FROST: Factors Predicting Orthopaedic Trauma Volumes

Orthopaedic surgeons often speculate weather and season impact the nature and volume of surgical trauma. Little evidence exists to support this. We aimed to identify the relationship between weather conditions, time of year, surgical orthopaedic trauma volumes, after-hours surgery, and surgical wait times.

Unscheduled surgical orthopaedic cases were retrospectively reviewed at major adult hospitals in Calgary, Alberta, Canada, over an eleven-year period (2008-2018). Weather variables were gathered and a predictive model for ice was generated. Multivariable Poisson regression was used to determine the effect of weather and time of year on orthopaedic trauma volumes and after-hours surgery. Linear regression was used to investigate surgical wait times.

41,421 unscheduled orthopaedic trauma surgeries were analyzed against daily weather patterns. 49% of all surgery performed was for hip (26.4%) or ankle fractures (22.6%). Same day snow (p=0.002) and ice for two days prior (p=0.031; p=0.003) were significantly associated with increased overall trauma volumes. Same day snow (p<0.001) and ice (p=0.002), as well as ice two days prior (p=0.001), predicted a significant increase in ankle fracture volumes. There was no correlation between weather patterns and hip fracture volumes. Independent of weather, time of year was highly predictive of large swings in orthopaedic trauma volumes and increased wait times. Generally, when patient volumes increased so did after-hours surgery.

Winter and summer months as well as ice and daily snow contributed to the most significant increases in overall orthopaedic trauma volumes. On a snowy day in February with ice present for three consecutive days, trauma volumes increased as much as 71%. Despite this, resources dedicated to orthopaedic trauma are consistent throughout the year, which highlights the need to allocate resources for orthopaedic trauma surgery based on seasonal demands. We suggest our predictive model be used to guide the amount of operating room time reserved for orthopaedic trauma to better reflect expected volumes. This contrasts the current system which relies on after-hours surgeries and increased patient wait-times to compensate for increased orthopaedic trauma volumes. Since orthopaedic trauma can be predicted by weather patterns, interventions should aim to decrease weather-related orthopaedic trauma and reduce the burden prolonged wait times have on our system.