Effect of the length of the superficial plate on bending stiffness, bending strength and strain distribution in stacked 2.0–2.7 veterinary cuttable plate constructs

S. Bichot; T. W. G. Gibson; N. M. M. Moens; R. J. Runciman; D. G. Allen; G. M. Monteith

doi:10.3415/VCOT-11-04-0065

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2011; 24(06): 426-434
DOI: 10.3415/VCOT-11-04-0065

Original Research

Schattauer GmbH

Effect of the length of the superficial plate on bending stiffness, bending strength and strain distribution in stacked 2.0–2.7 veterinary cuttable plate constructs

An in vitro study

S. Bichot

¹Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph (Ontario), Canada

,

T. W. G. Gibson

¹Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph (Ontario), Canada

,

N. M. M. Moens

¹Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph (Ontario), Canada

,

R. J. Runciman

²School of Engineering, University of Guelph, Guelph (Ontario), Canada

,

D. G. Allen

¹Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph (Ontario), Canada

,

G. M. Monteith

¹Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph (Ontario), Canada

› Author Affiliations

Abstract

Summary

Objectives: Use of stacked veterinary cut-table plates (VCP) increases the construct stiffness, but it also increases the stress protection and concentrates the stress at the extremities of the implants. We hypothesized that by shortening the superficial plate, it would not reduce the stiffness of the construct, but that it would reduce the stress concentration at the plate ends.

Methods: A 3 mm fracture gap model was created with copolymer acetal rods, stacked 2.0–2.7 VCP and 2.7 screws. The constructs consisted of an 11-hole VCP bottom plate and a 5-, 7-, 9- or 11-hole VCP superficial plate. Five of each construct were randomly tested for failure in four-point bending and axial loading. Stiffness, load at yield, and area under the curve until contact (AUC) were measured. Strains were recorded during elastic deformation for each configuration.

Results: During both testing methods, stiffness, load at yield and AUC progressively decreased when decreasing the length of the superficial plate. No statistically significant differences were obtained for load at yield in four-point bending and AUC in axial loading. The strain within the implant over the gap increased as the length of the superficial plate decreased.

Clinical significance: Shortening the superficial plate reduces the stiffness and strength of the construct, and decreases stress concentration at the implants ends. As the cross section of the implant covering the gap remained constant, friction between the plates may play a role in the mechanical properties of stacked VCP.

Keywords

Veterinary cuttable plate - stacked plates - four-point bending - axial loading - strain gauge

