Purpose: Slipped capital femoral epiphysis (SCFE) is a poorly understood condition impacting adolescents. Its consequences can be severe, even where there is early recognition and treatment is implemented. Prior studies have suggested that the etiology may be related to abnormal collagen comprising the growth plate cartilage, but no investigations have analyzed collagen or other structural proteins on a molecular level in the affected tissue. This study evaluates expression of mRNA for key structural proteins obtained from growth plate chondrocytes of patients suffering SCFE.

Method: The work utilizes laser capture microdissection (LCM) techniques followed by reverse transcription polymerase chain reaction (RT-PCR) to determine if a change or abnormality in type II collagen and/or aggrecan gene expression may be involved in weakening the physis, a characteristic of the pathology. With these techniques, correlation of chondrocyte spatial location and gene expression can be made to provide greater insight into this pathology and a more complete understanding of growth plate biology in general.

Results: Downregulation of both type II collagen and aggrecan was found in the growth plates of SCFE subjects when compared to age-matched controls. Expression levels for type II collagen mRNA of SCFE patients were less than 14% of their counterpart controls. SCFE aggrecan levels averaged only 26% of control expression.

Conclusion: The significant decreases in type II collagen and aggrecan expression would drastically affect the quantity, distribution, and organization of both components in SCFE growth plates. Such abnormal changes may contribute to the cause of a slip although possibly they may be the result of a slip. This is the first study using novel LCM and RT-PCR to determine specific gene expression levels for two principal structural proteins comprising the growth plates of human subjects suffering SCFE.