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Investigating the painful Total Knee Replacement


It is important to note there may be more than one reason for pain/problems present. It is important to identify all causes. A careful history and physical examination is therefore especially important. The commonest causes of pain after knee replacement are neuroma formation near the incision, patellar tendon tendinopathy and the global pain from instability. Infection and incorrect implant alignment must also be excluded as a cause of pain  Investigations are usually performed; these will include x-rays and blood tests.

The following are some of the tests and scans you may need to undergo:

  • Blood tests can sometimes rule out infection in painful joint replacements.

  • X-rays of the knee can help assess bone loss. Special views, including weight bearing or stress views (looking for issues with lax ligaments) and long leg alignment films, may be necessary.

  • Bone scan, looking for signs of loosening or infection.

  • CT scans are useful in assessment of alignment and bone damage.

  • MRI scans are occasionally useful.

  • Ultrasound scans, when performed by experienced musculoskeletal radiologists, can provide an excellent dynamic assessment of tendonitis and bursitis.

  • Examination under anaesthesia is useful for assessing ligament laxity.

  • Arthroscopy is useful for assessing the lining of the knee such as recurrent bleeds due to  trauma to the vessels in the lining of the knee. It is also excellent at identifying inflammation of the knee (synovitis) due to  polyethylene wear/damage  and ligament laxity.

  • Aspiration is useful to test for infection or bleeding as the cause of swelling/pain.

  • Injecting local anaesthetic into the knee joint is useful to identify if the cause of the pain is inside or outside the knee joint.

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