Osteochondritis Dissecans of the Knee Associated With Mechanical Overload.

BACKGROUND: Osteochondritis dissecans (OCD) of the knee is a rare but potentially incapacitating disorder in which subchondral bone detaches, leading to an osteochondral fragment that can become unstable and progress into a loose body. The exact cause is unknown, although several biological and mechanical factors have been described. PURPOSE: To provide insight into epidemiological data of a large cohort of patients affected by OCD of the knee and to identify potential factors contributing to the cause of this disorder. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 236 patients (259 knees) affected by OCD were included in our Knee Registry (2005-2022) and retrospectively analyzed. Patient characteristics were extracted from the medical records. Location and International Cartilage Regeneration & Joint Preservation Society grade (1-4) of OCD were assessed using magnetic resonance imaging. If available, a full-leg standing radiograph was used to assess alignment. Additionally, a statistical scoring system for instability risk was created. RESULTS: A total of 263 OCD lesions were identified in 259 knees, 66.2% on the medial femoral condyle (MFC), 26.6% on the lateral femoral condyle (LFC), 3.8% on the trochlea, 2.7% on the patella, and 0.8% on the lateral tibia plateau. Male patients made up 57.6% of the sample, which had a mean age of 21.8 years. A very high percentage of patients (77.1%; n = 182) practiced sports, of whom 67.6% (n = 123) were engaged in high-impact sports. The location of the OCD lesions and the leg alignment (n = 110) were significantly correlated: MFC lesions were associated with more varus than valgus alignment (47.5% vs 11.3%) and patients with LFC lesions had more valgus than varus alignment (46.7% vs 20.0%; P = .002). Based on age, smoking, sports activity, and preceding trauma, a multivariable scoring system (0-11 points) was created. An increased risk of lesion instability was associated with an increased score: 29.0% at 0 points and 97.0% at 11 points. CONCLUSION: This study provides detailed epidemiological data for 236 patients affected by OCD of the knee. Older age, smoking, inactivity, and preceding trauma were predictive for instability of OCD lesions. There was an association between OCD of the MFC and varus malalignment and between OCD of the LFC and valgus malalignment. This finding, in combination with the high percentage of patients practicing high-impact sports, suggests an important role for mechanical overload in the pathogenesis of OCD.

Internal Fixation of Unstable Osteochondritis Dissecans of the Knee: Long-term Outcomes in Skeletally Immature and Mature Patients.

BACKGROUND: Osteochondritis dissecans (OCD) is a disorder originating in the subchondral bone, leading to focal lesions with risk of fragmentation and secondary damage of the articular cartilage. It remains controversial if surgical treatment of such lesions is equally successful in skeletally immature and mature patients. PURPOSE: To determine (1) the long-term clinical success rate after internal fixation of unstable OCD in skeletally immature and mature patients based on physeal status, (2) if patient-specific and procedural variables influence the risk of failure, and (3) patient-reported outcome measures over time. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A multicenter retrospective cohort study was conducted investigating skeletally immature and mature patients treated for unstable OCD lesions of the knee between 2000 and 2015. The healing rate was assessed by radiological imaging and clinical follow-up. Failure was defined as any definitive reoperation for the initially treated OCD lesion. RESULTS: A total of 81 patients met inclusion criteria, including 25 skeletally immature patients and 56 patients with closed physes at the time of surgery. After a mean follow-up time of 11.3 ± 4 years, 58 (71.6%) patients had healed lesions, whereas the lesions failed to heal in 23 (28.4%) patients. No significant difference in risk of failure was observed based on physeal maturation status (hazard ratio, 0.78; 95% CI, 0.33-1.84; P = .56). Lateral versus medial condylar lesion location conferred an increased risk of failure (P < .05) for both skeletally immature and mature patients. Multivariate analysis of skeletal maturity status showed that a lateral femoral condylar location was an independent risk factor for failure (hazard ratio, 0.22; 95% CI, 0.1-0.5; P < .05). The mean patient-reported outcome scores (International Knee Documentation Committee [IKDC] score and Knee injury and Osteoarthritis Outcome Score [KOOS]) increased significantly after surgery and remained high at the final follow-up (P < .05). The final scores (mean ± SD) at a mean follow-up of 135.8 months (range, 80-249 months) were IKDC, 86.6 ± 16.7; KOOS Pain, 88.7 ± 18.1; KOOS Symptoms, 89.3 ± 12.6; KOOS Activities of Daily Living, 89.3 ± 21.6; KOOS Sport and Recreation, 79.8 ± 26.3; and KOOS Quality of Life, 76.7 ± 26.3. CONCLUSION: The long-term results after internal fixation of OCD fragments show high rates of healing and sustainable subjective improvement of knee function and quality of life. A healing rate of 72% was noted at a mean follow-up of 11.3 years. The stage of skeletal maturity had no significant influence on the rate of failure. Lateral femoral condylar lesion location is an independent risk factor for failure in skeletally mature and immature patients.