Clicking or snapping hip (coxa saltans) is a symptom complex characterised by an audible ‘snap’ around the hip on certain movements. It is often painless (approximately one third are associated with pain), but may become painful or uncomfortable as chronicity develops(20). In athletes it may pose a considerable problem.
There are no data in the literature giving the incidence or prevalence of this condition in the general public, but it is well recognised that it is more common in the young athlete(3,13,16,2) and that women are more commonly affected than men (16,21,26). Athletes whose sport involves repetitive twisting about the hip have been identified as being particularly prone to develop a clicking hip(8,20,21). Reid states that, in ballet dancers, hip injuries form about 10% of orthopaedic complaints, and that the ‘snapping hip’ syndrome accounts for around 45% of these.
There are a variety of underlying causes of the snap that can be categorised as either ‘external’ or ‘internal’.
This is by far the commonest cause of coxa saltans. The usual pathology is a thickened band of the iliotibial tract or gluteus maximus tendon slipping over the greater trochanter (3,6,7,26). In the swing phase of walking or on hip flexion, the band moves anteriorly; then in the stance phase, as the gluteus maximus contracts, it is pulled posteriorly and snaps back across the greater trochanter. There is often no more than mild discomfort associated with this but it may become more uncomfortable with time, especially if trochanteric bursitis develops(10,11,20). It is bilateral in an average of 20% of cases in the published series(7,10,12,17,18).
The history alone in terms of the timing of the snap, as well as its location and the location of any discomfort, is often sufficient to distinguish between an internal or external cause. Because discomfort usually takes time to develop, the patient has commonly had symptoms for many months at presentation; Brignal and Stainsby found the average duration of symptoms was two years and two months in their series. Patients are frequently able to demonstrate the snap in clinic and this should be carefully observed. There may be tenderness over the greater trochanter if there is any bursitis present and, unless there is any other underlying pathology, the patient should have a full range of movement of the hip. A specific diagnostic test, described by Brignall et al, involves the patient lying on the unaffected side with a pad under the buttock so that the affected hip is held in adduction. Keeping the knee in extension, the hip is then actively flexed and extended and the iliotibial band may be felt flicking over the greater trochanter.
If the history and examination are conclusive then no investigations, other than plain films to look for acetabular dysplasia or osseous loose bodies, are required. If there is any doubt, imaging studies may be required to rule out other, more serious pathology (see later). Two papers have shown that dynamic ultrasonography can demonstrate the band sliding over the greater trochanter (as well as conventional US being able to diagnose trochanteric bursitis, tendinitis or synovitis) (17,18); though if the diagnosis is clear clinically this should not be necessary.
Most patients respond well to conservative management, which involves rest (ie avoiding activities which provoke a click), non-steroidal anti-inflammatory drugs and physiotherapy. Physiotherapy involves both static and dynamic functional assessment and treatment is mostly centred on stretching the iliotibial band. A minority of patients’ symptoms will, however, be refractory to these measures and surgical intervention may then be appropriate. Several surgical interventions to lengthen or release the iliotibial band as well as excise the trochanteric bursa have been described(6,7,10,11,12). Brignal and Stainsby describe a Z-plasty technique with an 88% success rate in seven patients and this success was also achieved in the series by Faraj et al. Simple division of the band has not been shown to be successful.
This most commonly involves the iliopsoas tendon snapping over the iliopectineal eminence or femoral head (with or without an enlarged iliopsoas bursa), but it is important to distinguish it from intra-articular causes for clicking and pain. The underlying abnormality may relate to the size of the iliopectineal eminence or the position of the lesser trochanter but is not certain(16). It is an under-diagnosed condition and tends to be chronic with an average duration of symptoms at presentation of 23 months (19).
The click occurs when the hip is extended from a flexed, adducted and externally rotated position and there may be tenderness in the adductor triangle on palpation (13,16). If the snap of the iliopsoas can be palpated antero-medially over the hip, then the diagnosis can be made clinically (13), otherwise there are a number of imaging options available. Plain radiographs, arthrography and MRI can be used to rule out intra-articular lesions and hip instability. MRI and static ultrasonography may show tendinitis or bursitis but dynamic studies such as iliopsoas bursography and dynamic US can demonstrate the subluxation of the tendon.
