What separates a red flag from routine hip pain

Most hip pain does not need emergency attention. Gradual discomfort tied to activity, stiffness after sitting, or an ache that has built up over months is appropriate for a routine GP appointment or a period of self-management — and in many areas patients can refer themselves directly to NHS community physiotherapy without seeing a GP first.

A smaller but important group of presentations is different. Certain combinations of symptoms point to fracture, joint infection, malignancy, or vascular compromise — conditions where hours of delay can determine whether recovery is full or permanently limited. For suspected septic arthritis of the hip, for example, the difference between prompt treatment and a 'wait and see' approach may be the difference between a joint that heals and one that sustains irreversible damage.

The NHS structures this decision into three tiers. The first covers routine GP care for pain that disrupts daily life or has not settled after two weeks. The second calls for same-day assessment — via NHS 111 or an urgent GP appointment — when certain warning features are present without obvious injury. The third requires an immediate 999 call or A&E visit after trauma or when neurological symptoms appear.

Red flags are not diagnoses. They are clinical signals that indicate urgent assessment is needed, not certainty that something serious is wrong. The sections below work through each tier, starting with the presentations that cannot wait.

Hip symptoms that need 999 or A&E immediately

Call 999 or go to A&E without delay if any of the following apply after a fall or sudden injury to the hip.

Inability to bear weight If you cannot put any weight through your leg, treat it as a fracture until a clinician confirms otherwise. NHS guidance is unambiguous on this point: severe hip pain following a fall combined with inability to walk requires immediate hospital assessment, not a GP appointment.

Visible deformity — leg shortening or external rotation A leg that appears shorter than the other, or a foot that rolls outwards at rest, is a classic sign of a displaced neck-of-femur (NOF) fracture or hip dislocation. NOF fractures predominantly affect older patients with osteoporosis-weakened bone, but any age group can sustain one after significant trauma.

Neurological symptoms in the leg after hip trauma Tingling, numbness, or weakness spreading from the hip down into the leg or foot following an injury indicates possible nerve compromise and requires emergency imaging.

Cancer history with hip pain after minor injury Pathological fractures can occur with little or no trauma when bone is weakened by metastases or infection. In any patient with a history of malignancy, unexplained hip pain after even a trivial knock warrants emergency assessment rather than watchful waiting.

When a normal X-ray is not the all-clear Undisplaced NOF fractures may appear entirely normal on a standard A&E radiograph. Professor Paul Lee's medico-legal commentary on missed NOF fractures underlines the point: if pain and an inability to weight-bear persist after a normal plain film, MRI is the appropriate next step. A normal X-ray result alone should not be taken as reassurance that a fracture has been excluded.

Septic arthritis of the hip — a presentation that can mislead

Septic arthritis of the hip joint is unusual among musculoskeletal emergencies because it can present without the visible signs most patients expect from a serious infection. The joint sits beneath substantial layers of muscle and soft tissue, so redness, visible swelling, and surface warmth — the signs patients typically associate with infection — are often absent or hard to detect. This makes the systemic picture the more reliable guide.

The warning features to act on are: fever above 38°C, rigors or severe chills, sudden severe pain felt deep in the groin or hip, and inability to bear weight. These symptoms can develop over hours to days. NHS guidance is explicit: a hot swollen joint, skin colour change around the hip, or hip pain combined with a high temperature all warrant same-day assessment — call 111, arrange an urgent GP appointment, or go directly to A&E if the presentation is severe.

The stakes are high because delay directly worsens outcome. Septic arthritis of the hip requires hospital admission and intravenous antibiotics, with an average inpatient stay of around two weeks; hours of delay can be the difference between full recovery and irreversible joint destruction.

For patients who already have a hip replacement, the clinical picture can be still more subtle. Periprosthetic joint infection may develop without obvious systemic features in its early stages. If not identified promptly, treatment may ultimately require surgical removal of the prosthetic implant — underscoring why any unexplained pain, warmth, or discharge around a replaced hip joint should be assessed without delay.

