The plain answer
If you are a UK adult with new or worsening hip pain, the first imaging test is almost always a plain X-ray, not an MRI. X-ray costs less, delivers in minutes, and confidently answers the most common questions about a painful hip in someone over 40. MRI is the right next step only when X-ray is normal but symptoms persist, when the suspected diagnosis is soft-tissue, or when you are young, active, and have groin pain that no one has been able to explain.
The trap most patients fall into is the opposite - assuming any hip pain worth taking seriously needs the fancy scan. It usually does not. And when it does, the specific type of MRI matters enormously, because a standard hip MRI and a hip MR arthrogram are genuinely different tests with different roles.
What X-ray of the hip shows first
A plain X-ray of the hip is the workhorse first-line investigation. In under five minutes it shows:
- Osteoarthritis. Joint space narrowing, subchondral sclerosis, osteophytes and cysts - the whole classic picture of a worn hip.
- Fractures. Femoral neck fractures, intertrochanteric fractures, pelvic ring fractures. Displaced fractures are obvious.
- Hip dysplasia. A shallow acetabulum, seen on standing AP pelvis views, that predicts early arthritis and labral pathology.
- Bone lesions. Lytic or sclerotic lesions from primary or secondary malignancy, or from benign causes like a bone cyst.
- Heterotopic ossification and calcifications around the joint, tendon insertions and bursae.
Because osteoarthritis accounts for the majority of adult hip pain over the age of 55, and because X-ray shows it clearly, the algorithm in UK general practice is X-ray first. Only when the X-ray is normal but the patient is still struggling six weeks later does MRI usually get requested.
When to escalate to MRI
The clearest indications for a hip MRI in adults are:
- Persistent hip or groin pain beyond six weeks with a normal or near-normal X-ray. This is by far the most common trigger.
- Suspected labral tear. A young or active adult with mechanical symptoms - clicking, catching, giving way - especially with groin pain on hip flexion and internal rotation.
- A young adult with groin pain and no obvious cause on X-ray. The differential here includes femoroacetabular impingement, early avascular necrosis and stress fracture, none of which show on plain film early.
- Suspected avascular necrosis (AVN). Risk factors include long-term steroid use, alcohol excess, sickle cell disease, previous chemotherapy or a history of femoral neck fracture. MRI picks up AVN weeks to months before X-ray does.
- Suspected stress fracture in a runner, military recruit or dancer with load-related groin pain and a normal X-ray. Femoral neck stress fractures can be catastrophic if missed; MRI is the definitive test.
- Groin pain in athletes. Adductor tendinopathy, iliopsoas pathology, sports hernia and osteitis pubis all coexist in complex ways, and only MRI teases them apart.
If any one of these applies to you, an MRI - typically a musculoskeletal MRI read by a subspecialist - is the right test.
The eight diagnoses hip MRI is built for
Hip MRI earns its cost by finding conditions that X-ray, ultrasound and clinical examination cannot reliably diagnose. The eight most important are:
- Labral tear. The acetabular labrum is a rim of cartilage around the socket. Tears cause deep groin pain, mechanical clicking and catching, and are missed by X-ray. MR arthrogram remains the gold-standard imaging test.
- Femoroacetabular impingement (FAI). Abnormal bony morphology - cam (bump on the femoral head-neck junction), pincer (over-coverage by the acetabulum), or combined - causes labral and cartilage damage over time. MRI shows both the bony morphology and the resulting soft-tissue injury.
- Avascular necrosis (AVN). Bone-marrow oedema and the classic double-line sign on T2 sequences confirm early AVN long before X-ray becomes abnormal. Early diagnosis preserves the joint.
- Occult and stress fractures. Femoral neck stress fractures, sacral stress fractures and pubic ramus fractures can be entirely invisible on X-ray but obvious on MRI as bone-marrow oedema and a fracture line.
- Gluteal tendinopathy and tears. Greater trochanteric pain syndrome is the modern name for what used to be called trochanteric bursitis. MRI shows tendinopathy, partial or full-thickness tears of gluteus medius and minimus, and secondary bursitis.
- Iliopsoas bursitis and tendinopathy. Anterior groin pain with a snap on hip flexion. MRI shows fluid in the iliopsoas bursa and tendon changes.
- Sacroiliitis. Inflammation of the sacroiliac joints in axial spondyloarthropathy. MRI (specifically STIR and T2 fat-saturation) shows bone-marrow oedema years before structural change appears on X-ray. Essential for diagnosis in a young adult with inflammatory-pattern back and buttock pain.
- Occult fracture in the older patient after a fall with hip pain and a normal X-ray. MRI is highly sensitive and often diagnostic within hours.
MRI vs MRI arthrogram of the hip
This is the distinction that catches most patients (and some GPs) out. A standard hip MRI and a hip MR arthrogram are not interchangeable.
A standard hip MRI is entirely non-invasive. You lie in the scanner for 20 to 30 minutes and get high-resolution images of the joint, bone marrow, cartilage, tendons and surrounding soft tissue. It is excellent for detecting AVN, stress fractures, gluteal tendinopathy, bursitis and sacroiliitis. It will show large labral tears but misses smaller ones.
A hip MR arthrogram adds a step. Before the MRI, a radiologist injects diluted gadolinium contrast directly into the hip joint under X-ray guidance. The contrast distends the joint capsule, floats between torn labral fragments, and pushes into cartilage defects. It transforms sensitivity for labral pathology and small chondral lesions.
| Question | Standard hip MRI | Hip MR arthrogram |
|---|---|---|
| Suspected labral tear | Reasonable | Gold standard |
| Suspected AVN | Test of choice | Not needed |
| Suspected stress fracture | Test of choice | Not needed |
| Gluteal tendinopathy | Test of choice | Not needed |
| Suspected FAI with cartilage damage | Reasonable | Preferred if surgery being considered |
| Invasiveness | Non-invasive | Injection under X-ray guidance |
| Typical UK private cost, 2026 | £400 to £750 | £700 to £1,200 |
If a surgeon has already told you they suspect a labral tear or FAI and want to consider arthroscopic surgery, ask specifically about MR arthrogram before booking a plain MRI. Repeating the wrong scan wastes money and time.
