Improved Prediction of Femoral Shortening in Total Hip Arthroplasty for Developmental Dysplasia of the Hip Using the Etfal Classification: A 7-Center Validation Study.

BACKGROUND Developmental dysplasia of the hip (DDH) presents substantial surgical challenges during total hip arthroplasty (THA), particularly in cases of high-riding dislocations, which can require subtrochanteric shortening osteotomy. The newly proposed Etfal classification incorporates the proportional femoral-pelvic ratio and may offer improved preoperative guidance. MATERIAL AND METHODS A retrospective multicenter validity study was conducted across 7 tertiary centers, including 152 patients with 157 hips who underwent THA for DDH. The primary endpoint was the intraoperative requirement for subtrochanteric shortening osteotomy. Preoperative radiographs were classified using the Etfal and Crowe classifications. Diagnostic performance was evaluated using ROC analyses, AUC values, and optimal thresholds determined using the Youden index. Complication associations were assessed using a 2×2 contingency analysis with odds ratios. RESULTS A total of 157 hips from 152 patients were analyzed, with subtrochanteric shortening osteotomy performed in 50 hips (31.8% of hips). Subtrochanteric shortening osteotomy was required in 0% of Etfal type 1; 33% of type 2; 96.4% of type 3; and 100% of type 4 hips. In contrast, only 6.1% of Crowe type 3 hips required subtrochanteric shortening osteotomy, compared with 80% of Crowe type 4 hips. Diagnostic performance favored Etfal over Crowe (AUC, 0.98 vs 0.94). Etfal type 3 or greater demonstrated near-perfect specificity (0.99) and high sensitivity (0.82), outperforming Crowe type 3 or greater (specificity, 0.60; sensitivity, 1.00). Twelve complications occurred, predominantly in Etfal types 3 and 4. CONCLUSIONS Etfal classification demonstrated superior discriminative ability for predicting the intraoperative requirement for subtrochanteric shortening osteotomy and complication risk compared with the Crowe system.