Reliability and validity of the Hartofilakidis classification system of congenital hip disease in adults.

The reliability and validity of the Hartofilakidis et al. classification system in adults with congenital hip disease (CHD) were examined. The radiographs of 102 adult patients (158 hips) with CHD were independently assessed by three senior surgeons. Interobserver variability was assessed by examining the agreement between the three raters while validity of the classification system was assessed by examining the agreement between the assessment by either one of the three raters and the intraoperative finding (reference standard). The interobserver agreement between the three observers was high ranging from 0.720 to 0.854 (substantial to excellent) while the agreement of the preoperative prediction with the intraoperative findings was 87.4% (K = 0.823, excellent agreement). The Hartofilakidis et al. classification system reliably predicts from preoperative pelvis radiographs the bone deficiencies encountered during the operation.