Inadvertent hypothermia in hip and knee total joint arthroplasty

Background: This clinical study aims to establish rates of inadvertent hypothermia (IH) in both primary and revision total hip/knee arthroplasty (THA/TKA and rTHA/rTHA). We postulate differences exist between demographic, surgical and anesthetic variables and outcomes for IH and normothermic patients.

Methods: We conducted a single centre, retrospective study of 2431 total joint arthroplasty (TJA) patients having undergone THA (n = 1096), TKA (n = 1083), rTHA (n = 165) and rTKA (n = 87) from March 2013 to December 2016. Outcomes include length of stay (LOS), 31-day complication rates for thrombotic events and infection and 31-day readmission rates (RR).

Results: Overall rates of IH were 11.7%; with cohort analysis demonstrating rates of 13.2%, 11.2%, 8.3% and 3.9% in THA, TKA, rTHA and rTKA respectively. Patients with body mass index (BMI)<29 kg/m2 and undergoing THA were at risk of IH. For all TJA, no difference was observed in 31-day complications (1.6% vs. 2.8%, p = 0.19), 31-day RR (3.3% vs. 4.5%, p = 0.50) or LOS (4.6 ± 2.9 vs. 5.1 ± 4.5, p = 0.11). IH was associated with higher RR for haematoma in TKA (2.9% vs. 0.4%, p = 0.021) and higher deep infection rates in rTHA (20% vs 0%, p = 0.006).

Conclusion: Our study demonstrates a 3.9% to 13.2% rate of IH in TJA, with lower BMI, THA and primary cases as risk factors. We recommend protective steps are taken to maintain patient normothermia in these groups.