Sudden Hip Pain With No Injury

Most hip pain has a story behind it. You fell, you twisted, or it crept up over years. Sudden hip pain with no injury is different. The groin aches over a few days, standing on that leg becomes uncomfortable, and nothing explains it. This is a different problem from chronic hip pain that builds slowly, and the bone itself is often the source. Three conditions account for most cases: avascular necrosis, femoral neck stress fracture and transient osteoporosis of the hip.

At MTP Health, Dr Donald Cawthorne and our physiotherapy and exercise physiology team see this presentation regularly, and the earlier it is assessed the more options you keep.

Key Takeaways

• Hip pain that arrives without a fall or twist and hurts to stand on often comes from bone rather than muscle or tendon.
• Avascular necrosis, femoral neck stress fracture and transient osteoporosis look similar at first and behave very differently over time.
• X-rays are often normal in the early weeks, so MRI is the usual next step when bone is suspected.
• Reducing load through the hip while you wait for assessment protects bone that is temporarily weaker.
• Many people recover without surgery; the exceptions depend on which condition it is and how early it is found.

Why Bone Pain Feels Different: Causes of Hip Pain

Muscle and tendon pain is usually sore to touch, worse with one movement and eased by a few days of rest. Bone pain behaves differently. Pain from the femoral head or neck sits deep in the groin area, builds with every step, can throb at night, and unlike acute pain from a strain it does not settle with simple self care.

There is nothing to see, and a limp appears as your body shortens the time spent on that leg. Where you feel pain matters: soft-tissue problems tend to sit in the outer buttch or upper thigh, while this deep groin ache points to the bone.

As an orthopaedic and physiotherapy clinic on Sydney’s North Shore, we find the question is not which muscle is tight but why a bone that was fine a month ago is now struggling to carry your weight. Working that out shapes hip pain treatment, because how the hip pain is treated depends entirely on the underlying cause.

Avascular Necrosis Of The Hip

Avascular necrosis, also called osteonecrosis, occurs when the blood supply to the femoral head is reduced and the bone tissue begins to die. Weakened bone under the weight-bearing surface can eventually collapse and lead to osteoarthritis, with the grating sensation and osteoarthritis pain that follows.

It most often affects adults between 30 and 60. Risk factors include high-dose corticosteroids, heavy alcohol use, some blood and autoimmune conditions, and previous chemotherapy or radiotherapy, though in many people no cause is found. Around one in three people have changes in the other hip, so both sides are checked. Reduced blood flow to the bone is the common thread.

Femoral Neck Stress Fracture

A stress fracture develops when repeated load outpaces the bone’s ability to repair itself, an overuse hip injury common in people playing sports or ramping up training.

In the hip it forms in the femoral neck, the narrow bridge between the ball and the thigh bone. The classic patient is a runner who has increased training quickly, but it also occurs in older adults whose bone quality has declined, where even climbing stairs can aggravate it.

Where the crack sits changes the urgency. Fractures on the lower, compression side of the neck are usually stable and heal with protected weight bearing. Fractures on the upper, tension side can extend across the neck and threaten the blood supply to the femoral head, so a suspected tension-side hip fracture is treated as a priority.

Transient Osteoporosis Of The Hip

Transient osteoporosis of the hip, sometimes called bone marrow oedema syndrome, is the least known of the three and the most reassuring. The femoral head temporarily loses mineral and becomes swollen and painful for reasons not fully understood. It typically affects men in their forties and fifties, and women late in pregnancy or soon after birth.

The severe hip pain often arrives within a week and can be severe enough to need crutches. The key feature is that it resolves on its own, usually within six to twelve months. In the meantime the painful hip needs protecting, because softened bone can fracture under ordinary load. Early MRI changes can resemble early avascular necrosis, so Dr Cawthorne may repeat imaging to confirm the bone is recovering rather than progressing.

How The Three Are Told Apart

Not every ache in this age group is one of these three, so part of the job is sorting the bone causes from the many other causes of hip pain. Referred pain from spine problems such as spine arthritis, muscle irritation, tendon inflammation, hip impingement or labral tears that limit movement and can cause locking or clicking, hip bursitis, which is inflammation of fluid sacs near the hip joint, and, rarely, infection-related hip problems with a hot joint, high temperature, redness, swelling, and limited movement can all cause pain around the hip. Muscle weakness and joint pain elsewhere can muddy the picture too, and pain may also travel down the thigh to the knee.

