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Tuesday, June 6, 2023

Relationship between Hip Osteoarthritis and Gluteus Maximus Atrophy

Brent Brookbush

Brent Brookbush


Research Review: Relationship between Hip Osteoarthritis (OA) & Gluteus Maximus Atrophy

By Stefanie DiCarrado DPT, PT, NASM CPT & CES

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

Original Citation: Grimaldi, A., Richardson, C., Durbridge, G., Donnelly, W., Darnell, R., Hides, J. (2009). The association between degenerative hip joint pathology and size of the gluteus maximus and tensor fascia latae muscles. Manual Therapy. 14. 611-617 - ABSTRACT

Note the differences in side (arrows on bottom R) of the gluteus maximus.

Why is this relevant?: Osteoarthritis (OA) of the hip involves degeneration of the cartilage covering the femoral head and acetabulum as well as changes to the bone itself. Therapeutic exercise is often prescribed with varying short and long term outcomes. Information pertaining to specific muscle imbalances surrounding the hip in those with OA allows for a more specific and targeted rehab program with the potential for greater long term results. More importantly, it may provide a means of preventing OA all together using corrective exercise to restore proper muscle balance and prevent joint dyskinesis and excessive surface degeneration.

Study Summary

Study Design Controlled Descriptive Study
Level of Evidence IIa: Evidence from at least 1 controlled study without randomization
Subject Demographics
  • Age (mean):
    • Mild OA: 46.5 + 9.5
    • Advanced OA: 57.7 + 6.7
    • Control: 51.8 + 9.7

  • Gender:
    • Mild OA: 3 males, 3 females
    • Advanced OA: 3 males, 3 females
    • Control: 6 males, 6 females

  • Characteristics: 12 subjects with unilateral hip joint pathology; 12 age & sex matched controls (within 5 years)
    • Mild OA: Weight: 80.4 + 15.1; Height: 171.3 + 9.7
    • Advanced OA: Weight: 78.3 + 8.5; Height: 172.0 + 7.4
    • Control: Weight: 73.5 + 13.3; Height: 18.2 + 10.2

  • Inclusion Criteria: medical diagnosis with Xray/MRI showing OA or "atraumatic, degerative labral pathology" (pg 612).
    • Mild OA: early joint space narrowing and presence of osteophytes
    • Advanced OA: severe joint space narrowing and presence of osteophytes

  • Exclusion Criteria: systemic disease affecting the neuromuscular system, congenital/adolescent hip disease, history of trauma to the hip (including surgery), any inflammatory joint disease, tumors, lower limb injury or low back pain within previous 2 years, unilateral sport participation, use of ambulation assistive device, unable to receive an MRI.  Control group subjects excluded if any history of hip pain.
Outcome Measures
  • No significant side to side muscle volume differences in controls or Mild OA groups
  • No significant muscle volume differences between mild and advanced OA groups
  • No significant relationship between group characteristics, or self reported pain and functional measures and muscle volumes
  • Mild OA: no statistically significant side to side differences
    • TFL 10.5% larger on pathological side
    • LGM smaller on pathological side in 5 out of 6 subjects

  • Advanced OA: significant side to side differences & difference between experimental groups and controls in only gluteus maximus (Gmax) muscle
    • Greater asymmetry in UGM than LGM
    • UGM significantly larger on nonpathological side compared to pathological side
    • UGM significantly larger on nonpathological side compared to controls (30.5% larger)
    • LGM larger on nonpathological side as compared with controls (15.2% larger) - not statistically significant
    • LGM larger on nonpathological side as compared to pathological side - not statistically significant
    • TFL larger on pathological side (10.5% larger) - not statistically significant

ConclusionsMuscle asymmetries and imbalances are associated with hip pathology such as OA.  Further research is needed to determine if the muscle imbalances contribute to or result from the pathology.
Conclusions of the ResearchersThe similarity in muscle volumes of the TFL and UGM (considered more superficial abductors of the hip) on the pathological side as compared to healthy controls may indicate weakness and atrophy in deeper hip abductors such as the gluteus medius (Gmed).  The increase in size of the Gmax on the nonpathological side in individuals with hip OA creates asymmetry and muscle imbalances that may lead to bilateral OA over time.

Note the decreased joint space in Figure 2, a signature sign of hip osteoarthritis.

Review & Commentary:

Researchers implemented a strong methodology that allowed for intra- and inter-subject comparison as only those with unilateral pathology were imaged. They collected data pertaining to pain and function and established leg dominance to note any correlations therein. A skilled medical practitioner collected MRI data and ensured the leg was held stationary to prevent medial or lateral rotation. Both intra-tester and intra-rater reliability were found to be good with a low standard of error measurement.

This study addressed imbalances between the superficial hip muscles: TFL and Gmax . Grimaldi et al 2009, examined deeper muscles such as the Gmed , piriformis , and gluteus minimis (Gmin). Researchers not only looked at specific muscle volumes, but analyzed segments of the Gmax as the upper and lower portion have slightly different fiber orientation and therefore may exert different forces on the joints crossed. The UGM , was considered the portion originating on the posterior iliac crest. The LGM was considered the section originating on the inferior sacrum, upper lateral coccyx (Gibbons, 2004) . Previous studies noted a differentiation in the two parts during early fetal development and different primary functions. According to the authors, the UGM  acts above the rotational axis of the hip resulting primarily in abduction whereas the LGM  acts below the rotational axis of the hip resulting primarily in hip extension as well as absorption of ground reactive force during heel strike at gait. The researchers stated that collectively, both will externally rotate the hip.

