Orthopaedic Surgery - Lyme Disease

Basics

Lyme disease is a tick-borne infection caused by Borrelia burgdorferi that can produce inflammatory manifestations involving the skin, joints, heart, and nervous system.

Both children and adults may be affected.

Musculoskeletal involvement is particularly important because Lyme disease can present with:

Arthralgia, synovitis, or a large joint effusion, most commonly involving the knee.

Lyme disease is also historically known as deer tick disease.

Classification

Lyme disease can be considered in early and later stages.

Early Disease

Early manifestations may include:

Erythema migrans

Fever

Headache

Fatigue

Myalgia

Migratory arthralgia

Early disseminated disease may also produce neurologic or cardiac findings.

Later Disease

Later manifestations may include:

Lyme arthritis

Persistent or intermittent synovitis

Carditis

Peripheral or cranial neuropathy

Other neurologic manifestations may also occur.

Prevention

Prevention is based primarily on reducing tick exposure.

Important measures include:

Awareness of endemic regions, protective clothing, use of appropriate tick repellents, inspection for ticks after outdoor activity, and prompt removal of attached ticks.

Epidemiology

The incidence of Lyme disease varies substantially according to geographic location.

In the United States, the highest incidence occurs primarily in:

The Northeast and upper mid-Atlantic regions

The upper Midwest, particularly Wisconsin and Minnesota

Selected areas of the Pacific Coast

Historical descriptions listed cases from many other states, but risk is concentrated in areas where infected Ixodes ticks are established.

Risk Factors

Important risk factors include:

Residence in or travel to an endemic region

Exposure to wooded, brushy, or grassy environments

Contact with infected Ixodes ticks

Certain host immune-genetic characteristics have also been associated with persistent inflammatory manifestations.

Genetics

Some older studies linked the HLA-DR4 haplotype with an increased tendency toward persistent Lyme arthritis.

However, Lyme disease itself is an acquired infection rather than an inherited disorder.

Etiology

Lyme disease results from infection with the spirochete Borrelia burgdorferi.

Transmission occurs through infected Ixodes ticks.

In the northeastern and upper midwestern United States, the principal vector is Ixodes scapularis, historically referred to as Ixodes dammini.

In the western United States, Ixodes pacificus is the principal vector.

Historical Background

The disease became widely recognized after a cluster of patients with apparent juvenile arthritis was investigated in the region around Old Lyme, Connecticut, during the mid-1970s.

Subsequent investigation identified the tick-borne spirochetal cause and additional endemic regions.

Diagnosis

Signs and Symptoms

The clinical presentation depends on the stage of infection.

Early Lyme Disease

Erythema Migrans

The characteristic early skin lesion is erythema migrans.

It usually begins approximately 3–30 days after an infected tick bite.

The lesion gradually expands and may appear:

Oval, circular, uniformly erythematous, or occasionally target-like.

Not every erythema migrans lesion has classic central clearing.

Systemic Symptoms

Early infection may also produce:

Fever, headache, fatigue, malaise, myalgia, and migratory arthralgia.

Lyme Arthritis

Arthritis usually occurs later in the disease course.

The characteristic presentation is:

Intermittent or persistent swelling of one or several large joints, particularly the knee.

Pain

A striking feature may be a relatively large effusion with less pain than would be expected from the degree of swelling.

However, some patients can present with substantial pain and a picture resembling acute bacterial arthritis.

Cardiac Involvement

Lyme carditis may cause:

Atrioventricular conduction block, palpitations, syncope, or myocarditis.

The severity of conduction disturbance can fluctuate rapidly.

Neurologic Involvement

Neurologic manifestations may include:

Facial nerve palsy

Meningitis or meningoencephalitis

Radiculopathy

Peripheral neuropathy

Cranial nerve VII involvement with facial weakness is a well-recognized presentation.

Physical Examination

Skin

Inspect carefully for:

An expanding erythematous lesion compatible with erythema migrans.

Because the rash may have resolved before presentation, ask specifically about any previous expanding rash after possible tick exposure.

Neurologic Examination

Assess for:

Facial weakness, cranial neuropathy, sensory abnormalities, motor deficits, and signs of meningeal irritation or peripheral nerve involvement.

Joint Examination

Examine all major joints for:

Effusion, warmth, limited motion, tenderness, and synovitis.

A large painless or minimally painful knee effusion should raise suspicion for Lyme arthritis when epidemiologic exposure is compatible.

Cardiovascular Examination

Assess for:

Bradycardia, irregular rhythm, or other signs suggesting conduction abnormality.

Patients with symptoms of carditis require further cardiac evaluation.

Laboratory Tests

Laboratory testing depends on the clinical presentation.

Inflammatory Markers

The ESR and CRP may be elevated, particularly with arthritis, but these findings are nonspecific.

Serologic Testing

Diagnosis in patients without a classic erythema migrans lesion generally relies on two-tier serologic testing.

Historically, this involved:

An initial enzyme immunoassay followed by a more specific immunoblot when the screening test was positive or equivocal.

