→ a knee implant that becomes painful following the replacement operation.

Why would a knee replacement become painful?

Total knee replacement (TKR) is a common procedure that works well for most patients. Modern implants are made from very hard-wearing materials and typically last for 15 to 20 years, or even longer. Sometimes, however, a replacement may fail, or cause painful symptoms. This can happen for a variety of reasons. It might be because the implant is reaching the end of its life through wear and tear. Or it might be due to a complication with the implant or the replacement operation itself. Some of the possible causes of a painful TKR include infection, instability, loosening of the implant, bone loss, kneecap problems, stress fractures or osteolysis (where the bond between the bone and the implant begins to break down).

What are the symptoms of a knee replacement problem?

Pain is usually (though not always) the first sign of a problem with a knee replacement. The degree and extent of pain varies depending on the cause. An implant that is impinging on soft tissue in the knee, for example, could cause a sharp, catching pain during movement. An infected implant is more likely to be accompanied by ongoing pain even while the knee is at rest. Though rare, infections can occur at the time of surgery, or later. Other symptoms of a knee replacement problem include instability, swelling and stiffness.

How do doctors diagnose a knee replacement problem?

Diagnosing a knee replacement problem involves a very careful and thorough analysis of your knee and the symptoms you are experiencing. The doctor will want to know exactly what the pain or discomfort feels like, where it is located and whether you feel the discomfort during rest or activity. It’s important to establish when the symptoms first began, and whether they have changed since your replacement operation. Your doctor may also ask you to have an x-ray, MRI, blood tests or an aspiration (where fluid is drawn from the joint for testing) to help confirm the diagnosis.

What happens next?

Treatment for a painful knee replacement varies considerably depending on the cause of the problem. In more serious cases, and when the implant is beginning to fail, you may need to consider knee revision surgery. This is an operation to remove the old prosthetic and replace it with a new implant. Since bones naturally grow into an implant as it becomes established, this can involve the removal of bone in order to fit the new replacement. It is therefore major surgery and shouldn’t be undertaken without careful consideration.