Systemic warning signs pointing to serious disease

Not every serious cause of hip pain announces itself dramatically. Some of the most clinically significant red flags arrive quietly — a gradual ache, modest fatigue, or a lump that does not hurt — which is precisely why they merit attention.

Unexplained weight loss, night sweats, or persistent fatigue alongside hip pain These systemic features raise the possibility of metastatic bone disease or a primary bone tumour involving the proximal femur. The hip is a common site for skeletal metastases from breast, prostate, lung, and kidney primaries. In a patient with a personal history of cancer, new hip pain — even without trauma and even if relatively mild — is an urgent referral rather than a case for watchful waiting. Bone metastases can weaken the proximal femur before any fracture occurs, and the window for intervention matters.

Long-term corticosteroid use Prolonged oral steroid treatment is a well-established risk factor for avascular necrosis (AVN) of the femoral head, in which the blood supply to the bone is disrupted and the joint surface may collapse. If you have been treated with corticosteroids for more than a few months and develop new or worsening hip pain, it is worth raising the possibility of an orthopaedic review with your GP, even if the pain is currently manageable.

A groin lump or pulsatile swelling A palpable mass or a swelling that pulses in the groin alongside hip pain flags possible vascular pathology — such as a femoral artery aneurysm — or a soft-tissue tumour. This combination warrants same-day medical assessment.

Across all these presentations, the absence of severe pain does not make the finding less urgent. The underlying process may be advanced before pain becomes prominent.

Hip pain that isn't an emergency but shouldn't be left

Some presentations sit in an uncomfortable middle ground: not dramatic enough to call 999, but too significant to leave until a routine appointment opens in six weeks. These are the patients who are unsure whether their pain 'counts.'

Nocturnal hip pain that wakes you from sleep Acute, unilateral hip pain severe enough to interrupt sleep — and that fails to settle with paracetamol or ibuprofen — is a specific clinical red flag identified in ACPA clinical guidance, not merely a discomfort threshold. Same-day contact with NHS 111 or a GP is the appropriate first step, and an urgent X-ray should be arranged.

Sudden severe hip pain without injury Pain that arrives without a fall and without fever still warrants same-day advice. Avascular necrosis of the femoral head and acute labral pathology can both present this way and may deteriorate without timely assessment.

Rapidly worsening pain over days or weeks Gradual osteoarthritis progresses over months. Pain that has worsened sharply over days or a few weeks is clinically distinct and should prompt earlier review rather than a wait-and-see approach.

A practical way to think about urgency: night pain that consistently disrupts sleep is an amber signal — book a specialist appointment promptly, not at your convenience. Fever, confusion, or rapid unexplained weight loss alongside hip pain are red signals requiring immediate help. Most presentations in this section fall in the amber band.

This tier also includes patients who have already received a normal plain X-ray from their GP. That result does not close the question when pain remains severe or nocturnal; specialist assessment is still warranted.

When a specialist hip assessment is the right next step

Patients who have worked through the preceding tiers — no suspected fracture, no fever, no neurological deficit — but who still have persistent, worsening, or unexplained hip pain are in a different position: they need structured diagnosis, not emergency triage. That means clinical examination, appropriate imaging, and a clear management plan from a clinician who focuses specifically on the hip joint.

For patients across Lincolnshire and the wider non-London catchment, Lincolnshire Hip offers consultant-led assessment without the need for a GP referral. Consultations are available at MSK House in Sleaford and The Keep Clinic in Grantham. Professor Paul Lee, who leads the service, has particular experience interpreting X-rays and MRI in clinically ambiguous presentations — including cases where a normal plain radiograph has not resolved the diagnostic question, as discussed in the preceding section.

For those still uncertain about which tier applies, NHS 111 remains the right first call; a specialist appointment can follow once the immediate question is settled.

Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral for hip assessment.