Effect of stack pins on the stiffness of interlocking nails in an unstable osteotomy model

Summary

Interlocking nails have been shown to be an effective means to stabilise long bone fractures. When used in non-load sharing fracture repairs with minimal medullary canal filling, the authors noted instabilityofthe main fracture fragments. The addition of multiple intramedullary pins in stack pin fashion eliminated the instability. ILN and ILN/SP constructswere loaded in four-point bending using an unstable osteotomy model. The gap between the ILN and ILN/SP groups was compared. Significant changes were seen with the ILN/SP constructs in the cranial to caudal plane.

Keywords

Interlocking nails - stack pins - gap stiffness

• References

• 1 Alvaro L, Eich CS, Parker RB. et al. Repair of diaphyseal femoral fractures in cats using intramedullary nails: 12 cases (1996-2000). JAVMA 2001; 219: 1098-1104.
• 2 Dueland RT, Berglund L, Vanderby R. et al. Structural properties of interlocking nails, canine femora, and femur-interlocking nail constructs. J Vet Surg 1996; 25: 386-396.
• 3 Dueland RT, Johnson KA, Roe SC. et al. Interlocking nail treatment of diaphyseal long-bone fractures in dogs. JAVMA 1999; 214: 59-66.
• 4 Durall Durall, Diaz MC. Early Experience with the use of an interlocking nail for the repair of canine femoral shaft fractures. J Vet Surg 1996; 25: 397-406.
• 5 Palmer RH. Biological osteosynthesis. Vet Clin North Am Small Anim Pract 1999; 29: 1171-1185.
• 6 Claes L, Heitemeyer U, Krischak G. Fixation technique influences osteogenesis of comminuted fracture. Clin Orthop Relat Res 1999; 365: 221-229.
• 7 Aper RL, Litsky AS, Roe SC. et al. Effect of bone diameter and eccentric loading on fatigue life of cortical screws used with interlocking nails. Am J VetRes 2003; 64: 569-573.
• 8 Dejardin LM, Lansdowne JL, Sinnott MT. et al. In vitro mechanical evaluation of torsional loading in simulated canine tibiae for a novel hourglass- shaped interlocking nail with a self-tapping tapered locking design. Am J Vet Res 2006; 67: 678-685.
• 9 Reems MR, Pluhar GE, Wheeler DL. Ex-vivo comparison of one versus two distal screws in an 8mm Model 11 interlocking nail used to stabilize canine distal femoral fractures. Vet Surg 2006; 35: 161-167.
• 10 Suber JT, Basinger RR, Keller WG. Two unreported modes of interlocking nail failure: breakout and screw bending. Vet Comp Orthop Traumatol 2002; 15: 228-232.
• 11 DeYoung DeYoung, Probst CW. Methods of Internal Fracture Fixation. In: Textbook of small animal surgery. Vasseur PB, Slatter D. (eds). Philadelphia, PA: WB. Saunders; 1993: 1610-1640.
• 12 Nunamaker DM. Methods of Internal Fixation. In: Textbook of small animal orthopedics. Newton CD, Nunamaker DM. (eds). Philadelphia: Lippin- cott; 1985: 261-286.
• 13 Hulse Hulse, Hyman B. Fracture Biology and Bio- mechanics. In: Textbook of Small Animal Surgery. Vasseur PB, and Slatter D. (eds). Philadelphia, PA: WB. Saunders; 1993: 1595-1603.
• 14 Perren SM. Basic Aspectcs of Internal Fixation. In: Manual of Internal Fixation. New York: Springer-Verlag; 1991: 1-158.
• 15 Radasch RM. Biomechanics of Bone and Fractures. Vet Clin North Am Small Anim Pract 1999; 29: 1045-1082.
• 16 Basinger Basinger, Suber JT. Supplemental fixation of fractures repaired with interlocking nails: 14 cases (abstract). In Proceedings of the Veterinary Orthopedic Society, The Canyons, UT. 2002 p 27.
• 17 Bernarde A, Diop A, Maurel N. et al. An in vitro biomechanical study of bone plate and interlocking nail in a canine diaphyseal femoral fracture model. JVet Surg 2001; 30: 397-408.
• 18 Interlocking Nail Fracture Techniques and Wet Lab. ACVS symposium. Arlington, VA. Sept 2000
• 19 Bouvy BM, Markel MD. et al. Ex vivo biomech- anics of Kirschner-Ehmer external skeletal fixation applied to canine tibia. J Vet Surg 1993; 22: 194-207.
• 20 Dallman MJ, Martin RA. et al. Rotational strength of double-pinning techniques in repair of transverse fractures in femurs of dogs. Am J Vet Res 1990; 51: 123-127.
• 21 Muir P, Johnson KA, Markel MD. Area moment of inertia for comparison of implant cross-sectional geometry and bending stiffness. Vet Comp Orthop Traumatol 1995; 8: 146-152.
• 22 Rand JA, An KN, Chao EY. et al. A comparison of the effects of open intramedullary nailing and compression-plate fixation on the fracture-site blood flow and fracture union. J Bone Joint Surg 1981; 63 A 427-441.
• 23 Rhinelander Rhinelander. The normal microcirculation of diaphyseal cortex and its response to fracture. J Bone Joint Surg 1968; 50 A 784-800.
• 24 Rhinelander FW, Wilson WW. Blood supply to developing, mature, and healing bone. In: Bone in clinical orthopaedics: A study in osteology. Sumner-Smith G. (ed). Philadelphia: WB. Saunders; 1982: 81-158.
• 25 Palmer RH, Aron DN, Purinton PT. Relationship of femoral intramedullary pins to the sciatic nerve and gluteal muscles after retrograde and normo- graded insertion. JVet Surg 1988; 17: 65-70.