Cemented stems in healthy elderly patients result in higher hypoxia despite a paradoxical lower femoral increase of intramedullary pressure.

Abstract

Hypoxia is a well-known complication in cemented arthroplasty; however, it is not known whether the level of hypoxia is related to the intramedullary pressure or to the age of the patient; therefore, we studied the intramedullary pressure and level of hypoxia in patients undergoing cemented arthroplasty. A prospective study was performed during cemented arthroplasties in 25 patients with an average age of 66.2 ± 12.1 years old. The intramedullary pressure (IMP) was measured by placing a pressure transducer within the bone while simultaneously measuring the pulse oximetry arterial oxygen saturation (SpO2), pulse, and blood pressure. These variables were obtained immediately after spinal anaesthesia, five minutes after cementation, and 15 minutes after prosthesis insertion. One hundred percent of patients had hypoxia at some level, but 83% of elderly patients (older than 66.5 years) had hypoxia (SpO2 <94%) as compared to only 23% of younger patients (p = 0.006). In the group of young patients, IMP was roughly increased 32 times as compared with baseline level, with as consequences a decrease of 4% of SpO2 (from 98.3 to 94.15%); in the elderly group, the IMP was only increased 20 times, but a decrease of 6% of SpO2 (from 97.25 to 91%) was observed. This series demonstrated higher hypoxia in elderly healthy patients despite a paradoxical lower femoral increase of intramedullary pressure as compared with younger patients. This hypoxia is probably not only related to the cement but also to the patient's age with decline of maximum oxygen uptake capacity and increase bone porosity. ClinicalTrials.gov Identifier: NCT03930537 https://clinicaltrials.gov/ct2/show/NCT03930537.