Approach
Establishing the etiology of infection and classifying the disease helps in planning treatment for individual patients. No single antibiotic regimen or surgical procedure will be appropriate for all. The approach to treatment of osteomyelitis is complex, and often requires a multidisciplinary approach, with input from radiologists, vascular and orthopedic surgeons, infectious disease specialists, and wound care and rehabilitation specialists.[96]
Acute osteomyelitis: general principles
Treatment includes antibiotic therapy (empiric and subsequently culture-directed), and drainage of fluid collections, if present, by radiologic guidance or surgery.
The etiology of infection should be established and the disease should be classified to plan individual treatment. Initial antibiotic choice is based on the most likely causative organism, which depends on the patient's age, immunization history, comorbidities, the prevalence of organisms in the community, and antimicrobial sensitivities. Local protocols should be followed. Once the organism is identified by culture or polymerase chain reaction (PCR), and sensitivity to antibiotics is determined, antibiotic therapy should be narrowed accordingly.
The optimal duration of antimicrobial therapy is not certain.[57] However, the Infectious Diseases Society of America (IDSA) makes recommendations that are outlined for individual types of osteomyelitis below.
Response to antibiotic treatment is typically rapid. However, in acute peripheral osteomyelitis, if the affected limb deteriorates or imaging suggests progressive destruction of bone, choice of antibiotics should be discussed with microbiology. Surgery should be considered to prevent progression to chronic osteomyelitis.
Admission
Any patient who is systemically unwell should be admitted to the hospital for intravenous antibiotic therapy. Sepsis should be suspected if there is acute deterioration in a patient in whom there is clinical evidence or strong suspicion of infection. Local sepsis protocols should be followed. See Sepsis in adults.
Most children are admitted to the hospital for intravenous therapy.[12] Hospital admission may be particularly important in regions with a high rate of methicillin-resistant Staphylococcus aureus or Panton-Valentine leukocidin (PVL)-positive S aureus, if the patient's condition is clinically severe, and in high-risk patients (e.g., infants, immunocompromised children).[12] Some centers may use outpatient parenteral antimicrobial therapy with the insertion of a peripheral-inserted central line.[12]
Supportive care
Pain relief should be provided to all patients as required. First-line analgesics include acetaminophen and nonsteroidal drugs (NSAIDs) such as ibuprofen. Rectal administration of acetaminophen can provide pain relief longer than intravenous administration in children.[97] For more severe pain, an opioid (e.g., morphine, oxycodone) may be required for a short duration. If longer-term pain relief is required, a pain management specialist should be consulted.
The affected limb should be elevated and immobilized if necessary. Assessment should be undertaken for deep vein thrombosis, particularly with Staphylococcus aureus osteomyelitis since there is a high risk of venous thromboembolism during the first month following an episode of S aureus bacteremia.[98] See Deep vein thrombosis.
Any comorbidities should be addressed. It is particularly important to maintain strict blood glucose control in any patient with diabetes and a major infection such as osteomyelitis. See Diabetic foot complications.
A surgeon should urgently be consulted if a patient with diabetes develops severe infection or moderate infection complicated by extensive gangrene, necrotizing infection, signs suggesting deep (below the fascia) abscess or compartment syndrome, or severe lower limb ischemia.[37] For more information, see Diabetic foot complications.
Suspected acute peripheral osteomyelitis
If blood cultures are indicated, samples should be taken before commencing antibiotics.[1] Blood cultures should be considered in patients with fever suspected of having peripheral bone infection.[1]
Adults: empiric antibiotic therapy
In adults with suspected acute peripheral osteomyelitis in areas of low MRSA prevalence (<10%), empiric therapy options include vancomycin plus a third- or fourth-generation cephalosporin (e.g., ceftriaxone, cefepime). If the patient has a penicillin allergy, vancomycin plus a fluoroquinolone (e.g., ciprofloxacin) may be considered.[99]
In adults with suspected acute peripheral osteomyelitis in areas of high MRSA prevalence (>10%), vancomycin is the drug of choice. Daptomycin is a reasonable alternative if the patient cannot tolerate vancomycin or if vancomycin is contraindicated.
Adults: surgery
For adults who may require surgery (e.g., if the affected limb deteriorates or imaging suggests progressive bone destruction despite adequate antimicrobial therapy), a specialist orthopedic surgeon should be consulted.
