Widespread Pre-Op Knee Pain May Lead to More Pain Post-Op

Pre-surgical widespread body pain is associated with greater persistent pain in some patients following total knee arthroplasty, shows a study published in Osteoarthritis and Cartilage.

The goal of total knee arthroplasty, or total knee replacement (TKR), is to relieve pain. However, approximately 20 percent of patients who undergo the procedure still have insufficient pain relief. Using pain diagrams, this study evaluated the association between pre-surgical widespread body pain and pain relief after total knee arthroplasty. Lessons learned from this research may inform ways to better assess pain and identify those at risk for suboptimal surgical outcomes.

The study was led by Jeffrey N. Katz, M.D., of Brigham and Women's Hospital in Boston.

“The findings suggest that widespread pain may be a marker for a chronic pain state that is not entirely resolved by addressing a localized problem with a local solution, such as TKR for advanced knee OA,” Dr. Katz said in an email interview with Rheumatology Network. “The patients with widespread pain improved with TKR so the implication is not that all of their pain is refractory. Rather, pain did not resolve entirely with surgery suggesting that widespread pain may include elements that are not amenable to local, surgical approaches.”

To date, tools to identify patients at risk for poor outcomes from surgery have included the Western Ontario and McMaster Universities Osteoarthritis Index pain and physical function subscales, Pain Catastrophizing Scale, and the Mental Health Inventory-5.

“While such measures are useful for research purposes, they may be difficult to administer in a busy clinic. A simple tool that can identify those patients most at risk of poor TKA outcome may be helpful in clinical settings. We have begun to examine such a tool - a total body pain diagram that captures patient-reported pain in 19 different body sites,” the authors wrote.

The Study

This was a prospective cohort study of 241 patients (mean age 66 years, 61% female) with knee osteoarthritis (OA) undergoing elective unilateral total knee arthroplasty. Patients completed surveys pre-operatively, and then again at 6 months and 12 months post-surgery. Patients were also asked to report their levels of pain using checkboxes for 19 pre-determined body sites. These sites were later categorized into eight regions.

Key findings were that widespread body pain was associated with a higher likelihood of a Western Ontario and McMaster Universities Osteoarthritis Index pain score of greater than 15 and a greater likelihood of failing to achieve the minimal clinically important difference. Pain catastrophizing was also found to be a predictor of persistent pain.

Next Steps

Dr. Katz and his colleagues have begun to examine a total body pain diagram that captures patient-reported pain in 19 different body sites.

More research is needed to determine if additional pre-surgical care may benefit patients with high pain diagram and catastrophizing scores.

Disclosures:

This study was funded in part by the National Institute of Arthritis and Musculoskeletal and Skin Diseases in the United States.

References:

A.J. Dave , F. Selzer, E. Losina, et. al. “The association of pre-operative body pain diagram scores with pain outcomes following total knee arthroplasty,” Osteoarthritis and Cartilage. Published online Dec. 13, 2016. DOI:  10.1016/j.joca.2016.12.013