Anesthesia for Orthopedic Surgeries

Introduction

• Orthopedic surgeries pose several anesthetic challenges. Patients can include neonates with congenital limb deformities, healthy children and young adults with trauma, adults with multiple comorbidities, and elderly frail patients with hip fractures.
• This summary will focus on the perioperative care of patients undergoing common orthopedic surgeries.
• Special considerations such as bone cement implantation syndrome (Link), tourniquet management, fat embolism (Link), and venous thromboembolism are covered in separate summaries.

Hip Surgeries

Fracture Repair

• Most patients with hip fractures are frail elderly patients with multiple comorbidities. A comprehensive preoperative evaluation is critical.
• Hip fracture repair can be done under general or neuraxial anesthesia, and the choice of anesthetic approach largely depends on the anesthesiologist and surgeon’s preference. Multiple studies have been done to compare the efficacy of neuraxial and general anesthesia in patients undergoing hip fracture repair. Recently, a prospective, randomized superiority trial showed no superiority of neuraxial anesthesia compared to general anesthesia in elderly patients undergoing hip fracture surgery with respect to survival and recovery of ambulation at 60 days.¹
• Additionally, increased time to ambulation is associated with increased rates of delirium, pneumonia, and extended length of hospital stay; thus, early ambulation is encouraged, and epidural analgesia, femoral or fascia-iliacus blocks should be considered to facilitate this process.

Total Hip Arthroplasty

• Many patients undergoing total hip arthroplasty suffer from osteoarthritis or rheumatoid arthritis and can have significantly limited joint mobility, leading to difficulty in accurately assessing exercise tolerance. Therefore, a thorough cardiac workup may be warranted in high-risk patients. In addition, total hip replacements are associated with three potentially life-threatening complications: profuse hemorrhage, venous thromboembolism, and bone cement implantation syndrome. Due to these risks, adequate intravenous access and possible invasive monitoring with an arterial line should be considered in high-risk patients.
• Regarding the choice of anesthetic technique in these patients, multiple studies have been conducted comparing the safety and efficacy of general and neuraxial anesthesia in patients undergoing total hip replacements. A recent, large systematic review comparing the two found that neuraxial anesthesia was associated with lower odds of most complications, including mortality, pneumonia, acute renal failure, venous thromboembolism, strokes, and the necessity for blood transfusions, when compared to general anesthesia.² Based on current evidence, neuraxial anesthesia, or combination of general with neuraxial anesthesia, should be considered in these patients.

Revision Arthroplasty

• The major concern for patients undergoing revision arthroplasty is the potential for significant blood loss. Some techniques to reduce bleeding and decrease transfusion requirements include controlled hypotension, preoperative erythropoietin administration, intraoperative antifibrinolytics, maintaining normothermia, and the use of a cell saver.

Knee Surgeries

Knee Arthroscopy

• Knee arthroscopies are typically performed as outpatient procedures and can be done under either general or neuraxial anesthesia. Regional techniques can also be utilized in conjunction with local anesthesia infiltration and sedation to optimize and decrease postoperative pain. Options include a femoral nerve block, adductor canal block, and/or sciatic nerve block. Intraoperatively, surgeons may also choose to perform an intra-articular block with local anesthetics, morphine, and/or steroids.

Total or Partial Knee Replacement

• Most patients undergoing total knee arthroplasties typically present with bilateral knee degeneration. However, most surgeons still prefer to perform unilateral repair as the surgical risks are generally higher with bilateral repair (e.g., postoperative confusion, cardiopulmonary complications, and increased need for blood transfusions).
• While a select few patients will tolerate regional anesthesia with sedation, most patients require general anesthesia or neuraxial anesthesia during knee arthroplasty.
• Knee arthroplasties are typically painful, and adequate analgesia is essential for early mobilization and rehabilitation. Epidural or femoral catheters were commonly used, but due to motor weakness that precludes patients from participating in early rehabilitation, other motor-sparing techniques have been implemented. In conjunction with multimodal analgesia, the adductor canal block (ACB) with local anesthetic infiltration between the popliteal artery and capsule of knee (iPACK) block has been shown to be beneficial. The ACB anesthetizes multiple distal branches of the femoral nerve, including the saphenous nerve and nerve to vastus medialis, leading to coverage of the anterior and medial aspects of the knee while sparing quadricep motor function. The iPACK block is a muscle strength-sparing technique that consists of infiltrating the interspace between the popliteal artery and the posterior capsule of the knee, thereby anesthetizing the popliteal plexus for posterior knee coverage.
• Please see the OA summary on regional anesthesia techniques for total knee arthroplasty for more details.
• Complications of arthroplasties include bone cement implantation syndrome, especially with cement use in the distal femur, but the risk remains much lower than with hip arthroplasty. In addition, patients are at risk for significant postoperative blood loss, and consequently, may need to be monitored for 24 hours.

