Vet Comp Orthop Traumatol 2016; 29(06): 451-458
DOI: 10.3415/VCOT-16-01-0008
Original Research
Schattauer GmbH

The effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs under axial load

Tim Pearson
1   College of Veterinary Medicine, Murdoch University, Perth, Australia
Mark R. Glyde
1   College of Veterinary Medicine, Murdoch University, Perth, Australia
Robert E. Day
2   Department of Medical Engineering & Physics, Royal Perth Hospital, Perth, Australia
Giselle L. Hosgood
1   College of Veterinary Medicine, Murdoch University, Perth, Australia
› Author Affiliations
Further Information

Publication History

Received: 17 January 2016

Accepted: 12 July 2016

Publication Date:
19 December 2017 (online)


Objective: To investigate the effect of intramedullary pin size and plate working length on plate strain in locking compression plate-rod constructs.

Methods: A synthetic bone model with a 40 mm fracture gap was used. Locking compression plates with monocortical locking screws were tested with no pin (LCP-Mono) and intramedullary pins of 20% (LCPR-20), 30% (LCPR-30) and 40% (LCPR-40) of intramedullary diameter. Two screws per fragment modelled a long (8-hole) and short (4-hole) plate working length. Strain responses to axial compression were recorded at six regions of the plate via three-dimensional digital image correlation.

Results: The addition of a pin of any size provided a significant decrease in plate strain. For the long working length, LCPR-30 and LCPR-40 had significantly lower strain than the LCPR-20, and plate strain was significantly higher adjacent to the screw closest to the fracture site. For the short working length, there was no significant difference in strain across any LCPR constructs or at any region of the plate. Plate strain was significantly lower for the short working length compared to the long working length for the LCP-Mono and LCPR-20 constructs, but not for the LCPR-30 and LCPR-40 constructs.

Clinical significance: The increase in plate strain encountered with a long working length can be overcome by the use of a pin of 30–40% intramedullary diameter. Where placement of a large diameter pin is not possible, screws should be placed as close to the fracture gap as possible to minimize plate strain and distribute it more evenly over the plate.

  • References

  • 1 Chao P, Lewis DD, Kowaleski MP. et al. Biomechanical concepts applicable to minimally invasive fracture repair in small animals. Vet Clin North Am Small Anim Pract 2012; 42: 853-872. v
  • 2 Hulse D, Hyman W, Nori M. et al. Reduction in plate strain by addition of an intramedullary pin. Vet Surg 1997; 26: 451-459.
  • 3 Hulse D, Ferry K, Fawcett A. et al. Effect of intramedullary pin size on reducing bone plate strain. Vet Comp Orthop Traumatol 2000; 13: 185-190.
  • 4 Stoffel K, Dieter U, Stachowiak G. et al. Biomechanical testing of the LCP - how can stability in locked internal fixators be controlled?. Injury 2003; 34: 11-19.
  • 5 Pearson T, Glyde M, Hosgood G. et al. The effect of intramedullary pin size and monocortical screw configuration on locking compression plate-rod constructs in an in vitro fracture gap model. Vet Comp Orthop Traumatol 2015; 28: 95-103.
  • 6 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.
  • 7 Ellis T, Bourgeault CA, Kyle RF. Screw position affects dynamic compression plate strain in an in vitro fracture model. J Orthop Trauma 2001; 15: 333-337.
  • 8 Korvick DL, Monville JD, Pijanowski GJ. et al. The effects of screw removal on bone strain in an idealized plated bone model. Vet Surg 1988; 17: 111-116.
  • 9 Hoffmeier KL, Hofmann GO, Muckley T. Choosing a proper working length can improve the lifespan of locked plates. A biomechanical study. Clin Biomech (Bristol, Avon) 2011; 26: 405-409.
  • 10 Sebastian C, Patterson EA. Calibration of a digital image correlation System. Exp Techniques 2015; 39: 21-29.
  • 11 Amodio D, Broggiato GB, Campana F. et al. Digital speckle correlation for strain measurement by image analysis. Experimental Mechanics 2003; 43: 396-402.
  • 12 Withers PJ. Strain Measurement by digital image correlation. Strain 2008; 44: 421-422.
  • 13 Palanca A, Tozzi G, Cristofolini L. The use of digital image correlation in the biomechanical area: a review. International Biomechanics 2016; 3: 1-21.
  • 14 Johnson AL, Houlton JEF, Vannini R. AO principles of fracture management in the dog and cat. Switzerland: AO Publishing; 2005
  • 15 Silbernagel JT, Kennedy SC, Johnson AL. et al. Validation of canine cancellous and cortical polyurethane foam bone models. Vet Comp Orthop Traumatol 2002; 15: 200-204.
  • 16 Kanchanomai C, Muanjan P, Phiphobmongkol V. Stiffness and endurance of a locking compression plate fixed on fractured femur. J Appl Biomech 2010; 26: 10-16.
  • 17 Chen G, Schmutz B, Wullschleger M. et al. Computational investigations of mechanical failures of internal plate fixation. Proc Inst Mech Eng H 2010; 224: 119-126.
  • 18 von Pfeil DJ, Dejardin LM, DeCamp CE. et al. In vitro biomechanical comparison of a plate-rod combination-construct and an interlocking nail-construct for experimentally induced gap fractures in canine tibiae. Am J Vet Res 2005; 66: 1536-1543.
  • 19 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.
  • 20 Gautier E, Perren SM, Cordey J. Effect of plate position relative to bending direction on the rigidity of a plate osteosynthesis. A theoretical analysis. Injury 2000; 31 (Suppl. 03) C14-20.
  • 21 Ahmad M, Nanda R, Bajwa AS. et al. Biomechanical testing of the locking compression plate: when does the distance between bone and implant significantly reduce construct stability?. Injury 2007; 38: 358-364.
  • 22 Goh CS, Santoni BG, Puttlitz CM. et al. Comparison of the mechanical behaviors of semicontoured, locking plate-rod fixation and anatomically contoured, conventional plate-rod fixation applied to experimentally induced gap fractures in canine femora. Am J Vet Res 2009; 70: 23-29.
  • 23 Delisser PJ, McCombe GP, Trask RS. et al. Ex vivo evaluation of the biomechanical effect of varying monocortical screw numbers on a plate-rod canine femoral gap model. Vet Comp Orthop Traumatol 2013; 26: 177-185.