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Anaesthesiology
Anesthesia for Orthopedic Surgery
Built from Barash Clinical Anesthesia, 9th Edition
What’s inside
7 sections · 186 slides
Overview
- Scope of this topic
- Core themes of orthopedic anesthesia
- What the anesthesiologist must know
Preoperative Assessment and Choice of Technique
- Test according to the medical history and the planned operation, not by routine. Look hard for a difficult airway, and for problems with moving and positioning. Ask about long-term opioid use and about every blood-thinning drug. Heart and lung symptoms are hard to judge when a painful joint stops the patient walking. Because of that, drug stress testing of the heart or formal lung tests may be needed. Overall these patients carry intermediate risk of a heart complication around surgery.
- Rheumatoid arthritis attacks joints but also lung, heart and muscle. Neck joints and the jaw joint are involved, so the neck moves little and the mouth opens little. Atlantoaxial instability = the top two neck bones slip; the peg can press the cord. Extending the neck in such a patient can injure the spinal cord. Long-term steroid users may need extra steroid cover around surgery.
- Give the patient written instructions on what to stop and what to keep taking. Do not stop long-term opioids abruptly; weaning is best done by a pain specialist first. Opioid users may be tolerant and may have opioid-induced hyperalgesia (pain feels worse). Blood pressure drugs without a rebound effect can be held on the day of surgery. ACE inhibitors and ARBs are held when low blood pressure or kidney injury is feared. The anticoagulation plan must be agreed by medical and surgical teams, and told to the patient.
- Look for distorted airway anatomy and a neck that will not move. Inspect the skin where a block or a line will be placed for infection or odd anatomy. Do a brief nerve exam and write down any weakness or numbness that is already there. Think ahead about body size, painful or unstable joints, fractures and old fusions. Explain the operation, the anesthetic options and the rehabilitation plan.
- Advantages of regional anesthesia
- Match the block to how long surgery will take. Decide whether a sympathectomy (open blood vessels) is wanted after surgery. Decide how much numbness and weakness is wanted afterwards, and for how long. Physiotherapy may need muscle power preserved, which argues against dense motor block.
- The surgical site is not covered by any practical block. The patient is anticoagulated, or has infection at the needle site. There is pre-existing nerve injury or nerve disease, or the patient refuses. A block that is barred is not a bar to all blocks: choose another route. Coagulopathy blocks neuraxial and deep plexus blocks, yet a superficial block may be fine. With existing peripheral neuropathy, a neuraxial block may be the safer option.
- Deciding between regional and general anesthesia
Anesthesia for Spine Surgery
- Check the breathing, circulation and nervous system in every spine patient. Difficult airways are common in upper thoracic and cervical spine disease. Assess how far the neck moves, whether it is stable, and what movement does to symptoms. Discuss the neck films and stability with the surgeon before moving the neck. Decide before the day whether to intubate awake, asleep, or with advanced devices. Awake intubation is preferred when nerve function must be tested before traction is applied.
- Scoliosis (sideways curved spine) squashes the chest and gives restrictive lung disease. Nerve and muscle diseases bring repeated chest infections. Spinal cord injury patients may already be on a ventilator. Chest x-ray, blood gas and lung function tests help when restrictive disease is suspected. Vital capacity below 30% to 35% of predicted predicts prolonged ventilation after scoliosis surgery. Optimise first: physiotherapy, antibiotics and bronchodilators where indicated.
- Heart problems often travel with spine disease, and are the first sign in muscular dystrophy. Rarely scoliosis causes cor pulmonale: chronic low oxygen strains the right heart. Get an ECG and an echocardiogram for left ventricle function and lung artery pressures. Dobutamine stress echo helps when the patient cannot exercise enough to be tested.
- Existing weakness usually comes from the disease itself; document it in detail. Discuss the findings with both patient and surgeon before the operation. In cervical surgery, avoid further injury during intubation and turning. Neuromuscular disease raises the risk of aspiration when the airway is handled. After cord injury, watch for spinal shock and autonomic dysreflexia.
- Goals of positioning for spine surgery
- Positioning for spine surgery
- Pressure on the belly squashes the inferior vena cava, the big vein returning blood. That backs up blood into epidural veins, which have no valves, so the wound bleeds more. It also drops cardiac output and raises the risk of leg clots. Pad under the chest below the armpits and under the front hip bones. Keep arms abducted under 90 degrees, slightly turned in, to spare the brachial plexus. A flexed elbow puts the ulnar nerve at risk; protect it and tape the eyes shut.
- How abdominal pressure increases surgical bleeding
- The anterior thoracolumbar approach uses either supine or lateral position. In scoliosis the convex side of the curve is uppermost; a rib may be removed for access. Above T8 in the lateral position, a double-lumen tube may be needed to collapse one lung. Cervical spine: anterior approaches are supine, posterior approaches are prone. The head may face away from the machine, so circuit and line extensions are needed. Foot veins are sometimes the only access left once the arms are tucked.
- Secure the tracheal tube well without getting in the surgeon's way. Support the head on a padded ring or the horseshoe of a Mayfield attachment. Neck traction, when needed, uses pins and weights on the outer skull. Reverse Trendelenburg cuts vein bleeding and gives countertraction. Blood pooling in the legs plus carotid retraction can swing blood pressure fast. So place an arterial line, and place it before the arms are tucked at the sides.
- Blood loss in adult spine surgery
- Preoperative autologous donation: the patient banks their own blood beforehand. Careful positioning that keeps vein pressure low. Intraoperative blood salvage: wash and give back the patient's own shed blood. Antifibrinolytics such as tranexamic acid, which stop clots being broken down early. Tranexamic acid cuts bleeding and transfusion without more pulmonary embolism, DVT or heart attack.
