Influence of pre-operative co-morbidities on pain and function outcomes at 1 year after primary total knee...

Multimorbidity has been found to be associated with more pain and poorer function following total knee arthroplasty (TKA). We describe the relationship between both the total number of pre-operative co-morbidities, and individual co-morbidities, with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at 12 months after TKR.

We performed a secondary analysis on 290 participants from the Arthroplasty Pain Experience (APEX) trial, with seventeen imputations by Chained Equations. Using multivariable adjusted linear regression models, we analysed the relationship between total number of pre-operative co-morbidities, followed by individual co-morbidities, with WOMAC score at 12 months after randomisation.

Patients with ≥ 5 co-morbidities have worse outcomes compared to patients with 3 co-morbidities, scoring -9.6 points for function (95% CI -15.3 to -3.8), and -9.8 points for pain (95%CI -15.9 to -3.8). Patients reported worse pain with osteoporosis (-7.8 95%CI -14.1 to -1.6), peripheral vascular disease (-17.8 95%CI -34 to -1.8), depression (-9.8 95%CI -18.1 to -1.4), anxiety (-9.7 95%CI -18 to -1.4) or degenerative disc disease (-7.5 95%CI -13.3 to -1.7). Worse function was associated with osteoporosis (-7.1 95%CI -12.9 to -1.4), diabetes mellitus (-9.1 95%CI -15.6 to -2.6), anxiety (-8.1 95%CI -16 to -0.2) and degenerative disc disease (-8.6 95%CI -14.1 to -3.2).

Pre-operative multimorbidity is associated with worse outcomes after TKA. Patients with pre-operative osteoporosis, anxiety and degenerative disc disease had worse pain and function at 12-months. Surgeons may use these results during discussion with patients about their potential outcome after TKA.