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5.3. The management of Chronic Osteomyelitis and Septic Arthritis

5.3.1. Chronic non-tuberculous and non-fungal infections of bones

These considerable problems usually follow either an acute infection which presents late or has been inadequately treated, or are associated with the introduction of foreign material (usually by surgeons).

Infection associated with a metallic foreign body.

However, chronic bone infection may be associated with other medical conditions such as deep and long lasting leg ulcers (beware of malignant change), or very severe or inadequately treated open fractures.

Classically they will present with a chronic discharging sinus and associated stiffness of a local joint. There may be scars of previous surgery and/or of healed sinuses.

A radiograph is likely to reveal a sequestrum surrounded by an involucrum. This may be so dense/sclerotic that very penetrating X-rays may be necessary. Of course tomography, or CT Scanning are helpful in this condition, but rarely available. The chronicity of the condition is basically due to the continued presence of dead bone (or other ‘dead’ material) which remains infected. This ‘sequestrum’ is likely to be enclosed in an involucrum, which itself is forming an infected dead space.

Sequestration with some involucrum formation.

Thus the basic tenets for the successful treatment of chronic bone and joint infections are:

1. Removal of ALL dead tissue or material

2. Eradication of dead space

3. Production of good skin cover.

Although this sounds easy to do, any or all of these stages can be difficult.

       1. Removal of dead tissue involves thorough sequestrectomy or removal of implanted foreign material but this should only be done when an adequate involucrum has formed. Too early operation is likely to result in an infected ‘gap’ or a fracture. Thus at the appropriate time the infected area should be approached where possible through a curved incision and then deepened to allow adequate exposure of the diseased bone. Preferably this should be done with a pneumatic tourniquet in place, and avoiding damage to important structures such as nerves and vessels. Bone levers can then usually be placed on either side of the affected bone deep to the periosteum which should also be opened with a flap incision.

A sequestrum attempting 'self-seqrestectomy'	Sequestrum surrounded by involucrum

There is no need to excise sinus tracks as these will heal spontaneously once all the dead tissue or foreign material has been removed. In practice the incision can sometimes usefully be made to include one or more sinus openings.

The involucrum is then widely opened usually by starting with a window but taking care to leave enough bone to avoid fracture and to allow weight bearing or use of an arm. This is usually done with sharp gouges and chisels (and a mallet) but on occasion really dense bone can be ‘opened’ with a power saw (but avoid overheating bone). The sequestrum/ae surrounded by pus and unhealthy granulation tissue can usually be seen through the window which is then adequately enlarged to allow its/their careful removal. All unhealthy tissue is then removed by curettage, helped where possible by irrigation and suction.