The "CHARKAJ line": A novel radiographic parameter for the evaluation of adult hip dysplasia.

OBJECTIVE

Developmental dysplasia of the hip (DDH) is a primary driver of secondary osteoarthritis among the young adult population. The objective of this study is to introduce and assess the "CHARKAJ Line"-a linear vector drawn tangential to the superior cortical contour of the femoral neck and extended to the acetabulum-as an adjunctive radiographic indicator to distinguish between normal and dysplastic hips.

MATERIALS AND

METHODS

We performed a retrospective analysis of 132 hips (comprising 108 females and 24 males; mean age 27.6 years) that had radiographic imaging available. Using a Tönnis angle threshold of 10° to define normality, hips were classified into Normal (n = 71) or Dysplasia (n = 61) groups. On the frontal projection, the CHARKAJ Line was projected along the superior femoral neck edge extending medially toward the acetabulum. We measured the distance from the acetabulum's superolateral margin to the specific point where the CHARKAJ line transected the acetabular roof.

RESULTS

Analysis revealed that the mean intersection distance of the CHARKAJ line was significantly deeper in the normal cohort (16.97 +/- 6.76 mm) relative to the dysplastic cohort (11.59 +/- 8.29 mm). This disparity was statistically significant (p < 0.001). Interobserver reliability for the measurement was moderate (ICC = 0.75). There was statistically significant difference between LCEA and CHARKAJ line measurements between normal (LCEA between 25 and 40 degrees) and dysplasia (LCEA less than 20 degrees) cohort with p value of 0.0001.

CONCLUSION

The CHARKAJ Line reveals a statistically significant distinction in intersection depth between dysplastic and normal hips.