Abstract
Outcomes in arthroplasty have 3 general sources of variability: the patient, the prosthesis, and the medical-surgical-rehab. services. There are numerous factors that can contribute to earlier-than-usual clinical failure of a TKA (failure = need for revision). There are intense debates regarding design and material factors. There are technical factors such as misalignment, soft tissue imbalance, and inadequate fixation. The greatest source of variability in the outcome equation is, however, the patient.
In cohort studies, the amount and type of patient activity influences the longevity of TKA. Quantitative studies have demonstrated >45-fold variation in the number of steps per day. Semi-quantitative data and survey studies show variability in the types of recreational activities and in the intensity. Age is often used as a surrogate, but BMI has a better correlation with activity than age. There is no formula, however, that can predict the longevity of an arthroplasty in a specific patient. For this reason, activity recommendations following arthroplasty continue to be debated. Which do you prioritise; lifestyle or longevity? More importantly, which does the patient prioritise?
