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Anatomy of the Hip Capsule and Muscular Attachments

Tuesday, June 6, 2023 - 10 Likes

Brent Brookbush

Brent Brookbush

DPT, PT, MS, CPT, HMS, IMT

Research Review: Anatomy of the Hip Capsule and Pericapsular Structures

By Erik Korzen, DC, NASM CES

Edited by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation:

Cooper, H., Walters, B., Rodriguez, J. (2015). Anatomy of the Hip Capsule and Pericapsular Structures: A Cadaveric Study. Clinical Anatomy 28: 665-671. ABSTRACT

Why is this relevant?: The hip joint is a complex anatomical structure with relationships to often cited soft tissue structures, and other relationships that are less commonly cited. This research study attempts a detailed view of all structures that invest in the hip capsule. The hip joint is important in all load bearing activities and may be viewed as the pivotal structure between the core and lower extremity. As the hip joint is affected by motion of proximal and distal joints , a thorough understanding of capsular attachments may be imperative for optimal rehabilitation and performance enhancement interventions.

Right Posterior Hip GMin= gluteus minimus, *= capsule, PF= piriformis, CJ= conjoint tendons, OE= obturator externus, GT= greater trochanter, LT= lesser trochanter

Study Summary

Study Design Quantitative Analysis
Level of Evidence Level III: Evidence from non experimental descriptive study
Subject Demographics
  • 11 fresh-frozen cadavers
  • Mean Age 79.2 (at time of death)

  • Mean Body Mass Index (BMI) 24.6 kg/m2

Outcome Measures
Results
  • Piriformis muscle had NO contribution to the hip capsule
  • Iliocapsularis muscle had longest capsular contribution (mean of 73.8x16.1mm near anteromedial border)
  • Gluteus minimus tendon had large, broad insertion laterally (mean of 68.8x28.1 mm near superolateral border)
  • Conjoint tendons (obturator internus and gemelli muscles) have small, consistent capsular contributions
  • Capsular origin located approximately 13.0mm distal to Anterior Inferior Iliac Spine (AIIS) and 11.1mm lateral to pectineal eminence
    • capsular origin thickest superior and thinnest anteriorly

  • Capsular insertion located approximately 12.2mm distal and medial to tip of greater trochanter and 13.6mm proximal to lesser trochanter
    • capsular insertion thickest inferiorly and thinnest posteriorly

  • Acetabular origin of capsule thickest posterosuperior (mean 4.0mm) and thinnest anterior/anteroinferior (mean 1.3mm) locations
  • Center of capsule thickest posterosuperior (mean 4.2mm) and thinnest posteroinferior (mean 1.6mm) locations
  • Femoral insertion of capsule thickest anterosuperior (mean 2.5mm) and thinnest posterior (mean 0.7mm)
Conclusions of the Researchers
  • This study includes some of the first descriptions of gluteus minimus capsular attachments
    • suggested that this might retract capsule during hip motion to prevent entrapment

  • Iliocapsularis muscle routinely originated partly from near the AIIS, mainly from anteromedial hip capsule overlying anterior femoral head
    • suggested that his might tighten the capsule, helping to stabilize femoral head within dysplastic acetabulum

  • Knowledge of these structures and their relationships near the hip capsule is useful for surgical procedures (open and arthroscopic) as well as for biomechanical applications
 ConclusionsHuman movement professionals may need to consider both the thickness of various parts of the capsule and how that may relate to arthorkinematic dyskinesis, as well as give additional consideration to the gluteus minimus, rectus femoris and deep rotators of the hip relative to hip pain and performance.

Review & Commentary:

This study provides a unique perspective for human movement professionals through the use of cadaveric dissections. Anatomists, surgeons, physicians, therapists and trainers can all benefit from developing a deeper understanding joint anatomy. The acetabulofemoral joint (hip joint) is classically thought of as being stabilized by 3 main ligaments (iliofemoral, pubofemoral and ischiofemoral) via attachments into the capsule. However, ligaments are passive structures and further consideration should be given to the active structures highlighted in this study and their affect on the hip capsule. Since the hip joint is situated as the link between the lower extremity and trunk, it is functionally important to bear weight statically and dynamically.

Weakness and limitations

  • Digital calipers require manual manipulation and may not be as accurate as a 3 dimensional coordinate measuring system
  • Small sample size
  • Advanced age of sample could skew results due to age-related changes (comparison to imaging of a younger population may increase transferability of data.
  • Lack of histological analysis to determine composition (collagen type) of capsular contributions

Strengths

  • Quantitative information of capsular contributions
  • Beneficial knowledge to reduce iatrogenic injury (injuries caused by physician) during surgical procedures
  • Consistent and predictable findings between cadavers

Why is this study important?

Human anatomy is often segmented into different systems, especially when learning through through cadaveric dissection. As the knowledge base of human anatomy continues to expand, there is more focus on the interconnectedness of these systems, as opposed to the function of each as distinct and separate. This study demonstrates this concept well through quantitative measurements, indicating that certain muscles act on the hip capsule more than others and in specific locations. Although the study relates the cadaveric dissection to surgical procedures, there are biomechanical concepts that can be drawn from the findings.

How does it affect practice?

Many individuals will exhibit pathologies and performance impairments related to dysfunction of the lumbo pelvic hip complex and lower extremity, including pain in the hip itself. Functional anatomy knowledge is the foundation for designing any exercise or rehab intervention. This study provides evidence of capsular thickness patterns and muscular attachments which could imply optimal interventions for addressing hip motion. For example, the piriformis muscle (the largest of the "external rotators") has no capsular attachments whereas the conjoint tendons and obturator externus do have consistent capsular attachments. This may indicate that releasing the piriformis muscle, while indicated for certain conditions, may not have any direct impact on the hip capsule itself and that release of the deep rotators of the hip may provide better outcomes.

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSkKtfe_Y4G9znFPV6cy8m02VQ9GnedGYPqOt11DMfNHZI37Tea

How does it relate to Brookbush Institute Content?

The Brookbush Institute discusses dysfunction of the hip joint in both the predictive models of Lower Leg Dysfunction (LLD) and Lumbo Pelvic Hip Complex Dysfunction (LPHCD), as well as the variation of LPHCD, Lumbosacral Dysfunction . The muscles noted in this study, with the exception of the iliocapsularis muscle, are discussed and techniques are recommended for each in these predictive models (for more info, follow the hyperlinks above). The iliocapsularis muscle, while not commonly discussed in any text, could mimic iliacus , psoas or pectineus muscle issues based solely on anatomic location. Further research is needed. This study does a wonderful job on noting the variations in capsular thickness based on anatomical location, and this information will be included in future articles relative to commonly noted patterns of arthrokinematic dyskinesis.

Self-administered Hip Mobilization

Gluteus Minimus Release:

Piriformis and Deep Rotator Release:

Rectus Femoris Release:

Kneeing Hip Flexor Stretch:

© 2015 Brent Brookbush

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