Children: empiric antibiotic therapy
In children with presumed acute hematogenous osteomyelitis who appear ill or have rapidly progressive infection, the IDSA recommends that empiric antimicrobial therapy should be started immediately rather than withholding antibiotics until invasive diagnostic procedures are performed.[4] In children with presumed acute hematogenous osteomyelitis who are not clinically ill and for whom an aspirate or biopsy by invasive diagnostic procedure is being planned prior to initiating antibiotics, the IDSA recommends that antibiotics should be withheld for no more than 48-72 hours.[4]
Empiric therapy options for children with suspected acute peripheral osteomyelitis in areas of low MRSA prevalence (<10%) include nafcillin, oxacillin, or cefazolin.[4] In children with suspected acute peripheral osteomyelitis in areas of high MRSA prevalence (>10%), vancomycin or clindamycin may be considered.[4] Vancomycin is a common initial choice for children who are critically ill at presentation, regardless of regional MRSA prevalence.[4]
In the presence of a clinical presentation, physical examination, exposure history, or other risk factors that either are inconsistent with S aureus infection or suggest need for coverage for other organisms, additional empiric antimicrobial coverage for pathogens other than S aureus may be warranted. For example, additional coverage may be indicated in younger children (<4 years) for Kingella kingae or children with underlying hemoglobinopathies who have increased risk for Salmonella species infection).[4][9][12]
Switching from intravenous to oral antibiotics after 2-4 days should be considered when the child has been afebrile for 24-48 hours, shows clinical improvement with reduced pain, inflammation, and improved mobility, and has a C-reactive protein (CRP) level that has decreased by at least 30% of the highest value.[12] In children who respond well to initial treatment, early transition from intravenous to oral therapy (after 3 days to 1 week) may be as effective as longer courses of intravenous antibiotics.[100][101] In children with acute hematogenous osteomyelitis presumed or proven to be caused by S aureus who have had an uncomplicated course and respond to initial therapy, the IDSA suggests a 3- to 4-week duration of antibiotics (parenteral plus oral) rather than a longer course.[4] Longer duration may be necessary for other pathogens, including more virulent strains of S aureus, and for complicated cases.[4]
Children: surgery
In children with acute hematogenous osteomyelitis who present with sepsis or have a rapidly progressive infection, the IDSA recommends that debridement of the infected bone and any associated abscesses should be performed as soon as possible after diagnosis, rather than treating with medical therapy alone.[4] The European Society for Paediatric Infectious Diseases (ESPID) recommends that surgery should be considered in the following situations:[12]
Persistent or recurring fever after 3-4 days
Periosteal abscess with persistent fever and raised CRP
Sequestration
MRSA or Panton-Valentine leukocidin (PVL)-positive S aureus
Chronic osteomyelitis
Prosthetic material.
Pediatric orthopedic advice should be sought.
Suspected acute native vertebral osteomyelitis
Adults: empiric antibiotic therapy
In adults with suspected native vertebral osteomyelitis who have a normal and stable neurologic examination and stable hemodynamics, empiric antimicrobial therapy should not be given until a microbiologic diagnosis is established.[13]
In adults with suspected native vertebral osteomyelitis and neurologic compromise, the IDSA recommends immediate surgical intervention and initiation of empiric antimicrobial therapy instead of withholding antimicrobial therapy prior to an image-guided diagnostic aspiration biopsy.[13] In suspected native vertebral osteomyelitis and without neurologic compromise, the IDSA recommends that whenever possible, initiation of antibiotic therapy should be delayed for a limited period of time until bone cultures can be obtained.[13] Pending further studies, the IDSA recommends that holding antibiotics when feasible for 1-2 weeks is reasonable in these circumstances.[13] Local protocols should be consulted. The following regimens are based on recommendations from the IDSA:[13]
The antibiotic regimen should cover staphylococci (including MRSA), streptococci, and gram-negative bacilli.
An example of a suitable regimen is vancomycin plus a third- or fourth-generation cephalosporin (e.g., ceftriaxone, cefepime) or a carbapenem (e.g., meropenem) depending on risk of a resistant organism.
For patients with an allergy or intolerance to first-line options, daptomycin plus a fluoroquinolone (e.g., ciprofloxacin) should be given.
