Top three questions

1. In patients undergoing orthopedic surgery, does routine antibiotic prophylaxis, compared to antibiotic administration, prevent surgical site infections?
   
2. In patients with a suspected surgical site infection, what is the optimal workup leading to accurate diagnosis and treatment?
   
3. In patients with a surgical site infection and infected hardware, does hardware retention, compared to removal of hardware, result in improved outcomes?

Rationale

Optimal prophylactic antibiotic management in orthopedic surgery has not been fully answered and is an area of ongoing research.

Clinical comment

Despite established guidelines for surgical site infection (SSI) prevention, studies show that antibiotic prophylaxis is not always correctly administered.1,2 Antibiotics should be administered within 30 minutes prior to incision, and inappropriate utilization of antibiotics contributes to antibiotic resistance and increased health care costs.3–6

Available literature and quality of the evidence

• Level I: 16 studies
  
• Level II: 8 studies
  
• Level III: 14 studies
  
• Level IV: 6 studies
  
• Level V: 9 studies.

Findings

Prophylactic antibiotic effectiveness was first demonstrated in 1961 in a Staphylococcus aureus infection model in guinea pigs; antibiotics given within one hour of bacterial inoculation showed no inflammatory response.7 Guinea pigs that received antibiotics >3 hours after inoculation received no more benefit than those not receiving antibiotics. Lidwell et al. demonstrated a threefold decrease in total knee and hip arthroplasty infections with usage of antibiotic prophylaxis.8 A prospective, randomized double‐blind study of general orthopedic procedures showed that a group receiving cefamandole compared to placebo had a significantly reduced rate of infection.9 The Dutch Trauma Trial assigned 2195 patients with closed fractures to a single 2 g preoperative dose of ceftriaxone versus placebo, with a placebo group infection rate of 8.3% versus ceftriaxone rate of 3.6%.10

The optimal duration of antibiotics is not known with poor evidence.11,12 Current American Academy of Orthopaedic Surgeons (AAOS) guidelines recommend antibiotic duration <24 hours, even with drains or catheters present.12 In trauma and elective surgery populations, single‐dose antibiotic prophylaxis appears to be noninferior to multiple doses.13–15 In a meta‐analysis by Morrison et al., 921 patients pooled between two studies analyzing single versus multiple postoperative antibiotic doses demonstrated no significant differences. Multiple doses of postoperative antibiotics had a slightly lower deep SSI rate (risk ratio [RR] = 0.13; 95% confidence interval [CI]: 0.02–0.99).16 Antibiotics should be re‐dosed for operations >3 hours, >2 half‐lives of the antibiotic, or with blood loss >1500 mL.17 Antibiotic dosing should be weight based to ensure adequate tissue concentrations.1,18

Resolution of clinical scenario

• Antibiotics should be administered within 30 minutes prior to incision.
  
• Perioperative antibiotic course should not exceed 24 hours.
  
• Antibiotics should be re‐dosed when the duration of the procedure exceeds two‐times the antibiotic half‐life, with significant intraoperative blood loss, and dosed by weight.

Rationale

Accurate and timely diagnosis of SSIs is important for guiding treatment.

Clinical comment

The evaluation of a suspected wound infection is clinically based. C‐reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are useful for diagnosis and following treatment response.

Available literature and quality of the evidence

• Level II: 7 studies
  
• Level III: 4 studies
  
• Level IV: 1 studies
  
• Level V: 7 studies.

Findings

The Centers for Disease Control and Prevention categorizes SSIs as Superficial Incisional SSI (<30 days involving skin/subcutaneous tissues), Deep Incisional SSI (involves deep soft tissues <30 days without implant, <1 year with implant), or Organ/Space SSI (involves any part of the anatomy other than incision which was opened/manipulated, <30 days without implant, <1 year with implant).19 Infection course is subject to many variables, including organism virulence, wound condition, host factors, and presence of nonbiologic substances such as metallic implants.6,20,21 Failure of eradication leads to colonization and further bacterial adaptation including biofilm and glycocalyx formation.22

Drainage, erythema, fever, and pain may signify SSI. Laboratory workup should include blood cultures, white blood cell (WBC) count, ESR, and CRP. Erythrocyte sedimentation rate peaks five days postsurgery followed by a slow and irregular decrease, often remaining elevated at 42 days after uncomplicated spine surgery.23,24 CRP is a more effective marker for diagnosis of infection due to established postoperative kinetics, as demonstrated in spine literature, with a half‐life of 2.6 days and first‐order elimination kinetics.24 Most diagnostic data are drawn from the arthroplasty literature, so caution must be taken when interpreting for trauma populations. In fracture patients, studies show persistent elevation of CRP beyond postoperative day (POD) 4 is associated with an SSI; one study demonstrated 92% sensitivity and 93% specificity for deep infection, with elevation of CRP >96 mg/L beyond POD 4 associated with infection.25,26 When used together, ESR and CRP demonstrated a 98% sensitivity in a study of 265 children with osteoarticular infections.27

Related posts:

The Direct Anterior Approach Patient‐Specific Instrumentation in Total Knee Arthroplasty Management of Glenoid Bone Loss Distal Femur Fractures Periprosthetic Fractures: Knee Lisfranc Injuries

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