Inadequate involucrum which does not bridge the sequestrum
Stabilize and observe for 3–6 months; if no involucrum, then sequestrectomy; graft or bone transport
III. Sclerotic
Fusiform, dense cortical thickening, medullary canal may be obliterated, sequestrum may be hidden
Search for sequestrae, overexpose x-ray to visualize. May be difficult to remove cortical window
IV. Cortical
Localized sequestrum in cortex
Remove sequestrum
V. Walled-off solitary or multiple abscesses
Partial resorption of sequestrae, leaving well-defined lucencies in involucrum of various sizes
Look for sequestrae. If large can saucerize; if many and difficult to remove, consider antibiotics and observation
VI. Metaphyseal
Single or multiple abscesses with sclerotic margin only in metaphysis
Saucerization and curettage
X-rays of a typical presentationshow a well-defined sequestrum and an adequate involucrum with structural integrity bridging the sequestrum (Fig. 31.1). The treatment involves surgical removal of the sequestrum or sequestrae at the appropriate time. In the authors’ experience, about one-third of chronic osteomyelitis cases present in this manner.
Fig. 31.1
Stages of sequestrectomy. (a) A sequestrum is identified distal to a sclerotic region, with a draining sinus. (b) An oval window facilitates sequestrectomy and debridement
In an atrophic presentation,one or more sequestrae may be identified; however, there is inadequate involucrum. The sequestrum can extravasate spontaneously, leaving either focal bone loss or a large, segmental bone defect. The remaining bone is usually unstable, making more complex treatments likely (Fig. 31.2). About one-third of cases present as atrophic osteomyelitis.
Fig. 31.2
AtrophicType (a) This patient sequestered most of the radius (b) sequestrum protruding through the skin. (c) Forearm length was maintained after sequestrectomy with an external fixator. (d, e) Once sepsis was controlled, a single bone forearm was made. (f, g) Elbow flexion and extension were full, although forearm rotation was lost
Sclerotic presentation (Fig. 31.3) showsa robust vascular response with the sequestrum becoming encased in bone. It may be partially or completely resorbed. Three possible scenarios result: (1) fusiform, hypertrophic appositional growth occurs, resembling the “onion skin” periosteal reaction seen in Ewing sarcoma; (2) the periosteal reaction is so prolific that the medullary canal is obliterated; and (3) the diaphysis of the bone becomes densely sclerotic. Over-penetration of the radiograph may help define small sequestrae within the sclerotic bone. Overgrowth of the involved bone and angular deformities are common from the chronic hyperemia.
Fig. 31.3
(a) The sclerotic presentationexhibits a thick, dense involucrum. (b) Sequestrae may be difficult to appreciate on plain radiographs when the involucrum is as well developed, as in this image. Over-penetrated views or a CT scan can help identify the sequestrae. (c, d) In cases where no discreet sequestrum are identified, and when technically possible, (d) diaphyseal reaming can be considered to decompress the medullary canal
Cortical presentation(Fig. 31.4) is rare and represents a milder form of disease with isolated segmental cortical death that may become walled off as a sequestrum entirely within the cortical bone.
Fig. 31.4
In the cortical presentation, the sequestrum becomes walled off within the cortex of the bone. In this case the arrow points to a thin sclerotic sequestrum within the thickened cortex
In walled-off solitary or multiple abscess presentation(Fig. 31.5), the periosteal reaction is robust but not to the degree seen in the sclerotic presentation. A strong involucrum is formed with solitary or multiple abscess cavities containing sequestrae, often associated with cloacae and multiple sinus tracts. There is usually good structural integrity of the bone. A healthy vascular response by the involucrum may eventually resorb remnants of sequestrum, leaving multiple tiny abscesses and sequestrae (Fig. 31.6). The appropriate surgical procedure is a widespread saucerization (sometimes called a “canoe” saucerization or longitudinal partial diaphysectomy), opening a lengthy section of medullary canal to access all the walled-off abscesses and micro-sequestrae. With many small abscesses, it is important to plan a surgical approach that does not remove excessive bone and compromise its structural integrity. Look for and begin with the locations with the most obvious sequestrae and those causing the most functional disability.
Fig. 31.5
This case illustrates the walled-off abscess presentation with (a, b) extensive involvement of the tibial shaft. (c) A longitudinal partial diaphysectomy/saucerization is required to facilitate debridement in such cases
Fig. 31.6
Walled-off multiple abscesspresentation with many very small abscesses throughout a long section of diaphysis
Presumably, if left alone, these cases might progress to one of the sclerotic types or heal spontaneously as the last remnants of sequestrae are absorbed, making a watch and wait approach, along with long-term antibiotic therapy to reduce the bacterial load, a reasonable approach, while allowing the involucrum to mature. These patients require hospitalization preoperatively for antibiotics and nutritional support.
In metaphyseal presentation(Fig. 31.7), the infection is loculated in the metaphysis. Micro-sequestrae can form from trabecular necrosis, and the abscess cavity can be quite large due to the relative sponginess of the metaphyseal bone. The single or multiple walled-off abscesses may show a sclerotic margin or juxtacortical erosions. The surgical approach is limited saucerization and curettage, and the lesions usually reconstitute without requiring bone graft.
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