Ankle Surgeries

• Ankle surgeries may be done under epidural, spinal, combined spinal-epidural, or peripheral nerve blocks. The most commonly used blocks for ankle surgery include a distal sciatic block in the popliteal region (popliteal sciatic block) along with a saphenous nerve block for medial ankle coverage. With these two peripheral nerve blocks, both surgical anesthesia and postoperative analgesia can be achieved.

Foot Surgeries

• Forefoot procedures can be performed under an ankle block, targeting 5 specific branches: Posterior tibial, deep peroneal, superficial peroneal, saphenous, and sural nerves. An alternative approach includes the use of the popliteal sciatic and saphenous nerve blocks to achieve both surgical anesthesia and postoperative analgesia.

Shoulder Surgeries

• Shoulder surgeries are usually performed in the “beach chair” position, but some may be done in the lateral decubitus position. Special anesthetic considerations in the “beach chair” position include an increased risk of hypotension and decreased cerebral perfusion due to venous pooling and an increased risk for venous air embolism if there is a negative pressure gradient from the site of the surgery to the heart. To counteract the cardiovascular changes of positioning, hypotension should be aggressively treated with intravenous fluids and vasopressors.
• Typically, shoulder surgeries are performed under general anesthesia. They can be associated with high levels of postoperative pain, and regional anesthesia is frequently used to provide prolonged postoperative pain relief. The most commonly used block is an interscalene block; however, superior trunk or supraclavicular brachial plexus blocks may also be used in certain patients. In order to prolong the duration of analgesia, either interscalene perineural catheters or liposomal bupivacaine (Exparel) may be used.

Hand Surgery

• There is a wide breadth of hand surgeries, ranging from carpel tunnel release to total hand transplants. Shorter procedures (carpal tunnel release, trigger finger release, contracture release) can be performed using a Bier block or with surgical infiltration of local anesthetic. If the procedure is anticipated to be more extensive and painful, regional anesthesia using brachial plexus blocks is a very effective anesthetic technique.
• Various approaches to the brachial plexus include supraclavicular, infraclavicular, and axillary. If the patient can benefit from a prolonged block for postoperative analgesia, a perineural catheter, typically placed using the infraclavicular approach, is a great option. Notably, a supplemental intercostobrachial nerve (T1-T2) block in the axilla may be needed for upper arm tourniquet pain and/or for medial upper arm coverage during upper arm/elbow surgery.

Spine Surgeries

Cervical Spine

• Two of the most common cervical spine surgeries include posterior cervical discectomy/laminectomy and anterior cervical discectomy with fusion.
• Patients undergoing posterior cervical discectomy/laminectomy are placed in either a sitting or prone position, which increases the risk of venous air embolism or optic nerve injury, respectively. If the concern for venous air embolism is high, placing a precordial Doppler probe should be considered.
• Due to the cervical pathology necessitating these surgeries, patients may have significant limitations in neck range of motion and should be considered as high risk for difficult intubation. Video laryngoscopy or fiberoptic-assisted intubation are commonly utilized to maintain neutral neck positioning and prevent further damage to the cervical spinal cord.
• Neuromonitoring, specifically somatosensory evoked potentials (SSEP), is often utilized during cervical spine surgery due to a relatively high risk of nerve damage that can lead to quadriplegia. As a result, a total intravenous anesthesia technique with propofol and remifentanil infusions is preferred to limit the effect of anesthetic agents on neuromonitoring. If volatile agents are used, they should be limited to a maximum of 0.5 minimum alveolar concentration, and nitrous oxide should be avoided.
• The risk for significant intraoperative blood loss increases with an increasing number of levels that are instrumented. Consequently, arterial line placement is typically recommended for patients undergoing more than two levels discectomy or fusion or in high-risk patients. In addition, bispectral index monitoring may be a useful adjunct to ensure adequate depth of anesthesia.

