Canis ISSN: 2398-2942

Fracture fixation: plate

Synonym(s): Sherman plate, Venables plate, Burns plate, Finger plate, Compression plate

Contributor(s): Stephen Kalff, Susan Rackard

Introduction

  • See also: Fracture - internal fixation Fracture: internal fixation.
  • To stabilize a fracture using a bone plate held in place by screws, allowing early pain-free function until healing is complete.
  • Several types of plate are available of differing design and strength. These can be broadly categorized as locking and non-locking plates.

Non-locking plates

  • Rely on frictional interface between the bone plate and bone to create stability:
    • Hence plates must be perfectly contoured to maximize the friction at the screw/plate/bone interfaces.

Types

  • Various plate designs are available such as:
    • Dynamic conpression plates (DCP) Radius ulna: fracture (postoperative) 02 - radiograph CrCd.
    • Limited contact dynamic compression plates (LC-DCP).
    • Veterinary cuttable plates (VCP) Elbow: lateral humeral condylar fracture (postoperative) 01 - radiograph Elbow: lateral humeral condylar fracture (postoperative) 02 - radiograph mediolateral Distal radius and ulna fracture fixation 01: lateral radiograph Distal radius and ulna fracture fixation 02: radius plating.
    • Reconstruction plates.
    • Specialized plates, eg "acetabular", "T-plates", and "TPLO" plates, etc).

Locking plates

  • Screws lock to the plate forming a fixed angle construct - a so-called "internal fixator".
  • Unlike non-locking plates, exact contouring is not necessary. Though, pre-contouring the plate minimizes plate bone gap and the working length of the screw.

Types

  • Various designs are available including but not limited to the following:
    • Locking compression plates (LCP) - Synthes.
    • String of pearl plates (SOP) - Orthomed.
    • Advanced locking plates (ALPS) - Kyon.
    • FIXIN locking plates - Trauma Vet.

Uses

Plate function

  • Compression plating:
    • Load sharing function.
    • Eccentrically loaded screws cause axial compression of the fracture interface as screws are tightened.
    • Only the DCP, LC-DCP and LCP plates are specifically designed for this:
      • Other than the hybrid LCP, this function is limited to non-locking plates.
    • Over-contouring any non-locking plate can cause compression of the transcortex when tightening screws. This should be planned in advance to limit inadvertent suboptimal fracture reduction.
  • Neutralization plating:
    • Load sharing function.
    • Protects a primary reduction from fracture forces:
      • Eg useful to protect interfragmentary compression generated by a lag screw(s) or other device.
  • Buttress/Bridge plating:
    • Plate is subject to full loading.
    • Used in fractures where reconstruction is difficult or will result in excessive soft tissue disruption.
    • Useful in minimally invasvie techniques.
    • Can be combined with an intra-medullary pin to increase the fatigue life of the plate.

Advantages

  • Easy to maintain primary reduction:
    • Once the screw engages the plate, no further tightening is possible, hence the implants lock the bone segments in their position.
    • As the plate dosen't need to be in intimate contact with the bone, contouring whilst remaining important is less vital than for non-locking plates.
    • For the same reason, less invasive plating techniques are easier.
  • Preservation of blood supply:
    • Locking the screw to the plate dosen't generate compression between the plate and periosteum, hence interruption of blood supply to the fracture may be minimized.
  • Stability under load:
    • Locking the screw to the plate reduces the risk of screw loosening and toggle during loading.
  • Useful in poor quality bone.

Disadvantages

Non-locking plates

  • Blood supply:
    • The dissection required to achieve compression of the plate to the bone can interrupt blood supply to the fracture site.
    • This effect is reduced with "limited contact" designs.
  • Loss of reduction:
    • Primary loss: inexact contouring of the plate can lead to dislocation of the fracture fragments as the screws tighten the bone to the plate.
    • Secondary loss: axial load can lead to "toggling" of screws (plate sliding between the screws and the bone) leasing to a loss of stability.
  • Poor quality bone:
    • Poor quality bone may not withstand the compression or friction required for stability.

Locking plates

  • Many designs have fixed angle screw holes:
    • Require planning and contouring to avoid misplacement of screws, eg intra-articular screw with juxtarticular plates.
    • Recent variable angle designs help avoid this risk.
  • Implants tend to be more expensive.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Good when correctly applied.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Guiot L P, Déjardin L M (2011) Prospective evaluation of minimally invasive plate osteosynthesis in 36 noarticular tibial fractres in dogs and cats. Vet Surg 40 (2), 171-182 PubMed.
  • McGuiness K, Doyle R S & Glyde M R (2009) Use of a lateral tibial head buttress plate to repair a tibial fracture in a labrador retriever. Vet Rec 164 (10), 300-303 PubMed.
  • Perren S M (2002) Evolution of the internal fixation of long bone fractures. The scientific basis if biological internal fixation: choosing a new balance between stability and biology. J Bone Joint Surg (Br) 84 (8), 1093-1110 PubMed.
  • Hulse D A, Hyman W, Nori M (1997) Reduction in plate strain by addition of an intramedullary pin. Vet Surg 26 (6), 451-459 PubMed.
  • Avon D N, Johnson A L & Palmer R H (1995) Biologic strategies and a balanced concept for repair of highly comminuted long bone fractures. Comp Contin Educ Pract Vet 17 (1), 35-49 VetMedResource.
  • Glennon J C, Flanders J A, Beck K A et al (1994) The effect of long-term bone plate application for fixation of radial fractures in dogs. Vet Surg 23 (1), 40-47 PubMed.
  • Montavon P M, Pohler O E M, Olmstead M L et al (1988) The mini instrument and implant set and its clinical application. Vet Comp Ortho Traum (1), 44-51 VetMedResource.
  • Frey A J & Olds R (1981) A new technique for repair of comminuted diaphyseal fractures. Vet Surg 10 (1), 51-57 VetMedResource.

Other sources of information

  • Piermattei D l, Flo G L, DeCamp C E (2006)Handbook of Small Animal Orthopaedics and Fracture Repair.4th edn. Saunders Elsevier, Missouri.
  • Johnson A L, Houlton J E F, Vannini R (2005)AO Principles of Fracture Management in the Dog and Cat.AO Publishing.


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