Gluteus Medius Strengthening and the Use of the Donatelli Drop Leg Test on the Athlete

The gluteus medius serves as an integral component in the kinetic chain of the athlete, and is now commonly described separately and as having several anatomic subdivisions.1 The posterior fibers have been described to function as the primary segment active in stabilizing the femoral head in the acetabulum during weight transfer2, and to contribute to external rotation of the femur relative to the stable pelvis.1,3

Neumann reported the importance of the posterior segment of the gluteus medius in lunging and jumping by showing that the gluteus maximus produced less external hip rotational torque at hip flexion angles greater than 60 degrees. With greater hip flexion, a shift of the anterior fibers of the gluteus maximus anterior to the hip joint axis of rotation turns the anterior gluteus maximus into an internal rotator rather a femur stabilizer.1 In this situation, the posterior fibers of the gluteus medius act with the deep external rotators to provide control.3

Compromise of the gluteus medius has been linked most commonly to ankle inversion and knee injuries including: patellofemoral tendonitis, iliotibial band syndrome, anterior cruciate ligament tears, and medial collateral ligament tears. Powers et al. described an increased knee valgus posture and a shift of the center of mass as a means of biomechanical compensation for hip abductor weakness.3

The Drop Leg Test

The majority of current gluteus medius rehabilitation protocols utilize exercises with the hip in slight flexion, including the clam, closed chain lateral lunges, and side lying abduction without extension. The purpose of the Drop Leg Test is to establish a manual muscle test more specific for the inclusion of posterior fibers of the gluteus medius. The authors propose that the Drop Leg Test isolates weakness of the posterior fibers of the gluteus medius because of the emphasis on extension and abduction with the leg in neutral position. As the gluteus maximus is a primary external rotator of the femur with the leg in neutral position, hip abduction with extension reduces the gluteus maximus role as an external rotator and thus emphasizes the posterior fibers of the gluteus medius.

The Drop Leg Test is performed from the side lying position. The clinician passively abducts the leg to the end of the hip abduction range of motion and then extends the hip 20°. While holding the leg in the abducted and extended position, the patient is asked to maintain this leg position while the clinician lets go. A shortened lever arm with hip extension changes the gluteus medius angle of pull, thus requiring the abductor muscle to develop greater force, recruiting more fibers to counterbalance the effect of gravity.1

The test has exposed significant muscle deficits that would have been missed by testing in flexion or neutral position. With the weakness of the posterior segment of the muscle, the patient will be unable to hold the leg in the abducted and extended position and the leg will drop inches until the muscle lever arm is elongated and the muscle is capable of developing enough strength to stop the fall of the leg. If the limb drops several inches and the patient is able to hold the leg in abduction and extension, a manual muscle test may be performed to further determine the muscle deficits.


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References
  1. Neumann, D. A. (2002). Kinesiology of the musculoskeletal system (2nd ed.). St. Louis MO: Mosby Inc.
  2. Gottschalk, F., Kourosh, S., & Leveau, B. (1989). The functional anatomy of tensor fasciae latae and gluteus medius and minimus. Journal of Anatomy, 166, 179e 189. Retrieved from SCOPUS database.
  3. Powers, C. M. (2010). The influence of abnormal hip mechanics on knee injury: a biomechanical perspective. Journal of Orthopaedic and Sports Physical Therapy, 40(2), 42e51. Retrieved from SCOPUS database.