Prevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controls.
Level 4 - case-series / case-control
Case-control study comparing individuals with chronic non-specific low back pain to matched healthy controls.
PubMed 26006705 · doi:10.1007/s00586-015-4027-6
What was done
Researchers evaluated 150 patients with chronic non-specific low back pain (LBP) and 75 matched healthy control subjects. All participants underwent a standardized physical examination including manual muscle testing of the tensor fasciae latae, gluteus medius, and gluteus maximus, functional assessment via the Trendelenburg sign, and palpation tenderness testing over the lumbar, gluteal, and greater trochanter regions. Differences between groups and sides were analyzed using Friedman's test, Cochran's Q test, and Mann-Whitney U tests, followed by hierarchical linear regression to identify predictors of LBP.
What was found
Gluteus medius strength was significantly reduced in individuals with LBP compared to healthy controls and compared to the unaffected side (p < 0.001). The Trendelenburg sign was significantly more prevalent in the LBP group (p < 0.001). Palpation tenderness across the paraspinals, gluteals, and greater trochanter was also significantly higher in patients with LBP (p < 0.001). In hierarchical linear regression controlling for BMI, gluteus medius weakness, regional low back tenderness, and male sex were independent predictors of LBP. Specific percentages, means, and effect sizes were not reported in the abstract.
Why it matters
This study documents a strong cross-sectional association between gluteus medius impairment, pelvic instability signs, and chronic non-specific low back pain, highlighting hip abductor function as a potential target for clinical evaluation and rehabilitation.
Limits
The cross-sectional design precludes establishing whether gluteus medius weakness is a cause or consequence of chronic low back pain. Muscle strength was assessed via manual muscle testing rather than objective dynamometry, introducing potential examiner bias. Exact prevalence values, effect sizes, and confidence intervals were omitted from the abstract.