Postoperative Infections of the Spine

Youmans Chapter 41

Outline

• Incidence• Infection risk factor• Clinical• Evaluation• Bacteriology• Treatment• Antibiotic therapy• Prevention

Incidence

• Noninstrumented Spinal Procedures– anterior and posterior decompressive surgeries– Lumbar diskectomy

• extremely low rate of infection, • superficial wound infection or diskitis

– Laminectomy without fusion• Low rate, 2%

Incidence

• Noninstrumented Spinal Procedures– Noninstrumented posterior spinal fusion

• Higher rate than simple laminectomy or lumbar diskectomy

• More blood loss, greater soft tissue destruction, and placement of devascularized allograft.

– Chemonucleolysis and discography• Infection rate up to 4 % in the absence of

preoperative antibiotic

Incidence

• Instrumented Spinal Procedures– Posterior spinal procedure

• 3-7%• locus minoris resistentiae

– Type of instrumentation• Older steel implant• Corrosion and fretting at cross-connector

sites

Incidence

• Instrumented Spinal Procedures– Anterior instrument

• Extremly low rate of infection• use of avascular planes in dissections and

minimization of soft tissue trauma and necrosis– Minimally invasive surgery

• No reduction in wound infection rate– Implantation of intrathecal drug delivery systems

and spinal cord stimulators• 5 % rate infection

Infection risk factor

• Patient factors– Obestity

• longer operative time greater, amounts of retraction, which, in turn, causes increased soft tissue necrosis, greater amounts of poorly vascularized fatty tissue with decreased oxygen tension, decreased immune defense in adipose tissue, and poor tissue concentrations of prophylactic antibiotics

Infection risk factor

• Patient factors– Malnutrition

• impair immune response and wound healing• serum albumin < 3.5 mg/dL or total lymphocyte

count < 1500/ml, skin fold thickness, transferrin level, weight height ratio• Malignancy, trauma

Infection risk factor

• Patient factors– Diabetes up to 24%

• Impair wound healing wound healing and predisposes to wound infection

– Tobacco• deprivation of oxygen to tissues and

impaired wound healing and neutrophil defense

Infection risk factor• Surgical Factors

– number of levels treated– length of the surgery (> 5hr)– procedural complexity– amount of blood loss (> 1L)– revision surgery, – the use of allograft material,– surgery extending to the sacral region– two or more resident surgeons being involved in

the procedure

Infection risk factor

• Disease-Specific Factors– Malignancy

• Highest incidence 20%• Malnutrition, complex surgical procedure, corticosteroid

use– Traumatic

• prolonged stay in the intensive care unit, • urinary or fecal incontinence• large procedures all playing a role

– Prolonged presurgical hospitalization and postoperative stay in the intensive care unit

Infection risk factor

Clinical

• Superficial– lumbodorsal fascia in the dermis and

subcutaneous tissue– erythema, purulent drainage, and local

tenderness– low grade fever– ESR, CRP elevated, leukocytosis– GS, CS

Clinical

Clinical

• Deep– immediate postoperative period– 2 to 3 weeks postoperatively– several months to several years after surgery– Acute : significant pain, fever, anorexia, night

sweats– Delayed : back pain, wound drainage, and

erythema but may lack fever– Spinal epidural abscess : back pain, fever, and

neurological deficit

Evaluation

• Laboratory– WBC

• often normal,but can be elevated– ESR

• ESR rise to maximal value of 102 mm/hr after spine fusion surgery and 75 mm/hr after disk surgery on postoperative day 4 before declining to normal levels 2 to 4 weeks postoperatively

• Serial ESR

Evaluation

• Laboratory– CRP

• normal elevation of CRP is also seen in the immediate postoperative period

• returns to baseline more quickly than does the rise in ESR, 2 wk to normalization

– GS, CS from draining or open wound– Bloos CS

Evaluation

Evaluation

• Imaging diagnosis– Plain Radiographs

• assessment of spine alignment, local soft tissue reaction to infection, bony response to infection

• Early bony changes in response to infection are manifested approximately 2 to 3 weeks

• Acute : disk space narrowing, bony destruction, and blurring of end plates

• Chronic : vertebral body collapse or sclerosis of end plates and bony ankylosis

