Martin Fuerst MD, Presenter: Nothing to Disclose

Fritz Schäfer, Abstract Co-Author: Nothing to Disclose

Lydia Lammers, Abstract Co-Author: Nothing to Disclose

Daniela Fuerst MD, Abstract Co-Author: Nothing to Disclose

Thomas Pap MD, PhD, Abstract Co-Author: Nothing to Disclose

Wolfang Rüther MD, PhD, Abstract Co-Author: Nothing to Disclose

In OA cartilage, the actual prevalence and composition of calcium crystals as well as the mechanisms of their generation remain incompletely understood. Here, sought to analyse systematically the prevalence of these crystals and their identity in end-stage OA of the knee

100 patients with end-stage OA undergoing total knee replacement were included. Preoperatively, the X-rays were analysed for the presence of calcifications. During surgery, the medial and lateral menisci as well as 1 cm2 of cartilage from the medial femur condyle were obtained along with 2 ml of joint fluid from every patient. Synovial fluid was analysed under compensated light microscopy. Contact radiography was performed from each meniscus and cartilage using a high-resolution digital mammography device, and the area of mineralisation was measured by pixel analysis. For characterisation of the mineral deposits, a field emission scanning electron microscope (FESEM) equipped with an energy dispersive X-ray apparatus (EDX) was used.

While mineralisation in the joint space was found in only 26 radiographs (26%) contact radiography revealed mineralisation in all 100 cartilage probes. The mean area of mineralisation (MAM) was 1.7% (0.1%–25.2%) of total cartilage area. The lateral meniscus was mineralised in 57 (57%) knees (MAM: 5.2%, 0.3%–27.2%) and mineralisation of the medial meniscus was identified in 71 joints (71%, MAM: 5.3%, 0.1%–32.6%). Idiomorphic crystals were identified using FREM. EDX detected two different mineral phases containing basic calcium phosphates such as apatite and calcium pyrophosphate dihydrate crystals. In the synovial fluid of 69 patients (69.0%) CPPD crystals were identified.

Mineralisation of articular cartilage is a common event in end-stage OA, but the presence of calcium crystals cannot be predicted by radiography or synovial fluid analysis. Contact radiography using a high-resolution digital mammography device has high sensitivity in detecting these crystals and can be confirmed by FREM.

Mineralisation of articular cartilage is a common event in end-stage OA but the presence of crystals is difficult to detect. Digital mammography has high sensitivity.

Fuerst, M, Schäfer, F, Lammers, L, Fuerst, D, Pap, T, Rüther, W, Calcium Crystals in End-stage Osteoarthritis (OA) of the Knee.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5001652.html