In the seated position, inspection of posture can provide information on the function of the core muscles. Listing to one side – suggestive of a neuromuscular condition – and pelvic tilt can also be appreciated in this posture. Again, asking the patient to stand up before lying down will show how comfortable they are with resisted hip extension. Passive internal and external rotation of both hips may be carried out with the patient in the seated position when the hips are flexed to 90° [42]. Strength of iliopsoas can be assessed in the seated position by asking the patient to raise their knee off the examination couch against resistance.

The majority of the clinical examination is performed in this position. Inspection forms the initial part of the examination, looking for resting rotation and limb length. An excessively externally rotated limb may point towards laxity of the anterior capsule [43]. For completeness, a brief examination of myotomes and dermatomes can be undertaken here along with a straight leg raise.

Three studies have looked specifically at the diagnostic accuracy of clinical tests when examining the young adult hip [43–45].

Prior to moving the hip, bony and soft tissue palpation may be undertaken at this stage to look for tenderness and/or swellings. The sequence involves palpating the anterior superior iliac spine and inguinal canal and checking for a cough impulse at the hernia orifices, pubic symphysis, greater trochanter and ischial tuberosity. The adductors, abductors and iliopsoas and rectus are subsequently palpated for tenderness. It must be born in mind that tender soft tissues or tendinous insertion points may be a concomitant finding or an isolated one.

The logroll test involves internal rotation (IR) and external rotation (ER) of the resting extended hip. Although not sensitive, this is a specific test [21] and localises hip joint injuries by rolling the femoral head in relation to the acetabulum and isolating this from surrounding soft tissues. It is also a commonly performed test amongst musculoskeletal clinicians and has good inter-rater reliability [46]. Although thought to be specific, one study found that it so rarely produced a positive result; its usefulness in determining intra-articular pathology was questioned [46]. In another study, its positive predictive value was deemed to be low and there are no data available on its specificity [43].

The resisted straight leg raise (RSLR) test consists of hip flexion against resistance of the examiner with the fully extended leg in 30° or 45° of hip flexion whilst the patient lies supine (Fig. 3.2). In one meta-analysis, this test was described in 8 of 21 studies [43] and was noted to have a specificity of 0.9–1.0. Another study looked specifically at four pain provocation hip manoeuvres performed pre- and post-intra-articular fluoroscopically guided hip injection [47]. It showed that RSLR (also called the Stinchfield manoeuvre) was the most specific test for clinically localising pain arising from an intra-articular source, with a specificity of 0.32.

Thomas’ test is a well-known test used predominantly to isolate the hip from any lumbar spine pathology and also to elicit fixed flexion deformity of the hip. This test involves the patient lying supine and being asked to bring both knees towards their chest. They are then asked to extend one leg fully, whilst the examiner places one hand under the patient’s lumbar spine to identify lumbar lordosis. It can be used in the assessment of FAI to ensure pelvic tilt is not affecting the range of movement (ROM), but also may in itself be a sign of anterior impingement, as shown in one study used in a recent meta-analysis of diagnostic tests [43].

The range of movement (ROM) of the affected hip compared with the contralateral side is the most commonly performed test [46]. The inter-rater reliability of assessing ROM was studied by blinding nine independent examiners. To aid in their assessment, a goniometer was made available and proved that all examiners were within five degrees of each other when assessing flexion and within seven degrees of each other when assessing rotation [46]. Restricted flexion and restricted internal rotation in flexion are well established to be a common finding in patients with anterior FAI [2, 48, 49]. A cross-sectional study identified those asymptomatic adolescents with <10° IR with hips in 90° flexion [34]. They used age-matched controls, imaged the two groups and found that reduced ROM as described above has a high positive predictive value for anterior FAI. Clohisy et al. also reported that the average flexion in patients with symptomatic FAI is only 97° compared with 101° on the asymptomatic hip [16]. However, a study looking at 40 asymptomatic volunteers showed that the mean maximum midsagittal passive flexion, measured at the time of bony impingement, was 96° ± 6° [50]. Another study used 3D CT-based kinematic analysis to compare ROM in hips with FAI with anatomically normal hips [51]. They found a statistically significant decrease (p < 0.001) in the amount of achievable flexion in FAI hips, with 105° compared with 122° in normal hips.

Flexion-adduction-internal rotation test or anterior impingement test is another special test used in 20 of 21 studies included in a meta-analysis of diagnostic hip tests [43]. It is performed with the patient supine. The examiner passively moves the patient’s hip into 90° flexion and then applies adduction and finally internal rotation (Fig. 3.3a,b). It classically reproduces the patient’s pain due to impingement of the anterior femoral head-neck junction on the acetabular margin. It has been stated that 88 % of patients with FAI will have a positive anterior impingement test. Variations on the flexion-adduction-internal rotation position (FADDIR) have been described, with the patient in the lateral recumbent position rather than supine and with flexion taken to the maximal degree prior to adduction and IR forces being applied. Overall, the FADDIR test has been reviewed in a recent meta-analysis [44] and shown to be one of only 2 of 11 provocation tests found to be eligible to be in their study criteria. This manoeuvre has been deemed to have clinical value in the diagnosis of FAI and anterior labral tears [21, 43, 44, 51]. It should, however, be noted that although the test has a high sensitivity, it has a low specificity, and therefore caution should be used with using this test only for a diagnosis of FAI [5].

