Purpose: There is growing support in the medical literature that patient outcomes are adversely affected by physician fatigue in operator-dependent cognitive and technical tasks. The recent increase in total joint arthroplasty case load has resulted in longer operative days and increased surgeon fatigue. The purpose of this study was to determine if time of day predicts perioperative outcomes and complications in total hip and knee arthroplasty surgery.

Method: The records of all primary Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) surgery performed for primary osteoarthritis, during 2007 at one large university hospital, were retrospectively reviewed. Complete demographic data (age, gender, Body Mass Index), start time of surgery, intraoperative complications, duration of surgery, radiographic component alignment, and functional outcome scores (SF-12 and WOMAC) for 341 THA and 292 TKA patients were collected and analyzed using linear and nonparametric rank correlation statistics. Data was corrected for gender, body mass index (BMI), surgeon, and post-call operating days.

Results: In the THA cohort, a later start time of surgery was significantly related to duration of surgery (p=0.0013). In addition, there was a trend towards significance for intraoperative femur fracture (p=0.0542) later in the day. Postoperative complications, component alignment, and functional outcome scores were not significantly affected by start time of surgery. There were no significant findings for any of the intraoperative or postoperative outcomes in the TKA cohort.

Conclusion: This study demonstrates that duration of surgery and the incidence of intraoperative complications for THA may increase as the start time of surgery becomes later in the day. These findings should be taken into consideration when planning operative days involving THA.