Lyme Arthritis in Children: Knee Swelling Without Rash
Lyme arthritis in children may present with swollen knees without rash
Children may not recall a tick bite before symptoms develop
Early recognition may help prevent delayed diagnosis and joint complications
Lyme arthritis in children may appear months after a tick bite and often presents without a recognized early Lyme disease rash. In some cases, children develop unexplained knee swelling, limping, or gait changes long after the original infection has gone unnoticed.
Because symptoms may develop gradually, Lyme arthritis may initially be mistaken for sports injuries, growing pains, transient synovitis, juvenile arthritis, or orthopedic problems.
Guardado and Sergent described a child with unilateral knee swelling caused by Lyme disease despite no initial history of rash or recalled tick bite.
Child With Knee Swelling Without Rash
The child presented with significant right knee swelling, gait instability, and decreased range of motion caused by joint effusion.
The mother initially denied any history of tick exposure. However, after more detailed questioning, she later recalled the child had ticks on her approximately nine months earlier.
The child had not been evaluated at the time because no rash developed to suggest Lyme disease.
On examination, the child demonstrated:
- Right knee effusion
- Reduced range of motion
- Unsteady gait
- Swelling without significant skin changes
A Western blot test later confirmed Lyme disease.
Lyme Arthritis May Present Months Later
Lyme arthritis in children may develop long after the initial tick bite. Many children never develop or recognize an erythema migrans rash.
Instead, the first visible sign may be:
- Knee swelling
- Joint fluid accumulation
- Limping or gait instability
- Monoarticular arthritis
Large joints such as the knee are most commonly affected.
Children with Lyme disease symptoms may also experience fatigue, headaches, irritability, muscle pain, or intermittent joint symptoms before arthritis becomes obvious.
Why Lyme Arthritis Is Missed in Children
Lyme arthritis may be overlooked when children do not recall a tick bite or fail to develop the classic rash.
In endemic regions, Lyme disease should be considered in cases of swollen knee in a child without clear injury or trauma.
Clinicians may need to consider Lyme disease in children presenting with:
- Unexplained knee swelling
- Knee effusion without injury
- Intermittent limping
- Monoarticular arthritis
- Persistent joint swelling
Delayed diagnosis may prolong symptoms and, in some cases, increase the risk of chronic inflammatory joint changes.
Can Lyme Arthritis Become Chronic?
The authors warned that missed Lyme arthritis may occasionally lead to long-term morbidity that becomes more difficult to treat.
Some children with delayed diagnosis may develop persistent inflammatory arthritis despite antibiotic therapy.
In severe cases, prolonged inflammation has occasionally required synovectomy or more advanced rheumatologic management.
Early recognition and treatment may help reduce the risk of chronic complications.
How Lyme Arthritis in Children Is Treated
The child in this report experienced complete symptom resolution after treatment with intravenous ceftriaxone (Rocephin) followed by oral amoxicillin.
Lyme arthritis treatment may vary depending on:
- Severity of joint involvement
- Neurologic symptoms
- Treatment response
- Duration of illness
Children with persistent symptoms after treatment may require reassessment for ongoing inflammation, coinfections, or other overlapping conditions.
When to Suspect Lyme Arthritis in a Child
Clinicians and parents may consider Lyme disease evaluation when a child develops:
- Swollen knee without injury
- Persistent or recurrent knee fluid
- Limping or gait changes
- Joint swelling without fever
- Symptoms after outdoor tick exposure
Children living in Lyme-endemic regions may not remember tick bites, and symptoms may appear long after exposure.
These cases also overlap with broader concerns regarding delayed Lyme disease diagnosis when early symptoms are missed or never recognized.
Frequently Asked Questions
Can Lyme disease cause knee swelling in children?
Yes. Lyme arthritis commonly affects the knee and may cause swelling, joint fluid accumulation, limping, or reduced range of motion in children.
Can a child have Lyme arthritis without a rash?
Yes. Many children with Lyme arthritis never develop or recognize a bullseye rash before joint symptoms appear.
What joints are most commonly affected by Lyme arthritis?
The knee is the most commonly affected joint, although other large joints may occasionally be involved.
Can Lyme arthritis appear months after a tick bite?
Yes. Lyme arthritis may develop weeks or months after the original infection, even when the tick bite was unnoticed.
Can delayed Lyme arthritis become chronic?
Some children with delayed diagnosis may develop persistent inflammatory arthritis requiring prolonged management or additional treatment.
Clinical Takeaway
Lyme arthritis in children may present with swollen knees, limping, or joint effusion long after the original infection occurred.
Because many children do not recall tick exposure or develop a classic rash, Lyme disease may initially be overlooked in cases of unexplained monoarticular arthritis.
Early recognition of Lyme arthritis may help prevent delayed diagnosis, prolonged inflammation, and chronic joint complications in children.
Related Articles
These related articles explore pediatric Lyme disease, delayed diagnosis, knee arthritis, and treatment-related complications.
Will Steroid Injections Help Children With Lyme Arthritis of the Knee?
Preventing Unnecessary Surgery for Children With Lyme Arthritis
Why Pediatric Lyme Disease Is Misdiagnosed
Lyme Disease Symptoms Guide
Delayed Lyme Disease Diagnosis
References
- Guardado KE, Sergent S. Pediatric unilateral knee swelling: a case report of a complicated differential diagnosis and often overlooked cause. J Osteopath Med. 2022;122(2):105-109.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
My son has been suffering from Lyme for 5 years now. He has terrible knee pain and his gait has always been off for the past few years as well. The thing is his doctor does not think he has or had Lyme. Is there any treatment he can get for the pain?
I find a second opinion may help.
Could this happen in adults with Lyme as well? I am 57. Have been in and out of symptoms of Lyme since being diagnosed back in 2019. Was treated with longer term antibiotics, helped at first, but knee swelling and numbness still happening, seems worse in wet or humid weather. I hobble along with flare ups and sometimes need to use a walking stick or cane to help keep weight off it. Keep hoping it will get better, but it really doesn’t seem to improve. I wonder if it ever will. I have been getting so discouraged. The numbness and pins and needles sensation in the knee and thigh are difficult to deal with. Is anyone else going through this as an adult? Thanks.
I have also seen the problems in adults. I sometimes have had to change treatment.
My child is 4.5 and she has just finished 2 weeks of anti-biotics. However her knee seems to be worse now (taking longer each day before she starts to be active. Her gait is also seemingly completely off now when she is walking in-aided later in the day).
We have finished the prescribed 2 weeks. And will go back for further blood tests in another 2 weeks. Is it strange that symptoms have not subsided at all so far?
She has been taking Amoxicillin (Duomox).
I have patients who have not resolved their symptoms despite 2 weeks of antibiotics. The repeat test may not be all that helpful. The test may be negative due to antibiotics. Some doctors will not treat more than 2 weeks. Others do if their patient is still ill.
Thank you for your response. Is it the case that symptoms may well subside over more time, without further anti-biotics? In essence, should we be worried enough to bring forwards our next appointment on the basis of symptoms being worse now than at the start?
Some of my patient’s clear their symptoms over time. Others don’t. I am most concerned for my patients who have significant symptoms at the end of treatment.