The remaining 144 patients were separated in to two groups. Group I (n=54) consisted of those patients that received one or more recorded I/A steroid injections in their operated knee in an orthopaedic clinic, rheumatology clinic or general practice setting prior to surgery. Group II (n=90) consisted of those patients with no record of receiving an I/A steroid injection prior to surgery.
In addition to those patients with confirmed deep infections, five patients underwent post-operative investigations for suspected deep infection, due to symptoms of persistent swelling or pain. All had received an I/A steroid injection pre-operatively. The length of time between injection and subsequent post-operative infection leads us to speculate that the steroid agent might not fully dissolve, becoming trapped within the soft tissues or cystic areas of degeneration in the knee joint. Such steroids may become re-activated during operation, leading to catastrophic results. Indeed, there is experimental evidence to suggest an increased risk of infection with the intra-operative administration of steroids.