Can a knee replacement cause hip pain?

Hip pain following a total knee replacement (TKR) is a recognised clinical problem, not an unusual complaint. It can arise for two broad reasons: the surgery may have shifted how weight is distributed through your leg, placing new strain on the hip; or a hip problem that was present all along — but overshadowed by severe knee pain — may only become noticeable once the knee has been treated.

The clinical stakes are real. A peer-reviewed case series published by Dibra et al. in 2017 followed 21 patients who had been referred for knee pain but were ultimately found to have hip pathology as the true cause. Twelve of those patients had already undergone surgical knee procedures, including total knee arthroplasty, with little or no relief. Of the 17 who subsequently had a total hip replacement, 14 achieved complete resolution of their symptoms. Notably, the original misdiagnosis had occurred even among experienced orthopaedic surgeons, confirming that this is not a straightforward diagnostic picture.

The practical implication is clear: if hip-area pain persists after TKR, or develops where it was not present before, it warrants proper evaluation rather than being assumed to be a routine part of recovery.

Why the hip can start hurting after knee surgery

Three distinct biological routes can explain new or worsened hip pain after a total knee replacement, and in some patients more than one operates at the same time.

Shared nerve supply. The femoral, sciatic, and obturator nerves provide sensation to both the hip and the knee. When inflammation or altered signalling arises at one joint, the brain can misread the source and register pain at the other. This referred pain is well-recognised in musculoskeletal medicine: a hip problem can feel convincingly like knee discomfort, and vice versa.

Changed loading patterns. A knee replacement alters gait, leg alignment, and sometimes the effective leg-length relationship. During rehabilitation and everyday activity, the hip abductors and the pelvis take on new mechanical demands to compensate. Weak hip abductor muscles and adjusted pelvic loading can translate into pain around the lateral hip or groin, particularly in the months when walking patterns are still settling.

Unmasking of pre-existing hip arthritis. Some patients have mild-to-moderate hip osteoarthritis before their knee surgery, but the dominant knee pain overshadows it. Once the knee is treated and that pain recedes, the underlying hip condition may become noticeable for the first time.

Because these routes can overlap, assuming a single cause risks missing the real picture — which is precisely why a systematic clinical assessment is the appropriate next step.

Signs that point to the hip, not the knee

Not all discomfort after a knee replacement signals a problem requiring investigation — some aching and fatigue are a normal feature of recovery in the weeks that follow. Certain patterns, however, suggest the hip may need its own assessment rather than watchful waiting.

Musculoskeletal signals to watch for

• Startup pain and antalgic limp. Pain that is worst when first rising after rest, and that produces a noticeable limp even as the knee itself continues to settle, is a consistent signal of hip joint involvement rather than post-operative adaptation.
• Mechanical catching or giving way. A sense of instability, catching, or clicking that originates around the groin or lateral hip — rather than the knee — warrants clinical review.
• Night pain or pain at rest. Discomfort that persists or worsens when lying still is not a feature of routine surgical recovery; it suggests an active joint process that should be assessed.
• Leg-length discrepancy. If one leg feels or measures shorter or longer than the other following surgery, this may reflect altered hip loading or implant positioning.
• Progressive or non-improving symptoms. Where symptoms are not gradually settling beyond the expected recovery window, or are actively worsening, this is the clearest prompt to seek specialist assessment.

Signs requiring same-day or next-day contact

Fever, chills, wound redness, or discharge — together with sudden severe swelling of the calf or thigh — may indicate prosthetic infection or deep-vein thrombosis. These require urgent medical attention, not a routine physiotherapy appointment, and should be assessed before any hip-focused work-up begins.

What a clinical assessment of the hip involves

Arriving at an assessment already knowing what the clinician is likely to do — and why — tends to make the process feel less uncertain. Hip assessment after a knee replacement follows a deliberate sequence, because hip and knee symptoms can genuinely overlap and ruling things out is as important as confirming them.

Watching how you walk. The assessor will observe your walking pattern before any hands-on tests begin. A Trendelenburg sign — where the pelvis dips on the unsupported side during each stride — indicates weakness in the hip abductor muscles. An antalgic gait, where you unconsciously shorten the time spent on one leg, suggests joint pain rather than muscular fatigue.

Hip range of movement. The clinician will move the hip through its range, paying close attention to internal rotation. Restriction and pain specifically on this movement is an early clinical marker of hip osteoarthritis, and often appears before imaging changes are visible.

The FADIR test. Bringing the hip into flexion, adduction, and internal rotation simultaneously screens for femoroacetabular impingement — a separate condition in which the ball and socket make contact in a way that can produce groin or deep hip pain.

Neurological screening. A straight-leg raise and brief neurological check help distinguish lumbar radiculopathy — nerve pain originating in the spine — from true hip pathology. The two conditions can feel similar and occasionally co-exist.

Imaging as one input. Weight-bearing X-rays of the pelvis and hip show joint space narrowing, osteophytes, and subchondral changes. Long-leg alignment films assess whether the positioning of the knee replacement is placing abnormal load on the hip. Imaging findings inform the clinical picture; they are not a diagnosis on their own.

Other causes that look like hip pain after TKR

Identifying the hip as a potential pain source is an important step — but it does not close the differential. Two other causes can produce a very similar picture and must remain in the frame throughout assessment.

Lumbar spine pathology. Stenosis and nerve root irritation in the lower back can refer pain into the buttock, lateral hip, and thigh in a pattern that closely resembles hip joint disease. This is precisely why the neurological screening described in the previous section is a standard element of assessment rather than an optional extra. If examination raises suspicion of spinal involvement, MRI or lumbar X-ray may follow.

Prosthetic failure. Implant loosening, periprosthetic fracture, or low-grade infection of the knee replacement can generate new pain patterns that radiate beyond the knee itself. This remains a relevant differential — particularly where knee symptoms have never fully resolved since surgery.

The referral pathway reflects the findings. Physiotherapy-led assessment is appropriate when symptoms point to a biomechanical or muscular cause. Where the picture is structural, progressive, or suggests a problem with the implant itself, orthopaedic surgical review is the appropriate next step.

It is worth noting that robust prevalence data for each of these differentials in post-TKR patients is limited; current guidance draws substantially on clinical consensus. That evidence gap does not reduce the case for prompt assessment when symptoms are present.

Who to see and how to find the right specialist

The right first contact for most patients is a GP or MSK physiotherapist — someone who can take a full history, observe gait, and carry out hip-specific examination rather than treating the knee as the assumed cause. Do not delay this step if any of the warning features described in the previous sections are present.

Physiotherapy is the appropriate specialist route when symptoms point to hip abductor weakness, gait adaptation, or early-stage hip stiffness that responds to loading. A structured programme addressing these causes can produce meaningful improvement without further escalation.

Orthopaedic surgical review is warranted when symptoms are progressive rather than resolving, when imaging identifies structural joint disease, when conservative management has not produced meaningful improvement, or when there is any concern about the integrity of the knee implant itself.

On timing: there is no fixed evidence-based rule specifying how long to wait before investigating the hip after a TKR. Symptom trajectory — whether things are improving, plateauing, or worsening — is a more reliable guide than any calendar threshold, and clinician judgement based on that pattern should drive the decision.

Search MSK lists physiotherapists and orthopaedic specialists across the UK with joint-replacement and MSK expertise; filtering by region and specialty can help identify a clinician matched to your presentation.

Hip pain after knee replacement that is persistent or progressive deserves proper clinical attention. The earlier a systematic assessment takes place, the narrower the differential tends to become — and the more straightforward the path forward.