Gluteal Tendinopathy

Gluteal tendinopathy, referring to tendinopathy of gluteus medius and/or gluteus minimus tendons, is the most common cause of lateral hip pain and can lead to severe disability. Load management and graded strengthening is primary treatment.
==Terminology==
Greater trochanteric pain syndrome (GTPS) is an umbrella term encompassing different musculoskeletal entities that may contribute to chronic lateral hip pain including gluteus medius and minimus tendinopathy/ tears, trochanteric bursitis, and external coxa saltans. 
Any bursal distension (sub-gluteal minimus/medius) is invariably secondary to or co-exists with an underlying gluteal tendinopathy. The tendinopathy is a non-inflammatory condition. Therefore the term "trochanteric bursitis" (and the related terms "trochanteritis") is generally regarded as a misnomer. Primary trochanteric bursitis is very rare, and microbiological causes should be considered in those cases. 
==Anatomy==
The peri-trochanteric space is the interval located between the greater trochanter and the gluteus maximus, tensor fascia lata, and iliotibial band. The peri-trochanteric space contains the hip abductors: gluteus medius, gluteus minimus, and tensor fascia lata. 
In the "rotator cuff of the hip" there are six external rotators, three internal rotators, two trochanteric abductors, and three iliotibial band tensioners. 
*The external rotators are piriformis, gemellus superior and inferior, obturator internus, obturator externus, and quadratus femoris. 
*The internal rotators are gluteus minimus, gluteus medius, and tensor fascia lata
*The trochanteric abductors are gluteus minimus and gluteus medius.
*The iliotibial band tensioners are tensor fascia lata, gluteus maximus, and vastus lateralis.
The greater trochanter has four facets (anterior, lateral, posterior, and superoposteiror) with three tendon insertions. 
Gluteus medius is the most important muscle in gluteal tendinopathy. It is a large fan-shaped muscle that has its origin at the outer edge of the iliac crest running from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS). It has three equal portions: anterior, middle, and posterior. The anterior and middle portions with its vertically oriented muscle fibres assist with initiating hip abduction. The posterior portion with its horizontally oriented fibres is active in heel strike to full stance during gait to stabilise the hip. It inserts at the superoposterior and lateral facets of the greater trochanter.
Gluteus minimus has its orrigin from the gluteal surface of the ilium. It inserts onto the lateral facet and onto the hip capsule on the anterior facet, called the long head and capsular head respectively. There is a "bald spot" between the capsular attachment and the lateral facet.
There are three bursa in the lateral hip. The subgluteus medius bursa overlies the superior part of the lateral facet. The gluteus minimus bursa lies over the lateral facet. The subgluteus maximus mursa lies between the gluteus maximus and iliotibial band.
File:Posterior Hip Muscles 2.png|gluteus medius shown on the right
File:Posterior_Hip_Muscles.png|gluteus minimus shown on the right
File:Lateral hip illustration and cadaver.jpg|lateral hip with foot prints of gluteus medius, gluteus minimus, and vastus lateralis
File:Greater trochanter anatomy facets insertions and bursae.jpg|Anatomy of the greater trochanter. (a) Three peritrochanteric bursae, (b) osseous facets of the greater trochanter, and (c) insertion sites for the abductor tendons
==Aetiology and Pathophysiology==
Historically lateral hip pain was thought to be exclusively due to trochanteric bursitis. However it is now understood that tendon tears are the source of pain, and the presence of any bursitis is merely an epiphenomenon.
A healthy tendon has a homeostatic balance between anabolic and catabolic processes. Gluteal tendinopathy is caused by disturbance in this balance following a combination of excessive compression and high tensile loads. The tendon is particularly susceptible when there is a rapid increase in intensity of load without giving the tendon time to adapt. This could be due to a traumatic event (e.g. direct blow) or a frequent and repeated exposure to a load (e.g. jumping athlete). 
Three continuous stages of disease have been described: normal to reactive tendinopathy to tendon dysrepair to degenerative tendinopathy. Tendon tears can be intrasubstance, partial, or complete. This is explained in more detail in Tendinopathy. It is difficult to manage because pain is not closely connected to progression of pathology.
==Epidemiology and Risk Factors==
Gluteal tendinopathy is a common condition with a prevalence that is highest in women in their fourth to sixth decades. One study reporting 23.5% of females and 8.5% of men between 50-79 years being affected in community-based population. A rapid increase in intensity and/or frequency of loads on gluteal tendons puts individuals at risk. Both athletes and sedentary individuals are affected. Higher body weight is another association. 
==Clinical Features==
===History===
The patient typically complains of dull aching pain over the lateral hip. The onset is typically slow but can occur following a traumatic event (fall, forceful sporting action). The pain is typically worsened with time and can be associated with a change in physical activity. Pain can radiate to the buttock and/or down the lateral thigh. Associated symptom of stiffness of hip on standing or walking following sitting. Sleep can be significantly disturbed as pain is typically worse at night time and pain makes it difficult to sleep on the side.
