In our retrospective cohort we aimed to evaluate the predictive value of preoperative physical functioning for short stay THA. We found that perioperative performance based physical functioning (TUG) was independently associated with short stay THA. A basic model (age, sex and ASA) with TUG, score had a better predictive value then the basic model without TUG, with an acceptable AUC of 0.77. Patients with a TUG less than 10 seconds had an OR of 3.64 of being discharged within 36 hours.
Several studies already confirmed a performance based measure like TUG or gait speed as an independent determinant of LOS or functional recovery [13, 20, 21] or in most studies more specific prolonged LOS or functional recovery [14–16], but as far as we know no studies have been done on the value of TUG in selection models for short-stay or day treatment. Although Bodrogi et al. stated in a review about management of patients undergoing same-day discharge primary total hip and knee arthroplasty that a Timed Up and Go Test > 10 seconds is a relative exclusion criteria for outpatient TJA[12], this recommendations was based on the study of Poitras et al. in which they found an association between preoperative TUG (cut off point 11.7 seconds) and LOS (cut off point 3 days). Other studies found cut off points of 12.5 seconds [16] or 10.5 seconds [14] for predicting a delayed recovery of functioning after THA. Our study confirmed that a TUG < 10 seconds is associated with short-stay THA. However, this cut off point should be validated in each local setting based on the context and preferences and should be validated for an outpatient setting (without overnight stay).
Most outpatient protocol primarily focus on ASA-score or other tools assessing medical condition like the recently developed Outpatient Arthroplasty Risk Assessment (OARA)[11]. This screening instrument has 9 medical items to predict safe outpatient TJA and is effective for identifying patients who can safely undergo outpatient total joint arthroplasty. However, this is a one-dimensional approach and does not take into account the functional capabilities of patients. As reported in the study of Gromov et al., lack of safe mobilization might be one of the most common reasons for THA patients not being discharged at the day of surgery[22]. Therefore, it makes sense that better preoperative functional mobility is related to successful outpatient THA. We assume a measure of performance based physical functioning cannot simply be replaced by a questionnaire. Performance-based measures assess what an individual can do rather than what the individual perceives they can do. Furthermore, patients could under- or overestimate their functional ability by use of self-reported measures [23]. In our study both ASA and TUG were associated with short-stay THA, so we propose to take into account both physical functioning and comorbidity, by use of the ASA or the OARA score, in preoperative risk stratification to estimate whether a quick and uncomplicated recovery is likely.
A strength of this study is that we had a large cohort with patients who had surgery in our hospital without selecting candidates for short-stay THA prior to surgery. This provides a good reflection of daily practice without being biased. We assume a large number of patients who were discharged the next postoperative day in our cohort are candidates for outpatient THA when managing expectations, optimizing the mindset of patient and caregivers within a multidisciplinary approach and evidence based fast track protocols[3, 4, 12]. Another strength is that we used TUG as measures for physical functioning as TUG is widely used and simple to perform. TUG can be measured during preoperative physical therapy, which is part of most outpatient protocols [4] or even at the patients’ home. Furthermore, TUG is not only useful in predicting LOS after THA but may also be useful to predict long term outcome and other postoperative risks as TUG is also found to be associated with functional independence and risk of falling and frailty in elderly [24, 25] and with deep venous thrombosis after THA [26]. In addition, including preoperative measurement of physical functioning like TUG may be an important starting point to a more function tailored pathway. Van der Sluis et al. studied a function tailored approach and were able to reduce LOS by use of measurements of physical functioning, reduction of inactivity and stimulation of self-efficacy of the patients[27]. Functional mobility, measured by TUG, is a modifiable risk factor and could be a target in preoperative preparation of patients.
This study had several limitations. First, it was a single-center retrospective study without external validation. Second, although we took into account confounding factors like age, sex and ASA score, there are more preoperative factors related to short-stay THA, which may result in some residual bias. Thirdly, we only evaluated one single test of physical functioning. Further studies are necessary to validate the use of TUG or other measures of physical functioning in preoperative risk stratification for short-stay or outpatient THA and their added value to other existing risk assessment instruments like the OARA score.