Article
In Vivo Changes of Subchondral Bone and Cartilage in First Carpometacarpal Joint Osteoarthritis across Severity Stages
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Authors
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Michael Chu-kay Mak
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Hong Kong
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Wayne Yuk-wai Lee
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Hong Kong
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Ka-yee Cheuk
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Hong Kong
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Ryan Ka-lok Lee
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Hong Kong
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Pak-cheong Ho
- Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Hong Kong
| Published: | February 6, 2020 |
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Outline
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Objectives/Interrogation: In osteoarthritis (OA), the site of disease initiation and sequence of degenerative process in subchondral bone and cartilage is not known. Changes of the subchondral bone as degeneration progresses have not been characterized. We hypothesized that in the first carpometacarpal joint (CMCJ), subchondral trabecular bone change could be an early structural feature leading to cartilage loss. Our aim was to determine the in vivo changes of subchondral microarchitecture compared with cartilage volume from early to advanced OA.
Methods: A cross-sectional study on bone and cartilage morphology in patients with different severities of CMCJ OA was performed. 33 patients consecutively seen by a hand surgeon in our orthopaedic unit from August 2017 to June 2018 were recruited. Normal asymptomatic contralateral CMCJs of the patients were used as controls. A total of 57 CMCJs were included of which there were 8 in stage 1, 10 in stage 2, 28 in stage 3, 4 in stage 4, and 7 were normal controls. Severity was staged according to the Eaton and Glickel 1987 radiographic staging.
Subchondral trabecular microarchitecture and cartilage volume were measured by high resolution peripheral quantitative computed tomography (HR-pqCT, voxel size 82µm3) and 3T MRI with hand coil array respectively. A 4mm3 cube of subchondral trabecular bone was extracted at the center of the trapezium articular surface for Individual Trabecula Segmentation. Plate-like and rod-like trabeculae were analyzed. Parameters including volume, thickness, number and density of total, plate-like, and rod-like trabeculae were calculated. Plate-to-rod ratio was obtained.
Cartilage volume was obtained from segmentation with an in-house program.
Results and Conclusions: Osteoarthritic trapezia had decreased subchondral bone density vs controls (590.7 versus 631.3mgHA/mm3, p=0.036) and decreased cartilage volume (8.76 vs 26.78 p<0.001) that correlated with disease staging. There was a significant decrease in rod thickness across the stages starting from stage 1 (p=0.01), and a significant increase in plate-to-rod ratio from stage 2 (p=0.049).
This is the first in vivo study of subchondral bone microarchitecture in osteoarthritis using high-resolution CT, and demonstrated trabecular changes early osteoarthritis. Increase in P-R ratio starting at stage 2 is in agreement with other studies that transformation of rod-like to plate-like trabeculae occurs in advanced OA, which causes change in load-bearing properties, and ultimately cartilage damage.
