Classification Systems for Knee Osteochondritis Dissecans: A Systematic Review

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.

[Treatment of osteochondritis dissecans]

Osteochondritis dissecans (OD) is a rare condition with an incidence of 30/100,000. It especially affects male patients aged 10-20 years old. During the staged progression the osteochondral fragments can detach from their base. These can damage the adjacent articular cartilage, which can lead to premature osteoarthritis. Most commonly affected are the knee, ankle and elbow joints. The exact pathogenesis of OD has so far not been clearly confirmed. Several risk factors that can lead to the development of OD are discussed. These include repeated microtrauma and vascularization disorders that can lead to ischemia of the subchondral bone and to a separation of the fragments close to the joint and therefore to the development of free joint bodies. For an adequate clarification patients should undergo a thorough radiological evaluation including X‑ray imaging followed by magnetic resonance imaging (MRI) to assess the integrity of the cartilage-bone formation with determination of the OD stage. The assessment is based on criteria of the International Cartilage Repair Society (ICRS). The instability of the cartilage-bone fragment increases with higher stages. Stages I and II with stable cartilage-bone interconnection can be treated conservatively. For stages III and IV, i.e., instability of the OD fragment or the presence of free fragments, surgical treatment should be performed. Primarily, refixation of a free joint body should be carried out depending on the size and vitality of the fragment. In cases of unsuccessful conservative treatment or fixation, a debridement, if necessary in combination with a bone marrow stimulating procedure, can be employed corresponding to the size of the defect. For larger cartilage defects, an osteochondral graft transplantation should be considered. Overall, OD lesions in stages I and II show a good healing tendency under conservative treatment. In cases of incipient unstable OD, refixation can also lead to good clinical and radiological results.

A Multi-Disciplinary MRI Assessment May Optimize the Evaluation of Chondral Lesions in Acute Ankle Fractures: A Prospective Study

Chondral lesions (CL) in the ankle following acute fractures are frequently overlooked immediately after the injury or diagnosed at a later stage, leading to persistent symptoms despite successful surgery. The literature presents a wide range of discrepancies in the reported incidence of CLs in acute ankle fractures. The objective of this prospective study is to provide a precise assessment of the occurrence of chondral lesions (CLs) in acute ankle fractures through MRI scans conducted immediately after the trauma and prior to scheduled surgery. Furthermore, the study aims to highlight the disparities in the interpretation of these MRI scans, particularly concerning the size and extent of chondral damage, between radiologists and orthopedic surgeons. Over the period of three years, all patients presenting with an unstable ankle fracture that underwent operative treatment were consecutively included in this single-center prospective study. Preoperative MRIs were obtained for all included patients within 10 days of the trauma and were evaluated by a trauma surgeon and a radiologist specialized in musculoskeletal MRI blinded to each other's results. The location of the lesions was documented, as well as their size and ICRS classification. Correlations and kappa coefficients as well as the p-values were calculated. A total of 65 patients were included, with a mean age of 41 years. The evaluation of the orthopedic surgeon showed CLs in 52.3% of patients. CLs occurred mainly on the tibial articular surface (70.6%). Most talar lesions were located laterally (11.2%). The observed CLs were mainly ICRS grade 4. According to the radiologist, 69.2% of the patients presented with CLs. The most common location was the talar dome (48.9%), especially laterally. Most detected CLs were graded ICRS 3a. The correlation between the two observers was weak/fair regarding the detection and classification of CLs and moderate regarding the size of the detected CLs. To enhance the planning of surgical treatment for ankle chondral lesions (CLs), it may be beneficial to conduct an interdisciplinary preoperative assessment of the performed scans. This collaborative approach can optimize the evaluation of ankle CLs and improve overall treatment strategies.