Pericapsular hip muscle activity in people with and without femoroacetabular impingement. A comparison in dynamic tasks

Hip muscle activity in people with hip-related pain compared to asymptomatic controls: A systematic review

BACKGROUND

Altered hip and thigh muscle activity have been observed across a spectrum of articular hip pathologies, including hip osteoarthritis, femoroacetabular impingement syndrome, and labral pathology. No systematic reviews have examined muscle activity associated with hip pathology and hip-related pain across the life span. A greater understanding of impairments in hip and thigh muscle activity during functional tasks may assist in the development of targeted treatment strategies.

METHODS

We conducted a systematic review using the PRISMA guidelines. A literature search was performed in five databases (MEDLINE, CINAHL, EMBASE, Sports Discuss, and PsychINFO). Studies were included that (i) investigated people with hip-related pain (femoroacetabular impingement syndrome, labral tears) or hip osteoarthritis; and (ii) reported on muscle activity using electromyography of hip and thigh muscles during functional tasks such as walking, stepping, squatting, or lunging. Two independent reviewers performed data extraction and assessed risk of bias using a modified version of the Downs and Black checklist.

RESULTS

Non-pooled data demonstrated a limited level of evidence. Overall, differences in muscle activity appeared to be more prevalent in people with more advanced hip pathology.

CONCLUSIONS

We found that impairments in muscle activity in those with intra-articular hip pathology measured using electromyography were variable but appeared to be greater in severe hip pathology (e.g., hip OA).

Effect of Changes in Iliocapsularis Cross-sectional Area on Hip Arthroscopy Outcomes: Clinical and Magnetic Resonance Imaging Follow-up

Background

The function of the iliocapsularis (IC) muscle is still unclear. Previous studies have reported that the cross-sectional area of the IC may be useful in identifying borderline developmental dysplasia of the hip (BDDH).

Purpose

To evaluate the pre- to postoperative changes in IC cross-sectional area in patients with femoroacetabular impingement (FAI) and to determine if there are any associations with clinical outcomes after hip arthroscopy.

Study Design

Cohort study; Level of evidence, 3.

Methods

The authors retrospectively evaluated patients who underwent arthroscopic surgery for FAI at a single institution between January 2019 and December 2020. Patients were divided into 3 groups according to lateral center-edge angle: BDDH group (20°-25°), control group (25°-40°), and pincer group (>40°). Supine anteroposterior hip radiographs, 45° Dunn view radiographs, computed tomography scans, and magnetic resonance imaging (MRI) scans were obtained for all patients preoperatively and postoperatively. The cross-sectional areas of the IC and the rectus femoris (RF) were measured on an axial MRI slice at the level of the femoral head center. Preoperative and final follow-up scores on the visual analog scale for pain and the modified Harris Hip Score (mHHS) were compared between groups with the independent-samples t test.

Results

A total of 141 patients (mean age, 38.5 years; 64 male, 77 female) were included. The preoperative IC-to-RF ratio of the BDDH group was significantly higher than that of the pincer group (P < .05). In the BDDH group, there was significant pre- to postoperative decrease in IC cross-sectional area and the IC-to-RF ratio (P < .05 for both) as well as a significant correlation between the preoperative IC cross-sectional area and the postoperative mHHS (r = 0.434; P = .027).

Conclusion

Patients with BDDH had a significantly higher preoperative IC-to-RF ratio than patients with pincer morphology. A higher preoperative IC cross-sectional area was associated with better postoperative patient-reported outcomes after arthroscopy for the treatment of FAI combined with BDDH.

No Difference in Hip Muscle Volumes and Fatty Infiltration in Those With Hip-Related Pain Compared to Controls

Background

Little is known about muscle morphology in people with hip-related pain, without signs of femoro-acetabular impingement syndrome (FAIS). Identifying changes in hip muscle volume, fatty infiltrate and establishing relationships between muscle volume and strength, may provide insight into potential early treatment strategies.

Purposes

To: (i) compare the volumes and fatty infiltrate of gluteus maximus, gluteus medius, gluteus minimis, tensor fascia latae and quadratus femoris between symptomatic and less-symptomatic sides of participants with hip-related pain; (ii) compare the volumes and fatty infiltrate of hip muscles between healthy controls and symptomatic participants; and (iii) explore relationships of hip muscle volumes to muscle strength and patient-reported outcome measures in people with hip-related pain.

Study Design

Cross-sectional study.

Methods

Muscle volume and fatty infiltrate (from magnetic resonance imaging), hip muscle strength, patient-reported symptoms, function and quality of life (QOL) were determined for 16 participants with hip-related pain (no clinical signs of FAIS; 37±9 years) and 15 controls (31±9 years). Using One Way Analysis of Co-Variance tests, muscle volume and fatty infiltrate was compared between the symptomatic and less-symptomatic sides in participants with hip-related pain as well as between healthy controls and symptomatic participants. In addition, hip muscle volume was correlated with hip muscle strength, hip-reported symptoms, function and QOL.