Fluoroquinolones have been associated with serious, disabling, and potentially irreversible adverse effects, including tendonitis, tendon rupture, arthralgia, neuropathies, and other musculoskeletal or nervous system effects.[102] Warnings have also been issued about the increased risk of aortic dissection, significant hypoglycemia, and mental health adverse effects in patients taking fluoroquinolones.[103][104]
Empiric antifungal and antimycobacterial therapy should not be prescribed in most situations.[13]
Adults: surgery
Surgical intervention is required for adults with suspected native vertebral osteomyelitis and progressive neurologic deficits, progressive deformity, and spinal instability despite adequate antimicrobial therapy.[13] Surgical debridement with or without stabilization is needed for persistent or recurrent bloodstream infection (without alternative source) or worsening pain despite appropriate medical therapy.[13]
Children: empiric antibiotic therapy
For children with suspected spondylodiscitis or vertebral osteomyelitis, advice on empiric antibiotic regimens should be sought from microbiology and from an infectious disease specialist.
Children: surgery
Indications for surgical management of pediatric spinal disease include:[105]
Lack of response to antibiotics
Progressive kyphosis
Neurologic compromise.
In practice, if spondylodiscitis or vertebral osteomyelitis is suspected in a child, advice should be sought from pediatrics and/or pediatric orthopedics, depending on local resources.
Suspected acute osteomyelitis in a patient with a diabetic foot problem
Osteomyelitis is a limb-threatening or life-threatening diabetic foot problem.[36] Advice should be sought from the multidisciplinary foot care service.[36][42] Patients with a diabetic foot infection may particularly benefit from consultation with an infectious disease or clinical microbiology specialist and a surgeon with experience and interest in managing diabetic foot infections.[42]
Patients who have probable diabetic foot osteomyelitis with concomitant soft tissue infection should be urgently evaluated for surgical intervention as well as intensive postoperative medical and surgical follow-up.[37]
Antibiotic therapy without surgical resection of bone should be considered in patients with diabetes and uncomplicated forefoot osteomyelitis, for whom there is no other indication for surgical treatment.[37] Samples should be taken for microbiologic testing before, or as close as possible to, the start of antibiotic therapy.[36]
Empiric antibiotic therapy in patients with suspected diabetic foot infection should be commenced as soon as possible. Antibiotics should be chosen from among those that have demonstrated efficacy for osteomyelitis in clinical studies.[36][37] The duration of antibiotic treatment for diabetic foot osteomyelitis should be for no longer than 6 weeks.[37] If the infection does not clinically improve within the first 2-4 weeks, the need for collecting a bone specimen for culture, undertaking surgical resection, or selecting an alternative antibiotic regimen should be reconsidered.[37]
If surgical intervention to resect bone is indicated, obtaining a specimen of bone for culture (and, if possible, histopathology) at the stump of the resected bone should be considered to identify if there is residual bone infection.
Diabetic foot infections are uncommon in children. Specialist advice should be sought.
For more information, including detailed regimens, see Diabetic foot complications.
Pseudomonas antibiotic cover
If Pseudomonas is suspected in adults with suspected peripheral or native vertebral osteomyelitis, an empiric antibiotic regimen that covers Pseudomonas should be chosen. Hematogenous osteomyelitis caused by Pseudomonas aeruginosa and other Pseudomonas species occurs most often in people who inject drugs.[9] P aeruginosa is the most common bacterial cause of calcaneal osteomyelitis in patients who develop this infection after stepping on nails while wearing sneakers.[9] A local infectious disease specialist should be consulted about suitable options.
Pseudomonas is a rare cause of osteomyelitis in young children, unless there is trauma or puncture of the foot. If Pseudomonas is suspected, an empiric antibiotic regimen that covers Pseudomonas should be chosen. A local infectious disease specialist should be consulted about suitable options. The IDSA notes that non-fluoroquinolone oral antimicrobial agents are preferred for children, owing to concerns for cartilage/tendon injury noted in animal toxicity studies of fluoroquinolones.[4]
Confirmed acute osteomyelitis
When microbiologic results are available, the antibiotic should be reviewed and changed accordingly, using a narrow-spectrum antibiotic, if appropriate.[4][13]
Response to treatment is typically rapid. However, in acute peripheral osteomyelitis, if the limb deteriorates or imaging suggests progressive bone destruction, choice of antibiotics should be discussed with microbiology. Surgery should be considered to prevent progression to chronic osteomyelitis. Once dead bone or a biofilm has become established, antibiotics alone cannot cure the infection and thorough surgical debridement is required. See "Chronic osteomyelitis," below.
