Question
A 70 year old man with diabetes has a hot, swollen total knee replacement 3 weeks after surgery, with wound ooze.
- How would you investigate him?
- What is your management of this early infection?
- What would you do if he presented 2 years later with chronic infection?
Answer
Investigations
- CRP, ESR and blood cultures if febrile
- Knee aspiration before antibiotics for white cell count, neutrophil percentage and culture
- Early postoperative thresholds differ, with synovial white cells over about 10,000 per microlitre suggesting infection
- Radiographs to exclude fracture and loosening
Early infection management
- DAIR within about 4 weeks of surgery or 3 weeks of symptoms
- Radical synovectomy and debridement with exchange of the polyethylene insert
- Take at least five tissue samples with separate instruments
- Targeted intravenous then oral antibiotics, often with rifampicin for staphylococci, for about 12 weeks
- Success rates fall with delay, Staph aureus and host compromise
Chronic infection
- DAIR is not appropriate
- Two stage revision with an antibiotic loaded spacer and interval antibiotics
- Single stage revision in selected patients
- Arthrodesis or above knee amputation for recurrent infection with bone and soft tissue loss
- Long term suppression for patients unfit for surgery
Related pages
Author Contributions
Orthofracs team
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.