Results

No differences in all the studied muscle volumes or fatty infiltrate were identified between the symptomatic and less-symptomatic hips of people with hip-related pain; or between people with and without hip-related pain. Greater GMED volume on the symptomatic side was associated with less symptoms and better function and QOL (ρ=0.522-0.617) for those with hip-related pain. Larger GMAX volume was associated with greater hip abduction and internal rotation strength, larger GMED volume was associated with greater hip extension strength, and larger QF volume was associated with greater hip abduction strength (rho=0.507-0.638).

Conclusion

People with hip-related pain and no clinical signs of FAIS have hip muscle volumes that are not significantly different than those of matched pain-free controls or their less-symptomatic hip. Larger GMED muscle volume was associated with fewer symptoms and greater strength.

Level of evidence

Level 3a.

Anatomical features of the iliocapsularis muscle: a dissection study

Purpose

Iliocapsularis (IC) overlies the anteromedial hip capsule and is an important landmark in anterior approaches to hip arthroplasty. Previously believed to be part of iliacus, few publications describe the prevalence, attachments, fibre direction, blood supply, innervation, and size of IC. This study was aimed to determine these anatomical features using embalmed bodies and whether they vary between sides, sex, and age.

Methods

Thirty-eight formalin-fixed adult bodies were dissected and the prevalence, presence of a connective tissue raphe, attachments, fibre direction, blood supply, and innervation, were documented. Length and width were measured, and significant differences were investigated with t tests.

Results

Iliocapsularis was present in all bodies examined, originating from the inferior border of the anterior inferior iliac spine, and inserting 20 mm distal to the lesser trochanter in 54 muscles (71%). Iliocapsularis was supplied by a thin branch from the femoral nerve and by branches of the lateral circumflex femoral and deep femoral arteries and veins. Muscle fibre direction was from superolateral to inferomedial. Mean length was 116.8 ± 11.2 mm and width was 12.8 ± 3.1 mm, with no significant differences between sides, sex, and age.

Conclusion

This was the first study to document the venous drainage and compare the dimensions with sides, sex, and age, using adult bodies. However, the true function of IC is still unknown. Iliocapsularis is a constant muscle, distinct from iliacus, which is relevant to orthopaedic surgeons and physical rehabilitation specialists, particularly for postoperative patient care.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00276-022-02905-y.

Assessment of the iliocapsularis muscle on magnetic resonance imaging

INTRODUCTION

Morphologic features of Iliocapsularis (IC) may aid clinical decision-making in the symptomatic hip. The relationship between IC muscle size and underlying hip pathology is emerging; however, research is limited in the imaging literature. The purpose of this study was to determine the reliability and reproducibility of measurements of the IC muscle and its MRI appearances. It also looked for any association between IC dimension and axial levels, side, gender and bony features of hip instability.

METHODS

Retrospective study of 37 MRI scans were assessed by four observers. MRI axial T1 images were used to define the IC anatomy, measure the IC and rectus femoris at the femoral head centre (FHC) and adjacent levels and calculate the iliocapsularis-to-rectus femoris (IR) ratio. Measurements were repeated at least 2 weeks later. Radiographic assessment of the lateral centre edge angle, acetabular index and femoral neck-shaft angle were also conducted.

RESULTS

The IC was always present, but was well-defined in only 4% of cases with fair agreement. The intraclass correlation coefficient for reliability and reproducibility was the highest for IC width 0.94 (0.91-0.96). No significant correlation was identified between the IR ratio and radiographic parameters.

CONCLUSION

Iliocapsularis is visible and reliably measured on MRI despite observers considering the muscle to be not well-defined. Despite gender differences in muscle size, the IR ratio was unchanged. There is a significant difference in the IR ratio above and below the FHC; therefore, clinicians need to be aware of how this may impact the clinical use when utilising the IR ratio.

A systematic review and meta-analysis of iliocapsularis muscle: an important landmark in orthopedic surgery

PURPOSE

Iliocapsularis (IC) is a small muscle overlying the capsule of the hip joint. Although recent attention is being given to this muscle by orthopedic surgeons who encounter it during the anterior approach to total hip arthroplasty, little is known about its anatomical features. The aim of this study was to review the anatomy of IC, and describe its' origin, insertion, blood supply, innervation, muscle fiber characteristics and size. The function, clinical relevance and comparative anatomy of IC were also appraised.

METHODS

Using Evidence-Based Anatomy methodology, electronic databases were searched with the terms "iliocapsularis", "iliacus minor", "iliotrochantericus", and "ilioinfratrochantericus" to identify eligible studies.

RESULTS

Six studies (n = 287 lower limbs) examining the anatomy of IC were included. The pooled prevalence (PP) of the IC was 98.7% (95% CI 96.5-100.0). It arises from the inferior facet of the anterior inferior iliac spine (AIIS) and attaches inferior to the lesser trochanter. Attached to the anteromedial capsule along its entire length, IC has the largest capsular contribution of any of the hip muscles (73.8 ± 27.3 × 16.1 ± 4.4 mm). Thus, it is an important landmark in anterior surgical approaches to the hip joint.

CONCLUSION

The anatomy of IC is becoming more relevant with the increasing use of anterior approaches to hip surgery. With attachments to the AIIS, the lesser trochanter as well as the length of the capsule, this muscle is an important landmark in total hip arthroplasty.

LEVEL OF EVIDENCE

Level V.