Tip to apex distance in femoral intertrochanteric fractures: a systematic review

BACKGROUND: Hip fractures are associated with high morbidity, mortality, and cost. Implants used for hip fracture fixation can fail for many reasons including lag screw cut-out. Tip-apex distance (TAD) is indicative of the position and depth of a screw in the femoral head and has been shown to be associated with cut-out failure. We conducted a systematic review of the published literature to quantify the association between TAD and cut-out failure for patients undergoing hip fracture fixation surgery. METHODS: We performed a search of the Medline, Embase, and Cochrane databases. We performed abstract and full text reviews independently and in duplicate. We used a random effects model to combine, in duplicate, the incidence of cut-out for patients who had TAD <25 mm and TAD >25 mm. We also combined mean TAD values for patients who had cut-out failure and those who did not. RESULTS: Seventeen studies were eligible for this review, four of which were included in combined analysis of dichotomous outcomes and seven in combined analysis of continuous outcomes. Patients with TAD >25 mm had a significantly greater risk of cut-out than patients with TAD <25 mm (RR = 12.71). Patients who experienced implant cut-out had significantly higher TAD scores than those who did not (mean difference = 6.54 mm). CONCLUSION: Tip-apex distance is an important concept in relation to cut-out failure of hip fracture fixation surgery. Surgeons should understand and apply the concept of TAD to improve outcomes for their patients.