Subchondral bone plate remodels more rapidly than trabecular bone in osteoarthritis

• Main Authors: Zamli, Zaitunnatakhin, Robson Brown, Kate, Tarlton, John F., Sharif, Mohammed
• Format: Article
• Language: English
• Published: Elsevier 2015
• Subjects: R Medicine (General); RB Pathology
• Online Access: http://irep.iium.edu.my/43446/4/OARSI_2015.pdf; http://irep.iium.edu.my/43446/; http://www.oarsijournal.com/article/S1063-4584(15)00586-5/abstract

Objective: To determine the sequence and the relationship between bone remodelling in subchondral bone plate (Sbp) and trabecular bone (Tb), during the development of OA in two spontaneous animal models, the Dunkin Hartley (DH) guinea pig which develop OA around 12 weeks and the Bristol Strain 2 (BS2) which develops OA around 24 weeks of age. Methods: The right tibias were dissected from six male animals of each strain, at 10, 16, 24 and 30 weeks of age. Changes in tibial plateau cartilage were assessed histologically. Micro-computed tomography was used to quantify the growth plate thickness (GpTh), subchondral bone plate thickness (SbpTh) and trabecular bone thickness (TbTh), and bone mineral density (BMD) in both Sbp and Tb. Results: The growth plate was still open by 30 weeks of age in both strains (DH: 151.3µm±17.4, BS2: 153.4µm±15.7) and closure rate of the growth plate was similar prior to 24 weeks. The SbpTh and TbTh were greater in the medial side than the lateral side, and in the DH than BS2. In the DH strain, the bone mineral density (BMD) of Sbp increased between 10 and 16 weeks and then decreased, whereas in BS2 BMD gradually increased over the study period. The rates of SbpTh changes were generally higher in DH than BS2, and in the DH these changes were greater in the medial than lateral side, especially between 10 - 16 weeks (medial side: 22.7µm/week; lateral side: 14.8µm/week). In contrast, in the BS2 SbpTh changes were greater in the lateral side. Similarly, the highest rate of Sbp BMD change was observed in the DH medial side between 10 – 16 weeks (0.07g/cm3). However, after 16 weeks, both Sbp and Tb BMD decreased in the DH strain but not in the BS2 animals. Conclusions: The rapid increase during the early time points and consistently higher rate of increase of SbpTh in the medial side of DH when the medial and lateral sides in both strains showed a similar rate of TbTh suggest that there is more rapid remodelling of the Sbp than Tb during development of OA. The highest rate of BMD increase in the medial side of Sbp in DH between 10 to 16 weeks and a fall in BMD thereafter in both in Sbp and Tb suggest that increased BMD may be associated with initiation of OA but not progression.