Does Trochanteric Osteotomy Length Affect the Amount of Proximal Trochanteric Migration During Revision Total Hip Arthroplasty?

Abstract

BackgroundNonunion and proximal trochanteric migration is a known complication of trochanteric osteotomy. This study examines the effect of osteotomy length on proximal greater trochanter (GT) migration. MethodsWe analyzed 113 modified trochanteric slide osteotomies and 73 extended trochanteric osteotomies performed between 2008 and 2016. All osteotomies were fixed using cerclage wires and had minimum 6-month radiographic follow-up. Spearman correlations were used to assess association between osteotomy length and GT migration distance. Chi-squared test and logistic regression were used to assess association between patient and surgical factors and GT migration >1 cm. Receiver operating characteristic curves were constructed to determine the optimal cutoff osteotomy length for predicting GT migration >1cm. ResultsMean osteotomy length was 6.1 cm (range 3-12) for modified trochanteric slide osteotomies and 14.8 cm (range 8-23) for extended trochanteric osteotomies. Osteotomy length was negatively correlated (r = −0.340, P < .001) with GT migration distance. Longer osteotomy length was protective against GT migration >1 cm (odds ratio 0.67, P = .002). Receiver operating characteristic curve analysis demonstrated an optimal cutoff osteotomy length of 9.8 cm for predicting GT migration >1 cm (sensitivity 0.971, specificity 0.461). Among osteotomies <10 cm, those fixed using at least one distal wire below the lesser trochanter and vastus ridge demonstrated less mean GT migration (3.86 vs 7.12 mm, P = .009) and higher mean union rate (68.8% vs 31.2%, P < .001). ConclusionOsteotomies shorter than 10 cm are at higher risk of developing proximal GT migration >1 cm. A distal cerclage wire below the lesser trochanter and vastus ridge may help decrease the amount of GT migration. Level of EvidencePrognostic Level IV.