The authors reported the following limitations of the study: a small sample size and that muscle volumes were calculated based on the MRI size image. A larger study will solve the first limitation. If the contractile tissue was replaced with a more fatty tissue or dense connective tissue, which can happen with injury and disuse, it will erroneously be included into the volume measures. This may explain the lack of significant change in the LGM  to the same extent as the UGM . The replacement of viable contractile tissue with fatty or connective tissue, "fatty atrophy," has been documented in previous studies (Pfirrmann et al 2005). The authors pointed out that the increased black markings on the MRI images demonstrate differences in tissue quality throughout the LGM , therefore there may have been deterioration in that portion of the muscle.

Why is this study important?

This study is important because it clearly shows a relationship between muscle volumes and hip pathology. Hip musculature imbalances can change not only the resting position of the hip, but the resultant vector of movement which places excessive load onto certain areas of the bony surfaces and creates excessive wear on the cartilage. Additionally, the resulting pain may cause decreased weight bearing on the affected side creating further side to side asymmetry and further dysfunction. It would be beneficial to reassess the subjects continually and create a longitudinal study in the event subjects develop bilateral hip OA over time.

How does it affect practice?

The function of hip musculature must be assessed during functional movement patterns and individually muscle may need to be assessed for increased/decreased muscle bulk and altered neuromuscular activity. Any asymmetries or muscle imbalances must be fixed to ensure proper joint function and prevention of future injury. Typically, the Gmax  is found to be inhibited and weak with a synergistically dominant TFL . The findings within this study, particularly that of the atrophy of the LGM on the pathological side in hip OA supports previous findings of underactivity in the Gmax with local dysfunction: sacroiliac joint pain, knee valgus, and an anterior pelvic tilt (Hungerford, Gilleard, Hodges (2003)  & Padua, Bell & Clark (2012)  & Tateuchi, Taniguchi, Mori, Ichihashi, (2013) ) and dominance/over-activity of the TFL  (Padua et. al. (2012)  & Tateuchi et. al (2013) ). Research has shown it is possible to activate the GMax while reducing activity of its over-active synergists (biceps femoris  and TFL ) (Selkowitz, Beneck, & Powers. (2013)  & Kan, Jeon, Kwon, Cynn, Choi (2013) ).

If the client is in significant pain, they may require the attention of a medical practitioner (Physical Therapist or Orthopedic MD) to evaluate joint mobility and assist in correcting the decreased joint space or joint dyskinesis. These clients may be excellent candidates for TFL release and stretching , self-administered hip joint mobilization , and especially gluteus maximus activation (see below).

How does it relate to Brookbush Institute Content?

Muscle hypertrophy on the nonpathological side may indicate "favoring" of the pathological side. This is most notable as an antalgic (painful) gait or an "Asymmetrical Weight Shift" in the "Overhead Squat Assessment"  - in which the person bears little weight on the painful side and increases weight-bearing on the unaffected side. The model employed by the Brookbush Institute addresses obstructive dysfunction first followed by asymmetries (which are often one in the same) - described in the video below.

The hip, as part of the lower extremity, is subjected to ground reaction forces and alterations in mechanics of the entire lower extremity. With that being said, Lumbo Pelvic Hip Complex Dysfunction (LPHCD), Sacroiliac Joint Dysfunction (SIJD) , as well as, Lower Leg Dysfunction (LLD)  may have an impact on hip mechanics, and should be considered when constructing an intervention for hip osteoarthiritis. In the predictive models of LPHCD, SIJD and LLD , the TFL and other hip flexors are often short and overactive with the Gmax  long and under-active. The Brookbush Institutes promotes hip extension with abduction to increase recruitment of the Gmax over its synergist, the hamstrings , which has been supported by a study by Kan et al. (2013) . The videos below demonstrate TFL release and stretching, self-administered hip joint mobilization, and gluteus maximus activation:

How to decide which dysfunction to address first?

Ober's Test (TFL Flexibility Assessment)

Hip Mobilization

Glute Activation Circuit


1. Grimaldi A, Richardson C, Stanton W, Durbridge G, Donnelly W, Hides J. The association between degenerative hip joint pathology and size of the gluteus medius, gluteus minimus, and piriformis muscles, unpublished

2. Gibbons, S.G.T. (2004) The anatomy of the deep sacral part of the gluteus maximus and the psoas muscle: A clinical perspective. Proceeds of: The 5th interdisciplinary World Congress on Low Back Pain. November 7-11, Melbourne, Australia

3. Pfirrmann CWA, Notzli HP, Dora C, Hodler J, Zanetti. (2005). Abductor tendons and muscle assessed at MR imaging after total hip arthroplasty in asymptomatic and symptomatic patients. Radiology. 235:969–76.

4. Kan, S., Jeon, H., Kwon, O., Cynn, H., Choi, B. (2013). Activation of the gluteus maximus and hamstring muscles during prone hip extension with knee flexion in three hip abduction positions. Manual Therapy 18, 303-307

© 2014 Brent Brookbush

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