General Anaesthesia vs Spinal Anaesthesia: Patient Outcomes and Success in Outpatient Primary Total Knee and Hip Arthroplasty

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are among the most frequently performed elective surgical procedures and are highly effective treatments for advanced joint disease, most commonly osteoarthritis. Over the past decade, improvements in surgical techniques, perioperative care pathways, anaesthetic management, and postoperative rehabilitation have enabled an increasing proportion of these procedures to be performed as outpatient surgery, allowing patients to return home on the day of surgery. Outpatient arthroplasty has the potential to improve patient satisfaction, reduce hospital length of stay, lower healthcare costs, and decrease the risk of hospital-acquired complications. However, achieving safe and successful same-day discharge requires carefully optimized perioperative care.

Anaesthetic management is a central component of outpatient arthroplasty pathways. Both general anaesthesia (GA) and spinal anaesthesia (SA) are routinely used for TKA and THA, and both techniques are well established with extensive safety data. Neuraxial anaesthesia has traditionally been associated with reduced intraoperative blood loss and certain postoperative complications, and it is commonly recommended in clinical guidelines for hip and knee arthroplasty. In contrast, modern general anaesthesia using short-acting intravenous agents may offer advantages in the outpatient setting, including predictable onset and offset, rapid recovery of motor function, and reduced postoperative nausea and vomiting when volatile agents are avoided.

Despite widespread clinical use of both techniques, the optimal choice of anaesthesia for outpatient TKA and THA remains uncertain. Much of the existing evidence comparing GA and SA is derived from retrospective observational studies and registry-based analyses. These studies often include mixed inpatient and outpatient populations and are subject to confounding by indication, as patients receiving GA frequently differ from those receiving SA with respect to comorbidity, functional status, or anticipated surgical complexity. As a result, it is difficult to determine whether observed differences in outcomes are attributable to the anaesthetic technique itself or to underlying patient characteristics. Randomized clinical trials specifically designed to compare GA and SA in the outpatient arthroplasty setting are scarce.

The GASPS (General Anaesthesia vs Spinal Anaesthesia: Patient Outcomes and Success in Outpatient Primary Total Knee and Hip Arthroplasty) trial was designed to address this evidence gap. GASPS is a multicentre, randomized, phase IV clinical trial comparing GA and SA in adults undergoing outpatient primary TKA or THA. The overarching aim of the trial is to generate high-quality randomized evidence on whether the choice of anaesthetic technique influences the likelihood of successful same-day discharge and postoperative recovery in outpatient arthroplasty.

A total of 600 participants will be enrolled across multiple orthopaedic centres in Sweden. Eligible patients scheduled for outpatient primary TKA or THA are randomized on the day of surgery to receive either GA or SA. Randomization is performed using a stratified permuted block design, with stratification by type of surgery (knee or hip arthroplasty) and study site, to ensure balanced allocation across groups. Allocation concealment is maintained until shortly before surgery. Due to the nature of the interventions, blinding of patients and clinical staff is not feasible; however, data analysts remain blinded during analysis.