Bursae enable improved muscle mechanics over the lateral part of the proximal femur; most people have three to four bursae surrounding the lateral aspect of their hips. The largest bursa is found between the gluteus maximus muscle and gluteus medius tendon, which is located directly lateral to the greater trochanter and most often implicated in trochanteric bursitis. Increased acetabular anteversion has been associated with gluteal and trochanteric bursitis.³ Correlations have also been noted in patients with trochanteric bursitis and lumbar degenerative disease, and patients with concomitant lumbar degenerative disease as seen on scintigraphic imaging have been shown to be less likely to respond to treatment.⁴ According to a 2021 study, obesity, smoking, the presence of emotional distress, fibromyalgia, and hypothyroidism are correlated to an increased risk of poor clinical outcomes in patients with trochanteric bursitis.⁵

Abductor tears, typically at the gluteus medius and/or minimus musculotendinous junction, are a common underlying etiology for lateral hip pain and are often referred to as the rotator cuff tears of the hip. Although inflammation of the tendon is not necessarily a major feature, an element of tendinosis is typically present before tearing.⁶ In particular, the anterolateral part of the gluteus medius tendon is more prone to tears because of a thin tendinous portion.³ Relative risk factors for abductor tears include increased pelvic width, increased body weight moment arm and abductor moment arm, decreased femoral anteversion and enthesophyte present with the teardrop distance, and the presence of enthesophytes being the most predictive.⁷ The presence of an enthesophyte on the greater trochanter had an odds ratio of approximately 21 and a positive predictive value of 94% for having an abductor tendon tear.⁷,⁸ Additionally, as discussed in a 2020 study, patients with ischiofemoral impingement have a higher prevalence of gluteus medius/minimus partial-thickness and full-thickness tears and thus may have a related pathophysiology.⁹ Abductor tendon tears can also occur after undergoing arthroplasty for a femoral neck fracture or following elective total arthroplasty, and tendon dysfunction with avulsion or failure of repair following an anterolateral approach can also occur.¹⁰ Abductor tendon tears should be confirmed with MRI.

The external snapping hip is produced by the ITB snapping over the prominence of the greater trochanter during flexion and extension. Snapping hip syndrome is characterized by audible snapping and is frequently accompanied by pain, weakness, and a resulting loss of range of motion.¹¹ Although painless snapping in the hip is common in the general population, the symptomatic snapping hip with debilitating pain and weakness is more commonly seen in those who take part in activities such as ballet and running hurdles. The diagnosis can be made using dynamic ultrasonography to observe the snapping tendon in real time. Most patients with snapping hip can be treated nonsurgically; however, surgery may be indicated if the condition becomes chronically symptomatic.

Fortunately, most cases of GTPS are self-limited with nonsurgical measures. There is a wide variety of nonsurgical treatment options for peritrochanteric space pathology/GTPS, including home therapy, insoles and orthotics, formal physical therapy, eccentric physical therapy injections, shockwave therapy, platelet-rich plasma injections, and drug therapy.⁶,¹²,¹³ Corticosteroid injections have been shown to be the most effective at pain relief, without any additional benefit derived from image-guided injections.¹²,¹³ Ultrasound-guided and anatomic landmark injections of the trochanteric bursa have similar 2-week and 6-month outcomes; however, ultrasound guidance is more expensive and less cost effective; thus, anatomic landmark-guided injection remains the method of choice and should be routinely performed using a sufficiently long needle of at least 2 inches.¹⁴ The most effective treatment options were infiltrations with corticosteroids, resulting in symptom resolution in 49% to 100% of patients, and shockwave therapy.⁶,¹⁵ Both adjuncts are excellent to help improve patient symptomatology to enable better participation in physical therapy.¹³ Advancements in nonsurgical treatment modalities for tendinopathy continue to be developed, and some promising avenues include topical glycerol trinitrate therapy, matrix metalloproteinase-inhibitor injection, gene or stem cell therapy, autologous tenocyte injection, and sclerosant injections.¹²

