Spinal Anesthesia for Ambulatory Hip and Knee Arthroplasty Procedures

This educational video article details the technique of spinal anesthesia administration for total hip and knee arthroplasty. The presentation details key procedural elements, including anatomical landmarks, midline and paramedian techniques for spinal placement, equipment for spinal anesthesia, patient positioning and preparation, and local anesthetic selection. Spinal anesthesia offers distinct advantages for outpatient arthroplasty, including rapid onset, favorable operative conditions, and facilitation of same-day discharge. The video serves as a practical educational tool that reinforces evidence-based anesthetic practice and supports the continued advancement of safe, efficient care in ambulatory joint replacement surgery.

The transition of total hip and knee arthroplasty procedures from inpatient to ambulatory settings has been driven by a growing patient population requiring surgery, along with hospital capacity constraints and the need to optimize length of stay and resource utilization.^1,2 Spinal anesthesia has emerged as the preferred anesthetic modality for these procedures, offering several advantages over general anesthesia in the ambulatory setting. The utilization of spinal anesthesia for arthroplasty has been shown to provide several key benefits: rapid onset of action, excellent operative conditions for surgeons, facilitation of early discharge, and minimal side effects compared to general anesthesia.^3–6 With the increasing complexity and volume of hip and knee arthroplasty procedures performed on an outpatient basis, the selection of an appropriate anesthetic technique has become a critical factor in optimizing patient outcomes and facilitating same-day discharge criteria.

This educational video presents a detailed demonstration of the technique involved in administering spinal anesthesia for ambulatory hip and knee arthroplasty procedures.

Before the spinal anesthesia procedure is initiated, a thorough patient evaluation is performed and consent is obtained. Intravenous access is established, and mild sedation may be administered before the patient's transfer to the operating room. Patient positioning can be achieved either in the sitting position or in the lateral decubitus position for patients unable to maintain an upright posture. Once proper positioning has been established, a safety pause is conducted to verify the correct operative site, review patient allergies, confirm anticoagulation status, and ensure that coagulation parameters, including platelet count, partial thromboplastin time, and international normalized ratio, all fall within acceptable procedural guidelines.

The standard spinal anesthesia tray contains essential equipment, including a 20-gauge introducer needle and a 25-gauge Whitacre spinal needle. The local anesthetic agent used is low dose (5 to 10 mg) preservative free isobaric bupivacaine 0.5%, which is checked for an appropriate expiration date before use. Lidocaine 1% is utilized for skin and soft tissue infiltration before spinal needle insertion. Medications are carefully labeled to prevent any potential confusion or drug mix-ups. The medication is aspirated using a filter needle into a glass syringe, with attention to the elimination of air bubbles.

The patient's back is cleansed with chlorhexidine solution using sterile technique, with the antiseptic preparation applied twice to ensure adequate sterilization. The landmark technique is used for identifying the proper needle placement site. The iliac crests are palpated bilaterally, and an imaginary line (Tuffier’s line) is drawn between them, corresponding to L4–L5 interspace in most adults, which is a safe insertion level in the lumbar spine for spinal anesthesia placement.

Following identification of the appropriate interspace, lidocaine is injected subcutaneously to provide local anesthesia. The introducer needle is then inserted through the anesthetized skin and subcutaneous tissue, followed by advancement of the spinal needle through the introducer. As the spinal needle is advanced through successive tissue layers, distinct changes in resistance are appreciated as it traverses the supraspinous ligament, interspinous ligament, and ligamentum flavum before entering the subarachnoid space. Cerebrospinal fluid (CSF) free flow confirms proper intrathecal placement.

After confirming CSF flow, the syringe containing local anesthetic is securely attached to the spinal needle, and the medication is gently injected into the intrathecal space. Following completion of the injection, the spinal needle and introducer are withdrawn together as a unit. The patient is then positioned appropriately for the surgical procedure, and intraoperative sedation is usually provided using continuous propofol infusion.

