Trochanteric fractures treated by internal fixation using short intramedullary nails: Does the visual intraoperative estimation of the Tip-Apex Distance (TAD) concur with its digital postoperative measurement?

Abstract

Introduction: The tip-apex distance (TAD) is the only predictor for mechanical failure after internal fixation of trochanteric fractures. The main objective of our study was to assess whether the intraoperative visual estimation of the TAD concurred with the measurement taken on postoperative digital X-rays. We hypothesized that there was a good concordance between these 2 different methods of measurement.

Materials and methods: Patients with an isolated trochanteric fracture were included in our study. A hardcopy of the intraoperative X-rays were printed, and the TAD was calculated manually. Radiological and clinical follow-ups were scheduled at 6 weeks, 3 months and 6 months during which numerical measurements of the TAD were taken. We also recorded the fracture type (AO/OTA classification), degree of osteoporosis (Singh index), surgeon experience, age and ASA score.

Results: A total of 98 patients were included in our study. Of these, 70 had a 6-month follow-up and interpretable postoperative X-rays. The mean age was 87 years, with 77.14% women and a mean ASA score of 3. The coefficient of concordance between the intra and postoperative TAD was 0.7202 (95% CI=0.4905-0.9499). The secondary displacement rate was 3.28%. The univariate analysis showed no statistically significant association between an intraoperative TAD>25mm and fracture type (p=0.7290), degree of osteoporosis (p=0.5701) and surgeon experience (p=1).

Discussion/conclusions: There was a high degree of concordance between intraoperative visual estimation of the TAD and its measurement on postoperative digital X-rays. The treatment of unstable fractures in osteoporotic bone by junior surgeons was not a risk factor for intraoperative TAD>25mm. It is therefore important to educate young surgeons on the concept of TAD and its intraoperative visual estimation technique as it ensures that the cephalic screw is positioned properly during the fixation of trochanteric fractures.

Level of evidence: II.

Keywords: Concordance of measurements; Pertrochanteric fracture; Secondary displacement; TAD; Tip-apex distance.