Juvenile osteochondritis dissecans (JOCD) lesions contain cartilaginous, fibrous and osseous tissues which are difficult to distinguish with clinical, morphological magnetic resonance imaging (MRI). Quantitative T2* mapping has earlier been used to evaluate microstructure and composition of all aforementioned tissues as well as bone mineral density. However, the ability of T2* mapping to detect changes in tissue composition between different JOCD lesion regions, different disease stages, and between stable and unstable lesions has not been demonstrated. This study analyzed morphological and T2* MRI data from 25 patients (median age, 12.1 years) with 34 JOCD‐affected and 13 healthy knees. Each lesion was assigned a stage reflecting the natural history of JOCD, with stages I and IV representing early and healed lesion, respectively. T2* values were evaluated within the progeny lesion, interface and parent bone of each lesion and in the control bone region. T2* was negatively correlated with JOCD stage in progeny lesion (ρ = −0.871; p < 0.001) and interface regions (ρ = −0.649; p < 0.001). Stage IV progeny showed significantly lower T2* than control bone (p = 0.028). T2* was significantly lower in parent bone than in control bone of patients with stable lesions (p = 0.009), but not in patients with unstable lesions (p = 0.14). Clinical significance: T2* mapping enables differentiation between different stages of JOCD and quantitative measurement of the ossification degree in progeny lesion and interface. The observed T2* decrease in healed and stable lesions may indicate increased bone density as a result of the active repair process. T2* mapping provides quantitative information about JOCD lesion composition.

Objective: Evaluate articular cartilage by magnetic resonance imaging (MRI) T2* mapping within the distal femur and proximal tibia in adolescents with juvenile osteochondritis dissecans (JOCD). Design: JOCD imaging studies acquired between August 2011 and February 2019 with clinical and T2* mapping MRI knee images were retrospectively collected and analyzed for 31 participants (9F/22M, 15.0 ± 3.8 years old) with JOCD lesions in the medial femoral condyle (MFC). In total, N ¼ 32 knees with JOCD lesions and N ¼ 14 control knees were assessed. Mean T2* values in four articular cartilage regionsof-interest (MFC, lateral femoral condyle (LFC), medial tibia (MT), and lateral tibia (LT)) and lesion volume were measured and analyzed using Wilcoxon-rank-sum tests and Spearman correlation coefficients (R). Results: Mean ± standard error T2* differences observed between the lesion-sided MFC and the LFC in JOCD-affected knees (28.5 ± 0.9 95% confidence interval [26.8, 30.3] vs 26.3 ± 0.7 [24.8, 27.7] ms, P ¼ 0.088) and between the affected-and control-knee MFC (28.5 ± 0.9 [26.8, 30.3] vs 28.5 ± 0.6 [27.1, 29.9] ms, P ¼ 0.719) were nonsignificant. T2* was significantly increased in the lesion-sided MT vs the LT for the JOCD-affected knees (21.5 ± 0.7 [20.1, 22.9] vs 18.0 ± 0.7 [16.5, 19.5] ms, P ¼ 0.002), but this same difference was also observed between the MT and LT in control knees (21.0 ± 0.6 [19.7, 22.3] vs 18.1 ± 1.1 [15.8, 20.4] ms, P ¼ 0.037). There was no significant T2* difference between the affected-and controlknee MT (21.5 ± 0.7 [20.1, 22.9] vs 21.0 ± 0.6 [19.7, 22.3] ms, P ¼ 0.905). T2* within the lesion-sided MFC was not correlated with patient age (R ¼ 0.20, P ¼ 0.28) or lesion volume (R ¼ 0.06, P ¼ 0.75). T2* values were slightly increased near lesions in later-stage JOCD subjects but without statistical significance. Conclusions: T2* relaxations times were not significantly different from control sites in the articular cartilage overlying JOCD lesions in the MFC or adjacent MT cartilage in early-stage JOCD.

No abstract

No abstract

Juvenile osteochondritis dissecans (JOCD) is an orthopedic joint disorder of children and adolescents that can lead to premature osteoarthritis. Thirteen patients (mean age: 12.3 years, 4 females), 15 JOCD-affected and five contralateral healthy knees, that had a baseline and a follow-up magnetic resonance imaging (MRI) (mean interval of 8.9 months) and were treated nonoperatively during this interval were included.Retrospectively, patients were assigned to operative or nonoperative groups based on their electronic medical records. Volumetric mean T 2 * values were calculated within regions of interest (progeny lesion, interface, parent bone) and region matched control bone in healthy contralateral knees and condyles. The normalized percentage difference of T 2 * between baseline and follow up MRI in nonoperative patients significantly increased in progeny lesion (−47.8%, p < 0.001), parent bone (−13.9%, p < 0.001), and interface (−32.3%, p = 0.011), whereas the differences in operative patients were nonsignificant and below 11%. In nonoperative patients, the progeny lesion (p < 0.001) and interface T 2 * values (p = 0.012) were significantly higher than control bone T 2 * at baseline, but not at follow-up (p = 0.219, p = 1.000, respectively). In operative patients, the progeny lesion and interface T 2 * values remained significantly elevated compared to the control bone both at baseline (p < 0.001, p < 0.001) and follow-up (p < 0.001, p < 0.001), respectively. Clinical Significance: Longitudinal T 2 * mapping differentiated nonhealing from healing JOCD lesions following initial nonoperative treatment, which may assist in prognosis and improve the ability of surgeons to make recommendations regarding operative versus nonoperative treatment.