A clinical synthesis based on the Doha agreement (Weir 2015), the 2023-2025 meta-analyses and the systematic reviews on impingement after total hip arthroplasty.

How is this condition defined, who is affected and what are the risk factors?

• 🤸‍♀️ Young athletes : the condition is prevalent in sports involving repetitive, large-amplitude hip flexion, classical dance, football, athletics (hurdles, sprint), martial arts and gymnastics.⁵·⁶ In the reference cohort of Winston et al. (87 elite ballet dancers), 91 % report a snapping hip and 58 % associated pain; on dynamic ultrasound, abnormal movement of the iliopsoas tendon is objectified in only 59 % of the hips examined, a third of the cases remaining without an identified cause.⁷ An MRI study reports around 21 % of iliopsoas pathology in athletes consulting for groin pain.⁸
• 🔩 Patients with a total hip replacement (THR) : iliopsoas impingement is a recognised cause of persistent groin pain after arthroplasty. The 2025 systematic review (J Clin Med) consolidates a prevalence of between 0.4 % and 8.3 % depending on the diagnostic methods, with a weighted mean of around 4.3 %.⁹·¹⁰ The impingement is typically due to anterior overhang of the acetabular cup beyond the bony rim by more than 10-12 mm, creating a point of direct friction with the tendon on active flexion.¹¹

• Anatomical factors : a cam- or pincer-type femoroacetabular impingement (FAI) alters hip mechanics and increases the stress on the iliopsoas tendon.¹² A prominent anterior inferior iliac spine can also create a secondary point of impingement.
• Biomechanical factors : the weakness of the gluteal muscles (medius, maximus) and of the external rotators is documented in symptomatic FAI patients (a deficit of 0.34 to 0.38 Nm/kg in flexion-extension vs controls, Casartelli 2011).¹³ This weakness leads to compensatory overuse of the iliopsoas complex as an anterior stabiliser, which the biomechanical models of Lewis and Sahrmann confirm: reduced force in the glutes or the iliopsoas increases the anterior joint force under load.¹⁴
• Factors related to sporting load : the systematic review of Whittaker 2015 (BJSM) identifies older age, a history of groin injury and low adductor strength as robust predictors of groin injury.¹⁵ The IOC consensus 2016 (Soligard) stresses the « training-injury paradox »: too little load exposes the athlete as much as too much: it is the abrupt variation in load that is the main risk.¹⁶·¹⁷
• Surgical factors (after THR) : cup size, anterior overhang, low anteversion, the direct anterior approach and a large prosthetic head are the main determinants of iatrogenic impingement.⁹·¹⁰·¹¹

What happens in the body and how does the condition evolve naturally?

Which questions should you ask to understand the patient and their history?

• Precise site : pain specifically localised to the anterior part of the groin, at the inguinal crease, over the femoral triangle, is a key indicator.¹ Patients often describe it as a deep pain, sometimes hard to point to.
• Triggering activities and movements : symptoms typically exacerbated by activities with repeated or resisted hip flexion, running (especially uphill), kicking in football, climbing stairs, moving from sitting ↔ standing, getting out of a car.⁴·⁵ Patients after THR often describe pain arising when putting on socks or rising from a low chair.⁶
• Mechanical phenomena : the presence of an audible or palpable snap or click in the groin during hip movements (flexion → active extension against resistance) strongly suggests an internal snapping hip related to the iliopsoas.⁷·⁸ The patient should be asked whether they can reproduce the phenomenon voluntarily.
• History : record any history of hip arthroplasty (date, approach, type of implant), of hip surgery or of a recent joint procedure. Iliopsoas impingement after THR can appear several months after the operation, with a median delay of 5 to 8 months across the series.⁹·¹⁰
• Characteristics of the pain : mode of onset (sudden vs gradual), intensity (NRS 0-10), behaviour over the day (mechanical vs inflammatory), functional impact (a short HAGOS or the EQ-5D to quantify the disability).¹¹
• Red flags : fever, unexplained weight loss, night sweats, a history of cancer, night pain waking the patient, a pulsatile inguinal mass (femoral artery aneurysm), any such signal calls for prompt medical referral.¹²

Which clinical tests should you run and which other conditions must be ruled out?