Continuing on from the hip in flexion and IR, the hip may now be axially loaded in this position to elicit pain. This has been used to determine anterior labral tears, but in the meta-analysis by Tijssen et al. [43], it has no data available on its specificity and is noted to have a poor positive predictive value (PPV). Only 2 out of 21 studies utilised this test in their evaluation of the young adult hip.

Patrick’s test is a commonly used test and describes the hip being taken into a flexed, fully abducted and externally rotated position (FABER), so the leg is in a “figure of four” position (Fig. 3.3c). It is useful in localising sacroiliac joint dysfunction. In a study by Maslowski et al., FABER was deemed to have a sensitivity of 0.82 with a PPV of 0.46 [47]. In this study, the test was considered positive if downward pressure on the abducted, externally rotated knee reproduced the patient’s hip pain. Other examiners consider a positive result to be a decrease in ROM compared to the contralateral side; however this is likely to be due to a modification of Patrick’s test where the buttock is not off the table. What is considered a positive result varies enormously between the papers using this test to identify either FAI or labral tears.

The Fitzgerald test, as described by Tijssen et al. [43], is when the hip is brought into acute flexion, external rotation and full abduction and is then extended with internal rotation and adduction. The patient lies supine. Extension with abduction and external rotation from the fully flexed, adducted and internally rotated position completes the test. Pain or a click is a positive result. Only one of the papers reviewed by Tijssen et al. [43] utilised this test, which showed a high sensitivity for detecting labral tears or FAI; however not one paper from the more recent meta-analysis used it [44].

A multitude of other positions have been described to try and reproduce hip pain, but few are reproducible and none have been adequately analysed to provide sensitivity, specificity and PPV.

In the lateral position the patient can more completely be assessed for peritrochanteric disorders. Focal tenderness around the greater trochanter can point towards trochanteric bursitis and also the possibility of abductor tears or gluteus medius tendinopathy, which can accompany patients with FAI [52]. In addition, snapping hip may be elicited using Ober’s test. This test was originally described in 1935 to elicit a tight IT band [53]. In this test, the patient lies in the lateral position with the affected limb upward. The examiner stands behind the patient and passively flexes the uppermost (affected) knee. The examiner then abducts and fully extends the hip with one hand whilst placing a hand over the trochanteric region. The examiner then passively adducts the extended hip to see if the knee adducts past the midline whilst feeling for a “snap” of the IT band over the greater trochanter (Fig. 3.4). This test is mostly useful for excluding other soft tissue causes of hip pain and is itself not a useful diagnostic test for either FAI or labral pathology.

In this position, asking the patient to abduct their hip against resistance can also test gluteal weakness. The results should be compared to the contralateral side. Some examiners find this easier with the patient supine.

The prone examination should be performed to evaluate posterior hip pain due to proximal hamstring syndrome, ischial bursitis or sciatic nerve irritation. This position also allows for a clinical assessment of femoral version with the use of the Craig test [54]. This test involves flexing the patient’s knee to 90° whilst prone, with the examiner’s hand on the greater trochanter. An assessment of the amount of internal rotation necessary to make the greater trochanter maximally prominent can be carried out, which provides an estimation of femoral anteversion or retroversion. Posterior impingement test may also be carried out in this position and involves extension of the affected hip with the examiner taking the hip into full abduction and external rotation. This test can also be carried out in the supine position if the examiner wishes. Pain implies a positive result [55]. This test has not been carried out frequently enough to provide values regarding its sensitivity or specificity.

As with most other orthopaedic examinations, the history and clinical findings are taken together with plain radiographs in two views. There should be positive findings in all three basic elements in order to support a diagnosis of acetabular, labral or femoral pathology. Radiographic features, such as crossover sign or a high α angle, should not be taken as useful without correlating clinical features as studies have shown a high incidence of such findings in the asymptomatic population [35, 36]. Also, other investigations may be necessary to confirm the diagnosis such as MRI, MR arthrogram or fluoroscopically guided intra-articular injection to confirm that the symptoms are indeed intra-articular in origin.

Of the special tests for the examination of the young adult hip, the anterior impingement test and FABER test have been shown to have high sensitivity and reproducibility for establishing the diagnosis of FAI [43, 44, 57, 58], with a 96 % interobserver reliability of the impingement test.

Sceptics of FAI as a causative factor in osteoarthritis [5] are quick to point out the lack of good evidence to support either the aetiology or specificity of clinical findings, but this paucity of level I studies is likely due to the fact that 60 % of publications regarding FAI have been within the last 3 years [56]. Furthermore, clinical tests in many subspecialties have been found to have low specificity and sensitivity in their own right (e.g. special tests for shoulder examination), but when results are taken together, a reliable diagnosis can be made.

The direction currently taken for FAI is similar to previously described paths of other orthopaedic and sports medicine pathologies, but the time has come to define the condition and support its intervention with well-designed randomised trials [59].