Bodyexamination

Posterior rim impingement test / PRI test

Written by manual therapist Roar Syltebø

In 1991, Klaue and colleagues published “The acetabular rim syndrome”, which describes hip pain in acetabular dysplasia. This is the earliest description of the posterior rim impingement test that we have found. The test is not named, but is briefly described. Leunig and colleagues (1997) likewise describe the test only briefly. The name posterior rim impingement test (PRI test) first appears, to our knowledge, in two articles by Martin and colleagues from 2010 (Klaue et al., 1991; Leunig et al., 1997; Martin et al., 2010a, 2010b).

The test is intended to provoke the posterior acetabular rim. In 2003, Ganz and colleagues described how, in pincer-type impingement, the femoral neck abuts the anterior acetabular rim, levering the femoral head posteroinferiorly against the posteroinferior acetabulum, where a contre-coup chondral lesion may develop (Ganz et al., 2003). This provides the pathomechanical rationale for posterior provocation of the hip joint, even when the primary impingement is anterior.

Indication

The PRI test is indicated in patients with groin pain or pain felt “deep inside” the hip, when an injury or other pathology in or around the hip joint is suspected, and when the examiner wishes to distinguish hip pain from other possible sources of the patient’s symptoms. The test is particularly relevant when a posterior labral or chondral lesion is suspected, and it may also be informative when anterior hip instability is suspected (see Interpretation).

Procedure

Martin and colleagues describe the test as follows (Martin et al., 2010b):

The patient lies supine at the very end of the examination table so that the leg being examined can hang freely over the edge. The patient draws both legs towards the chest to flatten the lumbar lordosis. The leg being examined is then taken over the edge of the table into full hip extension, abduction and external rotation.

Cook and Hegedus (2012) describe a test they term the impingement provocation test, based on the same two sources as Martin and colleagues (Martin et al., 2010b; Cook & Hegedus, 2012). In this version, the leg being examined hangs over the long side of the examination table, and the lumbar spine is not stabilised by flattening the lordosis. We have tried both procedures to the best of our ability and do not find that the version described by Cook and Hegedus “hits the spot” in the same way as the procedure described by Martin and colleagues.

The PRI test is conveniently performed together with the Thomas test, as the two tests share the same starting position.

The starting position is also almost identical to that of the HEER test (hyperextension–external rotation test, also known as the anterior apprehension test), which is used when hip instability is suspected. In the HEER test, the hip is taken into hyperextension and external rotation while the examiner applies an anteriorly directed force to the hip (Hoppe et al., 2017). The PRI test differs in that the hip is also abducted, and in that the aim is to provoke deep or posterior pain (see Interpretation).

Interpretation

The PRI test is considered positive if it reproduces the patient’s familiar pain “deep inside” the hip, clicking, a sensation of locking or an apprehension response (Klaue et al., 1991; Leunig et al., 1997; Martin et al., 2010a).

The location of the pain is crucial to the interpretation. The same position may provoke both anterior and posterior structures of the hip. Deep or posterior pain is consistent with the purpose of the test, namely provocation of the posterior acetabular rim. Anterior pain or a stretching sensation in the groin may arise from the hip flexors, which are assessed with the Thomas test, or from anterior hip instability. We also note that apprehension, one of the original criteria for a positive test, is the same response that is used in tests for hip instability, and that the test was first described in patients with dysplasia (Klaue et al., 1991). A positive PRI test with apprehension or anterior pain should therefore be considered a possible sign of instability, not only of posterior impingement.

Frequency of a positive test

In 1997, Leunig and colleagues investigated MR arthrography for the detection of acetabular labral tears. The patients were also examined with the FADIR test and the PRI test. The PRI test was positive in 5 of the 23 patients included, and the FADIR test in 21 of 23. MR arthrography detected a labral tear in 21 of the 23 patients, and a labral tear was confirmed at surgery in 20. The article does not state whether the patients with positive clinical tests actually had labral tears, and therefore provides no information on sensitivity or specificity. Of interest, however, posterior labral tears were found at surgery in 51% of the patients and anterior tears in 49% (Leunig et al., 1997). This suggests that tests for posterior labral tears should be part of the clinical examination of patients with hip pain, even though scientific documentation is lacking.

In 2009, Clohisy and colleagues examined 51 patients with symptomatic femoroacetabular impingement (FAI). The article is somewhat unclear regarding the number of hips examined: a summary table reports 53 hips, whereas the PRI test was performed in only 47. The PRI test was positive in 10 of these hips, corresponding to a sensitivity of approximately 21%. By comparison, the FABER test had a sensitivity of 98.7% in the same study (Clohisy et al., 2009). These remain the only data we have found on the sensitivity of the test, and no study has reported its specificity.

