title: A biomechanical evaluation of proximal femoral nail antirotation with respect to helical blade position in femoral head: A cadaveric study.
abstract: OBJECTIVE
  Despite new developments in the management of osteoporotic fractures, complications like screw cutout are still found in the fixation of proximal femur fractures even with biomechanically proven better implants like proximal femoral nail antirotation (PFNA). The purpose of this cadaveric study was to investigate the biomechanical stability of this device in relation to two common positions (center-center and inferior-center) of the helical blade in the femoral head in unstable trochanteric fractures.
  
  
  METHODS
  Eight pairs of human cadaveric femurs were used; in one group [center-center (C-C) group], the helical blade of PFNA was fixed randomly in central position both in anteroposterior and lateral view, whereas in the other group it was fixed in inferior one-third position in anteroposterior and in central position in lateral view [inferior-center (I-C) group]. Unstable intertrochanteric fracture was created and each specimen was loaded cyclically till load to failure
  
  
  RESULTS
  Angular and rotational displacements were significantly higher within the C-C group compared to the I-C group in both unloaded and loaded condition. Loading to failure was higher in the I-C group compared to the C-C group. No statistical significance was found for this parameter. Correlations between tip apex distance, cyclic loading which lead to femoral head displacement, and ultimate load to failure showed a significant positive relationship.
  
  
  CONCLUSIONS
  The I-C group was superior to the C-C group and provided better biomechanical stability for angular and rotational displacement. This study would be a stimulus for further experimental studies with larger number specimens and complex loading protocols at multicentres.
authors: Department of Orthopaedic Surgery, Konkuk University School of Medicine, Seoul, Korea.
authors: Jin-Ho
authors: JH
authors: Hwang
authors: Anant Kumar
authors: AK
authors: Garg
authors: Jong-Keon
authors: JK
authors: Oh
authors: Chang-Wug
authors: CW
authors: Oh
authors: Sung-Jae
authors: SJ
authors: Lee
authors: Cho
authors: C
authors: Myung-Rae
authors: Min-Keun
authors: MK
authors: Kim
authors: Hyun
authors: H
authors: Kim
keywords: Biomechanical study; PFNA; cadaveric study; helical blade position; unstable trochanteric fracture