Accurate intra-articular knee joint injection in the obese? 'Fat Chance!'--A clinical lesson and recommendations for secondary referral.

Corticosteroid joint injections are perceived as being an effective treatment for symptomatic knee osteoarthritis, with a very low risk of complications. While the procedure is often performed in secondary care by orthopaedic surgeons and rheumatologists (and trainees in either specialty), the role of general practitioners (GPs) in chronic disease management has long existed with joint injections also frequently performed in primary care. The perception that serious complications from corticosteroid knee joint injections are rare and that their benefits in treating symptomatic knee osteoarthritis significantly outweigh the risks has not been well addressed. We present a case of a 71-year-old obese female who presented to her general practitioner (GP) with worsening left knee pain and radiographic changes consistent with osteoarthritis. She was administered a corticosteroid joint injection, which gave minimal relief, and over the next few days resulted in worsening severe pain, erythema and swelling. She returned to the GP who commenced oral antibiotics and referred her to casualty. A large knee abscess was diagnosed and intravenous antibiotics were commenced. The patient was admitted under the orthopaedic surgeons with her treatment consisting of multiple surgical procedures over a prolonged duration. Although lengthy, her postoperative recovery was unremarkable. Based on this case report and our review of the literature, we highlight the potential complications associated with corticosteroid knee joint injections and suggest certain patients for whom we would recommend secondary referral before any intervention in primary care.