Anatomical Investigation of the Gluteus Medius Muscle Innervation and Its Topographical Correspondence With Myofascial Trigger Points.

Background and Purpose: Hip pain, a common complaint among adults that often causes functional disability, can be caused by femoroacetabular impingement, labral injuries, stress fractures of the femoral neck, avascular necrosis of the femoral head, osteoarthritis of the femoroacetabular joint, hip fractures, greater trochanteric pain syndrome, pathology of the lumbar spine and sacroiliac joint, and myofascial pain syndrome (MPS). MPS is characterized by the presence of hyperirritable nodules, known as myofascial trigger points (MTPs), within muscles and fascia. MTPs limit the range of motion of the joints. Moreover, they induce a local contraction response triggered by mechanical stimulation. The stimulation of MTPs induces pain and sensory changes that can be localized or referred. The MTPs present in the gluteus medius muscle play a role in inducing patellofemoral pain, pain in the lower limbs, anterior region of the knee and thigh, and lower back; however, the anatomy of MTPs remains to be elucidated. This study is aimed at relating the entry points of the superior gluteal nerve into the gluteus medius muscle with the MTPs described in the literature via anatomical dissection. Method: Twenty gluteus medius muscles of 10 adult cadavers were divided into four areas: posterosuperior, posteroinferior, anterosuperior, and anteroinferior. The distribution of the nerve branches was classified according to these predetermined areas. Statistical analyses were performed using Poisson distribution and logarithmic link function, followed by Bonferroni multiple comparisons (p < 0.05). Results: All areas of the gluteus medius were innervated by the branches of the superior gluteal nerve. A significantly greater number of nerve entry points was observed in Areas II and IV (posterosuperior and anteroinferior, respectively). Conclusion: The areas of penetration of the superior gluteal nerve correspond to the clinically described MTPs.