Managing fracture complications

Introduction

Problems are commonly encountered during the period when the fracture is healing. These problems may be due to inadequate or slow healing of the fracture biologically, infection or problems with the fixation device. Whatever the cause these problems have to be recognised quickly and solved to ensure a successful outcome to fracture repair. Iatrogenic problems usually result when inadequate asepsis is present. When a case management plan has not been formulated or when some of the basic rules of applying fixation devices have been broken. Complications are considered under three separate headings (over)

1. Problems due to fixation device
2. Problems dure to failure of fracture healing
3. Infection

In many cases, all three of these will be present causing a clinical problem and inadequate healing.

1. Problems related to the fixation device

During assisted fracture repair, we use some method of splinting the healing bone to allow mobility while the fracture repairs. The bone is dependent on the fixation device, for a variable period, until it heals. If rapid healing can be achieved and this time of reliance reduced, then problems may not be encountered. However, if fracture healing is slow then the demands of the implants are amplified and failure may occur. This is especially true of fixation methods which involve other tissues other than the bone itself, for instance casts, external fixators and to a certain extent intra-medullary pins since they become loose with time and can produce irritation and soft tissue damage at the site of entry to the bone. Bone plates produce minimal interaction with surrounding tissue and may be left in place for considerable periods of time.

When implants fail they usually do one of three things:

1. Break
2. Bend
3. Loosen

Failure usually results from technical mistakes rather than material problems.
i) Inappropriate selection of implant
ii) Inappropriate fracture assembly
iii) Inappropriate demands on implant

i) If an implant is selected which is not strong enough to deal with the forces applied through it then failure is very likely.

ii) The bone and implant act as a unit for maximum strength. To allow this the bone’s tubular structure must be preserved. Failure to do this will mean that the implant will have to resist all the forces on its own. Under these circumstances failure is likely. If gaps are left at the fracture site additional stresses will be produced in the implant. Similarly, if the implant is applied without regard to the biomechanical forces acting through the bone i.e. plate applied to the compression side of bone failure is likely.

iii) If fracture healing is delayed then the fixation method must be retained until healing is achieved. This may produce problems. Soft tissue damage, biological rejection and material failure are all seen. Material failure due to cyclic stresses acting on metal must be considered. Many of the rules that we use in fracture repair exist to protect the metal implants from metal fatigue and so, failure of fixation.

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