Pain can cause significant disability, particularly with single leg standing activities e.g. dressing, walking and going up stairs or hills. Patients with gluteal tendinopathy have levels of disability that is comparable to patients with severe hip osteoarthritis. 
===Examination===
Gait: The patient is assessed during gait to evaluate for a Trendelenburg pattern. This test is highly specific but not sensitive, and is more suggestive of advanced disease.
Tenderness to palpation of the greater trochanter: This is a considered a cardinal sign. Any absence of tenderness should raise suspicion for an alternative diagnosis. 
Sustained single-leg stance (Trendelenburg Test): Lateral hip pain reproduced on 30s single-leg stance test has a sensitivity and specificity of 100% and 97.3% respectively for gluteal tendinopathy. The high utility of the test is only maintained if the patient is instructed not to hitch the pelvis into relative abduction (where there is reduced tendon compression load). The examiner may provide gentle fingertip support to steady the patient. 
Resisted abduction test: performed with the patient in lateral decubitus. It has a 73% sensitivity and 87% specificity. Patients with decreased hip power are more likely to fail non operative management. 
Resisted internal rotation test: See figure for picture and instructions. It is more accurate than Trendelenburg gait, greater trochanteric tenderness, and resisted abduction. This test is based on the function of gluteus medius as an internal rotator, with the internal rotation torque increased in a position of hip flexion. It has a sensitivity of 92% and specificity of 85% for the detection of gluteus medius tears. Note, this is different to the external derotation test which has the patient at significantly greater external rotation which is less specific to the hip abductors. 
FABER: The FABER test is useful in the differential diagnosis as limited range of movement is associated with hip joint pathology but not gluteal tendinopathy. 
The lumbosacral spine should also be examined. 
Leg Length Measurement: Gross leg length discrepancy may contribute to GTPS. The examiner stands behind the patient, paces their hands over the iliac crests, and estimates if they are level. Another method is measuring from the ASIS to the tip of the medial malleolus. 
Ober's test: has been shown to lack diagnostic utility for gluteal tendinopathy.
File:Gluteus medius tear resisted internal rotation test.jpg|The resisted internal rotation test. Patient is supine with affected hip and knee at 90° flexion and hip at 10° external rotation. The patient actively internally rotates the hip against resistance (knee away and foot towards examiner in photo). The test is positive with pain reproduction or weakness.
File:Hip abductor strength testing.jpg|Resisted abduction test. Pain or weakness with resisted abduction in lateral decubitus with the affected side up.
File:Trendelenburg test.jpg|Trendelenburg test. The test is positive if the contralateral pelvis tilts downwards when asked to stand on the affected foot.
==Investigations==
MRI is gold standard as it can visualise changes associated with gluteal tendinopathy, such as tendon thickening and soft tissue oedema, the clearest. MRI is also useful in excluding other causes of lateral hip pain. However, MRI is expensive and not very accessible. Consequently, ultrasound is typically used in clinical practice. The accuracy of ultrasound in identifying gluteal tendinopathy is variable and dependent on operator experience and patient characteristics. It is important to note that it is normal for radiological changes to be present in the asymptomatic population, thus, any findings need to be considered within the clinical context. 
===Imaging Findings===
Xray
Plain radiographs are helpful for ruling out hip osteoarthritis, femoroacetabular impingement, and calcific tendinopathy. However pincer-type FAI may be associated with the development of GTPS.
Ultrasound
Ultrasound is operator dependent. It has a higher PPV than MRI when done by an experienced musculoskeletal radiologist. Findings include:
*Thickened tendons
*Reduced echogenicity of tendons
*More heterogeneous echogenicity of tendons
*Increased echogenicity of muscles as reduced muscle bulk and increased fat
*Partial tears are indicated by thinning of the tendon and partial thickness area free from echo
*Complete tears are indicated by the full thickness of the tender being free from echo and a “bald” facet
*Deep to gluteus tendon insertions there may be cortical irregularities
On Doppler Ultrasound uncommonly one can see increased vascularity
MRI
Tears on MRI are classified as tendinosis, partial-thickness, or full-thickness. Findings do not correlate well with symptoms, with abnormalities seen in 50% of patients without lateral hip pain.
*Tendinosis is suggested by hyperintensity in T2-weighted images within the tendon of gluteus minimus and/or gluteus medius
*Fluid distension of the greater trochanteric bursa
*On coronal T1-weighted imaging there may be fatty streaks or fatty infiltration of gluteus minimus and/or gluteus medius
*Partial tears are indicated by hyperintensity  in T2 view within the tendon of gluteus minimus and/or gluteus medius along with a thickened tendon.
