Yoeri Bemelmans

Outpatient unicompartimental knee arthroplasty 81 6 during the first 48hrs postoperative. If pain or PONV was reason for delayed first mobilization and/or prolonged hospital stay, it was recorded in the patient’s clinical report. All patients filled in a diary on if they were affected with (extreme) pain and/ or PONV. All AE’s and re-admissions to the hospital were recorded throughout the entire study period of 3mth postoperative. Length of hospital stay was evaluated as time between hospital admission and discharge in days. Early mobilization (hrs) was recorded as time between the start of anesthesia until the first mobilization. PROMS were obtained pre- and 3mth postoperative including the Dutch validated Oxford knee score (OKS; 12 to 60, 12 being the best outcome) [14] and EuroQol-5D (EQ-5D; 0 to 1, 1 indicates the best health state) [6]. This case-controlled study was performed in compliance with the Helsinki Declaration of 1975, as revised in 2000, and was studied and approved by the local Institutional Review Board (IRB: Atrium-Orbis Zuyd, Heerlen, The Netherlands, IRB Nr. 14-N-52) and registered online at the Dutch Trial Register (www.trialregister.nl , Nr. NTR4579). Statistical analysis The primary outcome of this case-control pilot study was to investigate whether UKA patients can go home as scheduled on the day of surgery. Sample size calculations were performed based on the results with two different pathways we used before implementation of the OS pathway; Joint Care [28] and RR (seematerials andmethods). Ten random selected patients (Joint Care) undergoing elective UKA had a mean (SD) hospitalization of 3.7 (1.17) days. The mean (SD) hospitalization of 10 other random selected patients, who followed the RR pathway, was 2.6 (0.97) days. With an alpha of 0.05 and 1- beta error of 0.8, an expected reduction of 1.6 days in the OS group, we would need 18 patients; 20 taking into account if assumed that both groups have the largest SD (1.17). This study included 40 patients, 20 in each arm. Statistically significant differences between both groups were analyzed with non-parametric Mann-Whitney-U test, since datawere not normally distributed as testedwith the Shapiro-Wilk test. Chi-square tests was used for categorical variables. P-valueswere considered tobe statistically significant at P≤0.05 for all analysis. All statistical analysis were done with use of SPSS version 17.0 for windows (Inc., Chicago, IL). Results are presented as either with frequencies (%), mean (SD), or median (range).