Purpose: Shorter length of stay (LOS) after total knee arthroplasty (TKA) is cost-effective. Straight leg raise (SLR) is a common exercise prescribed after TKA, but the significance of early postoperative SLR is unknown. The primary aim of this study is to evaluate the association between early postoperative SLR and LOS. Secondary aims are to explore associations among early postoperative SLR, time to ambulation, and time to stairs climbing and identify factors related to postoperative SLR.
Methods: 888 TKAs (888 knees, 865 patients) performed at a tertiary hospital in 2016 were included for this retrospective study. All TKAs were performed with medial parapatellar approach and tourniquet. Time to events (SLR, ambulation, stair climbing), LOS and factors influencing these events were analysed using a multivariate Poisson regression model and logistic regression.
Results: Patients who performed SLR on postoperative day 1 (POD1) had shorter LOS than those who did not (adjusted Mean Ratio (aMR) = 0.846, p < 0.001), with estimated mean LOS being 3.5 days and 4.1 days, respectively. Performing SLR on POD1 was also associated with shorter time to ambulation (aMR = 0.789; p < 0.001) and stair climbing (aMR = 0.811, p < 0.001). Female gender and higher rest pain on POD1 were associated with delayed postoperative SLR.
Conclusion: Performing SLR on POD1 after TKA is associated with shorter LOS, time to ambulation, and time to stair climbing. Early postoperative SLR can prognosticate early recovery and discharge. Optimization of preoperative muscle strength and postoperative pain may be important in early recovery after TKA.
Keywords: knee; length of stay; replacement; straight leg raise; total knee arthroplasty.