Musculoskeletal Disease May Follow a Total Knee Replacement

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Roughly half of patients who undergo total knee replacement subsequently experience musculoskeletal symptoms in previously unaffected bodily areas, researchers reported in ACR Open Rheumatology.

Among 293 individuals aged 40 and older who underwent total knee replacement at Brigham and Women’s Hospital in Boston, the cumulative incidence of any new musculoskeletal symptomatic area over four years was 45 percent. The new symptoms occurred primarily in the opposite knee and back. 

Approximately 723,000 total knee replacements are performed annually in the United States, and postoperative outcomes have been a major focus of research in the knee osteoarthritis field. Several pre-operative factors associated with adverse total knee replacement outcomes have been identified, including older age, female sex, preoperative pain and function, lower socioeconomic status, anxiety, and depression.

However, this new study is believed to be the first to examine the development of new musculoskeletal symptomatic areas arising only after total knee replacement.

“If present, these symptomatic areas could contribute to the overall level of pain and functional limitation post‐ total knee replacement, ultimately creating new barriers to optimal recovery and delaying proper rehabilitation. Such limitations could also lead to greater postoperative patient dissatisfaction. By understanding the risk factors for incident musculoskeletal symptomatic areas, health care providers can adapt their preoperative conversations to offer realistic patient expectations,” wrote Jeffrey N. Katz, M.D., Brigham and Women's Hospital and Harvard Medical School, Boston.

The investigators used data from the randomized, controlled Adding Value in Knee Arthroplasty Postoperative Care Navigation Trial, which compared the effects of postoperative motivational interviewing with usual care following total knee replacement for knee osteoarthritis.

Participants completed questionnaires regarding pain and activity limitation prior to total knee replacement and at six time points over the next four years. Of the 293 who completed at least one follow up questionnaire, the mean age was 66 years and 61 percent were women. A majority (64 percent) had Charlson Comorbidity Index scores of zero or one, and about 75 percent had no musculoskeletal symptomatic areas other than the index knee at baseline.

After total knee replacement, cumulative incidences of new musculoskeletal symptomatic areas were 23 percent for the non-index knee, 15 percent in the back, 13 percent in the hands/wrists/arms/shoulders and 13 percent in the hips. Those proportions corresponded to rates per 100 person-years of 6.9, 5.3, 4.2, and 4.4 respectively.
Overall, the cumulative incidence for any new musculoskeletal symptomatic area was 45 percent with corresponding incidence rate 19.2 / 100 person-years.

“Of note, although 74 individuals had at least one symptomatic musculoskeletal area at baseline, no one had symptoms in all six regions at baseline. Thus, all 293 subjects were at risk for developing an incident symptomatic area,” the investigators wrote.

In multivariate analysis, factors associated with incident musculoskeletal symptom areas included female sex (relative risk 1.64), body-mass index 35 or higher (1.27), Charlson Comorbidity Index of 2 or more (1.28), baseline pain scores greater than 40 for the index knee on the Western Ontario and McMaster Universities Osteoarthritis Index (1.39) and symptoms consistent with anxiety/depression (1.70).

“These findings highlight the susceptibility of patients to new musculoskeletal symptomatic areas after knee replacement. Moreover, identification of these risk factors for incident musculoskeletal symptomatic areas ensures that health care providers can focus on vulnerable populations and offer appropriate counseling (ranging from weight to mental health) to best prepare patients for total knee replacement,” Katz and colleagues wrote.   

The effects of these new musculoskeletal symptomatic areas on pain, functional status, and quality of life for post total knee replacement patients are not known. Still, the investigators said, “understanding the prevalence, risk factors, and, ultimately, the impact of incident musculoskeletal symptomatic areas may offer guidance for clinicians on how to optimize the post total knee replacement rehabilitation process.”

REFERENCE

MaryAnn Zhang , Faith Selzer, Elena Losina , Jamie E. Collins, and Jeffrey N. Katz. "Musculoskeletal Symptomatic Areas After Total Knee Replacement for Osteoarthritis," ACR Open Rheumatology. Aug. 1, 2019.  DOI:10.1002/acr2.11055