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Open Access Research article

Articular cartilage mineralization in osteoarthritis of the hip

Martin Fuerst1*, Oliver Niggemeyer1, Lydia Lammers2, Fritz Schäfer3, Christoph Lohmann1 and Wolfgang Rüther1

Author Affiliations

1 Department of Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, Clinic Bad Bramstedt, Martinistr 52, 20465 Hamburg, Germany

2 Institute of Mineralogy, University Hospital Münster, Waldeyerstr 30, 48149 Münster, Germany

3 Breast Center, University Hospital Kiel, Arnold-Heller-Str 3, 24108 Kiel, Germany

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BMC Musculoskeletal Disorders 2009, 10:166  doi:10.1186/1471-2474-10-166

Published: 29 December 2009

Abstract

Background

The aim of this study was to examine the frequency of articular cartilage calcification in patients with end-stage hip OA. Further, its impact on the clinical situation and the OA severity are analyzed.

Methods

Eighty patients with OA of the hip who consecutively underwent total hip replacement were prospectively evaluated, and 10 controls were included. The patients' X-rays were analyzed for the presence of articular cartilage mineralization. A Harris Hip Score (HHS) was preoperatively calculated for every patient.

Slab specimens from the femoral head of bone and cartilage and an additional square centimeter of articular cartilage from the main chondral defect were obtained from each patient for analysis of mineralization by digital contact radiography (DCR). Histological grading was also performed. In a subset of 20 patients, minerals were characterized with an electron microscope (FE-SEM).

Results

Calcifications were seen in all OA cartilage and slab specimens using DCR, while preoperative X-rays revealed calcification in only 17.5%. None of the control cartilage specimens showed mineralization. There was a highly significant inverse correlation between articular cartilage calcification and preoperative HHS. Histological OA grade correlated positively with the amount of matrix calcification. FE-SEM analysis revealed basic calcium phosphate (BCP) as the predominant mineral; CPPD crystals were found in only two patients.

Conclusions

Articular cartilage calcification is a common event in osteoarthritis of the hip. The amount of calcification correlates with clinical symptoms and histological OA grade.