Question
A 78 year old woman develops a hot, swollen knee two days after a hip fracture operation.
- Describe the radiograph.
- How do you confirm the diagnosis and exclude infection?
- Outline management and associated conditions.
Answer
Radiograph
- Chondrocalcinosis, linear calcification of the menisci and hyaline cartilage
- Joint space narrowing
- Acute calcium pyrophosphate crystal arthritis (pseudogout) is likely
Diagnosis
- Aspirate the knee
- Weakly positively birefringent rhomboid crystals on polarised microscopy
- Gram stain, culture and cell count, as infection can coexist
- Crystals do not exclude sepsis
- Post operative flares are common after surgery or illness
Management
- Aspiration to dryness
- Intra-articular corticosteroid once infection is excluded
- NSAIDs or colchicine if renal function allows
- Oral prednisolone for polyarticular attacks
Associated conditions in younger patients
- Haemochromatosis
- Hyperparathyroidism
- Hypomagnesaemia
- Hypophosphatasia
- Gitelman syndrome
Related pages
Author Contributions
Orthofracs team
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.