The optimal duration of antimicrobial therapy for osteomyelitis is not certain.[57] However, the IDSA makes recommendations for some types of osteomyelitis. For instance, in children with acute hematogenous osteomyelitis presumed or proven to be caused by S aureus who have had an uncomplicated course and respond to initial therapy, the IDSA suggests a 3- to 4-week duration of antibiotics (parenteral plus oral) rather than a longer course.[4] Longer durations of antibiotics may be necessary for other pathogens, including more virulent strains of S aureus, and for complicated cases.[4] The IDSA recommends that most adults with confirmed bacterial native vertebral osteomyelitis should receive 6 weeks of parenteral or highly bioavailable oral antimicrobial therapy.[13]
In suspected native vertebral osteomyelitis, when the etiologic agent is Brucella, culture may be difficult and results slow to obtain, as the organism is intracellular and the number of circulating bacteria is usually low.[57] Therefore, targeted antibiotic therapy may need to be started once PCR results are available and infection has been confirmed, regardless of whether culture and sensitivity results are available. Local antibiotic protocols should be consulted with advice from microbiology in endemic areas. Evaluation by a spine surgeon and an infectious disease specialist should be sought in nonendemic areas.[13] A total duration of 3 months of antimicrobial therapy is recommended for most patients with native vertebral osteomyelitis caused by Brucella species.[13] For more information, see Brucellosis.
Chronic osteomyelitis
When there is dead bone, or a biofilm has become established, antibiotics alone cannot cure the infection and surgery is required.
Choosing an appropriate management plan
The decision on the best course of management for a patient with chronic osteomyelitis involves the assessment of several factors, including:
The effects of the disease
The benefits of treatment
The associated risks.
Not a surgical candidate or surgery not wanted
As full cure of chronic osteomyelitis may involve complex surgery with potential complications, antimicrobial drug reactions, staged reconstruction, and prolonged time in treatment and rehabilitation, an approach that controls current symptoms, but with the possibility of later recurrence, may be a more attractive option for some patients.
In group C patients under the Cierny-Mader classification (patients who are so severely compromised that treatment has an unacceptable risk-benefit ratio, or those with few symptoms from their infection) it is reasonable to withhold treatment or just to treat symptomatic flare-ups with short antibiotic courses. Selection of an appropriate antibiotic regime may be informed by radiologically guided biopsy.
Biopsy-guided or empiric antibiotic therapy may be considered in some cases where the patient is unfit for surgery or unwilling to have surgery. This is unlikely to cure chronic infection but may alleviate symptoms. If a trial of therapy is successful, long-term suppression may be considered. Long-term suppressive antibiotic usage needs to be balanced against significant risk of poor adherence, adverse effects, and drug interactions. More studies are needed to determine the best antibiotic regimen and duration of therapy.
Limited surgery may be an option for patients who are not candidates for curative limb salvage surgery (e.g., those with implants in situ that would provide a challenging reconstructive problem if they were removed). While not effecting a cure, it may reduce the infective load.
Surgical candidate
Curative limb salvage surgery for chronic osteomyelitis should be considered only if the likely outcome is better than amputation or continuing with the infection. Within specialist centers, eradication of infection with limb salvage is more often the case.
Repeated suboptimal antibiotic treatment without surgery increases microbial resistance and restricts the choice of effective drugs available following surgery. Definitive treatment should not be unduly delayed, particularly in infected fractures and nonunions, because further soft-tissue injury can occur through ongoing bone instability.
Immediate antibiotic treatment is required before debridement surgery if there are systemic signs of sepsis.[4]
Principles of surgical treatment for chronic osteomyelitis
The outcome of surgery is dependent on the physiologic status of the patient and the duration of the infection. Treatment should be tailored to each patient's need. The following considerations are important in effective management of osteomyelitis.