• Increased swelling noted in soft tissues : abscess

Evaluation

• Imaging diagnosis– CT

• Similar to radiograph• better detect paraspinal masses and epidural

collections• CT myelography may be useful in aiding the

diagnosis of epidural or subdural empyema

– Magnetic Resonance Imaging

Evaluation

• Imaging diagnosis– Nuclear imaging

• Tc 99m labeled methylene diphosphonate bone scans : diagnose and localize an infection, limited sensitivity and specificity

• F-fluorodeoxyglucose positron emission tomography (PET) : useful in differentiate tumour from infection however negative PET can rule out infection

Evaluation

• Imaging diagnosis– MRI

• sensitivity and specificity of approximately 95%• Early infection on MRI : hypointensity on T1-

weighted sequences and hyperintensity on T2/STIR (short tau inversion recovery) signals

• Loss of the normal low-intensity disk space cleft on T2-weighted sequences is another clue to the presence of infection

• Contrast media : homogenouse enhancement

Evaluation

• Imaging diagnosis– MRI

• Detecting soft tissue mass, paraspinal epidural abscess

• vertebral body edema signal and contrast enhancement, may be present in the postoperative setting in the absence of infection

Evaluation

Bacteriology

• Skin flora most common• Staphylococcal species, particularly

Staphylococcus aureus• Methicillin-resistant S. aureus (MRSA), gram-

negative organisms, and mixed flora• Delay infection : Propionibacterium and

Staphylococcus epidermidis

Treatment

• Nonoperative treatment– superficial wound infections(no wound

breakdown, purulent drainage, fluctuate): ATB without surgical

– Postoperative diskitis : Blood CS, broad spectrum ATB

– 6 wk for IV then 6 Wk for oral– surgical treatment is indicated : poor clinical

response to medical treatment, continued back pain, or instability

Treatment

• Surgical debridement– Wounds that have broken down, have

purulent drainage, or are fluctuant or otherwise concerning for deep extension usually require operative exploration

– goals : diagnosis the infective agent, débridement of nonviable tissue, assurance of stabilization

Treatment

• Surgical debridement– Opening of lumbodorsal fascia– Subfascial compartment aspirate– Gelfoam or fibrin sealant remnants, and

necrotic muscle and fat should be removed– Disk space was instrument : view, culture,

debridment

Treatment

• Surgical debridement– Wounds that have broken down, have

purulent drainage, or are fluctuant or otherwise concerning for deep extension usually require operative exploration

– goals : diagnosis the infective agent, débridement of nonviable tissue, assurance of stabilization

Treatment

• Surgical debridement– Newer Titanium for infected spine– Fusion loose : remove and alternative means

of fixation– If the infection has occurred in a delayed

fashion and the fusion is solid, however, the surgeon can consider removing the instrumentation

– Carefull follow up in this case

Treatment

• Surgical debridement– Before closure : wound should be thoroughly

irrigated. We often use a low-pressure pulsatile irrigator with copious amounts

(9 L) of antibiotic solution- Primary wound closure

Treatment

• Treatment of Intrathecal Pump and Spinal Cord Stimulator Infection– removal of the hardware– initial treatment with broad-spectrum

antibiotics– gradual narrowing of antibiotic coverage

once culture results have been obtained– Removal of intrathecal drug delivery devices

• Adjuvant Surgical Techniques– Vacuum-Assisted Closure

• negative pressure is applied to the wound, which aids in closure

• via mechanisms of edema removal, improvement of blood flow, stimulation of angiogenesis, stimulation of granulation tissue development, and reduced bacterial load

• 125 mmHg of suction

Treatment

• Adjuvant Surgical Techniques– Vacuum-Assisted Closure

• Replaced every 2-4 days• Complication : significant blood loss,

hypoalbuminemia, • toxic shock syndrome, and retained sponges

– Irrigation-Suction technique• Irrigation catheter, drain• ATB solution, 50 ml/hr• Drain place for 5-7 day

Antibiotic therapy

• Broad-spectrum ATB• G/S for initial therapy• 4-6 wk for iv then oral

Prevention

• Preopearive optimization• Smoking cesstion• Assess nutrition• Concomitant infection• Hair shaving with clippers• Prophylactic antibiotic in spine surgery:

cefazolin, vancomycin, 30- 60 min before surgery

Prevention

• Disk space, Diskography : clindamycin, aminoglycoside, glycopeptides (good penetration)

• Maintenance of strict aseptic techniqued• Require minimization for operating room traffic• Double gloving• Intraoperative irrigation c betadine• If drain is used, prophylaxis ATB used

Thank you