The Journal of Rheumatology Volume 40, no. 11

Cartilage-dependent Subchondral Ossification in Rheumatoid Arthritis

NAOKI SAWA and KENMEI TAKAICHIKEIICHI SUMIDA, EIKO HASEGAWA, MASAYUKI YAMANOUCHI, NORIKO HAYAMI, RIKAKO HIRAMATSU, YOSHIFUMI UBARA, TATSUYA SUWABE, JUNICHI HOSHINO,

http://www.jrheum.org/content/40/11/1923J Rheumatol 2013;40;1923-1924

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1923Hiramatsu, et al: Subchondral ossification in RA

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Cartilage-dependent Subchondral Ossification inRheumatoid ArthritisRIKAKO HIRAMATSU, MD, Nephrology Center, Toranomon Hospital; YOSHIFUMI UBARA, MD, Nephrology Center and Okinaka Memorial Institutefor Medical Research, Toranomon Hospital; TATSUYA SUWABE, MD; JUNICHI HOSHINO, MD; KEIICHI SUMIDA, MD; EIKO HASEGAWA, MD;MASAYUKI YAMANOUCHI, MD; NORIKO HAYAMI, MD; NAOKI SAWA, MD, Nephrology Center, Toranomon Hospital; KENMEI TAKAICHI, MD,Nephrology Center and Okinaka Memorial Institute for Medical Research, Toranomon Hospital, Tokyo, Japan. Address correspondence to Dr. Y. Ubara,Nephrology Center, Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo, Japan 105-8470. E-mail: ubara@toranomon.gr.jp. J Rheumatol2013;40:1923–4; doi:10.3899/jrheum.130201

We observed that, in rheumatoid arthritis (RA), subchondralbone may have a lamellar structure arranged in a verticaldirection because of the cushioning effect of cartilage, whilebone at the sites of cartilage defects develops a wovenstructure due to the lack of a cushioning effect.A 58-year-old Japanese woman with a 15-year history of

RA was admitted to our hospital for surgery on the left knee.Her RA had been treated using various antirheumatic drugs,including gold derivatives, penicillamine, methotrexate,steroids, and a soluble tumor necrosis factor receptorinhibitor (etanercept), but these medications had not beeneffective. She had also undergone operations including platefixation of the cervical spine, left hip replacement, and rightknee replacement. C-reactive protein (CRP) was 6.8 mg/dl,rheumatoid factor 33 U/ml (normal < 10 U/ml), anticycliccitrullinated peptide antibody 47 U/ml (normal < 4.5 U/ml),and matrix metalloproteinase-3 was 421 ng/ml (normal17–60 ng/ml). The Disease Activity Score-CRP was calcu-lated to be 8.3. Radiography showed narrowing of the left knee joint

(Figure 1A), and there was extensive sclerosis on a coronalview on computed tomography (Figure 1B). A biopsyspecimen was obtained from the proximal epiphysis of thetibia for histomorphometric evaluation after Villanuevastaining of undecalcified sections. Sclerosis of the tibia wasseen at the region denuded of cartilage, while the regionwith cartilage cover was nonsclerotic. In the former region,thickened cortical bone covered cancellous bone (Figure 2)that had a woven structure with irregularly arrangedtrabeculae (Figure 3A). In the latter region, the subchondralbone consisted of thin cortex and cancellous bone (Figure 2)with lamellar trabeculae growing in a vertical direction(Figure 3B).Cartilage provides a cushioning effect for load-bearing

joints and helps maintain the integrity of subchondral bone.In patients with RA, the articular cartilage is resorbedthrough the action of collagenase released from the synovialpannus, resulting in loss or narrowing of the joint space. Thesubchondral bone is also eventually affected. The findingsin our patient suggested that subchondral bone has a

Figure 1.A. Radiograph shows narrowing of the left knee joint. B. Computed tomography scan reveals extensivesclerosis in a coronal view.

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lamellar structure arranged in a vertical direction by thecushioning effect of cartilage, while bone at the sites ofcartilage defects develops a woven structure because of thelack of a cushioning effect.

ACKNOWLEDGMENTWe thank Akemi Ito of the Ito Bone Histomorphometry Institute forperforming histomorphometric analysis.

1924 The Journal of Rheumatology 2013; 40:11; doi:10.3899/jrheum.130201

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Figure 2.A biopsy specimen from the proximal epiphysis of the tibia shows sclerosis at the region denuded ofcartilage, while the region with cartilage cover was nonsclerotic (Villanueva stain; original magnification ×25).

Figure 3.A. Thickened cortical bone covers cancellous bone that has a woven structure with irregularly arrangedtrabeculae. B. Subchondral bone consisted of thin cortex and cancellous bone with lamellar trabeculae growingin a vertical direction (original magnification ×40).

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