Lyme Arthritis After Knee Replacement: A Case of Periprosthetic Joint Infection

Lyme arthritis can cause knee swelling and fluid buildup that mimics prosthetic joint infection following knee replacement—an uncommon but important clinical scenario.

This case illustrates how Lyme arthritis can present in unexpected ways, particularly after joint replacement.

For a full overview of Lyme arthritis, including symptoms, diagnosis, and treatment, see:
Lyme arthritis.

Case Report: Lyme Arthritis After Total Knee Replacement

In their article, “Medically Managed Lyme Periprosthetic Joint Infection: A Case Report,” Saar et al. describe a patient with acute Lyme arthritis complicated by prior knee replacement.

A 68-year-old man living in Virginia presented with suprapatellar swelling, pain, warmth, and mild erythema of the left knee. He reported pain with passive flexion and extension, along with a noticeable limp.

Twelve years earlier, the patient had undergone total knee arthroplasty for degenerative joint disease.

PCR testing of synovial fluid was positive for Borrelia. Although the joint was drained, follow-up testing continued to detect Borrelia DNA.

The patient was treated with a 90-day course of doxycycline.

Following treatment, swelling resolved and pain subsided.

The authors concluded that medical management may be a viable option in selected cases of Lyme-related periprosthetic joint infection.

Treatment Challenges in Lyme Periprosthetic Joint Infection

Lyme periprosthetic joint infections (PJI) are rare, and there are currently no standardized treatment guidelines.

Clinicians are often faced with combining two different treatment frameworks:

Lyme arthritis → typically treated with antibiotics
Periprosthetic joint infection → often treated with surgical intervention

This creates a clinical dilemma when Lyme disease presents in a prosthetic joint.

In the limited cases reported:

Most patients were treated with both surgery and antibiotics
A smaller number were successfully treated with antibiotics alone

This variability highlights the need for individualized clinical decision-making.

When to Suspect Lyme Disease in Joint Replacement Patients

Lyme disease should be considered in patients with joint replacement who present with:

Atraumatic knee swelling or joint effusion
Pain without a clear mechanical cause
Persistent inflammation despite standard treatment
Residence in or travel to tick-endemic regions

Failure to recognize Lyme disease in this setting can lead to unnecessary surgical intervention.

Clinical Insight

Lyme disease can mimic post-surgical complications.

When knee swelling persists after joint replacement and does not follow the expected recovery pattern, clinicians should reconsider the diagnosis and include Lyme disease in the differential.

This reflects a broader principle in Lyme disease:

Symptoms may resemble common conditions—but behave differently.

Clinical Takeaway

Lyme arthritis can present as a prosthetic joint infection, particularly when knee swelling occurs without a clear explanation.

In patients with unexplained joint effusion after knee replacement—especially in endemic areas—Lyme disease should be considered early in the evaluation.

Early recognition can help avoid unnecessary procedures and improve outcomes.

Lyme arthritis overview
Lyme disease knee pain
Lyme disease knee swelling
Lyme disease mimics prosthetic joint infection
Post-operative Lyme arthritis cases
MRI and Lyme arthritis in children