Chapter 8 – Orthopedic infections and other complications



Chapter 8 Orthopedic infections and other complications




Stephen Y. Liang

Michael C. Bond

Michael K. Abraham



Septic arthritis



Key facts





  • Infection occurs primarily through hematogenous seeding of the joint (bacteremia)



  • Contiguous soft-tissue infection or direct inoculation of the joint (e.g., penetrating trauma, recent arthrocentesis or intra-articular injection) may also play a part, albeit to a lesser extent



  • Risk factors include age, diabetes mellitus, rheumatoid arthritis, joint surgery, prosthetic joint (hip or knee), skin infection, intravenous drug use, and alcoholism



  • Staphylococcus aureus and streptococcus are the primary infecting organisms seen in adults, although immunocompromised patients may also be at risk for Gram-negative infection



  • Disseminated Neisseria gonorrhoeae infection can present as septic arthritis and should be considered in sexually active adults




Clinical presentation





  • Joint pain that is worse with range of motion is a primary complaint, most commonly involving the knee or hip



  • Fever is often present



  • Examination of the affected joint may reveal:




    • Joint effusion with erythema, warmth, and tenderness



    • Painful or limited range of motion



    • Overlying cellulitis or pustules (seen with disseminated Neisseria gonorrhoeae infection[DGI])



    • Multiple joint involvement is occasionally seen, particularly with DGI or sepsis




  • Symptoms and examination findings may be minimal in the setting of immunosuppression




Diagnostic testing





  • Definitive diagnosis rests upon arthrocentesis of the affected joint, preferably before antibiotics are given




    • If the affected joint is a prosthetic joint, the arthocentesis should be done by an orthopedic surgeon, preferably under sterile conditions in order to prevent potential seeding of the joint



    • Synovial fluid should be sent for white blood cell (WBC) count with differential, Gram stain, and aerobic culture



    • Synovial WBC > 50,000 cells/mm3 is generally indicative of septic arthritis, but is not sensitive enough to rule it out



    • A differential with > 90% polymorphonuclear cells increases the likelihood of infection



    • Gram stain is only 50–60% sensitive for detection of bacteria in synovial fluid



    • If minimal synovial fluid is recovered, culture should take precedence over all other tests




  • Obtain blood cultures prior to administering antibiotics



  • Check CBC, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP)




    • Not helpful acutely but can be followed to ensure resolution of the disease




  • Consider plain radiographs of the affected joint to exclude joint destruction or associated osteomyelitis



  • Bedside ultrasound may aid in detecting a joint effusion and facilitating arthrocentesis




Treatment





  • Antibiotic therapy




    • Empiric coverage of Gram-positive organisms, including methicillin-resistant S. aureus (MRSA) is recommended pending culture and sensitivity




      • Vancomycin 15 mg/kg IV (based on actual body weight and normal renal function) every 12 hours




    • In immunocompromised patients, the addition of a third-generation cephalosporin should afford adequate empiric coverage of most Gram-negative bacteria




      • Ceftriaxone 2 g IV once daily



      • Ceftazidime 1–2 g IV every 8 hours



      • Cefotaxime 2 g IV every 8 hours




    • Coverage should always be narrowed once antibiotic sensitivities are known for any organisms cultured




  • Surgery




    • Orthopedic surgery consultation is advised as irrigation and operative debridement versus serial arthrocentesis of the infected joint may be necessary



    • Infections involving prosthetic joints often require hardware removal




  • Admit to the hospital




Prognosis





  • Timely diagnosis and treatment are the keys to reducing mortality and preventing poor functional outcomes



  • Complications of untreated septic arthritis can include joint destruction, osteomyelitis, suppurative disease, and sepsis




PEARL: Septic arthritis must be considered in the patient presenting with a swollen, painful joint, particularly in the absence of a preceding injury.



PEARL: An arthrocentesis for synovial fluid analysis and culture should always be performed if septic arthritis is suspected.



PEARL: Infected joints require orthopedic surgery consultation for consideration of irrigation and debridement in the operating room.



Infectious tenosynovitis



Key facts





  • Infection of the tendon sheath, often involving the flexor tendons of the hand and wrist



  • Typically associated with penetrating trauma (e.g., lacerations, bites, punctures, intravenous drug use)



  • May also result from contiguous spread of an adjacent soft-tissue infection or hematogenous spread (DG mycobacteria)



  • Staphylococcus aureus and streptococcal infections are the most common infecting organisms although Gram-negative bacilli may be seen with bites and in diabetics




PEARL: Infectious tenosynovitis is an orthopedic emergency that requires early consultation with a hand surgeon.