Reliability

In 2020, Pålsson and colleagues investigated the reliability and diagnostic accuracy of several clinical tests in patients with longstanding hip and groin pain referred to specialist care. An orthopaedic surgeon and a physiotherapist, both with extensive clinical experience, independently examined 69 patients (138 hips). The tests were performed as described by Martin and colleagues and were considered positive when they reproduced the patient’s typical hip or groin pain. The two examiners agreed in 80% of cases, but because the test was rarely positive, kappa was only 0.36, indicating fair agreement. The PRI test was therefore excluded from the analysis of diagnostic accuracy, and the authors suggest that the test may be inappropriate for this patient group. By comparison, the FADIR test and the FABER test showed substantial agreement (kappa 0.64 and 0.62) (Pålsson et al., 2020).

Anterior pain and hip instability

In 2017, Hoppe and colleagues investigated three tests for hip instability in 109 patients undergoing hip arthroscopy, with arthroscopically confirmed microinstability as the reference standard. The HEER test, which is performed in almost the same position as the PRI test, was considered positive when it reproduced the patient’s anterior hip pain. The test had a sensitivity of 71.0% and a specificity of 85.1%. When all three tests were positive, the probability of microinstability was 95% (Hoppe et al., 2017). An international Delphi consensus from 2026 considered the abduction–hyperextension–external rotation (AB-HEER) test, the prone instability test and the HEER test clinically useful in the assessment of atraumatic hip instability (Karimijashni et al., 2026).

The PRI test has not been investigated as a test for instability. Given the similarity of the test positions, however, we consider that anterior pain or apprehension during the PRI test should prompt an assessment for instability, including the HEER test and the other instability tests.

Extra-articular posterior pain

Posterior pain on hip extension may also have an extra-articular source. In ischiofemoral impingement, the soft tissue between the lesser trochanter and the ischial tuberosity is compressed. In 2016, Gómez-Hoyos and colleagues investigated the ischiofemoral impingement test in 30 patients with posterior hip pain. The test is performed in side-lying with the hip in extension, first in adduction or neutral and then in abduction. It is considered positive when the patient’s familiar posterior pain is reproduced in the first position but not in abduction. The test had a sensitivity of 82% and a specificity of 85%, but the study was small and retrospective (Gómez-Hoyos et al., 2016).

As the PRI test is performed in abduction, which according to this study relieves the ischiofemoral space, posterior pain during the PRI test is probably less suggestive of ischiofemoral impingement. This has not been investigated, and ischiofemoral impingement should nevertheless be considered in patients with buttock pain on hip extension.

Recommendations in the literature

In two articles from 2010, Martin and colleagues recommend a set of tests for the examination of patients with hip pain, and the PRI test is described in both (Martin et al., 2010a, 2010b). One article maps the tests used by six hip surgeons, two of whom used the PRI test (Martin et al., 2010a). The other is a literature review concluding with an extensive list of recommended tests. The PRI test is the only test described for the assessment of posterior labral tears, and it is also listed as one of the tests for acute or chronic chondral lesions (Martin et al., 2010b).

A systematic review with meta-analysis from 2015 found that few clinical tests for FAI and labral tears have been investigated in high-quality studies. Only the FADIR test and flexion–internal rotation had sufficient data for meta-analysis, and both were considered to have screening value only (Reiman et al., 2015).

Cook and Hegedus refer to the test as the impingement provocation test and give it a utility score of 3, meaning that the evidence minimally supports or does not support its use (on a scale from 1, strong support, to 3, minimal or no support) (Cook & Hegedus, 2012). This assessment reflects the literature up to 2012. Little has changed since then: we have found no new studies of the diagnostic accuracy of the test, and the only reliability study shows no more than fair agreement between examiners (Pålsson et al., 2020).

Body Examination suggests the following interpretation of the PRI test:

  • The PRI test is considered positive if it reproduces the patient’s familiar pain in the groin or “deep inside” the hip, clicking or locking, or an apprehension response.
  • The test is thought primarily to assess posterior labral tears or secondary posterior chondral lesions, such as contre-coup lesions in pincer-type impingement.
  • The location of the pain should be recorded. Deep or posterior pain is most consistent with posterior intra-articular involvement. Anterior pain or apprehension may indicate anterior hip instability and should be followed up with the HEER test and other instability tests. A stretching sensation in the groin may arise from the hip flexors and should be interpreted together with the Thomas test.
  • The test has shown low sensitivity for FAI and poor inter-examiner reliability. A negative test therefore does not rule out an intra-articular hip lesion, and a positive test should be interpreted with caution.
  • The PRI test should be used only as a supplementary test, in light of the history and the preceding examination.

Literature search, updating and translation were carried out with the assistance of AI (Claude, Anthropic). The professional content has been reviewed and quality-assured by the editor-in-chief, Roar Syltebø.

References

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