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A charcoal-like synovial fluid
Joint Bone Spine 80 (2013) 539
Available online at www.sciencedirect.com
Images in rheumatology
A charcoal-like synovial fluid Baldi Caterina ∗ , Lorenzini Sauro , Selvi Enrico Section of Rheumatology, Department of Clinical Medicine and Immunological Science, University of Siena, Siena, Italy
Fig. 1.
An 82-year-old Caucasian woman presented with a painful and enlarging mass at the popliteal fossa of her right knee, indicative of a Baker’s cyst. The patient had undergone a metal-on-polyethylene total arthroplasty on her right knee 7 years previously. X-ray, revealed a mild linear radiodensity outlining the suprapatellar recess of the joint capsule and the popliteal cyst. Aspiration of the cyst yielded 10 ml of charcoal-like synovial fluid with a large number of black floating particles that sedimented rapidly (Fig. 1A and B). Synovial fluid analysis showed a good viscosity with a leukocyte count of 600 cells/mm3 , suggesting non-inflammatory synovial fluid. Evaluation under ordinary and compensated polarized light microscopy revealed the presence of extracellular flat birefringent plates of cholesterol and a large number of non-refringent intraand extra-cellular clumps of black globular particles. These black particles are known to derive from wear of the polyethylene liner, following long-term friction and abrasion of the metallic components of metal-backed prostheses [1].
Metallosis should be suspected in patients with joint prosthesis in the presence of joint pain, peri-prosthetic radiographic densities and, as in our case, dark-stained synovial fluid [2]. It is advisable to consider a revision of the prosthetic joint in the presence of metallosis. Disclosure of interest The authors declare that they have no conflicts of interest concerning this article. References [1] Niki Y, Matsumoto H, Otani T, Tomatsu T, Toyama Y. Five types of inflammatory arthritis following total knee arthroplasty. J Biomed Mat Res Part A 2007;81:1005–10. [2] Jason W, Romesburg, Paul L, Wasserman, Candace H, Schoppe. Metallosis and metal-induced synovitis following total knee arthroplasty: review of radiographic and CT findings. Radiol Case 2010;4:7–17.
∗ Corresponding author. Tel.: +39 338 6227297; fax: +39 057 740450. E-mail address: [email protected] (B. Caterina). 1297-319X/$ – see front matter © 2013 Published by Elsevier Masson SAS on behalf of the Société Française de Rhumatologie. doi:10.1016/j.jbspin.2013.01.014
Available online at www.sciencedirect.com
Images in rheumatology
A charcoal-like synovial fluid Baldi Caterina ∗ , Lorenzini Sauro , Selvi Enrico Section of Rheumatology, Department of Clinical Medicine and Immunological Science, University of Siena, Siena, Italy
Fig. 1.
An 82-year-old Caucasian woman presented with a painful and enlarging mass at the popliteal fossa of her right knee, indicative of a Baker’s cyst. The patient had undergone a metal-on-polyethylene total arthroplasty on her right knee 7 years previously. X-ray, revealed a mild linear radiodensity outlining the suprapatellar recess of the joint capsule and the popliteal cyst. Aspiration of the cyst yielded 10 ml of charcoal-like synovial fluid with a large number of black floating particles that sedimented rapidly (Fig. 1A and B). Synovial fluid analysis showed a good viscosity with a leukocyte count of 600 cells/mm3 , suggesting non-inflammatory synovial fluid. Evaluation under ordinary and compensated polarized light microscopy revealed the presence of extracellular flat birefringent plates of cholesterol and a large number of non-refringent intraand extra-cellular clumps of black globular particles. These black particles are known to derive from wear of the polyethylene liner, following long-term friction and abrasion of the metallic components of metal-backed prostheses [1].
Metallosis should be suspected in patients with joint prosthesis in the presence of joint pain, peri-prosthetic radiographic densities and, as in our case, dark-stained synovial fluid [2]. It is advisable to consider a revision of the prosthetic joint in the presence of metallosis. Disclosure of interest The authors declare that they have no conflicts of interest concerning this article. References [1] Niki Y, Matsumoto H, Otani T, Tomatsu T, Toyama Y. Five types of inflammatory arthritis following total knee arthroplasty. J Biomed Mat Res Part A 2007;81:1005–10. [2] Jason W, Romesburg, Paul L, Wasserman, Candace H, Schoppe. Metallosis and metal-induced synovitis following total knee arthroplasty: review of radiographic and CT findings. Radiol Case 2010;4:7–17.
∗ Corresponding author. Tel.: +39 338 6227297; fax: +39 057 740450. E-mail address: [email protected] (B. Caterina). 1297-319X/$ – see front matter © 2013 Published by Elsevier Masson SAS on behalf of the Société Française de Rhumatologie. doi:10.1016/j.jbspin.2013.01.014