• Direct palpation : palpation of the tendon over the lesser trochanter (in the femoral triangle, lateral to the artery). Reproduction of the familiar pain is a positive sign, but the test is technically difficult and not very specific.¹
• Resisted hip flexion (the Stinchfield test) : patient supine, hip flexed to 30° with the knee extended, against the clinician's resistance. Reproduction of the anterior pain is a positive sign.¹·⁴
• Modified Thomas test : beyond the measurement of flexibility, the reproduction of the anterior pain when the psoas is put under tension (passive hip extension with the pelvis held in posterior tilt) is the relevant diagnostic element, not the mere sensation of stretch.⁵
• Passive stretch in prone : can also provoke the pain by stretching the musculotendinous complex.⁵

• Femoroacetabular impingement (FAI) : the main differential diagnosis. The FADIR test (Flexion, Adduction, Internal Rotation) has high sensitivity (close to 99 %) but very low specificity (≈ 7 %) in the meta-analysis of Reiman 2015: it loads multiple anterosuperior structures and a positive test does not designate a single structure.³ The « C-sign » (a C-shaped hand around the hip) is typical of the FAI patient.
• Labral tears : often associated with FAI, they can cause pain, locking or intra-articular snapping.³
• Hip osteoarthritis : mechanical pain on weight-bearing, reduced range (internal rotation in particular).⁸
• Adductor-related pain : more medial pain, reproduced by palpation of the pubic insertion and by the squeeze test (isometric adduction).¹·¹³
• Athletic pubalgia (sports hernia) : peri-pubic pain, linked to the deep abdominal muscles, often in footballers.¹
• Non-musculoskeletal origins : L1-L2 radiculopathy, inguinal or femoral hernia (hence the importance of examining the patient standing and straining), urogenital disease, femoral aneurysm in the older atheromatous patient.

Should patients be classified according to the Doha agreement, and for what benefit?

1. Defined clinical entities for groin pain : pain related to the adductors, à the iliopsoas, to the inguinal region, to the pubic region.
2. Hip-related groin pain : intra-articular pathology (FAI, labral, osteoarthritis, osteochondral).
3. Other causes of groin pain in the athlete (neurogenic, visceral, etc.).

• Diagnostic clarity : it forces the clinician to identify the main structure involved, avoiding the vague diagnosis of « pubalgia ».
• Standardised communication between physiotherapists, sports physicians and surgeons.
• Better research through more homogeneous cohorts: essential to evaluate the effectiveness of interventions reliably.
• Targeted treatment direction : specific exercises according to the dominant structure, without falling into « one size fits all ».

Where do you start? What is the recommended hierarchy of interventions?

1. Activity modification + load management : relative rest (never complete), temporary avoidance of the most provocative activities (sprinting, steep climbs, kicking), maintenance of painless cross-training (cycling, swimming), pain education.⁴
2. Initial pharmacology (if needed) : NSAIDs over 7-14 days to manage the acute inflammatory phase, in the absence of contraindications. Paracetamol and tramadol can complement them.⁵
3. Structured active physiotherapy : the cornerstone (see 3.2). Focused on progressive strengthening, lumbopelvic motor control and load management.
4. Image-guided injections : after 8-12 weeks of failed physiotherapy, an injection of corticosteroid ± local anaesthetic under ultrasound guidance. It serves both as a diagnostic tool (confirmation) and a therapeutic one (an analgesic window in which to intensify rehabilitation). The 2025 JBJS Rev SR (12 studies, 235 patients) shows an improvement in NRS from 7.33 → 2.47 and in HHS from 58.5 → 89.9, with 28.9 % going on to surgery.⁶
5. Surgery : reserved for persistent failures. In the athlete: endoscopic release of the tendon (Ilizaliturri 2005) with return to sport at 4-6 months. In the patient after THR: see chapter 4.⁷

