Diagnosis, Management, and Treatment of Complex Regional Pain Syndrome after Total Knee Arthroplasty: A Systematic Review and Qualitative Assessment

Objective: To determine the incidence, presentation, and management of complex regional pain syndrome (CRPS) after total knee arthroplasty (TKA). Literature Survey: A Preferred Reporting Items for Systematic Reviews (PRISMA) compliant search was performed in February 2025 using PubMed, Embase, Ovid/MEDLINE, and Cochrane Central Register of Controlled Clinical Trials to identify TKA studies that describe CRPS. Case reports and non-English articles were included. Methodology: Two independent reviewers screened studies using specific eligibility criteria. Study characteristics, incidence, symptoms, physical exam findings, diagnostic modalities, therapies, and outcomes were extracted. Studies were evaluated according to the Newcastle-Ottawa scale and adherence to CARE case report guidelines. Synthesis: Fifteen studies comprising 125 TKA patients diagnosed with CRPS were included. The mean age was 64 7 years, 67.7% of patients were female, and mean follow-up was 16.9 15.9 months. The incidence of CRPS after TKA was 2.8% (83/2945). Mean time from surgery to diagnosis was 7 3.4 months (n=86). The most prevalent findings were edema (72.5%, 29/40), knee stiffness (62.5%, 25/40), hyperalgesia (62%, 43/69), allodynia (59%, 41/69), and skin temperature changes (50%, 20/40). Therapeutic sympathetic blocks were used in 75% (36/48) of cases, of which 42% (15/36) of patients had persistent symptoms after treatment. Manipulation under anesthesia was performed in 25% (n=11) of cases and resulted in an average increase in flexion of 29 (n=6). The average ROM at diagnosis was 3.4° - 66.1° (n=16) compared to 3.3° - 92.2° (n=12) at final follow-up. Conclusions: The archetypical CRPS TKA patient presents with disproportionate and unexplainable knee pain nine months postoperatively, often with burning and altered sensation, stiffness, edema, and temperature asymmetry on exam. Reported incidence varies significantly, likely due to evolving diagnostic criteria and a historical tendency to ascribe unexplainable pain to CRPS. However, the condition may be underdiagnosed after TKA given the multiple risk factors and prevalence of chronic unexplainable pain associated with knee replacement.