the hip in 5 positions. Three head sizes (28, 32, and 36 mm) with 3 neck lengths (anatomical 0, +5, and +10 mm) were compared.
Results: Internal and external rotation range of motion increased following THA, indicating late engagement of the capsule and reduced biomechanical function (p < 0.05). Internal rotation was affected more than external. Increasing neck length reduced this hypermobility, while too much lengthening caused nonphysiological restriction of external rotation. Larger head sizes only slightly reduced hypermobility.
Conclusions: Following THA, the capsular ligaments were unable to wrap around the reduced-diameter femoral head to restrain extreme range of motion. The posterior capsule was the most affected, indicating that native posterior capsule preservation is not advantageous, at least in the short term. Insufficient neck length could cause capsular dysfunction even if native ligament anatomy is preserved, while increased neck length could overtighten the anterior capsule.
Clinical Relevance: Increased understanding of soft-tissue balancing following THA could help to prevent instability and improve early function. This study illustrates how head size and neck length influence the biomechanical function of the hip capsule in the early postoperative period.
Methods: In cadavers, THA was performed through the acetabular medial wall, preserving the entire capsule, and avoiding the targeting of a particular surgical approach. Eight hips were examined. Capsular function was measured by rotating the hip in 5 positions. Three head sizes (28, 32, and 36 mm) with 3 neck lengths (anatomical 0, +5, and +10 mm) were compared.
Results: Internal and external rotation range of motion increased following THA, indicating late engagement of the capsule and reduced biomechanical function (p < 0.05). Internal rotation was affected more than external. Increasing neck length reduced this hypermobility, while too much lengthening caused nonphysiological restriction of external rotation. Larger head sizes only slightly reduced hypermobility.
Conclusions: Following THA, the capsular ligaments were unable to wrap around the reduced-diameter femoral head to restrain extreme range of motion. The posterior capsule was the most affected, indicating that native posterior capsule preservation is not advantageous, at least in the short term. Insufficient neck length could cause capsular dysfunction even if native ligament anatomy is preserved, while increased neck length could overtighten the anterior capsule.
Clinical Relevance: Increased understanding of soft-tissue balancing following THA could help to prevent instability and improve early function. This study illustrates how head size and neck length influence the biomechanical function of the hip capsule in the early postoperative period.
Date Issued
2018-07-18
Date Acceptance
2018-02-07
Citation
Journal of Bone and Joint Surgery: American Volume, 2018, 100 (14), pp.1-10
ISSN
0021-9355
Publisher
Lippincott, Williams & Wilkins
Start Page
1
End Page
10
Journal / Book Title
Journal of Bone and Joint Surgery: American Volume
Volume
100
Issue
14
Copyright Statement
© 2018 by The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved. This is an open access article
distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (E
Engineering and Physical Sciences Research Council
Identifier
https://journals.lww.com/jbjsjournal/Fulltext/2018/07180/Capsular_Ligament_Function_After_Total_Hip.9.aspx
Grant Number
EP/K027549/1
EP/N006267/1
EP/N006267/1
Subjects
Science & Technology
Life Sciences & Biomedicine
Orthopedics
Surgery
DIRECT ANTERIOR APPROACH
FINITE-ELEMENT-ANALYSIS
SOFT-TISSUE REPAIR
POSTERIOR-APPROACH
POSTEROLATERAL APPROACH
COORDINATE SYSTEM
SURGICAL APPROACH
FEMORAL-HEAD
SAFE ZONE
IN-VITRO
Aged
Aged, 80 and over
Arthroplasty, Replacement, Hip
Biomechanical Phenomena
Cadaver
Female
Humans
Joint Capsule
Ligaments, Articular
Male
Middle Aged
Range of Motion, Articular
Ligaments, Articular
Joint Capsule
Humans
Cadaver
Range of Motion, Articular
Arthroplasty, Replacement, Hip
Aged
Aged, 80 and over
Middle Aged
Female
Male
Biomechanical Phenomena
Orthopedics
0903 Biomedical Engineering
1103 Clinical Sciences
Publication Status
Published
Article Number
e94
Date Publish Online
2018-07-18