Why Prosthetic Implants Fail

Aseptic loosening is the most common cause of prosthetic hip failure. This painful and debilitating condition develops when bone recedes from an implanted prosthesis over time, causing the prosthesis to become “loose”. Aseptic loosening also affects other prosthetic joints including knees and shoulders. The major cause of loosening is related to wear particles originating from the articulating prosthesis. These activate a cascade of inflammatory processes, which in turn triggers bone resorption and the formation of a membrane of synovial-like tissue within the space between the remaining bone and prosthesis. 

The incidence of aseptic loosening is growing. Due to increased use of orthopaedic hip and knee implants, the ageing population and lifestyle factors including obesity, aseptic prosthetic loosening is becoming a more common disease in many countries. Globally, over 1 million hip and 1.5 million knee prostheses are implanted for a first time each year. Whilst most implants are successful in the long term, at least 10% of hip and 3% of knee recipients undergo revision surgery to replace an aseptically loosened prosthesis within 10 years of the primary joint replacement procedure. Typical sufferers are aged in their 70s and 80s. Many elderly patients cannot undergo revision surgery due to morbidity and mortality risks and consequently have no treatment options.