In vitro biomechanical comparison of three methods for internal fixation of femoral neck fractures in dogs

S. C. Fisher; R. M. McLaughlin; S. H. Elder

doi:10.3415/VCOT-11-03-0045

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2012; 25(01): 36-41
DOI: 10.3415/VCOT-11-03-0045

Original Research

Schattauer GmbH

In vitro biomechanical comparison of three methods for internal fixation of femoral neck fractures in dogs

S. C. Fisher

¹Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi, USA

,

R. M. McLaughlin

¹Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi, USA

,

S. H. Elder

²Department of Agricultural and Biological Engineering, Mississippi State University, Mississippi, USA

› Author Affiliations

Abstract

Summary

The in vitro biomechanical properties of three methods for internal fixation of femoral neck fractures were evaluated. Fifty cadaveric femora from Beagle dogs were used. Ten intact femora served as controls. In 40 femora, an osteotomy of the femoral neck was performed to simulate a transverse fracture. With the remaining 30 femora, three repair methods (two medium Orthofix pins, a 2.7 mm cortical bone screw placed in lag fashion and an anti-rotational Kirschner wire, or three divergent 1.1 mm Kirschner wires) were used to stabilize the osteotomies, and 10 osteotomies were stabilised per repair method. These 30 femora where then subject to monotonic loading to failure. Construct stiffness and load to failure were measured. In the remaining 10 femora, pressure sensitive film was placed at the osteotomy site prior to stabilization with either two Orthofix pins (n = 5) or a screw placed in lag fashion (n = 5) to determine the compressive pressure (MPa), compressive force (KN) and area of compression (cm²).

There was no significant difference in the stiffness or load to failure for the three repair methods evaluated. There was no significant difference in the compressive pressure, compressive force or area of compression in osteotomies stabilized with Orthofix pins and 2.7 mm bone screws.

Keywords

Femoral neck fractures - Orthofix pin - compression - lag screw - divergent pins

Full Text

References

References
1 Simpson DJ, Lewis DD. Fractures of the femur. In: Slatter D. editor. Textbook of Small Animal Surgery. 3rd ed.. Philadelphia: Saunders; 2003: 2059-2089.
2 Daly WR. Femoral head and neck fractures in the dog and cat: a review of 115 cases. Vet Surg 1978; 7: 29-38.
3 Johnson AL. Management of specific fractures. In: Fossum TW. editor. Small Animal Surgery. 3rd ed.. St. Louis: Mosby Elsevier; 2007: 1015-1142.
4 Tillson DM, Roush JK, McLaughlin RM. Biomechanical comparison of three repair methods of proximal femoral physeal fractures in shear and tension. Vet Comp Orthop Traumatol 1994; 7: 136-139.
5 Jeffery ND. Internal fixation of femoral head and neck fractures in the cat. J Small Anim Pract 1989; 30: 674-677.
6 Piermattei D L, Flo G L, DeCamp C E. Fractures of the femur and patella. In: Brinker, Piermattei, and Flo’s Handbook of Small Animal Orthopedics and Fracture Repair. 4th ed.. St. Louis: Saunders Elsevier; 2006: 522-538.
7 Hulse DA, Wilson JW, Butler HC. Use of the lag screw principle for stabilization of femoral neck and femoral capital epiphyseal fractures. J Am Anim Hosp Assoc 1974; 10: 29-36.
8 Brinker WO. Factors influencing the result in fractures of the femoral neck. Anim Hosp 1966; 2: 160-166.
9 Lanz OI, Lewis DD, Newell SM. Stabilization of a physeal fracture using an Orthofix partially-threaded kirschner wire. Vet Comp Orthop Traumatol 1999; 12: 88-91.
10 Guille AE, Lewis DD, Anderson TP. et al. Evaluation of surgical repair of humeral condylar fractures using self-compressing Orthofix pins in 23 dogs. Vet Surg 2004; 33: 314-322.
11 Vida JT, Pooya H, Vasseur PB. et al. Biomechanical comparison of Orthofix pins and cortical bone screws in a canine humeral condylar fracture model. Vet Surg 2005; 34: 491-498.
12 Pennig D, Gausepohl T. One-step fracture fixation. The Fragment Fixation System [document on the Internet]. Orthofix: Richardson, TX [cited 2011 January]. Available from: www.orthofix.com/intl/scientific/library/pdf/PG_160_E0.pdf
13 Daubs BM, McLaughlin RM, Silverman E. et al. Evaluation of compression generated by self compressing Orthofix bone pins and lag screws in simulated lateral humeral condylar fractures. Vet Comp Orthop Traumatol 2006; 20: 175-179.
14 Lambrechts NE, Verstraete FJM, Sumner-Smith G. et al. Internal fixation of femoral neck fractures in the dog – an in vitro study. Vet Comp Orthop Traumatol 1993; 6: 188-193.
15 Beale B. Orthopedic clinical techniques femur fracture repair. Clinical Tech Small Anim Pract 2004; 19: 134-150.
16 Muir P, Johnson KA, Markel MD. Area moment of inertia for compression of implant cross-sectional geometry and bending stiffness. Vet Comp Orthop Traumatol 1995; 8: 146-152.
17 Rovinsky D, Haskell A, Liu Q. et al. Evaluation of a new method of small fragment fixation in a medial malleolus fracture model. J Orthop Trauma 2000; 14: 420-425.
18 Tillson DL, McLaughlin RM, Roush JK. Fractures of the proximal femoral physis in dogs. Compend Contin Educ Pract Vet 1996; 18: 1164-1181.