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Imaging for hip-related groin pain: don’t be hip-notised by the findings
  1. Kieran O’Sullivan1,2,
  2. Ben Darlow3,
  3. Peter O’Sullivan4,
  4. Bruce B Forster5,
  5. Michael P Reiman6,
  6. Adam Weir7,8
  1. 1 Sports Spine Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
  2. 2 Department of Clinical Therapies, University of Limerick, Limerick, Ireland
  3. 3 Department of Primary Health Care and General Practice, University of Otago, Wellington, New Zealand
  4. 4 School of Physiotherapy and Exercise Science, Curtin University, Perth, Australia
  5. 5 Department of Radiology, Faculty of Medicine, University of British Columbia, Vancouver, Canada
  6. 6 Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA
  7. 7 Sports Groin Pain Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
  8. 8 Erasmus MC Center for Groin Injuries, University Hospital Rotterdam, Rotterdam, The Netherlands
  1. Correspondence to Dr Kieran O’Sullivan, Sports Spine Centre, Aspetar Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar; kieran.osullivan{at}aspetar.com

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Awareness of femoroacetabular impingement (FAI) syndrome, acetabular labral tears and chondral lesions as potential causes of hip-related groin pain has increased considerably due to advances in imaging and arthroscopic surgery. Consequently, hip imaging and surgery rates have grown rapidly.1 However, there is no strong evidence of improved clinical outcomes with arthroscopic interventions. Although imaging findings are only diagnostic for FAI syndrome when they exist together with clinical signs and symptoms, imaging remains the main criterion for FAI surgery.2 Most patients (71%) are willing to undergo surgery based solely on their physician’s recommendation.3 We question whether such reliance on imaging can be justified. Does it have risks (eg, radiation, downstream testing, costs) and may it lead to suboptimal management of hip-related groin pain?

Do imaging findings predict hip-related groin pain?

People with both large cam morphology and reduced hip internal rotation are 25 times more likely to develop future hip osteoarthritis (OA).4 While such high odd ratios cannot be ignored, many with such morphology do not develop future hip OA,4 and confounding variables could explain some of this relationship. Over 50% of athletes have cam morphology, and over 65% of asymptomatic people, including athletes, have acetabular labral tears.5 Some imaging findings (eg, pincer morphology) previously considered pathological might actually be protective.6 Additionally, imaging’s limited clinical utility7 and poor association with hip pain make it difficult to distinguish a clinically significant imaging finding from benign variation; thus we strongly support the term cam ‘morphology’, replace ‘deformity’ in this setting.8 Caution is therefore warranted in correlating imaging findings with pain.

Clinical considerations

Don’t rush to imaging

While imaging may be indicated in some patients with hip-related groin pain, determining with confidence which patients need imaging, and which findings should guide diagnosis and treatment requires careful correlation with history (eg, traumatic onset or not), physical examination findings and factors such as age and activity levels. Consideration of alternative causes for groin pain is critical, while correlation with diagnostic joint infiltration8 to confirm an articular aetiology, may be useful.

Interpret imaging cautiously

When imaging is performed, report findings using the CLEAR principle.9

Consistent Language: Minimally threatening language with accurate and easily understood words should be used to communicate imaging findings, without increasing fear that groin pain is always caused by structural ‘damage’.9

Epidemiological information: comparisons to age-matched findings for asymptomatic populations could help patients and healthcare professionals contextualise the findings.

Assessment of Relevance: explaining what imaging findings do, and do not, mean for individual patients in isolation from clinical features is fraught with difficulty. There is no clear cut-off which signifies pathology,8 with hip morphology being influenced by multiple factors such as ethnicity and loading history.

Learn from recent history

Technical advances in surgery have increased imaging and surgery rates without obvious clinical benefit in some clinical contexts, for example, lumbar discectomy as well as arthroscopic subacromial decompression and partial meniscectomy. It seems possible that history may be repeating itself at the hip joint; patients with common changes in tissue morphology which are presumed to be pathological undergo surgery. With respect to FAI syndrome, even when cam morphology is identified, and appears closely linked to pain, there is no strong evidence that any specific management approach (surgical, conservative care, rehabilitation or pharmacological) is superior.8

Consider the whole person

Musculoskeletal pain is influenced by multiple factors including training load, sleep, stress, fatigue, attitudes, beliefs and mood, as well as structural morphology. Imaging findings are only one part of the jigsaw puzzle. These ‘non-structural’ factors influence the pain experience as well as tissue resilience and local sensitivity, reinforcing the need to carefully interpret aggravating patterns and physical examination tests. Modifiable factors such as these often represent more potent therapeutic targets than structural tissue changes.

Future research directions

Some research avenues may enhance understanding and management. Future prospective studies should control for key confounding factors likely to be important in developing musculoskeletal pain (eg, training load, sleep, mood, stress) to better identify what unique contribution, if any, hip morphology makes in the development of hip-related groin pain. There are several trials currently underway which seek to compare the efficacy of arthroscopic FAI surgery with (1) well-described conservative care protocols and (2) placebo surgery. Unless, and until, these trials demonstrate additional value of arthroscopic FAI surgery, we feel it is prudent to be cautious in assuming that it is effective.

So, how to avoid hip-nosis?

Clinicians may currently be over-reliant on imaging findings when making treatment decisions. If requested, imaging should only form one part of the overall assessment to evaluate an athlete’s health. Findings should be reported in an understandable manner and reference the prevalence of such tissue changes in age-matched asymptomatic populations. In this way, imaging may inform, but does not necessarily dictate, management. This helps ensure that the athletes themselves are treated, rather than just their imaging findings.

Supplementary file 1

References

Footnotes

  • Twitter @kieranosull, @peteosullPT, @mikereiman, @brucebforster, @adamweirsports

  • Contributors All authors contributed substantially to this submission led by KOS and AW.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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