Central Sensitization and Neuropathic Pain Cumulatively Affect Patients Reporting Inferior Outcomes Following Total Knee Arthroplasty
Authors: Kim Man Soo , Kim Jae Jung , Kang Ki Ho , Lee Joong Hoon , In Yong 
Published: November 2023

Update
This article was updated on November 17, 2023, because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 102, the text that had read “In a post hoc analysis of the preoperative results, Group 1 showed significantly inferior WOMAC pain, function, and total scores compared with Group 4 (p < 0.05 for all). Groups 2 and 3 showed worse preoperative WOMAC pain, function, and total subscores compared with Group 4 (p < 0.05 for all). These results remained the same at 2 years after surgery.” now reads “In a post hoc analysis of the preoperative results, Groups 1, 2, and 3 showed significantly inferior WOMAC pain, function, and total scores compared with Group 4 (p < 0.05 for all). At 2 years postoperatively, Group 1 showed inferior WOMAC pain, function, and total scores compared with the other groups (p < 0.05 for all). Also, Groups 2 and 3 had worse WOMAC pain, function and total scores compared with Group 4 (p < 0.05 for all).” Also, on page 106, the title of Table IV, which had previously read “Inter-Group Comparison of Preoperative Scores (Post Hoc Analysis)” now reads “Inter-Group Comparison of Postoperative Scores (Post Hoc Analysis).”

Background:
Available studies on the relationship between central sensitization and neuropathic pain, and on their association with patient-reported outcome measures (PROMs), following total knee arthroplasty (TKA) are insufficient. The purpose of the present study was to investigate this association.

Methods:
A total of 316 patients who underwent primary unilateral TKA for the treatment of end-stage osteoarthritis (OA) of the knee were enrolled. Central sensitization was defined as a score of ≥40 on the Central Sensitization Inventory. Neuropathic pain was defined as a score of ≥19 on the painDETECT Questionnaire (PDQ). PROMs were also evaluated on the basis of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score preoperatively and at 2 years postoperatively. The patients were divided into 4 groups: Group 1 had both central sensitization and neuropathic pain, Group 2 had central sensitization only, Group 3 had neuropathic pain only, and Group 4 had neither central sensitization nor neuropathic pain. Preoperative and postoperative PROMs were compared among the groups.

Results:
All individuals who participated in the study were Asian, especially Korean. Fifty-five patients (17.4%) had both central sensitization and neuropathic pain, 68 (21.5%) had central sensitization only, 35 (11.1%) had neuropathic pain only, and 158 (50.0%) had neither condition. All WOMAC subscores showed significant differences among the 4 groups before and after surgery (p < 0.05 for all). In a post hoc analysis of the preoperative results, Groups 1, 2, and 3 showed significantly inferior WOMAC pain, function, and total scores compared with Group 4 (p < 0.05 for all). At 2 years postoperatively, Group 1 showed inferior WOMAC pain, function, and total scores compared with the other groups (p < 0.05 for all). Also, Groups 2 and 3 had worse WOMAC pain, function and total scores compared with Group 4 (p < 0.05 for all).

Conclusions:
Each condition, central sensitization and neuropathic pain, was associated with inferior PROMs following TKA. Furthermore, patients with both central sensitization and neuropathic pain showed worse PROMs compared with patients with either condition alone or without either condition.

Level of Evidence:
Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.