Original Article

Biomechanical Comparison of Intramedullary Versus Extramedullary Implants for Fixation of Simple Pertrochanteric Fractures

Schader, Jana F. MD^a,b; Zderic, Ivan PhD^a; Dauwe, Jan MD, PhD^a,c; Sommer, Christoph MD^b; Gueorguiev, Boyko PhD^a; Stoffel, Karl MD, PhD^d,e

Author Information

^aAO Research Institute Davos, Davos, Switzerland;

^bDepartment of Surgery, Cantonal Hospital Graubuenden, Chur, Switzerland;

^cDepartment of Orthopedic Surgery, UZ Leuven, Leuven, Belgium;

^dUniversity Hospital Basel, Basel, Switzerland; and

^eUniversity of Basel, Basel, Switzerland.

Reprints: Jana Felicitas Schader, MD, AO Research Institute Davos, Clavadelerstrasse 8, Davos Platz 7270, Switzerland (e-mail: [email protected])

Authors I. Zderic, and B. Gueorguiev are full time employees of the AO Research Institute Davos at the AO Foundation and receive salary support from this institution.

This investigation was performed with the assistance of the AO Foundation. C. Sommer and K. Stoffel received benefits in terms of travel from a commercial party (DePuy Synthes) related directly to the subject of this study.

The authors report no conflict of interest.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.jorthotrauma.com).

Journal of Orthopaedic Trauma 37(5):p 243-248, May 2023. | DOI: 10.1097/BOT.0000000000002552

Abstract

Objectives:

To evaluate the biomechanical performance of the intramedullary TFN-ADVANCED Proximal Femoral Nailing System (TFNA) versus the extramedullary Femoral Neck System (FNS) for fixation of simple pertrochanteric fractures in a human cadaveric model.

Methods:

Ten human cadaveric femoral pairs were implanted pairwise with either TFNA or FNS. A simple pertrochanteric fracture OTA/AO 31-A1 was created and all specimens were biomechanically tested under progressively increasing cyclic loading until failure. Interfragmentary and bone-implant movements were monitored by motion tracking.

Results:

Axial stiffness was comparable between TFNA and FNS, P = 0.34. Similarly, varus deformation, femoral head rotation around neck axis and implant migration remained without significant differences between TFNA and FNS after 3000 cycles (800 N peak load), P ≥ 0.10. However, cycles to 15-mm leg shortening were significantly higher for TFNA versus FNS, P < 0.01.

Conclusions:

From a biomechanical perspective, with its current design, FNS does not seem to be a valid alternative to TFNA for treatment of simple pertrochanteric fractures.