Background/Purpose:  : Total knee arthroplasty (TKA) has historically been viewed as a surgical procedure of last resort for older adults suffering with chronic arthritis. However, rates of TKA in younger, more medically complex patients have increased over the last several decades. A growing body of literature indicates that younger patients are less satisfied with their functional ability relative to older counterparts. The purpose of this study was to characterize this problematic subpopulation by examining whether a younger, poorer functioning subgroup differs in preoperative characteristics of health status, psychological status, or knee function, compared to others undergoing the procedure.

Methods:  We conducted a retrospective analysis of clinically-collected data from 181 patients (57% female, mean age 64.8 yrs. + 8.9, mean BMI 33.3 + 7.1 kg/m²) undergoing TKA and subsequent rehabilitation between January 2013 and August 2015. Using these data, we constructed a categorical variable to represent age and function, by dichotomizing age (younger than 65 vs older than 65) and postoperative (6-week) Timed Up and GO (TUG) time (median split at 8.65 seconds). This resulted in 4 subgroups: younger/poorer TUG (n=36), younger/better TUG (n=42), older/poorer TUG (n=46), older/better TUG (n=39). Analysis of Covariance was then performed to compare subgroups, with the younger/poorer group as the reference group. The following preoperative measures were examined across groups: health status (comorbidity score, body mass index), psychological status (depression, pain catastrophizing) and knee function (quadriceps strength, surgical knee range of motion).

Results:  After controlling for sex, the younger/poorer function subgroup demonstrated significantly worse quadriceps strength and pain catastrophizing scores relative to both young and old high-functioning subgroups. This subgroup also demonstrated worse depression scores relative to the older/better TUG subgroup relative to the younger/better TUG subgroup. No significant differences were seen in knee range of motion or comorbidity scores between any of the subgroups.

Conclusion:  A clinical picture emerges of a subgroup that is relatively young and poor functioning following surgery. Preoperative characteristics of this subgroup included poorer psychological status (worse pain catastrophizing and depression scores) and reduced quadriceps strength. These factors could be incorporated into treatment strategies to maximize outcomes in this problematic, but growing patient demographic.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/identifying-vulnerable-patient-populations-based-on-age-and-physical-function-on-clinical-outcomes-following-total-knee-arthroplasty/