Researchers from Hospital for Special Surgery (HSS) indicate that middle-aged women with rheumatoid arthritis (RA) or arthritis resulting from injury are more likely to experience severe pain post-knee replacement. In a news release from HSS, the organization reports that during two companion studies researchers reviewed hospital records for 273 patients who underwent total knee replacement from October 2007 to March 2010.

In the first study, the release says, researchers assessed demographic data such as gender, ethnicity, age, height, weight, type of arthritis and co-existing medical conditions. Next they examined the knee’s preoperative range of motion, how well the patients could walk, and the amount of pain they had prior to surgery.

The results of the first study suggest that key predictors for severe postoperative pain during rest included being female, being between the ages of 45 and 65 years old, and having post-traumatic arthritis facilitated by an injury, RA, or osteoarthritis (OA). Additional key predictors included being obese and having a higher level of pain at the time of hospital admission. The researchers add that patients with avascular necrosis exhibited significantly lower postoperative pain.

The release notes that the study also indicates that during periods of activity, the strongest predictors of postoperative pain included obesity, a high pain level during hospital admission, and being between the ages of 45 and 65 years old. According to the results, Asian and Caucasian patients, along with individuals with underlying OA or avascular necrosis or both exhibited lower postoperative pain during periods of activity.

Thomas P. Sculco, MD, study author, HSS surgeon-in-chief, advises surgeons to engage in a thorough discussion with patients regarding postoperative pain, “particularly in the groups that we found tended to have more pain. More aggressive pain management techniques may be necessary for these patients,” Sculco says.

In the second study, the release states that researchers used the same medical records to collect information about surgical variables including the length of incision, type of anesthesia, tourniquet time and pressure, duration of procedure, estimated blood loss, and radiographic assessment including the amount of knee deformity and implant positioning and alignment.

According to the release, risk factors for severe postoperative pain at rest included having general anesthesia rather than an epidural or spinal block, longer tourniquet time, more blood loss, and having a large kneecap. During activity, researchers say, key players in postoperative pain during activity included a large kneecap, and techniques such as overstuffing of the patellofemoral joint.

The two studies were recently presented at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) in New Orleans.

Source: HSS