Where does exercise fit in, and is there a superior approach? 🏋️‍♂️

• Strengthening the antagonist and synergist muscles : glutes (maximus, medius) and external rotators. Strong glutes improve the control of extension and rotation, which can reduce the overuse of the iliopsoas as an anterior stabiliser.⁹·¹⁰ Typical exercises: glute bridge (then single-leg), clamshells, side-lying abduction, standing sequences (mini-band side step, monster walk).
• Lumbopelvic motor control : core stability, lumbopelvic dissociation, control of pelvic anteversion, to reduce the compensatory stresses on the hip flexors.¹¹
• Progressive management of tendon load : after the initial phase, progressive reloading of the iliopsoas tendon. Isometric work in hip flexion first (analgesia), then eccentric and concentric as tolerated, with the pain-monitoring model of Silbernagel: pain acceptable up to 5/10 if it settles quickly after the exercise and does not worsen the next day.¹²·¹³
• Hip hinge and functional patterns : restoring the deep squat, the lunge and stair climbing without lumbar compensation.

Manual therapies and technologies: how effective are they really?

• Manual therapy : soft-tissue mobilisation of the iliopsoas complex, the quadriceps and the adductors; joint mobilisation of the hip, the sacroiliac joints and the lumbar spine. Symptomatic relief is often real, but the evidence of a long-term effect is weak without an associated active programme.²
• Dry needling : can reduce the pain of trigger points in the psoas and the glutes, making participation in rehabilitation easier. Data specific to the psoas are scarce.
• Extracorporeal shockwave therapy : studied mainly for calcific tendinopathies; extrapolation to the psoas in chronic tendinopathy, without solid specific data.
• TENS / electrotherapy : transient analgesic effect, an adjunct role.

Beyond the physical: how do you educate the patient and address psychological factors? 🧠

• Demystify the diagnosis : explain the mechanical nature of the pain in simple terms, without catastrophising language. Reassure the patient that pain does not mean serious structural damage.¹⁴
• Explain load management : give tools to modulate activities. The concept of optimal load is more useful than complete rest.¹³
• Promote self-efficacy : give the patient responsibility through adherence to the home programme.¹⁴

• Kinesiophobia (fear of movement): graded exposure to movement in a safe setting is the best therapy.¹⁵
• Catastrophising beliefs : reframe negative beliefs (« my body is damaged », « I am going to make things worse »).¹⁴
• Stress and anxiety : they increase the sensitivity of the CNS and amplify the perception of pain, stress management techniques are relevant.

Epidemiology and iatrogenic risk factors of impingement after THR

• Anterior overhang of the acetabular cup : the most powerful factor. Beyond 10-12 mm of overhang relative to the anterior bony rim (measured on CT or MRI), the risk of impingement increases significantly.¹·² A threshold of 8 mm of anterior cup protrusion is sometimes used in practice.
• Low acetabular anteversion : anteversion below 10° (ideal target 15-25°) increases the tension on the tendon in hip flexion.
• Direct anterior approach (DAA) : a higher rate of clinical impingement than with posterior or lateral approaches, possibly related to the change in the tendon's path caused by the approach.²·³
• A large prosthetic head (≥ 36 mm): increases the lever arm and the friction on the tendon.
• Anterior bone deficiency of the native acetabulum : limits the possibility of burying the cup without overhang.
• Long fixation screws protruding anteriorly (a screw-fixed cup).
• Dual-mobility cup : in certain designs it can itself come into contact with the tendon.

Specific diagnosis: imaging and the test injection

• Anterior groin pain of secondary onset (often 3-9 months after the surgery, sometimes later).
• Pain reproduced by active resisted flexion of the hip (straight leg raise, putting on socks, rising from a low chair, getting in and out of a car).
• Pain relieved by passive flexion, worsened when walking up stairs.
• No signs of infection (normal CRP/ESR, no fever) and no loosening (stable radiographs).

