The association between the“Tip-Apex Distance”value and cut-out of the lag screw from the femoral head:a clinical retrospective study / 中华创伤骨科杂志

ABSTRACT

Objective To confirm the association between the“Tip-Apex Distance (TAD)”and cut-out of the lag screw from the femoral head.and to analyze other factors leading to the cut-out.Methods The complete radiographic and clinical data of 106 patients with femoral intertrochanteric fractures were available for this study. They were 65 men and 41 women,with an average age of 52.4 years (range,20 to 83 years).According to Evans classification.19 cases belonged to typeⅡ.25 to typeⅢ,32 to typeⅣ,29 to typeⅤ,and one to type R.The bone quality was classified by Singh rating system44 cases were rated as typeⅥ.34 as typeⅤ,23 as typeⅣand five as typeⅢ.They were treated with open reduction and fixation with 135?dynamic hip screw (DHS).According to the finding of Baumgaertner that“TAD”beyond 25 mm would grcatly increase the risk of cut-out,the patients could be divided into two groups59 cases with“TAD”less than 25 mm and 47 greater than 25 mm.Results The mean duration of follow-ups was 14.45 months (range,4.5 to 28.0 months).Of the 15 cases whose“TAD”was more than 30 mm,one had the cut-out.Of the seven cases whose“TAD”was more than 40 mm,two had the cut-out (P=0.000). The average age of the three patients was 78.7 years (range75 to 83 years) and 27.1 years older than that of the 103 patients whose fracture healed (P=0.000).They belonged to the unstable intertrochanteric fracture of the femur (two to Evans type V and one to type R).The reduction was assessed as excellent in 43 cases,good in 47 cases,fair in nine cases (of whom one had the cut-out),poor in seven cases (of whom two had the cut-out). Conclusions The cut-out of the lag screw from the femoral head can be caused by age,fracture type and stability of reduction and“TAD”.The greater the“TAD”value,the greater possibility of cut-out.