Clinical presentation





  • Kanavel’s four cardinal signs of flexor tenosynovitis include:




    • Pain with passive extension of the finger



    • Semi-flexed position of the finger at rest



    • Symmetric swelling of the finger (sausage digit)



    • Tenderness to percussion over the tendon sheath




  • Localized erythema, lymphangitic streaking, and fever may be present



  • Subcutaneous purulence (secondary to tendon sheath rupture) and digital ischemia signal advanced infection



  • Vesiculopustular lesions and polyarthralgias may accompany gonococcal tenosynovitis




PEARL: Pain with passive extension of the finger is often the earliest of Kanavel’s cardinal signs to appear.



Diagnostic testing





  • Check CBC



  • Definitive diagnosis requires Gram stain and culture of tendon sheath fluid by aspiration or during surgical intervention by a hand surgeon



  • Plain radiographs may be helpful in identifying associated fractures and foreign bodies




Treatment





  • Antibiotic therapy




    • Empiric coverage of Staphylococcus aureus (including MRSA), streptococcus, and Gram-negative bacilli can be achieved with:




      • Vancomycin 15 mg/kg IV (based on actual body weight and normal renal function) every 12 hours




    • In combination with one of the following:




      • Ciprofloxacin 500 mg PO twice daily



      • Ceftriaxone 2 g IV once daily




    • If a human or animal bite is involved and MRSA is not a primary concern, consider:




      • Ampicillin–sulbactam 3 g IV every 6 hours




    • Coverage should always be narrowed once antibiotic sensitivities are known for any organisms cultured



    • Early and mild cases may occasionally be managed with antibiotics, splinting, elevation, and close observation




  • Surgery




    • Hand surgery consultation should always be sought to determine if operative drainage and debridement is warranted



    • In severe cases, amputation may be required




  • Administer tetanus prophylaxis if indicated



  • Admit to hospital




Prognosis





  • Complications of untreated disease can include tendon scarring and necrosis, loss of function, proximal spread of infection, and even compartment syndrome




PEARL: Tenosynovitis in the absence of penetrating trauma, should raise suspicion for DGI.



Clenched fist injuries



Key facts





  • Commonly referred to as a “fight bite



  • Associated with wounds over the dorsum of a metacarpophalangeal (MCP) or proximal interphalangeal (PIP) joint sustained after striking an opponent’s teeth with a clenched fist




    • Classically involves the third or fourth MCP joint of the dominant hand



    • May result in damage to and contamination of the extensor tendon, tendon sheath, and/or joint capsule with human oral flora



    • Bacteria inoculated into the wound may travel proximally into the dorsal hand upon relaxation of the extensor tendon and unclenching of the fist




  • Infection can range from cellulitis to septic arthritis and soft tissue infections involving the deep spaces of the hand



  • Common infecting organisms include Staphylococcus aureus, streptococcus, corynebacterium, Eikenella corrodens, and anaerobic bacteria




Clinical presentation





  • Examination of the affected MCP or PIP joint shortly after the injury may reveal deceivingly small lacerations



  • Erythema, swelling, purulent wound discharge, and decreased range of motion developing several days after a clenched fist injury signal infection




PEARL: A clenched fist injury should be suspected in any patient presenting with lacerations over the dorsal aspect of the MCP joint.



Diagnostic testing





  • Gram stain and culture (aerobic and anaerobic) should be obtained from infected wounds along with blood cultures prior to administering antibiotics



  • Plain radiographs of the hand may reveal concomitant fractures or foreign bodies (e.g., tooth fragments) after the initial injury, or osteomyelitis in delayed presentations with infection




Treatment





  • Initial care of the uninfected fight bite




    • Extensor tendon injury and joint capsule involvement may require hand surgery consultation and should be carefully investigated by examining the wound with fingers flexed in a closed fist



    • If surgical consultation is not indicated, the wound should be thoroughly irrigated and allowed to heal by secondary intention



    • Antibiotic prophylaxis should consist of amoxicillin–clavulanate for 3 to 5 days



    • Administer tetanus prophylaxis if indicated



    • The wound should be re-evaluated by a healthcare provider within 24–48 hours





PEARL: Antibiotic prophylaxis is always indicated after a clenched fist injury given the high risk of infection.