• Chronic prosthetic infection (CRP, ESR, joint aspiration at the slightest doubt).
• Aseptic loosening (comparative radiographs, bone scan).
• Periprosthetic stress fracture (mechanical pain, CT).
• Particle disease (granuloma).
• Referred lumbar pain (L1-L2 radiculopathy).
• Visceral disease (inguinal hernia, urological disease).

1. Standard radiographs anteroposterior + lateral: looking for anterior overhang of the cup, checking the positioning (target inclination 40°, anteversion 15-25°).
2. Low-dose 3D CT with acetabular reconstruction: quantifies the anterior overhang precisely in millimetres and the actual anteversion.
3. Dynamic ultrasound : visualises the tendon in movement, looks for dynamic impingement against the cup and makes it possible to guide the test injection.
4. MRI (METAL-suppressed sequences, MARS or SEMAC type) : looking for peri-tendinous oedema, bursitis and tendinopathy without major metal artefact.

The therapeutic cascade: from conservative care to endoscopic tenotomy

1. Conservative treatment (3-6 months) : education, activity modification (avoiding abrupt active resisted flexion), a short course of NSAIDs, physiotherapy focused on lumbopelvic motor control and strengthening of the glutes. Stretching the psoas is clearly contraindicated here (direct compression against the cup).
2. Ultrasound-guided injections : 1 to 3 injections 3 to 6 weeks apart, with intensive rehabilitation in the analgesic window. The 2025 JBJS Rev SR (12 studies, 235 patients) reports 28.9 % going on to surgery, which means that ~71 % avoid surgery thanks to this strategy.⁴
3. Endoscopic tenotomy of the iliopsoas tendon : a minimally invasive procedure carried out at the lesser trochanter or at the insertion. Reported success rate of 80 to 90 % on pain, but with 32 % residual weakness in hip flexion detectable on a dynamometer, often well tolerated functionally but to be explained before surgery.⁵·⁶
4. Acetabular revision : reserved for cases with a clearly malpositioned cup (major overhang ≥ 12-15 mm, very deficient anteversion). A major procedure, whose indication must be weighed carefully.²

How do you make the patient an actor in their own recovery through self-management?

• Understanding the condition and the risk factors : explain the mechanisms, the interaction between training load, personal biomechanics (lumbopelvic control, strength of the stabilisers) and anatomical factors. Pain is often a signal of overload rather than of damage, which can reduce kinesiophobia and encourage a return to activity.³
• Pain monitoring: the traffic-light model 🚦: pain 0-3/10 during the activity that settles quickly afterwards = green light; pain 4-5/10 settling within a few hours = amber light (adapt the volume); pain > 5/10 that persists or worsens the next day = red light (reduce sharply). An approach taken directly from the pain-monitoring model of Silbernagel 2007.⁴
• Adherence to a home exercise programme : not an endless list but a programme that is concise, targeted and progressive , combining progressive strengthening of the glutes, the external rotators, the flexors (respecting pain) and the core. This programme must be reviewed and adapted every 4 to 6 weeks.
• Progressive management of the training load : one of the greatest predictors of recurrence is an abrupt increase in volume or intensity.⁵ The patient must learn the principles of gradual progression: the 10 % rule (do not increase the weekly volume by more than 10 %), monitoring of the acute:chronic workload ratio, the importance of recovery days.⁶·⁷
• Recognising situations at risk : a rushed return after a break, an abrupt increase in load at the start of the season, dehydration, accumulated fatigue, all situations known as precipitating factors, identified by the Whittaker 2015 SR.⁸

When and how do you plan a safe return to sport and to activity?

