Quantification of cephalomedullary nail fit in the femur using 3D computer modelling: a comparison between 1.0 and 1.5m bow designs

BackgroundThe radius of curvature (ROC) misfit of cephalomedullary nails during anterograde nailing can lead to complications such as distal anterior cortical encroachment. This study quantified the anatomical fit of a new nail with 1.0-m ROC (TFN-ADVANCED™ Proximal Femoral Nailing System [TFNA]) compared with a nail with 1.5-m ROC (Gamma3 Long Nail R1.5 [Gamma3]).MethodsWe generated 63 three-dimensional models (48 female, 45 right femur) representing the cortical surfaces of the femora (31 Caucasian, 28 Japanese, and 4 Thai). The mean age of the specimens was 77 years (±8.1), and the mean height was 158.5 cm (±9.6). Utilizing a customized software tool, nail fit was determined from the total surface area of nail protrusion from the inner cortex surface and maximum distance of nail protrusion in the axial plane; the position of the distal nail tip within the canal was also determined.ResultsOverall, TFNA had both a significantly smaller mean total surface area of nail protrusion (915.8 vs. 1181.6 mm2; P < 0.05) and a mean maximum distance of nail protrusion in the axial plane (1.9 vs. 2.1 mm; P = 0.007) when compared with Gamma3. The mean total surface area of nail protrusion was significantly smaller with TFNA versus Gamma3 in both the Caucasian (P = 0.0009) and Asian (Japanese and Thai) samples (P = 0.000002); the mean maximum distance of TFNA protrusion was significantly smaller in Asians (P = 0.04), but not in Caucasians (P = 0.08). Most tip positions for both nail types were anterior, but TFNA had a higher number of center positions than Gamma3 (13 vs. 7) and a shift from the far anterior cortex to the center of the medullary canal (overall and in Caucasians). In Asians, the most prominent position was far anterior for both nails.ConclusionsThe 1.0-m ROC TFNA nail resulted in better fit than the 1.5-m ROC Gamma3 nail. Clinical trials and case studies should be conducted in the future to verify if these findings would also result in clinical improvements.

[1]  Peter Messmer,et al.  A CT Database for Research, Development and Education: Concept and Potential , 2007, Journal of Digital Imaging.

[2]  B. Mahaisavariya,et al.  Fit-and-fill analysis of trochanteric gamma nail for the Thai proximal femur: a virtual simulation study. , 2004, Journal of the Medical Association of Thailand = Chotmaihet thangphaet.

[3]  R. Ostrum,et al.  Penetration of the Distal Femoral Anterior Cortex During Intramedullary Nailing for Subtrochanteric Fractures: A Report of Three Cases , 2005 .

[4]  B. Schmutz,et al.  Fit Assessment of Anatomic Plates for the Distal Medial Tibia , 2008, Journal of orthopaedic trauma.

[5]  G. Haidukewych Intertrochanteric fractures: ten tips to improve results. , 2010, Instructional course lectures.

[6]  Beat Schmutz,et al.  Typical Accuracy and Quality Control of a Process for Creating CT-Based Virtual Bone Models , 2010, Journal of Digital Imaging.

[7]  Sheng Zhang,et al.  Using Three-Dimensional Computational Modeling to Compare the Geometrical Fitness of Two Kinds of Proximal Femoral Intramedullary Nail for Chinese Femur , 2013, TheScientificWorldJournal.

[8]  Kenneth Egol,et al.  Controversies in intramedullary nailing of femoral shaft fractures. , 2003, Instructional course lectures.

[9]  Beat Schmutz,et al.  3D Computer graphical anatomy study of the femur: a basis for a new nail design , 2017, Archives of Orthopaedic and Trauma Surgery.

[10]  Banchong Mahaisavariya,et al.  Geometric mismatch analysis of retrograde nail in the Asian femur , 2011, Surgical and Radiologic Anatomy.

[11]  Beat Schmutz,et al.  Automated fit quantification of tibial nail designs during the insertion using computer three-dimensional modelling , 2014, Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine.

[12]  Beat Schmutz,et al.  Effects of CT image segmentation methods on the accuracy of long bone 3D reconstructions. , 2011, Medical engineering & physics.

[13]  M A Schuetz,et al.  Quantitative fit assessment of tibial nail designs using 3D computer modelling. , 2010, Injury.

[14]  C. Collinge,et al.  Does Modern Nail Geometry Affect Positioning in the Distal Femur of Elderly Patients With Hip Fractures? A Comparison of Otherwise Identical Intramedullary Nails With a 200 Versus 150 cm Radius of Curvature , 2013, Journal of orthopaedic trauma.

[15]  K. Koval,et al.  Cortical Encroachment After Cephalomedullary Nailing of the Proximal Femur: Evaluation of a More Anatomic Radius of Curvature , 2013, Journal of orthopaedic trauma.

[16]  P. Procter,et al.  Geometric Mismatch of the Gamma Nail to the Chinese Femur , 1996, Clinical orthopaedics and related research.