Preoperative factors:
Assessment of the degree of disease allowing accurate clinical staging (using the Cierny-Mader classification)
Full discussion with the patient about the treatment options and the potential associated risks
Diagnostic tests to assess general health and the condition of the limb (blood tests, scanning, angiography, guided biopsy)
Optimization of associated medical comorbidities before surgery.
Operative principles:
Thorough debridement and excision of all infected tissue
Meticulous microbiologic and histologic sampling early during the procedure to obtain uncontaminated representative samples to diagnose the causative organism and rule out other potential differentials, such as tumor
Adequate dead space management to prevent the formation of hematoma that increases infection recurrence rates
Stabilization of the bone, when there is instability or risk of fracture, usually with an external fixator
Attaining immediate soft-tissue coverage with healthy vascularized tissue that can deliver systemic antibiotics.
Postoperative priorities:
Functional rehabilitation
Continued antibiotic therapy guided by intraoperative culture results
Close monitoring for early recurrence or adverse events
Second-stage reconstruction.
It is important to ensure that comorbidities are optimized before surgery to improve outcomes. Issues such as poor nutritional status, smoking, and substance dependence need to be addressed. Many patients have anemia of chronic disease or coagulopathies. Control of diabetes is often difficult in the context of uncontrolled infection and may require admission for optimization before surgery. Vascular insufficiency may need to be addressed before osteomyelitis surgery can be undertaken, to maximize healing potential. Those with sickle cell disease may need exchange transfusion before embarking on surgery to minimize the risks of bone infarct, sickle crisis, and wound healing problems caused by an anesthetic.
Immediate antibiotic treatment is required before debridement surgery if there are systemic signs of sepsis.[4] It is always advisable to obtain blood cultures or local pus samples for culture before starting antibiotics, if possible. Empiric broad-spectrum antibiotics may be initiated and the regimen modified when the results of cultures and sensitivity tests are known.
Surgical planning
The approach to surgery can be guided by imaging, with plain film x-ray and magnetic resonance imaging (MRI) being particularly useful in accessing the sequestrum and trying to avoid unnecessary damage to the healthy involucrum when making a window to enter the medullary canal. Furthermore, MRI is helpful in identifying localized active disease when the normal morphology of the bone is disrupted. A tourniquet is used wherever possible. Any sinus is excised with an ellipse of skin in the line of the incision.
Microbiologic sampling
To increase the accuracy of microbiologic diagnosis, multiple samples should be taken, with 5 recommended as being a good balance between achieving sufficient sensitivity and avoiding poor specificity with contamination.[106] A clean set of instruments should be used for each sample and there should be no handling of the instrument tips by the surgeon or scrub staff. Every effort should be made to avoid contact with the skin of the patient, and contamination can be further reduced by using clean gauze swabs in the wound rather than using fingers or suction tips before sampling is complete. Ideally these samples should be taken early in the operation when contamination of the wound is at its lowest. Once taken, these samples should be sent directly to the laboratory to prevent undue sample degradation. Samples for histology are also useful in supporting infection diagnosis as well as ruling out other potential conditions. Any longstanding sinus tracts should also be sent for histology to rule out the possibility of squamous cell malignant transformation.
Once sampling has been completed, antibiotics are given. The initial intravenous antibiotics must be continued until a definitive regimen is selected based on the intraoperative culture results. An empiric regimen appropriate to the flora encountered in the hospital's region is appropriate. A protocol using a glycopeptide and a carbapenem postoperatively in 166 cases of osteomyelitis debridement showed coverage of 96% of all organisms subsequently cultured.[107] This same study revealed that one third of organisms cultured were resistant to a penicillin-based empiric antibiotic regime. The carbapenem is usually stopped after 48 hours' culture if there are no gram-negative organisms cultured at that point.
Surgical debridement
Significant scarring and induration around sinuses is best removed as it has poor healing potential. Sinus tracts often take a convoluted path commonly passing between muscle planes. It is useful to follow these down to the cloacae arising from the infection. Following sampling, the extent of infection must be fully exposed to assess the limits of resection. The infected tissue is removed in a systematic fashion, working from one end to the other. This ensures that the infected zone is thoroughly debrided without missing an area of infection that might be left behind. Surgical excision of all affected necrotic tissue is necessary to eradicate infection.