The mainstay of treatment is physiotherapy, again primarily focused on a stretching regimen. Non- steroidal anti-inflammatory drugs are also useful in the early stages. These conservative measures are very effective but, as with the external snapping hip, a minority of patients will continue to have problems. Surgical treatment involves lengthening of the iliopsoas tendon either near its insertion or at the musculo-tendinous junction(13,14,16,27) with good results (85% success in the series by Jacobson and Allen). Lengthening procedures have fewer complications in terms of weakness of hip flexion and recurrence of the snap than the more traditional complete release of the tendon (13,27).
These include loose bodies, synovial chondromatosis, osteo-cartilaginous exostoses and acetabular labral tears. Many of these pathologies will be easily seen on either plain film or MRI scanning. Acetabular labral tears are, however, more difficult to diagnose (only three out of 55 were recognised on plain MRI in the series by Fitzgerald) and clinicians need to have a high index of suspicion in order to investigate and treat these patients appropriately. Patients with underlying hip pathology such as developmental dysplasia or previous Perthes disease are well known to be at increased risk of developing acetabular labral tears amongst other labral pathologies(15,24,25). More recently, it has been recognised that tears may occur in previously normal hips after relatively minor trauma (as well as the obvious damage caused by major trauma such as fracture dislocation of the hip). Athletes whose sport includes repetitive twisting at the hip are again most often affected as well as runners(8,25). It is an important condition to recognise and treat as it may be a precursor to the development of osteoarthritis (2,8,15,22,24,25).
Symptoms may be acute but more commonly occur over a number of months. The average length of history at presentation was approximately three years in both the series by Leung et al and by Fitzgerald. Patients will complain of a sharp ‘catching’ pain in the groin, which may radiate down the thigh. It is often provoked by a pivoting movement and initially only lasts for a few minutes but becomes more frequent and long-lasting. An associated click is present in about 60% of cases and the hip may give way(25,28). Another distinguishing feature is that most patients will have had a limp at some stage in their history, in contrast to the patients with extra-articular causes for their click.
Specific examination findings are pain on axial compression of the affected leg and pain and apprehension on impingement provocation tests. These involve flexion, adduction and internal rotation for anterosuperior tears and hyperextension, abduction and external rotation for posteroinferior tears (22,23,25).
Arthrography can be a useful diagnostic tool both in terms of visualising the tear (44/50 in the series by Fitzgerald) and in assessing the patient’s response to the local anaesthetic injected at the time of the procedure, and thus further differentiating between intra and extra articular pathology(25). Magnetic Resonance arthrography (MRa) is also becoming a more popular and reliable technique(22,24). Hip arthroscopy is the definitive investigation and a proportion of tears can be excised arthoscopically.
Treatment is somewhat controversial, as the natural history of labral tears is not fully understood. Conservative management, consisting of a period of non weight-bearing, appears to completely resolve some patients’ symptoms(15,2); however, on repeat arthroscopy, Ikeda et al found that, despite symptomatic relief and resolution of any inflammation, the tears had no signs of healing. Arthroscopic debridement has resulted in good short-term outcomes in terms of resolution of pain and clicking in many studies, though some tears are not amenable to arthroscopic debridement and no long-term data is available at present. Open arthrotomy and debridement are another possibility for cases where conservative management fails and arthroscopic debridement is not possible, but this a major operation and carries a risk of avascular necrosis, especially if the hip has to be dislocated in order to access the tear.
Clicking hip is a condition which affects mostly young athletes whose sport involves repetitive twisting. Women are more commonly affected than men. The two main varieties are the ‘external’ cause (snapping of the iliotibial band or gluteus maximus tendon over the greater trochanter) and the ‘internal’ cause (snapping of the iliopsoas tendon over the iliopectineal eminence). Other rarer but more serious causes such as acetabular labral tears, intra articular loose bodies, synovial chondromatosis and subluxation of the hip should be considered and excluded either clinically or by the vast array of imaging modalities available.
As with so many surgical and orthopaedic conditions, the history and clinical examination are paramount in obtaining the correct diagnosis.
Conservative management, involving rest, NSAIDS and physiotherapy, is effective in the majority of individuals with both internal and external snapping hip, but there are a variety of surgical procedures available for refractory cases.
Chris Pearce and Fares Haddad