My knee replacement feels wobbly and gives way. What could be wrong?

What instability feels like

• The knee shifts or buckles when going down stairs or rising from a chair
• A feeling that the knee slides forward and back, often with the knee bent
• Repeated swelling after walking or activity
• Aching around the knee and in the soft tissues, rather than deep in the bone
• Lack of confidence, holding rails or avoiding slopes

Common causes

Instability can come from a gap between the implant parts that is too loose when the knee is bent or straight, from a ligament that has stretched or been injured, from implant parts that have shifted or loosened, or from wear of the plastic insert. A fall can also injure ligaments around a replaced knee.

Sometimes the implant is fine and the main problem is weakness of the quadriceps, which can be improved with targeted rehabilitation.

What you can do now

Use a stick in the opposite hand if the knee is giving way, take stairs one at a time with a rail and remove trip hazards at home. Keep up thigh-strengthening exercises your physiotherapist has given you. Avoid ignoring repeated falls, as they risk fractures around the implant.

Assessment and treatment

At Aman Hospital, Dr. Gelber examines stability in different positions, reviews X-rays and, where needed, blood tests and joint fluid tests to rule out infection. If the instability is mild and mostly muscular, structured physiotherapy and a brace may help. If the implant balance is the problem, revision with a different insert or more constrained components may be advised.