Lyme Arthritis Symptoms in Children: Knee Swelling and Limping

Lyme arthritis symptoms in children most commonly include swelling of the knee or other large joints. This late manifestation of Lyme disease may appear weeks to months after the initial infection and may occur even when no tick bite or rash was recognized.

Because joint swelling may appear long after infection, Lyme arthritis can be mistaken for other joint conditions. Recognizing the characteristic pattern helps clinicians and parents consider Lyme disease earlier.

For a broader overview, see the Pediatric Lyme Disease guide.

Common Lyme Arthritis Symptoms in Children

Lyme arthritis symptoms in children usually involve one or more large joints.

• Swelling of a single knee
• Joint stiffness
• Limping
• Reduced activity or difficulty walking
• Occasional joint pain

In many children, swelling may be more noticeable than pain.

In some cases, the first sign parents notice is simply a sudden limp rather than severe pain.

When Lyme Arthritis Appears

Lyme arthritis usually develops weeks to months after the initial infection. By the time joint swelling occurs, early symptoms such as fever, fatigue, or rash may have resolved.

This delayed presentation often explains why the connection to tick exposure is missed.

Large Joint Involvement Is Typical

Lyme arthritis most commonly affects large joints. The knee is involved in the majority of pediatric cases.

Other joints such as the ankle, elbow, or wrist may also be affected, but knee swelling remains the most common finding.

Lyme arthritis often affects a single knee rather than multiple joints.

Clinical Clues That Suggest Lyme Arthritis

• Swelling of a single large joint
• Knee swelling without clear injury
• Joint swelling greater than pain
• Sudden limping in an otherwise healthy child
• Symptoms after outdoor exposure in tick-endemic areas
• Minimal fever compared with septic arthritis

Recurrent or Intermittent Joint Symptoms

Lyme arthritis may follow an intermittent pattern. Joint swelling may improve temporarily and then recur in the same joint or in another joint.

This fluctuating course can make diagnosis more challenging.

Why Lyme Arthritis Is Often Missed

Lyme arthritis symptoms in children may not be immediately recognized because:

• No tick bite was remembered
• A rash was absent or unnoticed
• Symptoms appear weeks or months after infection
• Joint swelling resembles other arthritis conditions

Because of these factors, Lyme disease may not initially be suspected.

Evidence From a Pediatric Study

A study from a pediatric rheumatology clinic in Nova Scotia examined children diagnosed with Lyme arthritis between 2006 and 2013.

Seventeen children were identified. Most presented with painful or swollen joints, and 94% had knee involvement.

Only three of the 17 children had a history of erythema migrans, and only four recalled a tick bite.

Lyme disease was initially suspected by the referring physician in only about one-third of cases.

These findings highlight that tick bite history and rash are not reliable markers for Lyme arthritis.

Conditions That May Mimic Lyme Arthritis

Several conditions may resemble Lyme arthritis in children.

• Septic arthritis
• Juvenile idiopathic arthritis
• Reactive arthritis
• Joint injury

Careful evaluation is important to distinguish among these conditions.

When Parents Should Seek Medical Evaluation

Parents should consider medical evaluation if a child develops:

• Unexplained knee swelling
• Limping without injury
• Persistent joint swelling lasting several days
• Reduced activity or difficulty walking

These symptoms warrant evaluation, especially in regions where Lyme disease is common.

Most Children Recover With Treatment

Most children with Lyme arthritis respond well to antibiotic therapy.

Joint swelling usually resolves after treatment, although recovery may take time.

A small number of children develop antibiotic-refractory Lyme arthritis, where joint inflammation persists despite antibiotic therapy.

Clinical Perspective

In my practice, children with Lyme arthritis often present with a swollen knee and relatively little pain. Parents may notice that their child suddenly begins limping or stops participating in sports.

When unexplained knee swelling occurs—especially in tick-endemic areas—Lyme disease should remain part of the differential diagnosis.

Reference

• Glaude, P. D., Huber, A. M., Mailman, T., Ramsey, S., Lang, B., & Stringer, E. (2015). Clinical characteristics, treatment and outcome of children with Lyme arthritis in Nova Scotia. Canadian Journal of Infectious Diseases and Medical Microbiology, 26(6), 321–324. https://doi.org/10.1155/2015/152095