Orthopedic Emergencies: Expert Management for the Emergency Physician 1st Ed.

Chapter 8. Orthopedic infections and other complications

Stephen Y. Liang, Michael C. Bond and Michael K. Abraham

Orthopedic Emergencies, ed. Michael C. Bond, Andrew D. Perron, and Michael K. Abraham. Published by Cambridge University Press. © Cambridge University Press 2013.

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:

o   Joint effusion with erythema, warmth, and tenderness

o   Painful or limited range of motion

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

o   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

o   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

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

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

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

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

o   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)

o   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

o   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

o   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

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

·        Surgery

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

o   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:

o   Pain with passive extension of the finger

o   Semi-flexed position of the finger at rest

o   Symmetric swelling of the finger (sausage digit)

o   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

o   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

o   In combination with one of the following:

§  Ciprofloxacin 500 mg PO twice daily

§  Ceftriaxone 2 g IV once daily

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

§  Ampicillin–sulbactam 3 g IV every 6 hours

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

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

·        Surgery

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

o   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

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

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

o   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

o   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

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

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

o   Administer tetanus prophylaxis if indicated

o   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

o   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

o   Surgery

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

o   Administer tetanus prophylaxis if indicated

o   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:

o   Erythema, warmth, swelling, and tenderness to palpation

o   Limited or painful range of motion of an adjacent joint

o   Draining sinus tract (chronic osteomyelitis)

o   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

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

o   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

o   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

o   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

o   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

o   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

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

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

·        Surgery

o   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

Prognosis

·        Outcomes are dependent on early diagnosis, antibiotic therapy, and operative debridement of infected bone, particularly in the setting of acute osteomyelitis

·        Complications of untreated disease can include pathologic fracture, suppurative disease, and sepsis

·        Chronic osteomyelitis can be a relapsing and remitting infection, even despite appropriate antibiotic therapy and surgical intervention

PEARL: Aggressive surgical debridement and appropriate antibiotic therapy (guided by culture) are essential to the successful treatment of osteomyelitis.

Vertebral osteomyelitis and discitis

Key facts

·        Infection of the vertebrae (vertebral osteomyelitis) can result from hematogenous spread (e.g., bacteremia associated with endocarditis, urinary tract infection, or intravascular device infection), contiguous spread of an adjacent soft-tissue infection, or direct inoculation (e.g., trauma or spine surgery)

·        Intervertebral disc spaces adjacent to infected vertebrae can subsequently become infected (discitis) as well

·        Often seen in patients with underlying diabetes mellitus, intravenous drug abuse, immunosuppression, malignancy, or chronic kidney disease requiring hemodialysis

·        Staphylococcus aureusStreptococcusEscherichia coli, and Pseudomonas aeruginosa are common causative organisms

Clinical presentation

·        Back pain is a predominant complaint and may evolve over days to weeks, often without fever

·        Neurologic symptoms including radiculopathy, sensory deficits, extremity weakness or paralysis, and urinary retention are uncommon unless an epidural abscess has formed

·        Examination may reveal tenderness on palpation of the affected vertebrae

PEARL: The most common site for vertebral osteomyelitis is the lumbar spine, followed by the thoracic and cervical spine.

Diagnostic testing

·        Check CBC, ESR, and C-reactive protein

·        Obtain blood cultures prior to administering antibiotics

·        Plain radiography of the spine may reveal vertebral endplate destruction and intervertebral disc space narrowing, but can be normal within the first few days to weeks of symptom onset

·        MRI is highly sensitive and specific for detecting vertebral osteomyelitis, discitis, and epidural abscess, even in its earliest stages

·        CT can be helpful in identifying cortical destruction and adjacent soft-tissue infection when MRI is not possible

·        Biopsy and culture of the affected vertebral bone or disc space, either by a surgeon or interventional radiologist, confirms the diagnosis

PEARL: Vertebral osteomyelitis presenting as non-specific back pain frequently leads to diagnostic delay, resulting in significant morbidity and adverse sequelae.

Treatment

·        Antibiotic therapy

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

o   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

o   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

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

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

·        Surgery

o   Spine surgery consultation is warranted in the following instances:

§  Cord compression or threatened cord compression caused by vertebral instability requiring stabilization and spinal decompression

§  Epidural or paravertebral abscess requiring operative drainage

§  Vertebral osteomyelitis because of infected spinal hardware requiring debridement and removal

·        Admit to hospital

Prognosis

·        Serious neurological complications (particularly with cervical spine osteomyelitis) can result from epidural abscess and cord compression when not identified early

·        Other complications may include paravertebral or psoas abscesses

·        Relapsing infection may occur, even despite appropriate antibiotic therapy and surgical intervention

PEARL: In most cases, antibiotic therapy alone guided by culture is sufficient to treat vertebral osteomyelitis.

Open fracture management

Key facts

·        Open fractures are at significant risk of contamination with skin flora (primarily Staphylococcus aureus) and bacteria present in the environment that can lead to post-traumatic osteomyelitis, particularly in tibial fractures

·        Early operative irrigation and debridement by an orthopedic surgeon reduces organism burden and is crucial to preventing later infections

·        Administration of prophylactic antibiotics soon after the time of injury can further reduce the risk of infection

o   Initial antibiotic prophylaxis in the ED should be guided by the Gustilo open-fracture classification (Table 8.1):

o   In areas seeing high rates of methicillin-resistant S. aureus (MRSA), the use of vancomycin in place of cefazolin may be considered

o   Duration of prophylaxis is dependent upon the extent of contamination and timing of surgical intervention

o   Antibiotic prophylaxis is unnecessary in open fractures resulting from low-velocity civilian gunshot wounds that do not require open reduction and internal fixation

·        Tetanus prophylaxis should be provided when indicated

PEARL: Early surgical intervention and antibiotic prophylaxis after an open fracture can significantly prevent later infectious complications.