The goal of debridement is to remove all necrotic tissue until punctate bleeding of the bone (the paprika sign) is achieved. Sequestered bone is often found within the medullary canal because over time it is surrounded and encased by new reactionary involucrum. If it is isolated to the medulla (type I Cierny-Mader disease), then it may be debrided through a cortical window placed in the metaphysis to limit the risk of subsequent fracture. The edges of the window should be kept round to reduce the risk of developing a stress fracture. There is often a layer of endosteal sequestrum on the inner surface of the cortex that must be removed back to bleeding bone. If the medullary involvement is purely at the isthmus it may be possible to use intramedullary reamers from one end of the bone without windowing the bone.
In type II Cierny-Mader disease, when the cortex is involved, the overlying soft tissues may need to be removed back to healthy cortical bone surface. The abnormal cortex is brittle and discolored, as opposed to normal bone, which has vascular periosteum that is adherent to the bone surface. A chisel is used and the cortical layer is removed until bleeding bone is encountered.
In type III Cierny-Mader disease a segment of healthy bone remains. However, careful preoperative planning is required to minimize the risk of fracture. It may be necessary to use a simple monolateral external fixator to support the bone following surgery until it is sufficiently healed. The medulla is reached by windowing the affected area of the bone and the endosteum is cleared along with any sequestra in the cortex, subperiosteal abscesses, involved soft tissues, and scarred skin. At this stage it is important to focus on the adequacy of the debridement without concern about the later reconstructive challenges. This concern may prevent adequate excision and failure of infection control, rendering reconstruction ineffective.
Type IV disease, by definition, requires a segmental resection to eliminate infection. The resection should also remove the involved soft tissues and skin but there should be care to ensure the neurovascular bundles are preserved. There is a good case to apply an external fixator before the resection is undertaken to ensure that the limb alignment and stability is maintained.
Following excision, the wound is washed. Saline is acceptable, but a 0.05% aqueous chlorhexidine solution has been shown to have increased antibacterial activity with minimal impact on the living tissues. In contrast, hydrogen peroxide has a disproportionate damaging effect on host cells, and iodine-based solutions are ineffective against bacteria once they come into contact with blood.
A clean set of drapes is applied, gloves are changed, and all contaminated instruments are removed. The tourniquet is released and the bone is observed for bleeding. If any small areas remain that are of dubious viability, then further resection is required.
Dead space management
At the end of debridement, the surgeon must assume that the whole operative field will be contaminated with bacteria disseminated during surgery.[108] Bone is an unyielding tissue, so any defect left at the end of the surgery will remain and will fill with hematoma, providing an ideal environment for the propagation of persisting planktonic bacteria and allowing early biofilm development. Systemic antibiotics are administered in an effort to target these remaining organisms, but the perfusion of antibiotics into bone defects may be poor, resulting in low antibiotic penetration. Well-vascularized tissue such as a muscle flap can obliterate shallow defects and facilitate the local delivery of high levels of parenteral antibiotics.[109][110]
Antibiotic carriers
The use of muscle to fill deeper defects is often unsatisfactory and may prevent bone healing. Voids can be filled with antibiotic-containing materials that can reduce the dead space and deliver high concentrations of local antibiotics. One of the clear advantages of using a local antibiotic carrier is the ability to achieve high local concentrations of antibiotic without systemic toxicity. The dosing of systemic antibiotics is limited by the potential toxic effects they may have on organs, such as the kidneys. Local antibiotic carriers can elute high concentrations of antibiotic locally, often in the order of 10 to 100 times the minimum inhibitory concentration of the organisms present, and potentially above the mean biofilm eradication concentration.[111][112]
Antibiotic-containing polymethyl-methacrylate cement (PMMA) in the form of beads on a wire or molded to fit the cavity has been used for this purpose.[113][114][115] Unfortunately, these must be removed, because if left in place the PMMA will prevent bone ingrowth over time.[116] Once the antibiotic has fully eluted there is a risk of secondary infection onto this foreign material.[117][118] Biodegradable antibiotic carriers have also been used in dead space management. These elute antibiotics at high concentrations but dissolve over several weeks. This negates the need for further surgery for removal once they have served their purpose, and makes single-stage surgery for osteomyelitis a viable option. Several authors have published outcomes for treating chronic osteomyelitis with ceramic antibiotic carriers.[119][120][121][122][123][124][125][126]
