1 Introduction

Plate fixation of fractures is a form of stabilization with the potential for both load-bearing and load-sharing properties. Functional treatment of the limb to preserve muscle strength, coordination, and joint mobility depends on the stability provided by the plate-bone construction. Fracture consolidation is to be expected if the mechanics of fixation and the biology of the fracture are compatible and mutually beneficial.

Biological bridge plating uses the plate as an extramedullary splint fixed to the two main fragments and spanning the fracture zone that is left virtually untouched. Length, alignment, and rotation are restored but anatomical reduction of each fragment is not attempted.

This concept produces relative stability and preserves the natural fracture biology to achieve rapid callus formation and fracture consolidation.

Bridge plating techniques are applicable to all multifragmentary long-bone fractures and where intramedullary nailing or conventional plate fixation is not suitable ( Fig 3.3.2-1 ).

With direct fracture reduction and plate fixation with absolute stability, the viability of soft tissues and bone fragments may be jeopardized. This risk exists to a lesser degree in simple fractures (with less soft-tissue injury and less dissection) and thus has less consequence on fracture healing. Fracture surgery must maintain vascularity at the fracture site. This calls for the use of bridging techniques in fracture patterns with significant fragmentation.

Simple type A diaphyseal fractures can be successfully treated with intramedullary nailing, a technique of relative stability, or by anatomical reduction and compression plate fixation, providing absolute stability.

Recent developments in plate design, including angular stability of the plate-screw construct with locking screws, have extended the indication for bridge plating to fractures with less fragmentation. Submuscular plates inserted using minimally invasive approaches and using locking head screws placed well away from simple fractures, can provide relative stability and subsequent bone healing with callus formation similar to intramedullary fixation.

Bridging simple type A diaphyseal fractures to produce relative stability can lead to delayed or nonunion and plate failure. If the soft tissues allow the surgeon to safely achieve absolute stability, this remains the method of choice for plating simple fracture patterns.

Bridge plating of simple fracture patterns should be avoided because the strain at the fracture site will be above the straintolerance of the tissue within the fracture site and so fracture healing will not take place ( Fig/Animations 3.3.2-2 – 5 ). In multifragmentary type C diaphyseal fractures with multiple fragments, a bridging plate allows micromovement between the different fragments but strain is within the strain tolerance of healing tissue, allowing normal callus formation ( Fig/Animation 3.3.2-5 ) [1]. If a complex, multifragmentary fracture is splinted in a cast or with a bridge plate, there will be some movement between fragments. However, the system as a whole will tolerate a significant amount of deformation, since it is distributed along the whole distance of the fracture zone. Thus, strain is low and this allows tissue differentiation to progress. Callus formation between intermediate fragments can occur rapidly, even in the presence of (controlled) movement. This is the basis of the Perren strain theory ( Fig/Animations 3.3.2-2 – 5 ). The prerequisites for successful bone healing in this situation are optimal preservation of fragment vascularity and a favorable mechanical and cellular environment for the production of callus ( Fig 3.3.2-6 , Video 3.2.2-7).

Bone fragments, once they have been stripped of their soft-tissue attachments (periosteum, muscles, etc) will not be incorporated into the early callus because they first need to be revascularized.

In diaphyseal type C fractures, the endosteal blood supply of fragments is, as a rule, interrupted. Preservation of bone vitality relies on periosteal vascularity, which also contributes to fracture healing. In the absence of mechanical continuity between the two main fragments, maintenance of stability entirely lies with the bridging plate. The technique of wide exposure with periosteal stripping to allow precise fragment reduction and fixation by interfragmentary compression and plating should be considered obsolete and must be avoided, as it increases the risk of bone-healing complications in type C fractures [2–3]. Misapplication and misunderstanding of the principles of internal fixation are responsible for most failures and complications in this situation.

Simple metaphyseal fractures (type A) that require plate fixation are best treated with techniques of absolute stability with anatomical reduction and interfragmentary compression. In general, the same principle should be applied to simple metaphyseal fractures with simple articular fractures (C1). However, this technique is not suitable for complex metaphyseal fractures (A3) or those associated with articular fractures (C2 and C3). Anatomical reduction and absolute stability of the joint surface is paramount. The metaphyseal bone, given its better blood supply and good healing qualities, will withstand a higher degree of iatrogenic damage from surgical dissection than will the diaphysis. The critical area is not the metaphysis but its junction with the more compact bone of the diaphysis. These regions of transition remain under significant bending loads and show a tendency to delayed or failed fracture healing. In the past, liberal use of bone grafting was advocated in attempts to restore the biological activity that was compromised by the injury and the subsequent treatment.

Current plating concepts embrace the principle of achieving the correct biomechanical environment while maintaining biology. Plates incorporating angular stability have greatly facilitated bridging multifragmentary metaphyseal segments of bone.

This development allows a more flexible and individualistic approach to internal fixation, based on the personality of the injury. Operative stabilization of a complex multifragmentary fracture requires fracture reduction without interfering with the blood supply and a fixation device that maintains length, alignment and rotation to produce a biological and mechanical environment that stimulates rapid healing by callus (see chapter 3.1-3).