Table 8.1 Gustilo open-fracture classification.



* Prophylaxis against Gram-negative organisms (including Pseudomonas aeruginosa) remains controversial but is recommended by some experts.

Compartment syndrome

Key facts

·        Normal compartment pressures are < 10 mmHg

·        Pressures > 20 mmHg are associated with impaired capillary blood flow and ischemia; however, this is also dependent on the diastolic blood pressure. The higher the diastolic blood pressure the less likely there will be compromised capillary blood flow

·        An increase in pressure in muscular compartments of the body can lead to death or loss of a limb

·        Compartment syndrome is classically associated with symptoms described as the five “P”s

o   Pain out of proportion to what is expected

o   Paresthesia

o   Pallor

o   Paralysis

o   Pulselessness

·        The loss of pulses is very uncommon and a very late sign. This ischemia occurs with loss of capillary flow, which occurs at pressures much lower than arterial blood pressures

·        The pressure in the compartment must be relieved in order to prevent long-term damage. This can be done via a fasciotomy

Clinical presentation

·        The majority of patients will present complaining of a painful and numb extremity

PEARL: Consider compartment syndrome in any patient with pain out of proportion to the injury or examination.

·        The onset of compartment syndrome is often linked to:

o   Burns

o   Envenomation from insects, snakes, or marine animals

o   Injection into the compartment (i.e., high-pressure injection injuries, intravenous drug abuse, infusion of medications or intravenous contrast)

o   Overuse (i.e., repetitive exercises leading to edema and rhabdomyolysis)

o   Recent trauma (i.e., fractures, crush injuries)

o   Restrictive jewelry, clothing or casts

·        Affected limb often held in flexion to reduce the stretch of the affected compartment, and pain is increased with extension of the limb

PEARL: Pain with stretching of the affected muscle groups is the most sensitive sign of compartment syndrome.

·        Physical examination findings consistent with compartment syndrome are:

o   Pain out of proportion to light touch

o   Paresthesia

o   Diminished capillary refill

o   Tense and swollen skin

Diagnostic testing

·        Definitive test is to measure the intra-compartment pressure

o   No laboratory or radiology studies can make the diagnosis

o   Check CBC, creatinine kinase (exclude rhabdomyolysis), renal function studies (exclude renal insufficiency secondary to rhabdomyolysis)

o   Obtain plain radiographs of the affected limb to exclude fracture

·        Measuring the intra-compartment pressure:

o   Intra-compartment pressures should be < 20 mmHg

o   Several techniques are available to test the compartment pressure

§  Stryker pressure tonometer:

§  A commercial device that measures the pressure needed to inject a small amount of fluid into the compartment

§  A self-contained unit that has a measure gauge, needle, and plunger

§  Can quickly estimate the pressure in the compartments

§  Pressure transducer – can be set up with supplies commonly found in the ED

§  Supplies needed:

§  1–4-way stopcock

§  1 – sterile 20 ml Luer-Lok syringe

§  2 – IV extension tubing sets

§  2 – 18-gauge needles

§  1 – bag of normal saline

§  1 – blood pressure manometer (manual guage)

§  Several gauze pads

§  Chlorhexidine scrub

§  Set up

§  Connect the 4-way stopcock to the 20 ml syringe

§  Connect one end of the IV extension tubing to the blood pressure manometer and the other end to a port on the stopcock

§  Connect the other IV extension tubing to another port on the stopcock and then to the bag of normal saline

§  Open the stopcock so that only the syringe and bag of normal saline are open

§  Aspirate U+223C15 ml of normal saline into the syringe

§  Disconnect the normal saline bag and attach an 18-gauge needle to the extension tubing

§  Clean the affected extremity with chlorhexidine

§  Using aseptic technique insert the 18-gauge needle into a compartment of the affected extremity

§  Turn the stopcock so that the syringe and both sets of IV tubing are open

§  Slowly and gently depress the plunger while watching the air/water meniscus that should be just below the syringe

§  The meniscus will move once the pressure on the syringe exceeds the pressure in the compartment. The pressure reading on the manometer at this point is the pressure in the compartment. Record in mmHg

Treatment

·        Reduce swelling in the extremity (i.e., elevate, apply ice)

·        Provide adequate pain control

·        Remove any restrictive clothing, splints, casts, jewelry, etc

·        Fasciotomy (consult orthopedics, surgeon or perform yourself if consultants are not available)

·        Treat the underlying cause (i.e., reduce fractures, provide appropriate antivenom)

·        Admit to hospital

o   All patients at high risk for development of compartment syndrome or those that have it should be admitted for definitive treatment and serial examinations

Prognosis

·        Prognosis depends on the duration of symptoms and how quickly the pressures can be lowered

·        A fasciotomy done within 6 hours of onset of pain is associated with good outcomes

·        A fasciotomy done > 6 hours is often associated with irreversible necrosis and permanent disability

Selected readings and references

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