without bone marrow oedema (BMO) should prompt the search for FAI (29). Despite a small sample size, they found that all had fibrocystic changes; the average cyst size was 9 mm (5–14 mm), and the size of the cysts and multiple cysts did not correlate with BMO. They concluded that BMO and cystic changes relate to the ongoing impaction between the femoral head and the acetabulum.

An increasing number of golfers suffer from FAI. Biomechanical studies have shown that during the downswing of a right-handed golfer, the right hip is forced into external rotation (ER) during axial loading, forcing the femoral head anteriorly. The repetitive nature of golf leads to focal anterior capsule laxity with stretching of the iliofemoral ligament and subsequent increased translation (3).

Injury to the ligamentum teres must also be considered, as this is the third most common finding during arthroscopy. Philippon reports an incidence of 8% of 1000 scopes (30). It becomes taut during adduction, flexion and lateral rotation. Its pathology can be classified into complete, partial and degenerative. In patients with hip instability, it is commonly found to be hypertrophic.

CLINICAL PRESENTATION The clinical presentation was evaluated by Neumann et al., who found that 48% had groin pain, 7% had groin/buttock pain, 56% described a “catching” sensation, 23% “clicking” and 7% “giving way” (31). In terms of range of movement, 62% had reduced range, with 81% of those being restricted in medial rotation; 68% had reduced flexion and 37% lateral rotation. The restricted medial rotation at 90o hip flexion is due to the osseous impingement of the anterolateral femoral head/neck junction with the acetabulum (31). Patients classically describe the

“C sign” by cupping the thumb and first finger over the greater trochanter. There are a number of tests described in the literature, the main ones being the FABER (flexion/abduction/external rotation) and the impingement test. It is vital to feel both the amount and the quality of all hip ranges, especially noting whether during passive flexion the hip drifts into abduction at terminal flexion. If so, assess whether the

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patient is able to adduct to neutral and beyond and whether the end feel is solid or springy.

CLINICAL TESTING Clinically, patients may describe the hip as being “tight”. This may be due to guarding by the iliopsoas and quadratus lumborum (30). The presence of hip instability must be addressed. A number of collagen disorders, such as Ehlers–Danlos, Marfan and Down syndrome, must be ruled out. Assessing elbow extension and wrist and finger laxity will give an indication. The log-roll test has been advocated by the Philippon group to assess hip capsule laxity, although no research has been published (30). Intra-articular anaesthetic injection can be used as a diagnostic. This has been shown to be 90% accurate (34). Field-based assessment can be performed post-injection if required. The FABER test (Fig. 1) is performed

by crossing the foot of the affected side on to the opposite leg. This is a good objective marker for measuring range, taking the lateral joint line to the bed; this is then compared with the contralateral limb.

The impingement test (Fig. 2), involves taking the hip to 90o ,

adducting and then medially rotating the hip. If the patient is acute and may have an acute capsulitis, then they may be positive even in this position. If not, then gently take the patient’s leg into the closed pack position and slowly extend the hip. You may feel a small clunk at a specific point in the range, which the patient may describe as their pain. If this is consistent, then by applying an axial load through the femur – try to imagine gapping the

Figure 3: 3D CT Image – showing CAM on femoral head-neck junction

anterior aspect of the joint – you should be able to offer temporary relief, giving further support to your diagnosis.

IMAGING

Standard magnetic resonance imaging (MRI) produces both false positive results and an underestimation of labral pathology and has only a 30% sensitivity and a 36% accuracy (9). A magnetic resonance arthrogram produces better results, with reported accuracies as high as 91% (32). More recently, advanced techniques such as T2 mapping have allowed us to get a clearer picture of the quality of the articular cartilage (Fig. 3).

Normal acetabular anatomy can be confirmed by measurement of the centre edge angle (CE) (33). An X-ray alpha angle of greater than 50.5o

is

quoted as a cut-off for diagnosis of cam-type FAI. The exact plane of measurement on MRI is unclear (3).

SURGERY The debate of how to deal with intra- articular hip pathology is beyond the scope of this article. However, surgical options include an open procedure called the mini-open, as described by Ganz (38), and the arthroscopy. Dienst has produced an excellent article on the technique and anatomy involved in hip arthroscopy, which is well worth reading (39). The type of surgery performed is dependant on the surgeons personal preference or if capsular restriction limit access.

Figure 2: Impingement test

online Video

CHONDROPLASTY Chondroplasty or osteoplasty involves removing the area of impingement on

sportEX medicine 2009;40(Apr):10-15