Modern testing may also use a modified two-enzyme-immunoassay strategy.

Serologic results must be interpreted according to:

Timing of infection, clinical presentation, and pretest probability.

Early infection may occasionally be seronegative before antibodies develop.

Arthrocentesis

Joint aspiration is not specific for Lyme disease but is often important when a patient presents with an acutely swollen joint.

It helps distinguish Lyme arthritis from:

Bacterial septic arthritis, crystal disease, and other inflammatory disorders.

Synovial Fluid

Lyme arthritis may produce a substantial inflammatory leukocyte count, historically reported around:

25,000–90,000 cells/mm³, often with a high proportion of neutrophils.

There is considerable overlap with bacterial arthritis, so synovial leukocyte count alone cannot reliably distinguish the two.

Organism Detection

Routine culture of synovial fluid does not recover the spirochete reliably.

Diagnosis is therefore based mainly on:

Clinical features and serologic evidence.

Electrocardiography

An ECG should be obtained when cardiac involvement is suspected.

It may demonstrate:

PR-interval prolongation or higher-degree atrioventricular block.

Imaging

Plain Radiographs

Radiographs of an affected joint are often nonspecific but may help exclude other causes of arthritis.

Early changes can include:

Soft-tissue swelling and joint effusion.

With prolonged inflammation, findings may include:

Periarticular osteopenia and, rarely, chronic joint-space changes.

Pathological Findings

Biopsy is rarely required.

When synovial tissue is examined, the findings generally show nonspecific inflammatory synovitis.

Differential Diagnosis

Important alternatives include:

Juvenile idiopathic arthritis

Bacterial septic arthritis

Rheumatic fever

Reactive arthritis

Other inflammatory arthropathies

Juvenile Idiopathic Arthritis

JIA generally requires persistent arthritis over a prolonged period and is not expected to resolve with antimicrobial treatment.

Lyme arthritis can closely mimic JIA, especially when pain is mild despite marked swelling.

Bacterial Septic Arthritis

Bacterial arthritis more commonly produces:

Severe acute pain, fever, inability to bear weight, pronounced tenderness, and systemic illness.

However, overlap can occur, so suspected septic arthritis must be evaluated urgently rather than excluded solely because Lyme disease is possible.

Rheumatic Fever

Acute rheumatic fever should be considered when there is:

Migratory polyarthritis, recent streptococcal infection, carditis, or other compatible systemic findings.

Treatment

General Measures

Management should be coordinated according to organ involvement.

Consultation with:

Infectious disease, neurology, rheumatology, or cardiology

may be appropriate in complicated cases.

Activity

Activity should be reduced when there is substantial:

Joint inflammation, cardiac involvement, or neurologic dysfunction.

Once symptoms improve, activity can be increased gradually.

Antibiotic Therapy

Treatment depends on the stage and manifestations of disease.

Early Localized Disease

Oral therapy is usually appropriate.

Common agents include:

Doxycycline, amoxicillin, or cefuroxime axetil, depending on age, pregnancy status, allergies, and other clinical factors.

Doxycycline in Children

Older teaching avoided tetracyclines in children younger than 8 years because of concern for tooth discoloration.

Current practice allows short courses of doxycycline in young children when clinically indicated, because modern evidence indicates minimal risk of permanent dental staining with brief treatment.

Lyme Arthritis

Lyme arthritis is generally treated initially with an appropriate course of oral antibiotics.

Persistent arthritis after initial therapy may require:

A second antimicrobial course or intravenous therapy in selected patients, depending on the clinical situation.

Neurologic or Cardiac Disease

More severe neurologic or cardiac manifestations may require:

Intravenous antibiotics and hospitalization, particularly when high-grade heart block or significant neurologic dysfunction is present.

Surgery

Surgery is rarely required.

Synovectomy

Synovectomy may be considered only in unusual cases of persistent inflammatory synovitis that continues despite:

Adequate antimicrobial treatment and appropriate specialist management.

Most patients do not require operative intervention.

Follow-Up

Prognosis

The overall prognosis is good, particularly when Lyme disease is recognized and treated appropriately.

Most patients recover without permanent joint damage.

Persistent Symptoms

A minority may experience:

Persistent synovitis, recurrent joint swelling, or prolonged neurologic symptoms.

Postinfectious inflammatory arthritis may persist even after the organism has been eradicated.

Complications

Potential complications include:

Lyme carditis with conduction block

Myocarditis

Facial or other cranial nerve palsy

Peripheral neuropathy

Meningitis or other neurologic involvement

Persistent inflammatory arthritis

Patient Monitoring

Follow-up frequency depends on disease severity.

Patients with uncomplicated disease can usually be followed clinically until:

Symptoms resolve and joint function returns.

Patients with significant cardiac or neurologic involvement require much closer monitoring and may need hospitalization.

Monitoring should include:

Joint swelling, pain, range of motion, neurologic function, cardiac symptoms, and response to antibiotic therapy.

New syncope, chest symptoms, progressive neurologic deficits, severe headache, fever, or a rapidly painful swollen joint should prompt urgent reassessment.