An Anatomic Study of the Greater Trochanter Starting Point for Intramedullary Nailing in the Skeletally Immature

作者：Park Paul J; Weinberg Douglas S; Petro Kathleen F; Liu Raymond W^*

来源：Journal of Pediatric Orthopaedics, 2017, 37(1): 67-73.

DOI：10.1097/BPO.0000000000000581

• greater trochanter
• greater trochanter anatomy
• intramedullary nailing
• trochanteric nail starting point
• pediatric femur fracture

Background: Trochanteric entry femoral nails have been increasing in popularity in the pediatric population for stabilization in fractures and osteotomies. The proper position for entry point in the coronal plane has been well studied; however, the sagittal plane in the pediatric population has not yet been well characterized.
Methods: Eighty-eight cadaveric femora aged 8 to 20 years were studied in an apparent neck-shaft angle (ANSA) position, with distal condyles flat on the surface, and a true neck-shaft angle (TNSA) position, with internal rotation to neutralize femoral anteversion. Anterior and lateral offset were measured on lateral and anteroposterior photographs, respectively, as the perpendicular distance from the greater trochanter apex to the center of the intramedullary canal. The effect of rotational position (ANSA vs. TNSA) of the proximal femur was compared using the intraclass correlation coefficient for anterior and lateral offset. Correlations between age, demographics, anteversion, and greater trochanter morphology with anterior and lateral offset were evaluated with multiple regression analysis.
Results: The mean age was 15.8 +/- 3.8 years. The mean anterior displacement of the trochanteric apex was 4.8 +/- 3.0 and 4.6 +/- 3.2mm in the ANSA and TNSA positions, respectively. The mean lateral displacement was 10.6 +/- 4.2 and 9.7 +/- 4.0mm in the ANSA and TNSA positions, respectively. The intraclass coefficient for anterior offset in the ANSA versus TNSA position was 0.704 and 0.900 for lateral offset. Change was minimal for anterior offset in the ANSA and TNSA positions versus age (standardized beta values 0.240, 0.241, respectively). There was a significant correlation with increasing lateral offset in the ANSA and TNSA positions with increasing age (standardized beta values 0.500, 0.385 respectively).
Conclusions: In the pediatric population, the tip of the greater trochanter is consistently anterior by approximately 5 mm. The mean lateral displacement was approximately 10mm and increased with increasing age.
Clinical Relevance: Nail entry at the pediatric greater trochanter apex would likely result in anterior placement. We recommend inserting the guidewire 5mm posterior to the apex of the trochanter and confirming coronal and sagittal position with fluoroscopy.

• 出版日期2017-1