Context: While the relationship between high-impact sports like football and basketball and the development of knee osteoarthritis is well established, the impact of martial arts on the knee joint remains unclear.
Objective: To compare the imaging abnormalities of knee joints and T2 relaxation times of cartilage in professional martial arts athletes and healthy controls.
Design: Cross-Sectional Study.
Setting: Hospital imaging center.
Patients or other participants: Nine asymptomatic professional martial arts athletes and eighteen healthy volunteers.
Main outcomes measure(s): 3T magnetic resonance imaging (MRI) of the knee was performed on the bilateral legs of athletes and the dominant leg of controls. The MRI protocol included conventional sequences used for morphological assessment (cartilage, meniscus, ligaments, joint effusion, and bone marrow edema) and T2 mapping used for quantitatively evaluating the cartilage. Knee cartilage was manually divided into eight regions, and T2 relaxation times of the corresponding subregions were measured. Fisher's exact test and t-test were utilized to compare the frequency of lesions and cartilage T2 values both among groups and between the athletes' limbs. P<0.05 was considered significant.
Results: Professional martial arts athletes exhibited significantly higher frequencies of cartilage (55.6% vs. 11.1%, P=0.023) and ligament lesions (66.7% vs. 16.7%, P=0.026) compared to control group. Athletes showed higher T2 values in three distinct cartilage segments: the central weightbearing of medial femoral condyle (P=0.006), medial tibial plateau (P=0.012), and trochlea (P=0.032) when compared to the controls. Additionally, the dominant leg of athletes showed significantly higher T2 values compared to their non-dominant legs.
Conclusions: The findings demonstrated the impact of martial arts on the knee joint, characterized by higher prevalence of lesions and elevated cartilage T2 values, particularly in the medial compartment. The dominant legs of martial arts athletes seem to have higher risk of cartilage degeneration due to the observed interlimb differences in T2 values.
Keywords: Interlimb asymmetry; Quantitative magnetic resonance imaging; Sports injury; T2 relaxation times.