Signs of Infection After Total Knee Replacement

Periprosthetic joint infection (PJI) is a serious complication. Watch for:

• Fever and chills (may be low-grade or absent in chronic/low-virulence infections)
• Knee swelling (new or increasing, tense, warm)
• Increased pain at surgical site (worsening, night pain, pain at rest)
• Warmth to touch over the joint
• Redness or drainage from incision (purulent, serosanguineous)
• Foul-smelling incision discharge
• Difficulty moving knee (new stiffness, giving way)
• General malaise, fatigue, loss of appetite
• Elevated inflammatory markers: CRP, ESR (blood tests)

Timing

• Early (≤4 weeks): Usually acute, aggressive organisms (Staph aureus, strep).
• Delayed (1–3 months): Often less virulent (Coagulase-negative Staph, Cutibacterium).
• Late (>3 months): Hematogenous seeding (dental, skin, UTI) or late chronic.

Action

Contact your orthopedic surgeon immediately if any signs appear. Diagnosis: aspiration (cell count, culture, alpha-defensin, leukocyte esterase), blood work, imaging. Treatment: antibiotics ± debridement (DAIR), 1- or 2-stage revision. Early detection saves the implant.