Osteomyelitis - Management& Treatment (Nonantimicrobial)
Management and Treatment
The management of osteomyelitis relies on a multidisciplinary approach, combining debridement, soft tissue coverage, and antimicrobial therapy to give the patient the best chance of cure (Table 5). The first step involves identifying (staging the host) and optimizing the host (treating the morbidity of the host and optimizing their physiologic condition, such as nutrition, smoking cessation, treatment of diabetes, medical or surgical management of vascular disease). Step two involves classifying the type of osteomyelitis (staging the disease). Then, identifying the organism is required to determine appropriate antimicrobial treatment (the tumor analogy of chemotherapy). Once the extent of disease, the nature of the host and infecting organism are noted, a determination should be made regarding one of several general treatment algorithms. The treatment options available include attempted ablation and cure of the offending infection or in selective cases, such as C-hosts, that are not suitable for this line of treatment , some type of suppressive treatment. Attempted ablation and complete cure has numerous issues and decision making steps but will often require the tumor equivalent of a wide resection with “clean” margins. While a surgically clean bed with extensive resection is desirable, efforts should be made to maintain axial stability when possible. Thus, retention of a well vascularized but affected involucrum, or a viable segment of bone adjacent to infection may be retained. At some point, if adequate resection will result in too extensive a reconstruction that is unsuitable for the host status, amputation is the best option and should not be considered a failure. In some cases of life or limb threatening infection, a “debulking” of the infection may be a suitable first step followed by chronic suppression. In such a circumstance, identification of the infecting bacteria is required to allow use of a narrow-spectrum antibiotic; otherwise, broad-spectrum antibiotics are needed. The increased incidence of methicillin-resistant staphylococcal species adds greater emphasis to the need for a microbiologic diagnosis.
|Table 5. Treatment Principles of Osteomyelitis|
1. Stage the disease based upon Cierny-Mader classification
2. Establish microbiological diagnosis
3. Surgical drainage, debridement and stabilization
4. Dead space management, wound protection and tissue transfer
5. Appropriate antibiotic therapy
6. Set realistic goals with the patient, support medical and psychological state of the patient
If surgical treatment is chosen, the hallmark of treatment is debridement. All non-viable and inert structures should be debrided to remove the infected material and debris without destabilizing the bony structure. The goal is to convert a necrotic, hypoxic, infected wound to a viable wound. The critical judgment for the clinician occurs when there is potentially infected bone, that may be partially vascularized, and that is critically needed to maintain the structural stability of the bone. The limits of debridement have classically been determined by the “Paprika sign” which is characterized by punctuate cortical or cancellous bleeding. Reactive new bone surrounding an area of chronic infection is living and usually does not require debridement. The sequestrum needs to be identified and removed, whereas the involucrum may be preserved. When the medullary canal is infected, intramedullary reaming is a good method of debridement. In general, one should over ream the medullary canal by 2 mm. Intramedullary reaming of the canal as a debridement technique has shown favorable results in the treatment of medullary osteomyelitis. In one series, 25 patients with posttraumatic osteomyelitis (of whom 22 were treated with intramedullary reaming) 21 of the 22 patients were free of any recurrent infection. In a more recent study, 40 patients suffering from chronic osteomyelitis were treated with intramedullary reaming. Only four patients suffered a recurrent infection following intramedullary reaming (Figure 4).
If the medullary infection is too proximal (or distal) for a tight reamer fit, a trough must be created to debride the canal directly (saucerization). Greater than 30% loss of circumferential cortical contact or any segmental resection requires stabilization.
Acute Post-operative Infection
Often, infection present with a recent reconstruction with the presence of metallic implants and other inert biologic tissue (compromised bone or bone graft). The question arises regarding the need to intervene operatively or the ability to remove implants (Table 6). If there are obvious signs of infection such as erythema, copious drainage, edema, and fever, acute surgical debridement and irrigation is needed. If there is satisfactory fixation and stability of the construct, only non-essential elements such as excess bone graft, should be removed. Placement of an antibiotic delivery depot (either PMMA or resorbable) with a more aggressive antibiotic regimen may curb the infection until healing has taken place. If this treatment is undertaken, suppression with antibiotics should continue until such time and when adequate healing has occurred, there should be strong consideration of re-debridement, removal of hardware and an intra-operative decision as to whether more antibiotic depot treatment is required (Figure 5). This algorithm is followed with the hypothesis that the original wound was contaminated and probably colonized with bacteria (with biofilm formation on all inert structures in the wound), and that the debulking and suppression was in an effort to prevent the need to “start over”. As such, with our current understanding of bio film bacterial, it would be unlikely that the wound could be free of bacteria, so there is a higher likelihood of recurrence of infection. It is for this reason that the threshold of hardware removal and re-debridement is lower than normal. If this approach is not successful, there should be consideration of “starting over”, which is complete removal and debridement of inert substances, placement of an antibiotic depot system, temporary stabilization with an external fixator or cast, and a staged reconstruction. Unlike the literature in arthroplasty, there is not much scientific literature on success/failure rates in such circumstances for fractures. It should be noted however, that bones can heal in the presence of active infection and unlike arthroplasty, where the implant is considered permanent, the fracture setting allows for implant removal once bone healing has taken place.
Table 6. Algorithm for Acute Infection.
I) Hardware Stable+Bone Not-healed = Retain hardware, antibiotics until healed, then hardware removal
II) Hardware Unstable + Bone not healed = Remove hardware, antibiotics, temporary stabilization, spacer, and reconstruction when clean
III) Hardware Stable + Bone Healed = Remove hardware, debride with effort not to destabilize, control dead space, and antibiotics
IV) Hardware stable + Bone not healed + systemic effects = Remove hardware, temporary stabilize, spacer, antibiotics, and reconstruction when able, consider amputation if bad host