Widespread preoperative pain sensitization may be associated with chronic pain after total knee replacement, according to results published in Osteoarthritis and Cartilage.
These findings suggest that further investigation is warranted into the role of preoperative pain sensitization in predicting chronic postsurgical pain,” Vikki Wylde, BSc (Hons), PhD, and colleagues wrote in their study. “Larger studies, in which other known risk factors are assessed and controlled for, are needed to establish the sensitivity and specificity of preoperative measures of pain sensitization in the prediction of chronic pain after [total knee replacement] TKR.
Fifty-one patients who underwent TKR for osteoarthritis participated in a preoperative Quantitative Sensory Testing (QST) session where researchers assessed their pain thresholds for knee and forearm pressure (PPT) and heat (HPT). The investigators compared preoperative median QST thresholds to thresholds they obtained from a database of 50 individuals without knee pain.
One year after TKR, patients’ preoperative median WOMAC scores significantly improved from 40 points to 90 points, and 29% had a WOMAC score of less than 75 points. Researchers found the patients’ median preoperative knee and forearm PPTs were significantly lower vs. the healthy individuals.
While Wylde and colleagues found no correlation between preoperative HPTs or knee PPTs and 1-year WOMAC scores, they observed a small but statistically significant correlation between the preoperative forearm PPTs and 1-year WOMAC scores. When they grouped patients by low and high preoperative forearm PPTs, the low PPT group reported significantly worse 1-year WOMAC pain scores compared to the high PPT group.