For contemporary hip and knee arthroplasty pathways that prioritize early ambulation and same-day discharge, the choice of local anesthetic is a major determinant of recovery. Mepivacaine produces a shorter and more predictable motor block, allowing for earlier ambulation when compared with bupivacaine, which translates into higher same-day discharge rates. Bupivacaine produces a prolonged motor and sensory blockade that can delay hospital discharge. Rates of side effects are similar between agents.⁷ Lower doses of bupivacaine produce significantly shorter block durations and favorable recovery profile well suited for ambulatory surgery.^8,9

Several adjuncts including opioids, alpha-2-agonists, and other drugs can be co-administered, often allowing for a reduction in the required dose of local anesthetic, thereby facilitating motor-sparing anesthesia and faster recovery while maintaining equivalent analgesia. The most commonly used intrathecal opioids are morphine and fentanyl. Hydrophilic opioids such as morphine are associated with a higher risk of delayed respiratory depression, which, although rare, represents one of the most serious complications of intrathecal opioid administration. In addition, intrathecal opioids may cause other adverse effects, including nausea and vomiting, pruritus, and urinary retention.^10,11

Urinary retention may occur in up to one third of patients following neuraxial anesthesia. Local anesthetic blockade of the S2, S3, and S4 nerve roots inhibits normal urinary function by weakening detrusor muscle activity. Neuraxial opioids may further exacerbate urinary dysfunction by suppressing detrusor contractility and diminishing the sensation of bladder fullness. Spontaneous recovery of normal bladder function is generally expected once the sensory block regresses below the S2-S3 level. Intrathecal morphine is strongly associated with urinary retention, and other risk factors may include male sex and advanced age.^11-14

Standard monitoring is maintained throughout the procedure, including electrocardiography, arterial blood pressure measurement, pulse oximetry, temperature monitoring, and end-tidal carbon dioxide measurement. Additional medications include the administration of prophylactic antibiotics, tranexamic acid to minimize surgical blood loss, antiemetics, and intravenous fluids for hydration.

Administration of spinal anesthesia can be performed using a midline or paramedian approach. In the midline approach, the needle is inserted in the midline and advanced through supraspinous ligament, interspinous ligament, ligamentum flavum, and dura. This technique is feasible in patients with easily palpable landmarks. In the paramedian approach, the needle is inserted approximately one to two centimeters lateral to the midline and angled medially and cephalad toward the presumed midline. This approach is particularly useful in patients with lumbar spine pathologies such as scoliosis and calcified ligaments where midline access may be limited. If bony contact is encountered, the needle trajectory is adjusted until an unobstructed path is identified and free flow of CSF is obtained confirming correct intrathecal placement.

Following surgical completion, propofol sedation is discontinued, and the patient is transferred to the post-anesthesia care unit. Spinal anesthesia gradually resolves following the procedure; its duration depends on the specific agents and dosage of the local anesthetic, the use of adjuncts, and other patient factors. Continuous monitoring is maintained to ensure patient comfort and the absence of anesthesia-related adverse effects. Once sensory and motor function return to the lower extremities, patients progress to physical therapy evaluation to complete necessary recovery milestones before being discharged home the same day.

This video serves as a resource for healthcare professionals involved in the multidisciplinary care of arthroplasty patients, including physicians, nurses, physical therapists, and care coordinators who support patients through enhanced recovery after surgery programs. Understanding the technical aspects of spinal anesthesia, appropriate patient monitoring, complication recognition and management, and postoperative care protocols ensures optimal patient safety and outcomes. The demonstrated techniques, from proper patient positioning and sterile preparation through medication administration and postoperative monitoring, provide a comprehensive educational foundation for safe and effective practice in the rapidly evolving field of ambulatory arthroplasty.

Nothing to disclose.

The patients referred to in this video article have given their informed consent to be filmed and are aware that information and images will be published online.