The peritrochanteric space is located between the greater trochanter and iliotibial band. The boundaries of this space are formed by tensor fascia lata muscle anteriorly, the insertion of the gluteus maximus tendon to the femur just below the vastus lateralis inferiorly, and the gluteus medius and minimus tendons superiorly.

The greater trochanter of the hip, much like the greater tuberosity of the humerus, has an osseous contour that reflects the attachments of the gluteal muscles.

Four facets on the greater trochanter have been described⁷: anterior, lateral, superoposterior, and posterior facets (FIG 1).

The gluteus medius is a large, fan-shaped muscle consisting of three equal-sized segments—the anterior, middle, and posterior—that originates from the external surface of the ilium. Each segment is innervated by a separate branch of the superior gluteal nerve. Its tendon attaches at two distinct facets on the greater trochanter. The anterior and most of the central fibers are attached to the lateral facet, and the posterior fibers are attached to the superoposterior facet¹⁶ (FIG 2).

The anterior and central insertion of the gluteus medius tendon on the lateral facet is rectangular in shape, occupying an area of approximately¹⁶ 440 mm². The portion of the tendon inserting into the superoposterior facet is more robust, with a circular shape, and a smaller surface area of approximately¹⁶ 200 mm².

The fiber orientation of the gluteus medius is thought to correlate with function during the gait cycle. The anterior and middle muscle segments are vertically oriented and aid in initiating hip abduction.⁸ The anterior segment also externally rotates the pelvis during the swing phase of the contralateral limb.⁸ The fibers in the posterior segment are more horizontal and act to stabilize the hip joint at heel strike.⁸

The gluteus minimus also originates from the external ilium, running between the anterior inferior and posterior inferior iliac spines.¹

Distally, the gluteus minimus tendon attaches via two heads— the capsular head is fascial thickening that inserts into the
superior aspect of the hip capsule, just anterior to greater trochanter at the iliofemoral ligament.¹ The long head inserts on the inner aspect of the anterior margin of the greater trochanter at the anterior facet. The trochanteric insertion of the gluteus minimus is separated from the gluteus medius tendon footprint on the lateral facet by the trochanteric bald spot (FIG 3).

The gluteus medius and minimus muscles have been likened to rotator cuff of the shoulder.³,¹⁰ The gluteus medius has a moment arm similar to both supraspinatus and infraspinatus with its lateral and superoposterior insertion on the greater trochanter.³ The gluteus minimus inserts on the anterior facet and has several different moments depending on the position of the femur relative to the pelvis—it can affect flexion, abduction, external, and internal rotation; and when these moments are counterbalanced, it acts as a primary stabilizer of the head in the socket.¹ Due to the strong internal rotation moment of the gluteus minimus in many functional positions, its action is also analogous to the subscapularis (FIG 4).

When repairing tears of the gluteus medius, familiarity with the insertional anatomy is essential to prevent overestimation of the size of the true tendon footprint. Incorporation of the bald spot into an anatomic footprint repair of the medius tendon can occur if anchors are mistakenly placed in the bald spot of the trochanter—a situation that should be avoided.¹⁷

Tears of the gluteus medius and minimus tendons were first described in the late 1990s and much like rotator cuff tendon tears in the shoulder, most likely result from a degenerative process.³,¹⁰,¹⁶

Tears of the gluteus medius can be interstitial, partial thickness or full thickness, with full-thickness tears tending to be large in size.¹⁶

Tears of the gluteus medius are significantly more common than those of the minimus. It follows that most tears occur in the anterior portion of the gluteus medius tendon as it attaches to the lateral facet of the greater trochanter.

Tear propagation occurs by degeneration of the undersurface of the tear progressing posteriorly into a full-thickness tear.

Tears were initially identified in the setting of open release of the iliotibial band for recalcitrant trochanteric bursitis,¹⁰ total hip arthroplasty,⁹ and femoral neck fracture treatment.³

In performing iliotibial band release for trochanteric bursitis, Kagan¹⁰ found a partial tear of the gluteus medius in seven patients that was picked up on magnetic resonance imaging (MRI) but not on physical examination. Tears were repaired with nonabsorbable suture through bone tunnels and all patients were pain free at a median follow-up of 45 months.

In a series of 176 consecutive patients undergoing total hip arthroplasty for osteoarthritis, Howell et al⁹ found that 20% of the patients had degeneration of the abductor muscles with majority occurring in elderly women.

In a prospective study of 50 consecutive patients being treated for femoral neck fractures, Bunker et al³ found rotator cuff tears of the hip in 22% of patients. The typical appearance was described as a circular or oval defect in the insertion of gluteus medius and minimus tendons. The tears had a rolled edge and were often associated with free fluid in the trochanteric bursa and an eburnated underlying surface of the greater trochanter.³

A traumatic etiology in otherwise normal hips in the background of abductor tendinopathy is less common but can occur.¹³,¹⁵

Tendinopathy and tears of the abductor tendons are a common cause for intractable pain along the lateral side of the hip.

In patients with greater trochanteric pain syndrome (GTPS) where conservative management has failed, a high index of suspicion should be maintained for an abductor tear.

In keeping with a degenerative etiology, patients describe lateral-sided hip pain that is insidious in onset and is usually debilitating.

Degenerative abductor tear states likely to represent a continuum of pathology with partial-thickness tears eventually progressing to full-thickness tears over time if left untreated, much like the rotator cuff of the shoulder.

Tears are four times more common in women than men and the prevalence increases with age.¹⁸ It is estimated that 25% of middle-aged women will develop a tear of the gluteus medius tendon. The increased incidence in women may partly be related to the wider female pelvis.⁹

A full-thickness tear of the abductors is likely to cause severe lateral pain and a significant limp, resulting in a poor prognosis for those left untreated after failure of conservative management.