Introduction

Postoperative infection following internal fixation involves the soft tissues (skin, subcutaneous tissues, muscle fascia, and muscle), hardware, and potentially the bone. The infection is typically bacterial (▶Video 6.1).

I. Preoperative

1. 
   

   History and physical exam

   
   
   
   
   1. 
      

      Presentation:

      
      
      
      
      1. 
         

         Purulent discharge from the surgical site and/or incision with or without associated erythema, tenderness, or fever.

         
         
      2. 
         

         Symptoms (local or regional pain or joint stiffness) which may be less obvious signs of infection.

         
         
      3. 
         

         Absence of radiologic evidence of bone healing after several months, with or without fixation failure, may also suggest infection.

         
         
      4. 
         

         Intermittent fevers, chills, sweats (particularly, night sweats in the setting of chronic infections), and general malaise are common symptoms.

         
         
      5. 
         

         An untreated infection may progress rapidly and threaten the limb, lead to septic shock, or even lead to death.

      
      
   2. 
      

      Physical exam findings at the surgical site:

      
      
      
      
      1. 
         

         Pain.

         
         
      2. 
         

         Erythema or overlying cellulitis (▶ Fig. 6.1 ).

         

         
         
      3. 
         

         Drainage.

         
         
      4. 
         

         External appearance may be benign with deep space infection.

      
      
   3. 
      

      Host risk factors for developing infection:

      
      
      
      
      1. 
         

         Diabetes mellitus.

         
         
         
         
         • 
           

           i. Perioperative hyperglycemia.

           
           
         • 
           

           ii. Micro- and macrovascular disease.

           
           
         • 
           

           iii. Immunologic dysfunction.

         
         
      2. 
         

         Peripheral vascular disease.

         
         
      3. 
         

         Malnutrition.

         
         
      4. 
         

         Obesity.

         
         
      5. 
         

         Advanced age.

         
         
      6. 
         

         Immunocompromised (HIV).

         
         
      7. 
         

         Immunomodulating drugs:

         
         
         
         
         • 
           

           i. Steroid treatment.

           
           
         • 
           

           ii. Chemotherapy (cancer treatment).

           
           
         • 
           

           iii. Disease-modifying anti-rheumatic drugs (DMARDs) for autoimmune disorders.

         
         
      8. 
         

         Polytrauma.

II. Anatomy of Infection

1. 
   

   Superficial surgical site infection

   
   
   
   
   1. 
      

      Early fracture site colonization and proliferation.

      
      
   2. 
      

      Affects the incision but does not extend to the fracture site and remains superficial to the level of the fascia.

   
   
2. 
   

   Deep surgical site infection

   
   
   
   
   1. 
      

      Infection that penetrates deep to fascia and involves the fracture site.

      
      
   2. 
      

      Surgical devices represent a substrate for microbial colonization and biofilm-associated infection.

      
      
      
      
      1. 
         

         Variety of organisms have been associated with indwelling implants, some of the most common are:

         
         
         
         
         • 
           

           i. Staphylococcus (aureus, epidermidis).

           
           
         • 
           

           ii. Streptococcus pyogenes.

           
           
         • 
           

           iii. Klebsiella pneumoniae.

           
           
         • 
           

           iv. Pseudomonas aeruginosa.

           
           
         • 
           

           v. Acinetobacter baumannii.

           
           
         • 
           

           vi. Escherichia coli.

      
      
   3. 
      

      Pathogenesis of biofilm includes following four stages (▶ Fig. 6.2 ):

      

      
      
      
      
      1. 
         

         Planktonic—free-floating which represents the inoculation phase.

         
         
      2. 
         

         Sessile phase: bacteria settle and form a mature biofilm.

         
         
      3. 
         

         Persister cells: dormant, multidrug tolerant cells that live within mature biofilm and have the ability to repopulate the biofilm.

         
         
      4. 
         

         Quorum-sensing molecules: chemomodulators within a mature biofilm permitting intercellular communication to permit bacterial resistance.