*Partial tears can presents with or without tendon thinning
*Complete tears are indicated by disruption of the tendon of gluteus minimus and/or gluteus medius
*Osseous avulsion may or may not be present in a complete tear
===Other Investigations===
Other imaging techniques are currently being developed. These include ultrasound tissue characterisation and elastography. 
==Diagnosis==
No clear diagnostic criteria exists for gluteal tendinopathy. Typically the diagnosis is made clinically. The history most commonly involves lateral hip pain that is exacerbated by activity and lying on the affected side. On examination, one would expect to find tenderness on palpation of the greater trochanter. This is the most common clinical finding in gluteal tendinopathy.
Hip osteoarthritis is  a common differential diagnosis for lateral hip pain. Asking about difficulty in manipulating shoes and socks is a useful way to differentiate the conditions. A paper published in the British Journal of Sports Medicine suggested that diagnostic criteria for gluteal tendinopathy should include the patient reporting to have no difficulty in manipulating socks and shoes. This paper also suggested the diagnostic criteria to include lateral hip pain reproduced on the FABER test as the FABER test should not produce lateral hip pain in hip osteoarthritis.
==Differential Diagnosis==
==Treatment==
Gluteal tendinopathy for the majority is self limiting. It has been reported that more than 90% of people are responsive to conservative treatment. Those who are not are considered refractory cases. Conservative treatment can include patient education, physiotherapy, NSAIDs, corticosteroid injections (CSI), shockwave therapy, and PRP injections. There are varying levels of evidence for each of these interventions. Evidence does not support the conservative treatment of deep transverse friction massage, therapeutic ultrasound and acupuncture.
===Education===
Patients should be advised to avoid sitting with crossed legs, sit with hips higher than knees, stand evenly on both feet and hip width apart, avoid lying on the painful hip and place a pillow under the top leg if side-lying, sleep on the back if possible, continue exercising as tolerated, but avoid aggravating exercise.
===Exercise===
Physiotherapy that is based around graded exercise has been shown to be effective in other tendinopathies. There is no universally recommended treatment protocol for gluteal tendinopathy. The LEAP protocol has shown promise when compared to no treatment and a single corticosteroid injection. The LEAP protocol involves education on load management (e.g. avoiding lying on side of affected leg) and a specific graded exercise programme. This study and its results can be found in the resources below and the .
The concept of an activity ladder can be used. The patient should state an activity goal. Start at low tendon load such as swimming with gentle kicking or other water based activities. Progress through medium pace walking or bicycling on the flat, to bicycling with a gradual slope, to faster paced walking or bicycling, to slow running intervals on the flat, to walking up hills and stairs, to running and a medium to high pace, to running up and down hills, finally to plyometrics. The patient stops progressing at their desired goal. Pain can be used as a guide to know if the load is manageable for the tendon, with low levels of pain meaning that the load is not excessive.
===Injections===
There is some evidence for injection therapies. Common injectates are corticosteroid and leukocyte rich platelet rich plasma (LR-PRP). The injectate is deposited around the tendon or sometimes into the tendon itself. Ultrasound can be used for needle guidance, however no significant difference between ultrasound guided and blind injection outcomes have been found. corticosteroid may provide benefit in the short term but with a high recurrence rate and poorer results in the long term. 
Given the paucity of treatments for chronic gluteal tendinopathy (>3 months) and transient amelioration effect of CSI, there is interest whether biologic products such as PRP may provide better long-term outcomes for this condition. The use of PRP has been controversial. Technician skills, method of preparation, patient variables, and the grade of tendinopathy used can all potentially alter effectiveness.
===Surgery===
Gluteal tendon reconstruction is experimental with no standardised techniques. If surgery is done it involves a combination of some of the following procedures: bursectomy, ITB release, trochanteric reduction osteotomy and gluteal tendon repair.
==Follow Up and Prognosis==
Over 90% respond to conservative treatment but there are still large number of patients thar fail non-operative treatment with significant levels of dysfunction making it important to find novel treatment strategies.
==Summary==
*Aetiology and pathophysiology for gluteal tendinopathy remains incompletely known.
*Prevalence is highest in women over 40 years
*Both athletes and sedentary individuals are affected
*History of lateral hip pain
*Examination of lateral hip pain reproduced on FABER test and 30s single-leg stance test
*No set diagnostic criteria
*Diagnosis is typically clinical
*Imaging can be done with MRI being gold standard but ultrasound more clinically available
*No universally prescribed treatment protocol but LEAP protocol provides some promise
*Conservative treatment effective in more than 90% of cases
==Resources==
==External Links==
How physiotherapists treat gluteal tendinopathy by Dr Alison Grimaldi
==References==
Category:Pelvis, Hip and Thigh Conditions
Category:Tendinopathies