術後痛の慢性化に影響する認知的・精神的因子の検討

抄録

　Total knee arthroplasty (TKA) is a surgical treatment for conditions such as knee osteoarthritis; the treatment aims to relieve knee pain and improve quality of life. Treatment outcomes are stable; however, it has been reported that postoperative pain becomes chronic in 15 - 20% of cases. The aim of this study was to examine the factors involved in the chronicity of postoperative pain by investigating the effects of cognitive and psychological factors on postoperative pain at 3 weeks, 5 weeks, and 4 months post-operation. Subjects were 50 patients who underwent TKA (8 men and 42 women, mean age: 74.8 ± 6.5 years). Cognitive factors in this study comprised an assessment of neglect-like symptoms; such symptoms included decreased “cognitive function regarding the existence of one's own limbs" or “cognitive function regarding the motion perception of one's own limbs." The severity of these symptoms was assessed using the method described by Galar et al. Psychological factors comprised assessments of anxiety and catastrophic thinking about pain. Anxiety was assessed using the state-trait anxiety inventory, while catastrophic thinking about pain was assessed using the pain catastrophizing scale (comprises categories of helplessness, magnification, and rumination). Postoperative pain was assessed using a visual analog scale (VAS). Multiple regression analysis by using VAS as the dependent variable and all other factors as independent variables showed the following factors to be significantly correlated with VAS: neglect-like symptoms at 3 weeks, 5 weeks, and 4 months post-operation and rumination at 3 weeks and 4 months post-operation. Sensory integration becomes difficult because of decreased sensory function in neglect-like symptoms; this is thought to be caused by body image becoming inaccurate. On the basis of these findings, it is considered necessary to approach for the improvement of sensory function in postoperative rehabilitation. In addition, rumination is persistent in pain, which is believed to result in a prognosis of a psychological state of severe anxiety. Therefore, methods for dealing with postoperative pain and giving patients a prognosis that is as precise as possible are thought to be necessary. These measures are thought to be factors in relieving postoperative pain and preventing it from becoming chronic.