Pain relief in your knee is the main reason why you opt for total knee replacement, arthroplasty (TKA). But, most studies that talk about the success of TKA haven't actually taken a look at the factors that predict the freedom of pain in the years that follow the surgery. In a study published in the summer of 2008 this subject was addressed noting that 13% to 30% of people who had a TKA have a slow, painful or incomplete recovery from surgery, the researchers also found two new key factors that will help predict who among those people with osteoarthritis (OA) would be likely to still feel pain after two years from their surgery. The two factors were other medical problems and people's particular way of experiencing pain.
The study followed 55 consecutive OA patients scheduled to have a TKA in a hospital in Nova Scotia, Canada. The patients, 35 women and 20 men averaging 69 years old, completed pain questionnaires before surgery, and then again 3 months, 12 months, and 2 years later. Researchers used standard surveys to assess the pain of the men and women in the study and used their medical records to find out about their other health problems. The problems included, OA in joints other than the knee, high blood pressure, smoking, diabetes, under active thyroid, heart disease, depression, and being overweight. Researchers also looked at a psychological feature of how the men and women experienced pain called "catastrophizing." A widely used survey called the Pain Catastrophizing Scale (PCS) that ask these men and women to rate how often 13 statements about pain would apply to them. These statements gauge how much they reflected on their pain; how much they magnify its potential impact; and how helpless they feel about managing their pain.
Scientist found that the men and women catastrophizing was a stable trait, unchanging over the two years of the study, and on average, their pain dropped dramatically after knee replacement surgery, but there was a wide variation among the men and women in the study. The goal of the study was to identify which presurgery factors are responsible for the variance and can they be used to predict whose pain will persist. Age, gender, length of hospital stay, and the type of anesthesia the men and women received didn't predict pain after two years and not surprisingly, the patients who reported the most presurgery pain were more likely to be in the group still in pain at two years. Researchers suggest that this calls into question the practice of delaying TKA until pain is unbearable.
The men and women whose catastrophizing score, especially the reflecting about pain, was a significant predictor of who would have pain after two years. The other predictor of pain two years on was the number of other medical problems the men and women who participated had at the time of surgery. The scientists tried to explain how catastrophizing could lead to the continuing experience of pain, they said that reflecting and focusing attention on pain may make cells more sensitive, actually amplifying pain. Medical problems just might, likewise focus constant attention on pain, therefore, altering the pain experience compared to individuals whose only medical problem was the OA in one knee. The drawbacks to the study are its small size and that the study didn't examine whether pain immediately after the TKA surgery predicts long-term pain.\