Many of these materials are osteoconductive and there is potential that some might aid in bone healing. There is a potential for wound ooze for several weeks in a proportion of cases following the use of these biodegradable antibiotic carriers, although postoperative wound discharge was not found to be predictive of recurrence of infection and can be managed conservatively.[125][127]
A range of biodegradable carriers is available. Some contain calcium sulfate and others contain compounds that dissolve at different rates. These composite carriers are available in a paste that sets to form a solid cold-curing cement. This gives the theoretical advantage of more initial structural support with the potential for supporting osseous healing through osteoconduction as it becomes more porous during dissolution.[128][129][130]
Surgical management of type IV disease
In type IV segmental defects, an acute shortening of the limb may be the simplest way of abolishing dead space. Acute shortening is safe in the tibia by up to 4 cm, the femur by 6 cm, and the humerus by 5 cm, assuming the soft tissues remain supple and no scars constrict the neurovascular bundles. This shortening can be combined with a single-stage or delayed corticotomy distant from the zone of infection to relengthen the limb, if the patient is fit for reconstruction.[131][132]
Large segmental defects (>5 cm) are the most challenging group to manage. Staged reconstruction in type IV osteomyelitis has been used successfully. The bone defect is filled with a temporary antibiotic-containing spacer and then the skin is closed. Once the infection has been treated and the soft tissues recovered, a second-stage procedure is performed to remove the spacer and reconstruct the defect. In one type of staged reconstruction for type IV osteomyelitis, the defect is filled with a large PMMA spacer and the soft tissues closed over it. Over several weeks, a membrane forms around the PMMA spacer, which is probably osteoinductive. After 6-8 weeks, the spacer is removed, bone graft is packed into the defect, and the membrane is closed tightly around the graft. Over many months, the graft is incorporated and remodeled.
Single-stage surgical reconstruction
Single-stage reconstruction is becoming a more common treatment philosophy. The attraction of this approach is a single surgery to deal with infection. For a large defect an option is a combination of a vascularized free fibula graft and an overlying free-muscle flap, although this is probably not appropriate in patients with significant comorbidities. Ilizarov bone transport is a safer technique, which allows immediate limb functioning.[133][134][135][136] This technique is technically demanding and requires careful planning to ensure that complications are minimized. It still requires that sufficient bone remains to allow the creation of a transport segment. If planned carefully, bone transport techniques can be combined with free-muscle flaps, assuming the pin and wire placement will not impinge upon the pedicle during transport.
Bone stabilization and soft tissue cover
Instability must be addressed to cure infection. Following debridement the bone may need temporary support with a monolateral frame to prevent fracture and aid postoperative rehabilitation.[47] In type IV infection there is inherent instability, and a circular frame may be required. Frames should allow early weight-bearing to allow the limb to be used. Fixator pins must be placed outside the zone of infection. This may involve spanning a joint to achieve adequate stability. If a free flap is required, the frame must be planned preoperatively to give sufficient access to vessels for microvascular anastomosis. Antibiotic-coated implants for internal fixation are available but are safe only when the surgeon is confident that the infection has been completely excised with good soft-tissue cover. Exchange nailing for infected tibial nonunions is not recommended as it carries a high failure rate.[137]
Soft-tissue cover
In femoral, humeral, and spinal disease, primary closure of wounds is usually achievable. In wounds around the pelvis, closure may be made easier by bone resection of the ilium or ischium. Extensive pressure sores may prevent primary closure, and a local flap may be required. Free-muscle flaps covered with split skin grafts are suitable because they provide a robust coverage of bone and are highly vascular and consequently able to support bone healing and supply systemic antibiotics to the soft tissues.[108][138]
Vacuum-assisted closure devices are of very limited use in osteomyelitis. These should not be applied to sinuses with untreated bone infection as they unduly delay time to definitive surgery.
Antibiotic treatment following surgery
The optimal duration of antimicrobial therapy is not certain. If the osteomyelitic bone has been fully resected, a shorter course of antibiotic therapy (2-6 weeks) may be adequate as long as operative wounds are healing without any signs of infection. This can include an appropriate course of oral antibiotics, based on microbial cultures and sensitivities.
One multicenter, randomized controlled trial of 1054 patients demonstrated that oral antibiotic therapy is noninferior to intravenous antibiotic therapy following surgical treatment of bone or joint infection.[57]
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