Progression of Epiphyseal Cartilage and Bone Pathology in Surgically Treated Cases of Osteochondritis Dissecans of the Elbow

Abstract

Background: Although a variety of pathologic conditions associated with osteochondritis dissecans (OCD) have been reported, the pathological progression has remained unclear. Hypothesis: Separation of the immature epiphyseal cartilage is an early event in OCD, and osteonecrosis in the articular fragment is a late event. Study Design: Case Series; Level of evidence, 4. Methods: The participants were 26 boys (mean age, 13.8 years; mean skeletal age score for the elbow, 24.6 points) with capitellar OCD who underwent osteochondral autograft transplantation. A total of 28 cylindrical osteochondral plugs, including the articular fragment, an intermediate layer, and proximal epiphyseal bone, were harvested from the central area of the capitellum and were examined histologically. The articular fragments of OCD were independently assessed by 5 observers and divided into 4 pathological variations: IA, nearly normal-cartilaginous; IB, deteriorated-cartilaginous; IIA, cartilage-ossifying; and IIB, cartilage-osteonecrotic. The reliability of assessment and the correlation of the pathological variations with the clinical data were examined. Results: The reliability of the assessment among 5 observers was almost perfect (Cohen kappa value = 0.91). OCD variations of IA, IB, IIA, and IIB were evident in 5, 10, 5, and 6 patients, respectively. OCD-I (cartilaginous) and OCD-II (osteochondral) corresponded significantly to radiographic stage I (radiolucency or slight calcification with open physis) and stage II (delayed ossification or bony fragment), respectively (Cohen kappa value = 0.79; percentage agreement = 81%). The pathological OCD variations were significantly correlated with the clinical data, including the period from symptom onset to surgery, patient age, and the skeletal age score ( P < .01, in each). Conclusion: The present study has revealed that the pathological variations correspond to the progression of OCD, thus proving our hypothesis. OCD-IA was shown to be an early lesion caused by separation of the immature epiphyseal cartilage. OCD-IB appeared to result from ossification arrest over a prolonged period from the onset of OCD-IA, whereas OCD-IIA showed delayed ossification in the epiphyseal cartilage where vascularization from the surrounding bone had been established. Osteonecrosis in OCD-IIB was shown to be a late pathological event caused by disruption of the vascular supply to OCD-IIA.

Association of Stability and Size of Unhealed Area With Failure After Internal Fixation for Osteochondritis Dissecans Lesions of the Knee: Radiological Evaluation Using Computed Tomography

“…In addition, Yonetani et al 34 showed in their cylindrical histological examination that the tissue specimen was macroscopically separated at the endochondral ossification interface and could be distinguished into 2 microscopic patterns: subchondral defect type and osteochondral type. Recently, Takahara et al 25,26 reported a similar histological classification for OCD of the elbow. Furthermore, Yonetani et al 35 also showed that CT evaluation clearly reflected not only these 2 characteristic preoperative patterns, but also postoperative reossification status after transarticular drilling.…”

Physical functions, to be or not to be a risk factor for osteochondritis dissecans of the humeral capitellum?

“…One risk factor for OCD might be immaturity in development. Takahara et al 23 showed that separation of the immature epiphyseal cartilage is an early event in OCD. Our study suggests that OCD begins at an age at which the epiphyseal cartilages are immature.…”

Qualitative and quantitative assessments of radiographic healing of osteochondritis dissecans of the humeral capitellum

“…A histologic study on OCD of the capitellum revealed that ossification of the lesion was associated with a significantly dominant fibrocartilage connection to the underlying bone, in other words, the arrest of ossification was associated with separation rather than fibrocartilage connection. 29 We consider that the arrest of ossification during nonoperative treatment can be caused by micromovement of the OCD lesion. This study showed that the progression of ossification during the first 3 months was one of the predictors of successful nonoperative treatment and radiographic healing.…”