The Effect of Comorbidities and Age on Functional Outcomes After Total Knee Arthroplasty in the Octogenarian: A Matched Cohort Study

INTRODUCTION: According to the World Health Organization data repository, the average life expectancy at birth for Singapore in 2015 has risen to 83.4 years, and many octogenarians (OG) remain active socioeconomically. The aim of this study is to compare the improvement and the impact of comorbidities on functional recovery after total knee arthroplasty (TKA) between OG and their younger counterparts. METHODS: This is a retrospective study of prospectively collected data from a single institution arthroplasty register. Between January 2006 and December 2011, 209 OG with primary knee osteoarthritis underwent TKA. Each OG (mean age 82 ± 2.1) was then carefully matched to a younger control group (YG, mean age 66 ± 4.5). Their postoperative outcomes measured include Oxford Knee Score (OKS), SF36-Physical Function (SF-PF), and knee society rating score comprising of Knee Score (KS) and Function Score (FS). Their respective degrees of improvement were compared and adjusted for their baseline comorbidities, measured using the Deyo-Charlson Comorbidity Index (D-CCI). RESULTS: There were more comorbidities among the OG (P < .05). Both groups saw the largest improvement (P < .05) during the first 6 months. There was no statistical significance between their improvement for OKS, KS, and FS between baseline and 6 months and OKS, FS, and SF-PF between 6 and 24 months. Adjusted for D-CCI using linear regression, the above results remained largely unchanged. DISCUSSION: In our study, both groups showed significant improvement across all functional outcomes, especially during the first 6 months. The improvement observed in OG at 6 and 24 months was comparable to that of YG, despite an overall higher baseline D-CCI. CONCLUSIONS: Total knee arthroplasty is a viable treatment option for the OG, offering good functional outcomes and results at 6 and 24 months when compared to their younger counterparts.