  • Management of the infected fight bite




    • Antibiotic therapy




      • Empiric regimens include:




        • Ampicillin–sulbactam 3 g IV every 6 hours



        • Ceftriaxone 2 g IV once daily + metronidazole 500 mg IV/PO every 8 hours




      • Coverage should always be narrowed once antibiotic sensitivities are known for any organisms cultured




    • Surgery




      • Hand surgery consultation is advised as irrigation and operative debridement are often required




    • Administer tetanus prophylaxis if indicated



    • Admit to the hospital





PEARL: Infected fight bites should be evaluated by a hand surgeon for irrigation and debridement in the operating room.



Prognosis





  • Delayed presentation and inadequate debridement of infected wounds can lead to poor outcomes including septic arthritis, joint destruction, and loss of function




Osteomyelitis



Key facts





  • Infection of bone can result from hematogenous seeding (bacteremia), contiguous spread of an adjacent infection (e.g., cellulitis, abscess, infected ulcer), or direct inoculation (e.g., open fracture, orthopedic surgery)



  • Risk factors include diabetes mellitus, peripheral vascular disease, sickle cell disease, chronic corticosteroid use, immunosuppressed states (including HIV), joint disease, history of open fracture or orthopedic hardware, intravenous drug use, and alcoholism



  • Staphylococcus aureus, coagulase-negative staphylococci, and Gram-negative bacilli (including Pseudomonas aeruginosa) are commonly implicated organisms




Clinical presentation





  • Acute osteomyelitis is marked by localized pain, erythema, and swelling for several days with or without fever or malaise



  • Chronic osteomyelitis develops over a longer period of time and is more likely to present solely with non-specific symptoms



  • Examination of the affected site may reveal:




    • Erythema, warmth, swelling, and tenderness to palpation



    • Limited or painful range of motion of an adjacent joint



    • Draining sinus tract (chronic osteomyelitis)



    • Non-healing ulcer (chronic osteomyelitis)




      • Ulcer area > 2 cm2 and probing to bone within a diabetic foot ulcer are highly predictive of osteomyelitis






PEARL: Normal plain radiographs do not rule out osteomyelitis.



Diagnostic testing





  • Check CBC, ESR, and C-reactive protein



  • Obtain blood cultures prior to administering antibiotics



  • Superficial wound or sinus tract cultures are of limited use as they may not accurately reflect the organisms responsible for infection of the bone



  • Definitive diagnosis rests upon bone biopsy and culture




    • Consider discussing with orthopedics or admitting service on holding off on antibiotics until a bone biopsy or culture can be obtained



    • If septic, antibiotics should be started immediately after blood cultures are obtained




  • Plain radiography of the affected bone may reveal periosteal elevation or cortical bone destruction




    • Radiographic changes may not be evident within the first few days to weeks after onset of symptoms




  • MRI is highly sensitive and specific for detecting bone marrow edema, cortical destruction, soft-tissue infection (cellulitis, abscess), and sinus tracts, even in early disease



  • CT can be helpful in identifying cortical destruction when MRI is not possible




PEARL: MRI can be extremely useful in making the early diagnosis of osteomyelitis.



Treatment





  • Antibiotic therapy




    • In the absence of sepsis, neutropenia, or other critical illness, it is reasonable to briefly delay antibiotics in order to improve yield and better guide therapy if a bone biopsy and culture can be obtained in a timely manner



    • Empiric coverage of Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) is recommended pending culture and sensitivity:




      • Vancomycin 15 mg/kg IV (based on actual body weight and normal renal function) every 12 hours




    • Gram-negative coverage is also warranted with the addition of one of the following:




      • Cefepime 2 g IV every 12 hours



      • Ciprofloxacin 750 mg PO twice daily




    • Coverage should always be narrowed once antibiotic sensitivities are known for any organisms cultured



    • Infectious disease consultation is recommended as prolonged antibiotic therapy (typically 6 weeks) is needed




  • Surgery




    • Orthopedic surgery consultation is advised as operative debridement of infected or necrotic bone and removal of infected prosthetic hardware may be necessary




  • Admit to hospital


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Jan 19, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 8 – Orthopedic infections and other complications
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