Effects of the Competitive Season and Off-Season on Knee Articular Cartilage in Collegiate Basketball Players Using Quantitative MRI: A Multicenter Study

Abstract

Background: Injuries to the articular cartilage in the knee are common in jumping athletes, particularly high-level basketball players. Unfortunately, these are often diagnosed at a late stage of the disease process, after tissue loss has already occurred.

Purpose/hypothesis: To evaluate longitudinal changes in knee articular cartilage and knee function in National Collegiate Athletic Association (NCAA) basketball players and their evolution over the competitive season and off-season.

Study type: Longitudinal, multisite cohort study.

Population: Thirty-two NCAA Division 1 athletes: 22 basketball players and 10 swimmers.

Field strength/sequence: Bilateral magnetic resonance imaging (MRI) using a combined T_1ρ and T₂ magnetization-prepared angle-modulated portioned k-space spoiled gradient-echo snapshots (MAPSS) sequence at 3T.

Assessment: We calculated T₂ and T_1ρ relaxation times to compare compositional cartilage changes between three timepoints: preseason 1, postseason 1, and preseason 2. Knee Osteoarthritis Outcome Scores (KOOS) were used to assess knee health.

Statistical tests: One-way variance model hypothesis test, general linear model, and chi-squared test.

Results: In the femoral articular cartilage of all athletes, we saw a global decrease in T₂ and T_1ρ relaxation times during the competitive season (all P < 0.05) and an increase in T₂ and T_1ρ relaxation times during the off-season (all P < 0.05). In the basketball players' femoral cartilage, the anterior and central compartments respectively had the highest T₂ and T_1ρ relaxation times following the competitive season and off-season. The basketball players had significantly lower KOOS measures in every domain compared with the swimmers: Pain (P < 0.05), Symptoms (P < 0.05), Function in Daily Living (P < 0.05), Function in Sport/Recreation (P < 0.05), and Quality of Life (P < 0.05).

Conclusion: Our results indicate that T₂ and T_1ρ MRI can detect significant seasonal changes in the articular cartilage of basketball players and that there are regional differences in the articular cartilage that are indicative of basketball-specific stress on the femoral cartilage. This study demonstrates the potential of quantitative MRI to monitor global and regional cartilage health in athletes at risk of developing cartilage problems.

Level of evidence: 2 Technical Efficacy Stage: 2.

Keywords: articular cartilage; basketball; general; imaging; knee; magnetic resonance; relaxometry; swimming.

Figure 1:

Schematic overview of the study methodology.

Figure 2:

(a, b) Summary of KOOS season 1 and season 2 subsections and (c) reference values. In the graphs, circles represent outliers, and the whiskers indicate the 10th and 90th percentiles.

Figure 3:

Summary of femoral cartilage difference results. Competitive season represents the difference in quantitative magnetic resonance imaging (qMRI) metrics for (postseason 1 – preseason 1), off-season represents the difference in qMRI metrics for (preseason 2 – postseason 1), and 1 year represents the difference in qMRI metrics for (preseason 2 – preseason 1). The horizontal line above basketball players and swimmers in T₂ and T_1ρ relaxation times represents significant differences within each athlete group at different timepoints. In both graphs, circles represent outliers, and the whiskers indicate the 10th and 90th percentiles.

Figure 4:

Two-dimensional projection maps of the three-dimensional femoral cartilage surface for a representative basketball player and swimmer. For the basketball players, the white box outlines the anterior region where the most significant change occurred in the competitive season, and the red box outlines the central region where the most significant increase occurred during the off-season.

Figure 5:

Cluster analysis maps from a representative basketball player and swimmer. Positive and negative cluster maps shown are after the intensity and size thresholds had been applied. The cluster analysis of the femoral cartilage shows a basketball player with significant positive clusters in the medial central compartment and significant negative clusters in the lateral central compartment compared to a swimmer with no significant positive or negative clusters.

Figure 6:

(a) A summary of coefficient of variance (CV) for phantom repeatability analysis across two timepoints for T₂ and T_1ρ relaxations. (b) A summary of CV for MAPSS repeatability analysis in two back-to-back scans. (c) A representative subject from the MAPSS repeatability analysis.