Surgical interventions have anecdotally been reported to provide pain relief when nonsurgical treatment modalities fail.² Surgical treatment modalities vary greatly and depend on the presumed etiology of the GTPS. Surgery can include bursectomy, ITB release, trochanteric reduction osteotomy, or gluteal tendon repair.¹³,¹⁵ For patients requiring repair of abductor tendon tears, most patients reported good to excellent functional outcomes and pain reduction after both open and endoscopic repair.¹⁶ Intraoperatively, tears of the gluteus medius and partial-thickness tears were encountered most often, with tears involving both the gluteus medius and minimus occurring 29% of the time.¹⁶ Complication rates were low for both the open and endoscopic approaches, but no tendon retears were documented after endoscopic repair, whereas the retear rate after open repair was 9%.¹⁶ As discussed in a 2021 study, the anatomy and chronicity of the lesion, the extent of fatty infiltration, and neurologic integrity of hip abductor muscles may influence both treatment choice and outcome.¹⁷ For more challenging cases, reconstruction with a gluteus maximus muscle flap or Achilles tendon allograft has provided promising short-term results in small series.¹⁰ For patients with external snapping hip, the endoscopic release of the ITB or the endoscopic release of the femoral insertion of the gluteus maximum tendon is the most popular technique and they provide fewer complications compared with open surgery, a lower recurrence rate, and good clinical outcomes.¹⁸ A fanlike technique can be used to release the ITB in a stepwise manner.¹⁹ When intra-articular
lesions causing discomfort can be identified, arthroscopy may play a key role in treatment.²⁰ There has also been a recent study purporting the success of treatment using ultrasound-guided release of the external snapping hip using only local anesthesia.²¹ In a cohort of 14 patients with an average age of 43 years, the snapping hip resolved in all patients following ultrasound-guided release, with significantly improved patient-reported outcome measures and without complications or recurrences.²¹

The pathogenesis of internal snapping hip syndrome is multifactorial, and it is traditionally thought to be caused by the tendon snapping over the anterior femoral head or the iliopectineal ridge, although labral tears, cartilage defects, and loose bodies are also possible intra-articular sources. Patients typically present with pain aggravated by activities including flexion and rotation.³⁰,³¹ There is no significant difference between males and females, although these symptoms are more common in elite athletes and dancers, especially with hip flexion beyond 90°.³² When making the diagnosis, plain radiographs and dynamic ultrasonography are the best imaging modalities, with MRI being reserved for only unresolved and challenging cases.³³,³⁴ Dynamic ultrasonography is the gold standard, as its real-time imaging capabilities enable detection of the mechanism of the abnormal tendon friction during hip movement in a noninvasive way and it also allows for a diagnosis of additional hip tissue changes that may be causing the pain.³⁴ However, dynamic ultrasonography, similar to all ultrasonography, is limited by operator experience as well as patient compliance with the requested maneuvers. Recent studies have tried to define parameters to increase the diagnostic acumen of MRI. Using minimum-intensity projection protocol, the sagittal opening angle was shown to be a statistically significant parameter where a sagittal opening angle of more than 140° correlates with symptomatic iliopsoas tendon pathology; however, neither pelvic incidence nor coronal angle consistently was correlated with pathology.³⁵ As discussed in a 2019 study, the sagittal opening angle is measured by forming an angle centered at the apex of the iliopsoas tendons curvature in the sagittal plane and is then determined by measuring the angle formed between a line tangent to the proximal portion of the tendon versus the distal portion of the tendon relative to the apex of the curve.³⁵ Most cases of internal snapping hip syndrome resolve with nonsurgical treatment, which includes avoidance of aggravating activities, stretching, and NSAIDs.³⁶ In recalcitrant cases, surgery may be indicated. Arthroscopic and open surgical techniques are both acceptable; however, there has been a decreased failure rate, fewer complications, and decreased postoperative pain reported with arthroscopic management.³⁷,³⁸,³⁹ It is important for surgeons to be aware that a subset of patients, approximately 18%, have multiple iliopsoas tendons, and failure to release all tendinous attachments can be a source of recalcitrant cases.³⁹,⁴⁰