Why do knee replacements fail and need revision?

The common reasons

• Aseptic loosening: the bond between the implant and bone weakens over time, without infection
• Infection: bacteria settle on the implant, early after surgery or years later
• Instability: the ligaments and implant balance do not hold the knee steady
• Stiffness: scar tissue limits bending or straightening
• Wear of the plastic insert, sometimes with bone loss around the implant
• Fracture of the bone near the implant, often after a fall
• Problems with the kneecap, such as poor tracking

Why the cause matters

Each problem needs a different solution. A loose implant needs new fixation, an infected one usually needs a staged approach, and an unstable knee may need more constrained parts. Revising a knee without knowing why it failed risks the same problem returning.

Pain alone, without a clear mechanical or infective cause, is the hardest situation, and revision in that setting often does not help as much as people hope.

Factors that affect longevity

Implant longevity varies. Younger, more active patients and those with higher body weight place more load on their knees over a longer life. Alignment at the time of surgery, bone quality, diabetes and other health conditions also play a part. Many people never need a revision at all.

When to have your knee checked

See a knee surgeon if a replaced knee becomes newly painful, swells repeatedly, feels wobbly, grinds or clicks in a new way, or loses movement. Fever, redness and increasing pain need prompt review because of the possibility of infection. At Aman Hospital, Dr. Gelber reviews old operation records and X-rays alongside new tests.