Crystal-induced arthritis after arthroplasty: 7 cases.

OBJECTIVES: To describe the occurrence in prosthetic joints of crystal-induced arthritis (CIA) defined as the deposition within the synovial membrane and/or joint cavity of calcium pyrophosphate dehydrate (CPPD) (chondrocalcinosis), sodium urate (gout), or hydroxyapatite.

METHODS: We retrospectively reviewed the 7 cases of prosthetic-joint CIA seen between 1993 and 2013 at a medical-surgical center specialized in the management of osteoarticular infections.

RESULTS: The 4 females and 3 males ranged in age from 67 to 79 years. Acute CIA occurred at the knee in 6 patients (5 with total knee arthroplasty and 1 with unicompartmental knee arthroplasty) and at the hip in 1 patient (with total hip arthroplasty). Time from arthroplasty to CIA varied from 7 days to 9 years. An abrupt onset was a consistent feature, with pain, complete loss of function, and local evidence of inflammation. A single patient had a fever and 6 patients had laboratory evidence of systemic inflammation. Joint aspiration showed hemarthrosis in 3 patients and inflammatory joint fluid with 20,000 to 79,000neutrophils/mm(3) in 6 patients. Joint fluid cultures were negative in 6 patients. CPPD crystals were evidenced in 5 patients, including 1 who also had hydroxyapatite crystals detected by electron microscopy after alizarin red staining. Monosodium urate crystals were found in 1 patient. The remaining patient had both CPPD crystals and positive cultures for Campylobacter fetus. In 5 patients, treatment with colchicine or a nonsteroidal antiinflammatory drug ensured prompt control of the symptoms and systemic inflammation. The patient with total hip arthroplasty underwent joint aspiration for hemarthrosis. In 1 patient, an intraarticular injection of triamcinolone hexacetonide improved the symptoms and systemic inflammation. The patient with Campylobacter fetus infection was treated with antibiotics, excision of the abscess, and synovectomy.

CONCLUSION: CIA may occur after arthroplasty, within synovial membrane remains or neosynovium developed around the prosthetic joint. CIA is a manifestation of a metabolic disease that persists and can reactivate after surgery. Routine testing for crystals is rarely performed in patients with sterile arthritis of a prosthetic joint, and crystals are difficult to detect in joints with hemarthrosis; consequently, the frequency of prosthetic-joint CIA may be underestimated. Although rare, CIA should be considered routinely when symptoms suggesting septic arthritis develop in a prosthetic joint, in order to avoid unnecessary prolonged antibiotic therapy and, in some cases, surgery. The treatment is usually simple.