Vet Comp Orthop Traumatol 2016; 29(06): 459-465
DOI: 10.3415/VCOT-16-03-0040
Original Research
Schattauer GmbH

Effect of monocortical and bicortical screw numbers on the properties of a locking plate-intramedullary rod configuration

An in vitro study on a canine femoral fracture gap model
Elinor J. Field
1   Langford Veterinary Services, University of Bristol, Langford, N Somerset, UK
,
Kevin Parsons
1   Langford Veterinary Services, University of Bristol, Langford, N Somerset, UK
,
Julie A. Etches
2   Advanced Composites Centre of Innovation & Science, University of Bristol, Queen’s Building, University Walk, Bristol, UK
,
Katie Hamilton
3   Cave Veterinary Specialists, George’s Farm, West Buckland, North Wellington, UK
,
Neil J. Burton
1   Langford Veterinary Services, University of Bristol, Langford, N Somerset, UK
› Institutsangaben
Weitere Informationen

Publikationsverlauf

Received: 02. März 2016

Accepted: 12. Juli 2016

Publikationsdatum:
19. Dezember 2017 (online)

Summary

Objectives: To evaluate the effect of varying the number and configuration of locking bicortical and monocortical screws on a plate-rod construct using a mid-diaphyseal femoral ostectomy model.

Methods: Thirty Greyhound femurs were assigned to six groups (A-F). An intramedullary pin was placed in each bone following which a 3.5 mm locking plate was applied with six differing locking screw configurations. Groups A to C had one bicortical screw in the most proximal and distal plate holes and one to three monocortical locking screws in the proximal and distal fragments. Groups D to F had no bicortical screws placed and two to four monocortical locking screws in proximal and distal fragments. Each construct was axially loaded at 4 Hz from a preload of 10 Newtons (N) to 72 N, increasing to 144 N and 216 N, each of 6000 cycles with a further 45,000 cycles at 216 N to simulate a three to six week postoperative convalescence period. Constructs were then loaded to failure.

Results: No construct suffered screw loosening or a significant change in construct stiffness during cyclic loading. There was no significant difference in load to failure of any construct (p = 0.34), however, less variation was seen with monocortical constructs. All constructs failed at greater than 2.5 times physiological load, and failure was by bending of the intramedullary pin and plate rather than screw loosening or pull-out.

Clinical significance: Axially loaded locking monocortical plate-rod constructs applied to the canine femur may confer no difference biomechanically to those employing locking bicortical screws.

 
  • References

  • 1 Unger M, Montavon PM, Heim UFA. Classification of fractures of long bones in the dog and cat: Introduction and clinical application. Vet Comp Orthop Traumatol 1990; 3: 41-50.
  • 2 Perren SM. The concept of biological plating using the limited contact — dynamic compression plate (LC-DCP). Injury 1991; 22: 1-41.
  • 3 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.
  • 4 Horstman CL, Beale BS, Conzemius MG. et al. Biological osteosynthesis versus traditional anatomic reconstruction of 20 long-bone fractures using an interlocking nail: 1994-2001. Vet Surg 2004; 33: 232-237.
  • 5 Reems MR, Beale BS, Hulse DA. Use of a plate-rod construct and principles of biological osteosynthesis for repair of diaphyseal fractures in dogs and cats: 47 cases (1994-2001). J Am Vet Med Assoc 2003; 223: 330-335.
  • 6 Hulse D, Hyman W, Nori M. et al. Reduction in plate strain by addition of an intramedullary pin. Vet Surg 1997; 26: 451-459.
  • 7 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.
  • 8 Hansmann C. Eine neue Möglichkeit der Fixierung der Fragmente bei komplizierten Frakturen [A new possibility for fixation of fragments in complicated fractures]. Verh dtsch Ges Chir 1886; 158.
  • 9 Ramotowski W, Granowski R. Zespol. An original method of stable osteosynthesis. Clin Orthop Relat Res 1991; 272: 67-75.
  • 10 Perren S, Buchanan J. Point contact fixator: Part I. Scientific background, design and application. Injury 1995; 26 (Suppl. 02) B57-B60.
  • 11 Frigg R, Appenzeller A, Christensen R. et al. The development of the distal femur Less Invasive Stabilization System (LISS). Injury 2001; 32 (Suppl. 03) SC24-C31.
  • 12 Sommer C, Gautier E, Müller M. et al. First clinical results of the Locking Compression Plate (LCP). Injury 2003; 34 (Suppl. 02) B43-54.
  • 13 Russell T. An historical perspective of the development of plate and screw fixation and minimally invasive fracture surgery with a unified biological approach. Techniques in Orthopaedics 2007; 22: 186-190.
  • 14 Petazzoni M, Urizzi A, Verdonck B. et al. Fixin internal fixator: Concept and technique. Vet Comp Orthop Traumatol 2010; 23: 250-253.
  • 15 Barnhart MD, Rides CF, Kennedy SC. et al. Fracture repair using a polyaxial locking plate system (PAX). Vet Surg 2013; 42: 60-66.
  • 16 Irubetagoyena I, Verset M, Palierne S. et al. Ex vivo cyclic mechanical behaviour of 2.4 mm locking plates compared with 2.4 mm limited contact plates in a cadaveric diaphyseal gap model. Vet Comp Orthop Traumatol 2013; 26: 479-488.
  • 17 Uhl JM, Kapatkin AS, Garcia TC. et al. Ex vivo biomechanical comparison of a 3.5 mm locking compression plate applied cranially and a 2.7 mm locking compression plate applied medially in a gap model of the distal aspect of the canine radius. Vet Surg 2013; 42: 840-846.
  • 18 Chao P, Conrad BP, Lewis DD. et al. Effect of plate working length on plate stiffness and cyclic fatigue life in a cadaveric femoral fracture gap model stabilized with a 12-hole 2.4 mm locking compression plate. BMC Vet Res 2013; 9: 125.
  • 19 Demner D, Garcia TC, Serdy MG. et al. Biomechanical comparison of mono- and bicortical screws in an experimentally induced gap fracture. Vet Comp Orthop Traumatol 2014; 27: 422-429.
  • 20 Bilmont A, Palierne S, Verset M. et al. Biomechanical comparison of two locking plate constructs under cyclic torsional loading in a fracture gap model. Two screws versus three screws per fragment. Vet Comp Orthop Traumatol 2015; 28: 323-330.
  • 21 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.
  • 22 Ochman S, Doht S, Paletta J. et al. Comparison between locking and non-locking plates for fixation of metacarpal fractures in an animal model. J Hand Surg Am 2010; 35: 597-603.
  • 23 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 (Suppl. 02) B11-19.
  • 24 Haaland PJ, Sjöström L, Devor M. et al. Appendicular fracture repair in dogs using the Locking Compression Plate system: 47 cases. Vet Comp Orthop Traumatol 2009; 22: 309-315.
  • 25 Field JR, Hearn TC, Caldwell CB. Bone plate fixation: an evaluation of interface contact area and force of the dynamic compression plate (DCP) and the limited contact-dynamic compression plate (LC-DCP) applied to cadaveric bone. J Orthop Trauma 1997; 11: 369-373.
  • 26 Vallefuoco R, Le Pommellet H, Savin A. et al. Complications of appendicular fracture repair in cats and small dogs using locking compression plates. Vet Comp Orthop Traumatol 2015; 29: 46-52.
  • 27 Beierer LH, Glyde M, Day RE. et al. Biomechanical comparison of a locking compression plate combined with an intramedullary pin or a polyetheretherketone rod in a cadaveric canine tibia gap model. Vet Surg 2014; 43: 1032-1038.
  • 28 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.