Disclaimer: This article is intended solely for informational and educational purposes only. It does not constitute medical advice.
Total knee arthroplasty is one of the most commonly performed orthopedic procedures, with spinal anesthesia being an effective anesthetic technique for the procedure. The technique involves injection of a local anesthetic into the cerebrospinal fluid and produces temporary sensory, motor, and sympathetic nerve blockade. Placement is most commonly performed at the L3–L4 or L4–L5 interspace because these levels lie below the termination of the spinal cord, providing safe access to the subarachnoid space (1). The sensory and motor blockade that results from lumbar placement of the spinal block provides reliable anesthesia in the leg to safely perform total knee arthroplasty while avoiding some of the physiological effects associated with general anesthesia.
Accurate lumbar placement is essential to the success of the spinal block. Surface landmarks, particularly a line connecting the upper borders of the iliac crests, are commonly used to identify the appropriate vertebral level. However, many patients undergoing total knee arthroplasty are older adults with obesity, osteoarthritis, spinal degeneration, or limited mobility, all of which can complicate needle placement. These factors may increase procedural difficulty and the likelihood of multiple needle passes, emphasizing the importance of careful patient positioning and anatomical assessment. Successful lumbar placement promotes consistent anesthetic spread within the cerebrospinal fluid, reducing the likelihood of inadequate blockade and the need for conversion to general anesthesia.
Following injection, the local anesthetic spreads within the cerebrospinal fluid and blocks nerve conduction in the spinal nerve roots supplying the lower body. The extent and duration of anesthesia are influenced by factors such as anesthetic dose, patient positioning, and individual anatomical variation. For total knee arthroplasty, the objective is to achieve a level of analgesia and stillness sufficient for surgery while maintaining cardiovascular and respiratory stability—goals for which spinal anesthesia is well suited. Bupivacaine is the most commonly used spinal anesthetic because of its predictable onset and duration of action. More recently, shorter-acting agents such as mepivacaine have gained attention in enhanced recovery programs because they may facilitate earlier return of motor function and faster postoperative mobilization (2).
The clinical benefits of spinal anesthesia extend beyond the provision of intraoperative anesthesia. By blocking sensory and sympathetic nerve transmission, spinal anesthesia attenuates the physiological stress response to surgery and may reduce postoperative opioid requirements. Studies have reported lower rates of postoperative nausea and vomiting, decreased pulmonary complications, and improved pain control when compared with general anesthesia in selected patient populations (3). These advantages are particularly relevant in orthopedic surgery, where early ambulation and participation in physical therapy are critical components of recovery. Evidence from the International Consensus on Anaesthesia-Related Outcomes after Surgery (ICAROS) supports the use of neuraxial anesthesia for primary hip and knee arthroplasty because of its association with favorable perioperative outcomes and enhanced recovery (1). Similarly, large propensity-matched analyses have demonstrated that spinal anesthesia can be effectively incorporated into outpatient total knee surgery pathways while maintaining a high degree of patient safety.
Despite its benefits, spinal anesthesia is associated with potential complications. Hypotension resulting from sympathetic blockade is among the most common adverse effects and may require fluid administration or vasopressor therapy. Other complications include urinary retention, post-dural puncture headache, and more rarely, infection, bleeding within the spinal canal, and neurological injury. Careful patient selection, meticulous technique, and appropriate perioperative monitoring are therefore essential to minimizing risk (1). Overall, spinal anesthesia remains a highly effective strategy for total knee arthroplasty, combining safety, dependable surgical anesthesia, and outcomes that support modern recovery-focused arthroplasty care.
References
- Memtsoudis SG, Cozowicz C, Bekeris J, et al. Anaesthetic care of patients undergoing primary hip and knee arthroplasty: consensus recommendations from the International Consensus on Anaesthesia-Related Outcomes after Surgery group (ICAROS) based on a systematic review and meta-analysis. Br J Anaesth. 2019;123(3):269-287. doi:10.1016/j.bja.2019.05.042
- Siddiqi A, Mahmoud Y, Secic M, et al. Mepivacaine Versus Bupivacaine Spinal Anesthesia for Primary Total Joint Arthroplasty: A Systematic Review and Meta-Analysis. J Arthroplasty. 2022;37(7):1396-1404.e5. doi:10.1016/j.arth.2022.03.031
- Kim HJ, Roychoudhury P, Lohia S, et al. Comparison of General and Spinal Anaesthesia on Systemic Inflammatory Response in Patients Undergoing Total Knee Arthroplasty: A Propensity Score Matching Analysis. Medicina (Kaunas). 2021;57(11):1250. Published 2021 Nov 15. doi:10.3390/medicina57111250