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Subchondral bone and cartilage disease: a rediscovered functional unit
H Imhof1, I Sulzbacher, S Grampp
1Osteologie, Univ. Klinik für Radiodiagnostik, AKH-Vienna, Austria. herwig.imhof@univie.ac.at
Insights
Subchondral bone
Area of Science:
- Orthopedics
- Biomedical Engineering
- Cartilage Research
Background:
- Subchondral bone's role in cartilage damage is underestimated.
- It functions as a shock absorber and influences cartilage metabolism.
- The subchondral region is highly vascularized, with vessels supplying cartilage nutrients.
Purpose of the Study:
- To highlight the underestimated role of subchondral bone in cartilage damage.
- To explain the vascular supply and metabolic contribution of subchondral bone to cartilage.
- To explore how variations in subchondral bone characteristics influence joint pathology.
Main Methods:
- Review of existing literature on subchondral bone and cartilage pathology.
- Analysis of vascularization and metabolic contributions of subchondral bone.
- Comparison of pathological outcomes in different joints under similar stress.
Main Results:
- Subchondral bone perfusion supplies over 50% of cartilage's glucose, oxygen, and water.
- Differences in subchondral bone structure and vascularization lead to varied responses to stress.
- Common etiological pathways link osteonecrosis, osteochondritis dissecans, and degenerative disease.
Conclusions:
- Subchondral bone is critical for cartilage health and metabolism.
- Variations in subchondral bone can predispose joints to specific pathologies like osteonecrosis or degenerative disease.
- Understanding subchondral bone's role is key to addressing cartilage damage and joint degeneration.
Abstract:
The role of subchondral bone in the pathogenesis of cartilage damage has likely been underestimated. Subchondral bone is not only an important shock absorber, but it may also be important for cartilage metabolism. Contrary to many drawings and published reports, the subchondral region is highly vascularized and vulnerable. Its terminal vessels have, in part, direct contact with the deepest hyaline cartilage layer. The perfusion of these vessels accounts for more than 50% of the glucose, oxygen, and water requirements of cartilage. Bony structure, local metabolism, hemodynamics, and vascularization of the subchondral region differ within a single joint and from one joint to another. Owing to these differences, repetitive, chronic overloading or perfusion abnormalities may result in no pathological reaction at all in one joint, while in another joint, these same conditions may lead to osteonecrosis, osteochondritis dissecans, or degenerative changes. According to this common etiological root, similar pathological reactions beginning with marrow edema and necrosis and followed by bone and cartilage fractures, joint deformity, and insufficient healing processes are found in osteonecrosis, osteochondritis dissecans, and degenerative disease as well.