The gluteus maximus works with the semitendinosus and semimembranosus muscles to extend the hip. The muscle also works in conjunction with the iliopsoas, piriformis, and the obturator muscles to externally rotate the hip.

The literature documents anatomical and biomechanical variation of the gluteus maximus. One study focused on the muscle’s variability regarding its moment arms (the of length between the joint axis and line of force acting on that joint) in a sample population. The study results demonstrated high variability in the gluteus maximus muscle and attributed these results to the variation in insertion points along the iliotibial tract and gluteal tuberosity.[12]

Variation of the gluteus maximus also involves physiological differences. In athletes, the gluteus maximus muscle is among the most important to train due to its action of extension of the hip joint which translates to explosive movements. A 2018 study looked at the correlation between gluteus maximus muscle to quadriceps femoris ratio in faster athletes compared to slower athletes. Results yielded that the larger the ratio, the faster the athlete.[13]   

Another 2018 study suggests that associated hip muscles may become more atrophied after hip arthroplasty, but larger cohorts would be needed to clarify the results.[14] Variability in the neuromuscular activity of the gluteus maximus in patellofemoral pain syndrome compared to healthy individuals was also documented.[15]

Posterior Approach to the Hip Joint

The gluteus maximus muscle is involved in many surgical approaches that involve the joints around the muscle. The posterior approach to the hip joint involves the gluteus maximus to a significant degree. An incision near the posterior aspect of the greater trochanter reveals the gluteus maximus. The muscle is then completely incised to reveal the posterior aspect of the joint capsule. Due to the anatomy of the superior and inferior gluteal arteries, splitting the muscle will inevitably cause bleeding of the vessels, so bleeding is expected. Incising the vessels might be advantageous as the surgeon will be able to cut and coagulate them before being avulsed during retraction. The incision does not risk denervation because the muscle receives its supply medial to the split.[16]

Other Approaches

The anterolateral approach to the hip mainly involves retracting muscles such as the gluteus medius and tensor fascia lata to gain access to the anterior capsule of the hip joint. During dislocation of the femoral head from the acetabulum, the fibers of the gluteus maximus are incised to gain greater access to the joint.[17]  

The posterior approach to the sacroiliac joint also involves the gluteus maximus. This specific approach allows for open reduction and internal fixation of disruptions of the sacroiliac joint. Although this approach is not used widely due to percutaneous screw fixation techniques, it becomes an important procedure if appropriate imaging is not needed. First, the gluteus maximus is exposed by an incision along the iliac crest. The muscle is then detached from its origin on the ilium and is reflected downward and laterally.  Two structures that are at risk of injury are inferior gluteal nerve and inferior gluteal artery. Both neurovascular structures penetrate the gluteus maximus and are imperative for its function. Therefore, careful inferior mobilization of the muscle is warranted. The gluteus maximus is also of importance during the posterior approach to the acetabulum. Much like the approach posterior approach to the iliac crest, it also involves retracting the gluteus maximus. However, when the muscle is exposed, the muscle is retracted superiorly by removing the insertion point on the proximal femur.[18]

Uses of the Gluteus Maximus During Surgery

The gluteus maximus also plays an important role in reconstructive surgery, which is especially so for myocutaneous flaps employing the gluteus maximus for the treatment of ischial and sacral ulcers. This procedure allows for a simple procedure that provides adequate thickness to cover bony prominences and to cover the lesion.[19][20]

 The gluteus maximus is also useful to address surgical complications, particularly after hip arthroplasty. Indications for using the gluteus maximus advancement flap procedure include persistent wound breakdown due to infection leading to soft tissue deficiency, aseptic pseudotumor, and abductor insufficiency with recurrent hip instability. Results for patients that underwent this procedure correlated with no repeat infection or hip instability.[21][22] Therefore, using the gluteus maximus advancement flap procedure for hip instability should be on considered a treatment option for surgeons after hip arthroplasty. Reconstruction after resection of tumors has also used myocutaneous gluteus maximus flaps.[23]

Arthroscopy is also important in the case of gluteus maximus dysfunction. Post-op arthroscopic results for the treatment of femoroacetabular impingement have shown to improve function and contraction of the gluteus maximus.[24]

Gluteus maximus function is testable in the clinical setting. The test begins with the patient in the prone position with the lower limb straight. The patient tightens the buttocks as much as possible while the examiner palpates the gluteus maximus and feels for contraction. Gluteus maximus dysfunction is most likely due to inferior gluteal nerve dysfunction; this would cause difficulty in rising from a seated position, climbing up stairs and loss of hip extension. The most common cause of inferior gluteal nerve dysfunction is a posterior hip dislocation. Another etiology is incorrect intramuscular (IM) injection placement. IM injection placement should be in the upper outer quadrant of the buttock. Otherwise, both the inferior and superior gluteal nerves are at risk of injury.[25]

Paralysis of the gluteus maximus does not affect walking on a plane surface. The gluteus maximus only contracts during a part of the stance phase. This phase occurs when the heal strikes the ground to when the foot is flat. The gluteus maximus works by resisting further flexion of the hip and initiate extension. The gluteus maximus actively functions when climbing upstairs or lifting from a seated position.[26]