Use of the Tip-Apex Distance in predicting Dynamic Hip Screw Cut Out in Intertrochanteric Fracture of the Femur in Asian Population

The objective of this study was to assess the rate of screw cut out in elderly patients treated with the dynamic hip screw and the relationship to the Tip Apex Distance (TAD). This is a retrospective radiological evaluation of 100 cases of elderly patients with intertrochanteric fracture treated with dynamic hip screw fixation surgically treated between 1998 and 2002. The incidence of screw cut out was assessed and correlation of risk of cut out with the TAD was assessed. The rate of screw cut out was 9.0% and the average length of time to screw cut out was 3.8 months (range, 1 to 6 months) postoperatively. The incidence of screw cut out increased significantly when the TAD was 20 mm or more. The screw cut out rates were 2.9%, 20.0%, 30.8%, 50% and 100% for TAD of 20-24 mm, 25-29 mm, 30-34 mm, 35-44 mm and > 45 mm respectively. Overall, a TAD of 20mm or more was associated with a statistically significant screw cut out risk in this Malaysian population.

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

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 system:44 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 groups:59 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 (range:75 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.

The Value of the Tip - Apex Distance in Predicting Failure of Fixation of Intertrochanteric Fractures of the Hip / 대한정형외과학회잡지

Failure of fixation of intertrochanteric fractures that have been treated with a fixed-angle sliding hip-screw device is frequently related to the position of the lag screw in the femoral head. The purpose of this study is to introduce the concept of the tip-apex distance and to demonstrate its clinical usefulness as a predictor of cutout of the screw used for fixation of the intertrochanteric fractures of the hip. The tip-apex distance is the sum of the distance from the tip of the lag screw to the apex of femoral head on an anteroposterior radiograph and this distance on a lateral radiograph after controlling for magnification. To determine the value of tip-apex distance in the prediction of cutout of the lag screw, 67 intertrochanteric fractures that have been treated with a fixed-angle sliding hip screw device were studied. The minimum duration of follow-up was three months during which period all of the fractures either healed or had failure of the fixation. The average tip-apex distance was 21mm (range,22.8-65.8mm) for the successfully treated fractures compared with 35mm (range,8.4-65.8mm) for those in which the screw cutout. There was strong statistical relationship between an increasing tip-apex distance and the rate of cutout. An unstable fracture, a poor reduction were also associated with a significantly increased risk of failure due to cutout.