Staging of osteochondritis dissecans of the elbow based on pathologic progression in the partially detached articular...

Osteochondritis dissecans (OCD) is considered to show the following stages of pathologic progression: IA, nearly normal-cartilaginous; IB, deteriorated-cartilaginous; IIA, cartilage-ossifying; and IIB, cartilage-osteonecrotic. However, the validity of this pathologic staging for OCD has yet to be confirmed in a large number of cases.

The aim of the present study was to confirm the clinical validity of the proposed pathologic staging of OCD.

The subjects were 74 patients (mean age, 14.2 years; mean skeletal age score, 25.6 points) with capitellar OCD. Partially detached articular fragments were surgically removed and were examined histologically. The articular fragments were independently assessed by 5 observers, and the reliability of assessment was examined. The correlation between the pathologic stages and the clinical data was analyzed.

The reliability of the assessment among 5 observers was almost perfect. OCD stages of IA, IB, IIA, and IIB were evident in 8, 36, 10, and 20 patients, respectively. OCD-I (cartilaginous) and OCD-II (osteochondral) corresponded significantly to radiographic stage I (radiolucency) and stage II (delayed ossification), respectively. The pathologic OCD stages were significantly correlated with the clinical data, including the period from symptom onset to surgery, patient age, and the skeletal age score (P < .01).

Our results confirmed that the proposed pathologic staging of OCD corresponds to the observed clinical progression of OCD, thus validating the staging system. Our findings revealed that OCD begins with separation beneath the epiphyseal cartilage, which is programmed to be replaced with bone. When a stage IA articular fragment has remained partially detached for a prolonged period, the epiphyseal cartilage may be deteriorated and become degenerated, and subsequent ossification may not occur, as is evident in OCD-IB. In contrast, stage IA with a vascular supply through the fibrocartilaginous connection can progress to stage IIA. During the prolonged period in which the osteochondral articular fragment remains ununited, microtrauma can cause to disturb the blood supply to the bony fragment, resulting in osteonecrosis (stage IIB).