From the Guidelines
C-Reactive Protein (CRP) is expected to return to baseline within 2 months after surgery under normal circumstances. The duration of CRP elevation can vary depending on several factors, including the type and extent of surgery, presence of complications, and individual patient factors 44. According to a recent study, CRP has a sensitivity of 73% to 91% and a specificity of 81% to 86% for the diagnosis of prosthetic knee infection when a cutoff of 13.5 mg/L is used 1.
Factors Affecting CRP Elevation
- Type and extent of surgery: Major surgeries can cause elevations lasting 1-2 weeks, while minor procedures may have shorter durations 1
- Presence of complications: Infections, hematoma, or other post-surgical issues can lead to persistent elevation of CRP levels 1
- Individual patient factors: Age, underlying health conditions, and use of certain medications can influence the duration of CRP elevation 1
Clinical Significance of CRP Monitoring
Regular monitoring of CRP levels, combined with other clinical assessments, helps healthcare providers track recovery progress and detect potential complications early 1. A normal CRP level does not exclude infection, and a large multicenter study found CRP and joint aspiration to be the most useful tools to diagnose infection 1. The American Academy of Orthopaedic Surgeons (AAOS) guidelines strongly recommend the use of ESR, CRP, and serum interleukin-6 testing for patients being assessed for peri-prosthetic joint infection 1.
Diagnosis of Infection
The diagnosis of infection can be challenging, and laboratory findings are often nonspecific 1. However, a recent review suggests that the preoperative workup for periprosthetic infection should include serum ESR rate and CRP, serum D-dimer, synovial fluid culture, cell count, and differential, leukocyte esterase, alpha-defensin, and synovial fluid ESR 1. The use of an alpha-defensin laboratory test has been described for the diagnosis of peri-prosthetic joint infection, with high accuracy and sensitivity 1.
From the Research
C-Reactive Protein (CRP) Levels After Surgery
- CRP levels are expected to increase after surgery, with peak levels typically occurring on the second or third postoperative day 2, 3, 4, 5
- The extent of the CRP response is affected by the type and severity of the surgical trauma 2, 3
- In non-infected patients, CRP levels usually decrease after the third postoperative day, but may remain elevated for up to 7-14 days after surgery 6, 4, 5
- A second rise in CRP levels or persistently high levels after the fourth postoperative day may indicate a postoperative infection 2, 6, 5
- The normal range for CRP levels after surgery can vary, but levels above 10 mg/dl may indicate infection 2 or other complications
- It is essential to consider CRP levels in conjunction with clinical signs and other laboratory parameters to accurately diagnose postoperative infections 2, 5
Time Course of CRP Elevation
- Peak CRP levels: 2-3 days after surgery 2, 3, 5
- Decrease in CRP levels: after 3-4 days, but may remain elevated for up to 7-14 days 6, 4, 5
- Normalization of CRP levels: usually within 21 days after surgery 5