M Hélin1, A Pelissier1, P Boyer1, T Delory2, C Estellat2, P Massin3. 1. Département de chirurgie orthopédique, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; Université Paris Diderot, Sorbonne Paris Cité, EA REMES, 75010 Paris, France. 2. Département de biostatistiques, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France. 3. Département de chirurgie orthopédique, hôpitaux universitaires Paris Nord Val-de-Seine, site Bichat, 46, rue Henri-Huchard, 75877 Paris cedex 18, France; Université Paris Diderot, Sorbonne Paris Cité, EA REMES, 75010 Paris, France. Electronic address: philippe.massin@bch.aphp.fr.
Abstract
INTRODUCTION: Femoral neck shortening after dynamic fixation of extra-capsular fracture may impair functional results, but is rarely assessed. The present study measured impaction in stable and unstable fractures (on the Ender classification) treated by PFNA™ nail. The objectives were: 1) to validate the Ender classification to assess fracture stability; 2) to determine whether neck shortening and head purchase quality varied with stability; and 3) to determine the functional impact of femoral neck shortening. HYPOTHESIS: The study hypothesis was that the PFNA™ nail stabilizes unstable as well as stable fractures. MATERIALS AND METHODS: One hundred and fifteen consecutive patients, aged over 70 years, operated on for intertrochanteric fracture using the PFNA™ nail were followed up prospectively for 6 months. Multivariate analysis, including age, gender, assembly quality and body-mass index, was applied to assess the predictive power of the Ender classification with respect to femoral neck shortening. Secondly, patients were grouped according to stable versus unstable fracture (n=70 and 45, respectively), and impaction and femoral head purchase were assessed on a dedicated radiographic protocol. Functional results were assessed on Parker score. RESULTS: In the unstable fracture group, 3 assembly failures required revision by total hip replacement. Ender grade>2 was significantly predictive of>5mm neck shortening. Neck shortening was greater in unstable fracture: 8.1 ± 8.4mm (range, 4-32 mm), versus 2.5 ± 3.7 mm (range, 3-14 mm) (P=0.0004). Mean blade cut-through was 1.2 ± 2.9 mm (range, 1-12 mm) in unstable fracture, versus 0.3 ± 1.3 mm (range, 1-6mm) (P=0.02). Mean cut-out was 2.3 ± 6 mm (range, 2-21 mm) in unstable fracture, versus 0.5 ± 2.6 mm (range, 1-8mm) (P=0.03). Parker scores diminished comparably in the two groups, without significant difference at follow-up: 3.9 ± 2.6 (range, 0-9) in stable and 3.1 ± 1.9 (range, 0-8) in unstable fracture; reduction in Parker score showed no correlation with femoral neck shortening (r=0.013, P=0.88). DISCUSSION: The PFNA™ nail provides poorer stabilization of unstable compared to stable fracture. Femoral neck shortening should be taken into account in assessing internal fixation hardware perfomances. LEVEL OF EVIDENCE: Level III. Prospective case-control study.
INTRODUCTION:Femoral neck shortening after dynamic fixation of extra-capsular fracture may impair functional results, but is rarely assessed. The present study measured impaction in stable and unstable fractures (on the Ender classification) treated by PFNA™ nail. The objectives were: 1) to validate the Ender classification to assess fracture stability; 2) to determine whether neck shortening and head purchase quality varied with stability; and 3) to determine the functional impact of femoral neck shortening. HYPOTHESIS: The study hypothesis was that the PFNA™ nail stabilizes unstable as well as stable fractures. MATERIALS AND METHODS: One hundred and fifteen consecutive patients, aged over 70 years, operated on for intertrochanteric fracture using the PFNA™ nail were followed up prospectively for 6 months. Multivariate analysis, including age, gender, assembly quality and body-mass index, was applied to assess the predictive power of the Ender classification with respect to femoral neck shortening. Secondly, patients were grouped according to stable versus unstable fracture (n=70 and 45, respectively), and impaction and femoral head purchase were assessed on a dedicated radiographic protocol. Functional results were assessed on Parker score. RESULTS: In the unstable fracture group, 3 assembly failures required revision by total hip replacement. Ender grade>2 was significantly predictive of>5mm neck shortening. Neck shortening was greater in unstable fracture: 8.1 ± 8.4mm (range, 4-32 mm), versus 2.5 ± 3.7 mm (range, 3-14 mm) (P=0.0004). Mean blade cut-through was 1.2 ± 2.9 mm (range, 1-12 mm) in unstable fracture, versus 0.3 ± 1.3 mm (range, 1-6mm) (P=0.02). Mean cut-out was 2.3 ± 6 mm (range, 2-21 mm) in unstable fracture, versus 0.5 ± 2.6 mm (range, 1-8mm) (P=0.03). Parker scores diminished comparably in the two groups, without significant difference at follow-up: 3.9 ± 2.6 (range, 0-9) in stable and 3.1 ± 1.9 (range, 0-8) in unstable fracture; reduction in Parker score showed no correlation with femoral neck shortening (r=0.013, P=0.88). DISCUSSION: The PFNA™ nail provides poorer stabilization of unstable compared to stable fracture. Femoral neck shortening should be taken into account in assessing internal fixation hardware perfomances. LEVEL OF EVIDENCE: Level III. Prospective case-control study.
Authors: J-B Hong; Y Dan; L Ouyang; Y Liu; L-M Xiong; S Li; X-B Feng; Z-W Shao; C Yan; S H Yang; P Liu Journal: J Musculoskelet Neuronal Interact Date: 2017-12-01 Impact factor: 2.041