Assessment of any persistent or chronic pain begins with the history: how the pain started, training load, medications, pregnancy and general health, followed by examination of your walking pattern and hip rotation. Blood tests may also be used if infection or inflammatory disease is suspected. An X-ray is usually done first, but in the early weeks all three bone conditions can look normal because the changes are inside the bone.

MRI is the usual next step among imaging tests if pain persists after clear X-rays, and ultrasound may sometimes be used for soft-tissue concerns; MRI shows the size of any lesion and whether a crack or collapse is present.

Dr Donald Cawthorne, orthopaedic surgeon, uses this to answer the question that guides everything else: is this bone likely to heal if protected, or is it at risk of collapse or fracture without intervention? Your GP or primary care physician can start this process if pain in your hip persists. Seek urgent medical care for severe pain or signs of infection.

Protecting The Hip While You Heal: Hip Pain Treatment

For transient osteoporosis, compression-side stress fractures and early avascular necrosis without collapse, the first line of treatment is reducing the load through the femoral head while the bone recovers.

That usually means a period on crutches, pausing running and impact, and switching to cycling or swimming to maintain fitness. Simple measures ease pain in the meantime: an ice pack after activity, short-term pain medications for pain relief, and rest for the affected leg all help relieve pain while the diagnosis is confirmed.

This is where the MTP physiotherapy and exercise physiology team takes the lead. Physical therapy keeps the muscles around the hip and trunk working within safe limits, and carefully chosen hip pain exercises maintain strength without loading the injured bone.

The team plans a graded return to walking and then running once imaging and symptoms allow, and the return to physical activity is paced by bone healing rather than how you feel on a good day.

Alongside these other treatments, where a risk factor can be changed, such as steroid dose, alcohol or training load, it is addressed at the same time with your GP or our team, which also helps prevent hip pain from returning.

When Surgery Is Discussed and Physical Therapy Considered

Surgery is one part of a broader journey and is reserved for specific situations, once the underlying cause is clear and depending on the medical condition driving it. In avascular necrosis diagnosed before collapse, core decompression may be offered: a narrow channel is drilled into the affected bone to relieve pressure and encourage new blood vessels. It can slow progression in smaller lesions, though results vary.

Once the femoral head has collapsed or arthritis has developed, hip replacement becomes the more reliable option, and it is a discussion about timing and your goals rather than an emergency.

A tension-side or displaced femoral neck stress fracture is usually stabilised with screws to stop it extending, a smaller operation that still carries risks such as infection and non-union. Transient osteoporosis does not need surgery unless a fracture occurs. In every case the non-surgical alternative and the risks of each of the treatment options are laid out so the decision is yours.

Frequently Asked Questions (FAQs)

Can hip pain come on suddenly without an injury?

Yes. When there is no fall or twist and the pain is deep in the groin and worse with standing, the source is often bone. Avascular necrosis, femoral neck stress fracture and transient osteoporosis of the hip are the three most common explanations.

How quickly should sudden hip pain be assessed?

If you are limping, have night pain, are pregnant, have recently taken corticosteroids or have sharply increased your running, aim to be assessed within days rather than weeks. Early diagnosis keeps more options open.

Can avascular necrosis of the hip be treated without surgery?

In its early stages, yes. Protected weight bearing, addressing risk factors and monitoring with repeat MRI can allow small lesions to stabilise. Larger lesions are more likely to progress, which is when core decompression or, later, hip replacement is discussed.

Does transient osteoporosis of the hip go away on its own?

In most cases it does. Bone density in the femoral head returns to normal over six to twelve months and the pain resolves. The main risk during that time is a fracture through the softened bone, which is why protected weight bearing and follow-up imaging are recommended.

Should I keep exercising with sudden hip pain and no injury?

Stop running and impact activity until the cause is known, because all three conditions involve bone that is temporarily weaker. Cycling, swimming and upper body training are usually safe, and your physiotherapist will guide the return to load once the diagnosis is clear.

Conclusion

Sudden hip pain with no injury is a sign that a bone is under strain it cannot currently handle. Whatever the cause, two things help: an early diagnosis and a plan that protects the bone while it recovers.

Dr Donald Cawthorne and the MTP Health physiotherapy and exercise physiology team work together on both. If your hip has started hurting without a clear reason, book an assessment with MTP Health on Sydney’s North Shore or call (02) 9437 9794.