Total Joint Arthroplasty Time-of-Day Start Time Has Minimal Effect on Intraoperative Efficiency

Total hip (THA) and knee arthroplasties (TKA) are common elective procedures, and dedicated arthroplasty teams perform multiple procedures per day. Little is documented about how time-of-day scheduling affects the intraoperative efficiency of total joint arthroplasties (TJA). In this study, we analyzed the effects of surgical start time on TJA operative lengths. A retrospective study was performed for primary TJA patients done within a four-year period at a single academic medical center. Surgical start time, operative duration, and patient demographics were collected. Based on a 12-hour operative day, surgical start times were categorized as early (7AM to 11AM), mid-day (11AM to 3PM), or late (after 3PM). A chi-squared test was performed to examine for associations between patient demographics and surgical start time. A multivariate linear regression (MLR) was performed to determine the effect of surgical start time on operative duration. P-values less than 0.05 were considered significant. This study identified 1663 TJAs – 869 total knee (TKA) and 791 total hip arthroplasties (THA) who met inclusion criteria. Among TKAs, we identified 319 (36.7%) early, 437 (50.3%) mid-day, and 113 (13.0%) late operations. Among THAs, we identified 407 (51.4%) early, 297 (37.5%) mid-day, and 87 (11.0%) late operations. MLR demonstrated that for TKA there was a 4.9 (p =0.018) and 7.3 (p=0.013) minute increase for mid-day and late cases, respectively. For THAs, a non-early start time was associated with an increased operative duration of 9.1 to 12 minutes (p<0.001). Surgical start time has a statistically significant, but minimal, effect on operative length for TJAs, with later cases being slightly longer than first-start cases.