Thoracic Spine

• Patients undergoing thoracic surgery often suffer from scoliosis or other skeletal deformities that cause a restrictive lung disease pattern. In addition, they may also have other associated congenital abnormalities, such as heart disease or neuromuscular disease. In patients with restrictive lung disease, further formal pulmonary function tests may be warranted to determine how well patients will tolerate the surgery and to predict the necessity for extra pulmonary support during recovery.
• Specific anesthetic concerns for these surgeries include neuromonitoring, intraoperative blood loss, and postoperative pain management.
• Neuromonitoring with SSEPs, motor-evoked potentials (MEPs), and electromyography (EMG) are common. If neuromonitoring is used, total intravenous anesthesia is preferred, although low concentrations of inhaled anesthetic may be used, up to 0.5 MAC. Previously, wake-up (Stagnara) tests were the gold standard for neuromonitoring but are becoming less common. Their major advantage over SSEPs, MEPs, and EMG is that wake-up tests are unaffected by anesthetic agents.
• Due to the potential for significant blood loss and hemodynamic instability, adequate vascular access is essential. Similar to cervical spine surgeries, instrumentation of more than two levels may also necessitate arterial line placement.
• Typically, these patients already utilize opioids for managing their pain and may have higher opioid requirements. Multimodal analgesia is recommended for adequate postoperative pain control. In a recent review on the current evidence for various multimodal pain management techniques in spine surgery, there is grade A evidence for the utilization of acetaminophen, gabapentinoids, neuraxial anesthesia, and local infiltration with extended-release local anesthetic to reduce postoperative pain in these patients.³ In addition, there is evidence that ketamine boluses or infusions may reduce pain scores and opioid consumption.⁴

Lumbar Spine

• Lumbar spine surgeries can range from minimally invasive procedures to more extensive surgeries, as in the thoracic spine. Smaller surgeries, such as lumbar discectomies and laminectomies, may be done under lumbar spinal or epidural anesthesia. In addition, newer, less invasive surgical procedures such as endoscopic transforaminal lumbar interbody fusion may be done under conscious sedation.
• Larger lumbar surgeries, including multilevel discectomies and fusions, involve similar anesthetic considerations as those stated above for thoracic spine surgeries.

Pediatric Orthopedic Surgeries

Cerebral Palsy

• Children with cerebral palsy undergoing orthopedic surgery often have multiple comorbidities, such as bronchopulmonary dysplasia, tracheomalacia, reactive airway disease, recurrent pneumonia, and restrictive lung disease. In addition, due to contractures and impaired neck range of motion, these patients might present with difficult airways, and video laryngoscopy or fiberoptic bronchoscopy may be necessary to secure the airway.
• These patients are also at increased risk for gastroesophageal reflux and aspiration due to a decreased tone in the lower esophageal sphincter, and rapid sequence intubation along with adequate postoperative nausea and vomiting prophylaxis should be considered. In addition, these patients are at an increased risk for intraoperative hypothermia.
• Due to extensive contractures and spasticity, intraoperative positioning is oftentimes difficult, and ligamentous laxity increases the risk of intraoperative neurologic injury.

Juvenile Rheumatoid Arthritis

• Patients with juvenile rheumatoid arthritis can present with difficult airways due to cervical spine fusion and a hypoplastic mandible. Thus, video laryngoscopy or fiberoptic bronchoscopy may be required. In addition, many of these children also have lumbar hyperlordosis, which may complicate the use of neuraxial techniques to provide anesthesia and analgesia.

Regional in Pediatric Orthopedics

• Studies have shown that regional anesthesia is not associated with permanent neurological injuries in pediatric patients. Current practice guidelines encourage performing blocks under general anesthesia or sedation, as there is an increased risk of neurologic injury when blocks are performed in awake patients.⁵