The Prevalence of Complex Regional Pain Syndrome after Primary Total Knee Arthroplasty - A Longitudinal Study.

Introduction: Osteoarthritis is a degenerative joint disease commonly affecting the knee, especially the medial compartment, causing cartilage loss, joint space narrowing, deformity, and limited mobility. Radiological severity is graded by the Kellgren-Lawrence system. Advanced or tricompartmental disease requires total knee arthroplasty (TKA). Complex regional pain syndrome (CRPS) is a rare but recognized complication following TKA. Objectives: The objective of the study was to determine the proportion of patients developing CRPS after TKA and to assess factors associated with its development. Materials and Methods: This prospective observational study was conducted at a tertiary care center and included 110 patients undergoing primary TKA. Patients were followed up at 2 weeks, 6 weeks, and 12 weeks postoperatively. CRPS was diagnosed clinically using the Budapest criteria. Quantitative variables were expressed as mean and standard deviation, while qualitative variables were presented as frequencies and percentages. Associations were assessed using the Chi-square test, with P < 0.05 considered statistically significant. Results: The incidence of CRPS was 19.1% at 2 weeks, 9.1% at 6 weeks, and 1.8% at 12 weeks postoperatively. Increasing age and longer duration of osteoarthritis (OA) symptoms showed a statistically significant association with the development of CRPS. Conclusion: The study found a high initial proportion of CRPS at 2 weeks post-TKA, which declined progressively by 12 weeks, indicating that CRPS is an early but largely transient complication when diagnosed by the Budapest criteria. Advancing age and a longer duration of pre-operative OA symptoms were identified as significant factors associated with its development, whereas gender showed no significant correlation. After 3 months of follow-up, CRPS was found to be uncommon following TKA.