Relationship Between Pre- and Post-Operative C-Reactive Protein (CRP), Neutrophil-to-Lymphocyte Ratio (NLR), and Platelet-to-Lymphocyte Ratio (PLR) With Post-Operative Pain After Total Hip and Knee Arthroplasty: An Observational Study.

Background: Anesthetic technique and postoperative pain management are crucial for total joint arthroplasty (TJA) patients. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and C-reactive protein (CRP) are new, simple, and cost-effective predictors for prognosis. The predictive value of NLR as an inflammatory marker can predict post-operative pain caused by inflammatory pathways secondary to surgical trauma. CRP is also the most sensitive and specific biomarker of inflammation whereas PLR was also recently considered a possible marker for inflammation which may further contribute to pain and sequelae. Thus, anesthetists can make decisions about the amount, time, and type of analgesic to use based on preoperative values of these parameters to provide maximum postoperative pain control and facilitate early rehabilitation. Thus, the current study was conducted to determine the relationship between CRP, NLR, and PLR levels and the intensity of pain in patients following total hip arthroplasty (THA) and total knee arthroplasty (TKA).

Materials And Methods: A total of 105 patients scheduled for THA and TKA fulfilling the study's inclusion criteria were enrolled. Inclusion criteria of the study were all the patients giving written consent, ASA Grade I-III, patients between 18 and 90 years who were scheduled for elective lower extremity TJA, and all the patients who remained admitted until stitches were removed. Patients were given intrathecal 15 mg hyperbaric bupivacaine via 25G atraumatic spinal needle in the L3-L4 interspace. The recorded data were demographic characteristics, preexisting comorbidities, number of blood transfusions, and operation time, postoperative analgesics given, duration of hospital stay, time of mobility, pain scoring as per visual analog scale (VAS) scoring system with an aim to establish a relationship between pre- and post-operative (Days 3 & 5) CRP, NLR, and PLR with post-operative pain after THA and TKA.

Result: The present study demonstrated a significant correlation (p < 0.002) between preoperative and postoperative NLR with pain after TJA whereas PLR and CRP did not show any significant relationship with post-operative pain after THA and TKA. A significantly higher NLR ratio was observed for patients on all the periods of observation (pre-op., Day 3, and Day 5). Pre-op. and Day 5 NLR of patients who required transfusion were significantly higher than those who did not require transfusion and patients with higher NLR values could be mobilized significantly later and had significantly higher duration of hospital stay. The correlation of CRP levels and PLR levels at different time intervals did not show a significant correlation with Day 3 and Day 5 pain scores.

Conclusion: The present study demonstrated a significant correlation between preoperative and postoperative NLR with pain after TJA.