• Criterion 1. Pain-free : no pain on palpation, on resisted flexion, or during activities of daily living for at least 14 days.
• Criterion 2. Symmetrical strength : strength of the key hip muscles (flexion, extension, abduction, adduction, rotations) ≥ 90 % of the unaffected side on a hand-held dynamometer (HHD).⁹·¹⁰
• Criterion 3. Functional tests passed : able to perform hop tests (single, triple, crossover), changes of direction (cutting) and sport-specific movements without pain, without apprehension and with good movement quality.
• Criterion 4. Psychological readiness : confidence regained, no kinesiophobia. Validated scales such as the Injury-Psychological Readiness to Return to Sport (I-PRRS) can quantify this crucial aspect.¹¹
• Criterion 5. Sport-specific tests : reproduction of the movements of the sport without pain (kicking in football, the splits in dance, sprinting with changes of direction in athletics).

Analysis of a classic case: the ballet dancer cohort (Winston 2007)

• Activity modification (temporary reduction of the movements that provoke the snap: développé, aerial splits).⁴
• Specific strengthening of the glutes and external rotators to improve the dynamic stability of the pelvis.⁵
• Education about the « asymptomatic » snap: the click is not pathognomonic in itself: many dancers have an audible snap without pain; it is the associated pain that defines the condition.²
• Proprioceptive and motor control work over the lumbo-pelvi-femoral chain.
• Progressive return to technique with criteria of strength ≥ 90 % and being pain-free for 14 days.

The diagnostic challenge: when bursitis mimics an inguinal hernia

• Ultrasound : visualises a hypoechoic fluid collection communicating with the hip joint in 15 % of cases, typical of iliopsoas bursitis. It also allows a femoral aneurysm to be told apart (Doppler essential).
• MRI : confirms the bursitis with T2 hyperintensity, shows any intra-articular communication, looks for an associated tendinopathy and rules out a tumour mass.⁷
• CT : useful if an associated hernia is suspected or in a traumatic context.

Study of a complex case: impingement after arthroplasty treated by tenotomy

1. Ruling out the emergencies : no fever, normal CRP, normal ESR → infection unlikely. Stable radiographs → no loosening and no periprosthetic fracture.
2. Targeted imaging : 3D CT quantifying the anterior overhang of the cup at 13 mm (above the critical threshold of 10-12 mm). MRI with METAL-suppressed sequences showing peri-tendinous oedema and tendinopathy of the iliopsoas.
3. Diagnostic test injection under ultrasound : 8 mL of 1 % lidocaine + 40 mg of methylprednisolone, with a fall in the NRS from 8/10 to 2/10 at 30 min, confirming the diagnosis.

Critique and controversy: where do clinical cases sit in the hierarchy of evidence?

When, and to which other health professionals, should you refer?

• Sports physician : for prescribing targeted imaging (MRI, dynamic ultrasound) and advising on injections.
• Interventional radiologist : for the diagnostic and therapeutic injections under ultrasound.
• Orthopaedic surgeon (hip) : advice on tenotomy or acetabular revision after prolonged conservative failure.
• Rheumatologist : if an inflammatory cause is suspected (spondyloarthritis, rheumatoid arthritis).
• Psychologist / psychiatrist : for significant yellow flags.

How do you measure outcomes and overcome the barriers to implementation?

• HAGOS (Copenhagen Hip and Groin Outcome Score, Thorborg 2011): 37 items, 6 subscales: pain, symptoms, daily living, sport/recreation, participation, quality of life. COSMIN-validated, available in French.⁷
• iHOT-33 (international Hip Outcome Tool): 33 items, validated for athletic hip pathology.
• HOOS (Hip disability and Osteoarthritis Outcome Score): for patients after THR and with hip osteoarthritis.
• NRS or the pain VAS: an unavoidable minimum, simple and quick.
• I-PRRS (Injury-Psychological Readiness to Return to Sport): for the psychological dimension at the time of return to sport.⁸

• Active continuing education : interactive workshops, peer mentoring, more effective than passive reading of articles.¹⁰
• Audit and feedback : analysing one's own practice data and comparing it against standards (Ivers Cochrane 2012).¹¹
• Organisational support : the most powerful enabler, a work culture that values learning, protected time for training, access to the databases.⁹
• Technological integration : patient records with PROMs built in, telehealth platforms, pain-monitoring apps.