Applying the femoral neck-lesser trochanter anteversion to evaluate the proximal femoral deformity of unilateral developmental dislocation of the hip in children / 中华骨科杂志

ABSTRACT

Objective:A new measurement index, femoral neck-lesser trochanter anteversion (FN-LTA), is proposed. To explore the feasibility and advantage of applying the FN-LTA to evaluate the proximal femoral deformity of unilateral developmental dislocation of the hip in children, so as to solve the current clinical problems.Methods:The imaging data of 90 patients with unilateral DDH admitted to our department from February 2016 to April 2017 were retrospectively analyzed, There were 13 males and 77 females. The age ranged from 0.6 to 11 years, with an average of 2.6±2.3 years. Femoral neck anteversion (FNA) and FN-LTA were measured at the affected and healthy sides. Analyze the correlation between FN-LTA and FNA, analyze the influence of gender, age, side, dislocation degree and other factors on FN-LTA, compare the difference between the affected side and the healthy side of FNA, FN-LTA, and analyze the influence of dislocation degree on this difference, compare the diagnostic efficacy and intra group consistency of FNA and FN-LTA. The possible advantages of FN-LTA in clinical application were preliminarily analyzed.Results:There was a positive correlation between FN-LTA and FNA in both healthy and affected sides (healthy side r=0.217, P=0.040, affected side r=0.298, P=0.004). FNA and FN-LTA in the affected side of DDH children were both larger than the healthy side, FNA affected side 38.86°±11.70°, healthy side 35.44°±11.16°; FN-LTA affected side 72.19°±9.17°, healthy side 61.17°±10.30°. The difference had statistical significance. FN-LTA was not affected by gender, side, degree of dislocation and other factors (gender P=0.060, side P=0.550, degree of dislocation of healthy side P=0.130, affected side P=0.705), but negatively correlated with age (healthy side r=-0.261, P=0.013, affected side r=-0.287, P=0.006). The diagnostic efficiency of FN-LTA is better, AUC FNA=0.561, AUC FN-LTA=0.736 ( P<0.05). FN-LTA and FNA had excellent intra group and inter group consistency. Inter group ICCFNA=0.956, ICCFN-LTA=0.973; intra group ICCFNA1=0.937, ICCFNA2=0.893, ICCFN-LTA1=0.887, ICCFN-LTA2=0.874. With the increase of dislocation degree, the difference between FNA and FN-LTA decreased. This decreasing trend was statistically significant in FNA ( P=0.030) but not in FN-LTA ( P=0.180). Conclusion:FN-LTA is a reliable method with a higher degree of differentiation for the assessment of anteverted deformity in DDH children' proximal end of femur, the measured data are more capable of guiding the rotation of osteotomy.