Full Text

References

References
1 Théoret MC, Moens NM. The use of veterinary cut-table plates for carpal and tarsal arthrodesis in small dogs and cats. Can Vet J 2007; 48: 165-168.
2 Fruchter AM, Holmberg DL. Mechanical analysis of the veterinary cuttable plate. Vet Comp Orthop Traumatol 1991; 4: 116-119.
3 Brüse S, Dee J, Prieur WD. Internal fixation with a veterinary cuttable plate in small animals. Vet Comp Orthop Traumatol 1989; 1: 40-46.
4 Montavon PM, Pohler OEM, Olmstead ML. et al The mini intrument and implant set and its clinical application. Vet Comp Orthop Traumatol 1988; 1: 44-51.
5 Koch D. Screws and plates. In: Johnson AN, Houlton JEF, Vannini R, editors. AO principles of fracture management in the dog and cat. New York, NY: Thieme; 2005: 42.
6 SYNTHES Vet United States. 20 mm 27 mm-CutTo-Length-Plate [Information from Internet]. (SYNTHES Vet United States; 2009 [cited 2011 February 10]. Available from. http://us.synthesvet.com/27mm20mm-Cut-To-Length-Plate--C286.aspx.
7 SYNTHES Vet United States. 20 mm 15 mm-CutTo-Length-Plate [Information from Internet]. SYNTHES Vet United States; 2009 [cited on 2011 February 10]. Available from. http://us.synthesvet.com/20mm15mm-Cut-To-Length-Plate--C285.aspx.
8 Zahn K, Frei R, Wunderle D. et al Mechanical properties of 18 different AO bone plates and the clamp-rod internal fixation system tested on a gap model construct. Vet Comp Orthop Traumatol 2008; 21: 185-194.
9 Rose BW, Pluhar GE, Novo RE. et al Biomechanical analysis of stacked plating techniques to stabilize distal radial fractures in small dogs. Vet Surg 2009; 38: 954-960.
10 Hammel SP, Elizabeth Pluhar G, Novo RE. et al Fatigue analysis of plates used for fracture stabilization in small dogs and cats. Vet Surg 2006; 35: 573-578.
11 Perren SM, Cordey J, Rahn BA. et al Early temporary porosis of bone induced by internal fixation implants. A reaction to necrosis, not to stress protection?. Clin Orthop Relat Res 1988; 232: 139-151.
12 Hulse D, Hyman B. Biomechanics of fracture fixation failure. Vet Clin North Am Small Anim Pract 1991; 21: 647-667.
13 Stoffel K, Klaue K, Perren SM. Functional load of plates in fracture fixation in vivo and its correlate in bone healing. Injury 2000; 31 (Suppl. 02) SB37-50.
14 Terjesen T, Svenningsen S. The effects of function and fixation stiffness on experimental bone healing. Acta Orthop Scand 1988; 59: 712-715.
15 Cristofolini L, Viceconti M. Mechanical validation of whole bone composite tibia models. J Biomech 2000; 33: 279-288.
16 Cristofolini L, Viceconti M, Cappello A. et al Mechanical validation of whole bone composite femur models. J Biomech 1996; 29: 525-535.
17 Reaugh HF, Rochat MC, Bruce CW. et al Stiffness of modified type 1a linear external skeletal fixators. Vet Comp Orthop Traumatol 2007; 20: 264-268.
18 Neat BC, Kowaleski MP, Litsky AS. et al Mechanical evaluation of pin and tension-band wire factors in an olecranon osteotomy model. Vet Surg 2006; 35: 398-405.
19 Maxwell M, Horstman CL, Crawford RL. et al The effects of screw placement on plate strain in 3.5 mm dynamic compression plates and limited-contact dynamic compression plates. Vet Comp Orthop Traumatol 2009; 22: 125-131.
20 Uhl JM, Seguin B, Kapatkin AS. et al Mechanical comparison of 3.5 mm broad dynamic compression plate, broad limited-contact dynamic compression plate, and narrow locking compression plate systems using interfragmentary gap models. Vet Surg 2008; 37: 663-673.
21 Tornkvist H, Hearn TC, Schatzker J. The strength of plate fixation in relation to the number and spacing of bone screws. J Orthop Trauma 1996; 10: 204-208.
22 Lonner JH, Laird MT, Stuchin SA. Effect of rotation and knee flexion on radiographic alignment in total knee arthroplasties. Clin Orthop Relat Res 1996; 331: 102-106.
23 Kanakis TE, Cordey J. Is there a mechanical difference between lag screws and double cerclage?. Injury 1991; 22: 185-189.
24 Gibson TW, Moens NM, Runciman RJ. et al Evaluation of a short glass fibre-reinforced tube as a model for cat femur for biomechanical testing of orthopaedic implants. Vet Comp Orthop Trauma-tol 2008; 21: 195-201.
25 Chong AC, Friis EA, Ballard GP. et al Fatigue performance of composite analogue femur constructs under high activity loading. Ann Biomed Eng 2007; 35: 1196-1205.
26 Lopez MJ, Markel MD. Bending tests of bone. In: An YN, Draughn RA, editors. Mechanical testing of bone and the bone-implant interface. CRC Press LLC ed. Boca Raton, Florida: CRC Press LLC; 2000: 207-217.
27 Hulse D, Hyman B. Fracture biology and biomechanics. In: Slatter D, editor. Textbook of Small Animal Surgery. Third ed. Philadelphia, PA: Saunders; 2003: 1785-1792.
28 Burstein AH, Frankel VH. A standard test for laboratory animal bone. J Biomech 1971; 4: 155-158.
29 Johnston SA, Lancaster RL, Hubbard RP. et al A biomechanical comparison of 7–hole 3.5 mm broad and 5–hole 4.5 mm narrow dynamic compression plates. Vet Surg 1991; 20: 235-239.
30 Brunner H, Simpson JP. Fatigue fracture of bone plates. Injury 1980; 11: 203-207.
31 Palmer RH, James SP. Fractures biomechanics of the appendicular skeleton. In: Bojrab MJ, Monnet E, editors. Mechanics of Disease in Small Animal Surgery. Third ed. Jackson,WY: Teton NewMedia; 2010: 676.
32 Riggs CM, DeCamp CE, Soutas-Little RW. et al Effects of subject velocity on force plate-measured ground reaction forces in healthy greyhounds at the trot. Am J Vet Res 1993; 54: 1523-1526.
33 Woo SL, Lothringer KS, Akeson WH. et al Less rigid internal fixation plates: Historical perspectives and new concepts. J Orthop Res 1984; 1: 431-449.
34 Hsu JT, Chang CH, Huang HL. et al The number of screws, bone quality, and friction coefficient affect acetabular cup stability. Med Eng Phys 2007; 29: 1089-1095.
35 Gibson TW, Moens NM, Runciman RJ. et al The biomechanical properties of the feline femur. Vet Comp Orthop Traumatol 2008; 21: 312-317.

Supplementary Material

Online Supplementary Material (PDF)