Abstract
Magnetic resonance imaging (MRI) is commonly used to evaluate the morphology of the knee in athletes with high‐knee impact; however, complex repeated loading of the joint can lead to biochemical and structural degeneration that occurs before visible morphological changes. In this study, we utilized multiparametric quantitative MRI to compare morphology and composition of articular cartilage and subchondral bone shape between young athletes with high‐knee impact (basketball players; n = 40) and non‐knee impact (swimmers; n = 25). We implemented voxel‐based relaxometry to register all cases to a single reference space and performed a localized compositional analysis of T 1ρ‐ and T 2‐relaxation times on a voxel‐by‐voxel basis. Additionally, statistical shape modeling was employed to extract differences in subchondral bone shape between the two groups. Evaluation of cartilage composition demonstrated a significant prolongation of relaxation times in the medial femoral and tibial compartments and in the posterolateral femur of basketball players in comparison to relaxation times in the same cartilage compartments of swimmers. The compositional analysis also showed depth‐dependent differences with prolongation of the superficial layer in basketball players. For subchondral bone shape, three total modes were found to be significantly different between groups and related to the relative sizes of the tibial plateaus, intercondylar eminences, and the curvature and concavity of the patellar lateral facet. In summary, this study identified several characteristics associated with a high‐knee impact which may expand our understanding of local degenerative patterns in this population.
Highlights
The knee is vulnerable to articular cartilage degeneration and injury in jumping athletes who exert high compressive and shear forces during practice and competitive play.[1,2,3,4,5] Imparting large loads to the articular cartilage is a known risk factor for chronic musculoskeletal conditions such as early‐onset osteoarthritis (OA)[1] and pain.[2]
Previous studies have used magnetic resonance imaging (MRI) to find that degenerative changes are consistently prevalent in knee cartilage of basketball players across all levels of competition.[3,4,5]
Biomechanical stiffness of articular cartilage is provided by the collagen and proteoglycan (PG) organization and content, respectively, of the extracellular matrix (ECM)
Summary
The knee is vulnerable to articular cartilage degeneration and injury in jumping athletes who exert high compressive and shear forces during practice and competitive play.[1,2,3,4,5] Imparting large loads to the articular cartilage is a known risk factor for chronic musculoskeletal conditions such as early‐onset osteoarthritis (OA)[1] and pain.[2]. Though the high prevalence of abnormal imaging findings in high‐knee impact athletes is well‐established, biochemical changes of macromolecules associated with cartilage degeneration occur before visible morphological changes.[6,7] Biomechanical stiffness of articular cartilage is provided by the collagen and proteoglycan (PG) organization and content, respectively, of the extracellular matrix (ECM) Damage to this macromolecular environment results in an increase of mobile water and a concomitant reduction in tissue stiffness. Advanced segmentation methods transform images from individual knees to a single reference template, allowing comparison of local spatial distribution between subjects on a voxel‐ by‐voxel basis This technique, voxel‐based relaxometry (VBR), has been shown to agree with ROI‐based analyses.[18] Notably, it can be performed in a fully automated fashion and can provide local information and patterns of imaging markers in articular cartilage evaluation.[18]. We hypothesized that the basketball players would demonstrate localized prolonged T1ρ‐ and T2‐relaxation times and bone shape differences as compared to the swimmers
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