Optional Entry Point for Retrograde Femoral Nailing: An Anatomical Study Using the Reverse Engineering Method
Nattapon Chantarapanich PhD*, Banchong Mahaisavariya MD**, Kriskrai Sitthiseripratip DEng***, Pongwit Siribodhi PhD****
Affiliation : * Department of Mechanical Engineering, Faculty of Engineering, Kasetsart University, Chonburi, Thailand ** Department of Orthopaedic Surgery and Rehabilitation, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand *** National Metal and Materials Technology Center (MTEC), National Science and Technology Development Agency, Pathumthani, Thailand **** Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University, Bangkok, Thailand
Objective : To investigate the optimal entry point for retrograde femoral nailing using medical imaging and reverse engineering
technologies.
Material and Method: One hundred and eight adult cadaveric femurs were scanned using a computed tomography (CT)
scanner. To obtain three-dimensional models, medical imaging and reverse engineering technologies were used. The insertion
assessment was performed using computer aided design (CAD) software. The curve representing the mid-line in the
intramedullary canal in the mid-shaft region was approximated using regression analysis. The curve was extended tangentially
toward the femoral condyle, where the intersection between the curve and the condylar surface is the insertion site. The
location of the insertion site was determined using the center of the anterior most of the intercodylar notch as a reference point.
The measured distances were presented in medial-lateral and anterior-posterior perspectives from the reference point.
Results : Average insertion site for Thai population was 0.56 mm lateral to and 12.67 mm medial to the anterior most of the
intercondylar notch. The distance measured from intercondylar notch to the insertion site in the anterior-posterior direction
was not significantly different between males and females; however, a significant difference in the insertion site was found in
medial-lateral directions.
Conclusion : The insertion site can be clinically approximated lying on the anterior-posterior axis, since the distance from the
anterior-posterior axis to the insertion site is relatively small. The insertion site for the Thai population was found to be 12 mm
anterior to the center of the anterior most of the intercondylar notch.
Keywords : Computed tomography, Reverse engineering, Insertion site, Retrograde nailing, Femoral fracture
