SIGNIFICANCE OF TIP APEX DISTANCE (TAD) IN PROXIMAL FEMORAL NAIL ANTIROTATION (PFNA) II SYSTEM USED IN TRAUMA CASES OF PROXIMAL FEMORAL FRACTURES

Abstract

Introduction: Proximal femoral fractures of trochanteric region are common orthopaedic trauma in routine practice and the ideal implant for treatment is still not found. After the sliding hip screw and various intramedullary nails having been used for so long, newer implants like PFNA II (Asian version of PFNA) with helical blade are now available. But ideal position of helical blade in femoral head has been in debate till date. For sliding hip screw, concept of maintaining Tip Apex Distance (TAD) less than 25mm is well accepted. So, the purpose of this study is to determine the optimal TAD for PFNA II in trochanteric femoral fractures. Materials and methods:100 cases of proximal femoral fractures of trochanteric region which were treated with PFNA II between August 2015 to July 2019 at Geetanjali Medical College and hospital, Udaipur, Rajasthan, India were included in this study. TAD value and position of helical blade tip in femoral head was correlated with failure of fixation. 60 cases were studied retrospectively and 40 cases prospectively. Results: The mean TAD found in this study was 17.97 mm. The overall fixation failure in this study was 3 out of 100 cases (3%). TAD of more than 25 mm was seen in 7 cases out of which 1 case failed (14.28%). However, only 2 out of 93 cases (2.15%) failed in cases with TAD less than 25 mm. Position of helical blade tip in failed cases was superior-centre in 2 cases, while centre-posterior in 1 case. However, all 60 cases with centre-centre position healed successfully. Failed cases showed implant breakage in 2 cases and fracture collapse in 1 case. Conclusion: This study recommends that maintaining TAD less than 25 mm prevents fixation failure in treating trochanteric femoral fractures with PFNA II. Central position of helical blade tip shows most successful result. Also, helical blade of PFNA II provides better hold in osteoporotic bones. Keywords: trochanteric fractures, TAD (Tip Apex Distance), PFNA II, helical blade