Geometric mismatch analysis of retrograde nail in the Asian femur

Abstract

The geometric mismatch analysis of the retrograde nail was performed in 108 Asian cadaveric adult femora. The insertion was done virtually based on a three-dimensional geometric model derived from computed tomographic images. The investigation was performed at eight levels located at 120, 140, 160, 180, 200, 220 and 240 mm above the condylar surface. The evaluation of each level included: (1) the diameter of the intramedullary canal, (2) the percentage of area filled by the nail in the unreamed intramedullary canal, (3) the minimal reamer diameter that required enlargement of the canal to accommodate retrograde nail insertion, (4) the minimal inner cortical reaming thickness that needed to be removed, (5) the percentage of the cortical bone area that needed to be removed prior to nail insertion and (6) the deviation of the nail center from the center of the intramedullary canal. The result showed significant mismatch of the nail to most of the study specimens (94 femora, 87%), which the intramedullary canal needed extensive reaming to accommodate the nail insertion. This may lead to a high possibility of clinical complications. Redesign for proper shape and size of retrograde nail should be considered for the use in Asian population.

Kangal ve Alman Çoban Köpeklerinin Proximal Femur Bölümünde Cavum Medullare’nin Geometrik Özellikleri

“…The anatomists and orthopedic surgeons have long been interested in the variations of proximal femoral morphology especially associated with the femoral implant design and implantation in total hip arthroplasty (THA) (Abadie et al, 2010;Husmann et al, 1997;Noble et al, 1988;Palierne et al, 2008;Rawal et al, 2012;Tawada et al, 2015). Although different types of the implants are available from the manufacturers, the database for size and shape characteristics of proximal femur has still required to designing new implant and auxiliary equipment and to enhance the performance or longevity of the implants (Casper et al, 2012;Chantarapanich et al, 2011;Ganz et al, 2010;Laine et al, 2000;Noble et al, 2003;RashmirRaven and DeYoung, 1992;Umer et al, 2010;Yang et al, 2014). Understanding the variations of the proximal femur may also guide surgeons in proper implant selection to decrease postoperative complications.…”

“…This allows examining the complex geometry which may be difficult to carry out based on conventional twodimensional radiographic technique (Chantarapanich et al, 2011) Therefore, in human medical literature, threedimensional measurement methods have been widely used for reliable measuring of head-neck position and medullary canal shape of femur regarding new designs of hip implants. (Husmann et al, 1997;Noble et al, 2003;Sugano et al, 1998;Tawada et al, 2015).…”