12 of 12 Top Hip Papers of 2024 | Contribution of hip abductor muscles to hip joint stability
Here we are, on the final day of my 12 Hip Days of Christmas for 2024! I hope you enjoyed catching up on the 12 top hip papers of 2024 - papers that have contributed to our understanding of hip conditions and/or the assessment or management of hip pain or injury. If you haven't already, you can pick up the ebook for the 12 top hip papers of 2023 series. Keep an eye out in January for the ebook from the 2024 series.
Our last paper is one that looked at the contributions of the hip abductor muscles to rotational and distractive stability of the hip. I hope you enjoy this last edition, and don't forget this in your last day to take advantage of my Christmas gift ...
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12 of 12 Top Hip Papers of 2024: Contributions of the hip abductor muscles to rotational and distractive stability of the hip1
Background:
While the gluteus minimus and medius and often considered to be important stabilisers of the hip joint due to their architecture and close relationship with passive joint structures, there is not actually a lot of hard scientific evidence to support the role of the abductors in joint stability. This research team aimed to investigate this role in a cadaveric study.
Study Aim:
This study aimed to:
i) establish a reproducible biomechanical cadaveric model of the hip abductor complex, and
ii) assess the effects of loading the Gluteus Minimus (GMin) and Gluteus Medius (GMed) on femoral rotation and distraction.
What was done:
A controlled laboratory study, using cadaveric models.
- All soft tissues were resected from 10 cadaveric hemipelvises, leaving the capsule and distal GMed and GMin structures.
- The hips were secured to a multiaxial hip jig.
- Muscle loads were applied via cables, pulleys, and weights attached to the tendons to replicate the lines of action.
- 4 muscle loading states were tested: (1) unloaded, (2) with GMin loaded, (3) with GMed loaded, (4) with both GMin and GMed loaded.
- Hips were tested under internal rotation; external rotation; and axial traction forces at 0°, 15°, 30°, 60°, and 90° of hip flexion.
The cadaveric hips were prepared so that only the passive joint structures and the distal portions of the gluteus medius and minimus remained. Cables, pulleys and weights were used to test the rotational and distractive stability provided by these muscles through sagittal range.
Key Findings:
- Both the GMin and GMed stabilize the hip against rotational torques and distractive forces, with their relative contributions determined by position of hip flexion.
- GMin and GMed resisted internal rotation torques at all hip flexion angles except 60°. GMin was required at 90°.
- GMin and GMed resisted external rotation torques at all hip flexion angles except 0°. GMed was required from 30°.
- GMin and GMed resisted distractive forces at all hip flexion angles.
Clinical Implications:
- The GMed and GMin work together with passive joint stability mechanisms to resist extremes of hip rotation and distraction.
- Optimising hip abductor muscle function has the potential to augment hip joint stability.
- Additional muscular support is required to check internal rotation at 60° and external rotation of the extended hip.
The findings of this study support the beliefs that the gluteus medius and minimus provide important rotational and distractive stability for the hip joint.
However, there are a couple of ranges through the sagittal plane, where the abductors alone are not sufficient in providing rotational support for the hip:
- At 60 degrees hip flexion, gluteus medius and minimus are insufficient to control forced internal rotation.
- Through this range, the lines of action of the GMed and GMin are close to the centre of rotation and the fibres that are external rotators in lower ranges of hip flexion are shifting to become internal rotators.
- Through this range, there also won't be high capsuloligamentous tension. This means we really need something else to control hip internal rotation in this range.
- The deep external rotators and gluteus maximus will be important contributors here.
- In hip extension (0 degrees hip flexion), gluteus medius and minimus are insufficient to control forced external rotation.
- This may be one of the reasons that the hip is often so challenged and painful in hip extension, if the passive stability systems are insufficient and overloaded (e.g., at end stance phase).
- What other muscles can help? Well, we don't have any primary hip internal rotators, but the iliacus has a small moment arm for internal rotation, and parts of the adductor muscle group can also contribute.
This is an area that would certainly warrant further investigation, considering the challenges we face in controlling symptoms in some of our patients' hips - particularly against that combination of hip extension and external rotation.
Like to learn more about managing hip joint related pain?
In this course, you can find information on pathoaetiology, assessment and management of hip joint related pain, and other soft tissue and nerve related anterior hip and groin pain conditions. To learn more, take the anterior hip and groin pain online course, or join me in an anterior hip and groin pain workshop.
This online course is included in Hip Academy and Hip Academy members receive discounts for online workshops.
Thank you to all the authors of the papers featured in this year's 12 Top Hip Papers of 2024! Your contributions are essential to assist clinicians to better understand, assess and manage hip pain, and optimise outcomes for those suffering with such conditions.
I hope readers enjoyed the key learnings and infographics that I have shared acros the 12 Hip Days of Christmas for 2024. Thanks once again for joining me, and don't forget to keep an eye out for the ebook in January.
Have a wonderful Christmas or Holiday period, and I look forward to catching up with many of you in Hip Academy, or in online or practical workshops over 2025!
Cheers,
Alison
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