- Why spinal cord monitoring is used
- Three methods of intraoperative cord monitoring
- The patient is woken during surgery, once the metalwork is in, and asked to move. If hands move but feet do not, distraction on the rod is released one notch and it is repeated. Anesthesia can be volatile plus nitrous oxide and opioid, with or without propofol. Opioid matters: it gives analgesia and lets the patient tolerate the tube while awake. Recall happens in 0% to 20% and is rarely felt to be unpleasant. Describe the test beforehand so any recall does not frighten the patient.
- An uncooperative patient may move, pull out the tube, or even fall off the table. It shows function only at that single moment in the operation. It can falsely reassure: injury may still occur after the test is done. Best kept for when other monitoring is unavailable, unclear, or has failed.
- SSEPs follow the dorsal columns, which carry position sense and vibration. Those columns are fed by the posterior spinal artery. SSEPs are dulled by nerve injury, volatile agents, high carbon dioxide, low oxygen, low pressure and cold. MEPs watch the motor pathways fed by the anterior spinal artery. MEPs are harder to use because muscle relaxants block them. For both, use short-acting opioid infusion with low-dose volatile, or TIVA with EEG or BIS.
- Paraplegia has happened despite normal SSEPs throughout. MEPs added to SSEPs may catch cord ischemia earlier. A sudden drop in signal size or delay in timing means the cord may be compromised. Causes include direct trauma, poor blood supply, compression or a haematoma. Stop surgery, raise blood pressure to normal or 20% above, cut or stop volatile agent. Check a blood gas; if signals stay abnormal the surgeon releases distraction, then wake-up test.
- Response to a loss of evoked potential signal
- Immediate assessment of spinal cord injury
- Spinal shock begins straight after injury and can last up to three weeks. Injury at or above T5 causes low blood pressure from a physiologic sympathectomy. The splanchnic (gut) vessels lose their tone and blood pools there. Lesions above the cardiac accelerator fibres (T1 to T4) also give a slow heart rate. This hypotension responds poorly to fluids and vasopressors. Pouring in fluid instead risks pulmonary edema (fluid flooding the lungs).
- After spinal shock settles, 85% with complete transection above T5 develop it. It can also follow lower lesions. Severe sudden high blood pressure, with a slow pulse from the baroreceptor reflex. Skin constricts below the lesion and dilates above it; rhythm disturbances occur. A full bladder or rectum usually triggers it, but so can surgery or any noxious stimulus. Treat by removing the trigger, deepening anesthesia and giving direct-acting vasodilators.
- Autonomic hyperreflexia if left untreated
- The higher the lesion, the worse the breathing. A high cervical lesion involving C3 to C5 paralyses the diaphragm; ventilation is life-saving. Lesions from C5 to T7 remove abdominal and intercostal support. Floppy chest muscles cause paradoxic breathing and cut vital capacity by 60%. The patient cannot cough or clear secretions, so atelectasis and infection follow.
- Succinylcholine is safe for the first 48 hours after the injury. After that, muscle grows extra acetylcholine receptors and becomes hypersensitive. The drug then dumps potassium out of muscle into the blood. Potassium can reach 14 mEq/L, causing ventricular fibrillation and cardiac arrest. Risk is highest between 4 weeks and 5 months after injury. Avoid it after 48 hours; nondepolarizing relaxants can be used instead.
- These patients are poikilothermic: body temperature drifts with the room. Sympathetic pathways carrying temperature sensation are cut. Below the lesion the blood vessels no longer constrict to conserve heat. Warm the skin, raise room temperature, warm the fluids and humidify the gases.
- Scoliosis of the spine
- Chronic low oxygen and high carbon dioxide constrict the lung blood vessels. Those vessels eventually change permanently, causing pulmonary hypertension. The right ventricle thickens and finally fails: cor pulmonale. Untreated idiopathic scoliosis can progress fast and is often fatal by the fourth or fifth decade. It is often linked to congenital heart disease: mitral valve prolapse, coarctation, cyanotic lesions. That link suggests a shared embryonic insult or a collagen defect.
- Long term, surgery halts the decline in lung function. Short term, lung function gets worse for 7 to 10 days after the operation. Preoperative vital capacity reliably predicts respiratory reserve. A vital capacity below 40% of predicted usually means ventilator support afterwards.
- Long prone operation with wide exposure, so hypothermia is expected. Plan for replacing substantial blood and fluid loss. Good venous access and hemodynamic monitoring are essential. An arterial line allows close pressure monitoring and repeated blood gases. A central line helps judge fluid balance and can aspirate air in venous air embolism. A pulmonary artery catheter may be needed with pulmonary hypertension or severe heart or lung disease.
- Duchenne muscular dystrophy
- Cardiac abnormalities occur in 50% to 70% of patients. Late in the disease a dilated cardiomyopathy develops with mitral valve incompetence. Up to half have conduction defects that predispose to rhythm disturbances. Those rhythm problems have caused cardiac arrest during spine surgery. Patients are sensitive to nondepolarizing neuromuscular blocking drugs. Succinylcholine can cause dangerous hyperkalemia.
- Degenerative vertebral column disease
- Cerebrospinal fluid leaks and vertebral artery injury have also been reported. General anesthesia is preferred for nearly all degenerative thoracic and cervical procedures. A regional technique would need an unacceptably high spinal level. General anesthesia secures the airway, is better accepted, and suits long operations. For lower thoracic and lumbar surgery, either general or neuraxial anesthesia is safe.
- Spinal versus general anesthesia for lumbar spine surgery
- Extubation after spine surgery
- Ventilate for a few hours, head of bed up, until cold and metabolic problems are corrected. Wait for face and airway swelling to settle before extubating. Aggressive chest physiotherapy with incentive spirometry prevents atelectasis and pneumonia. Watch blood pressure, urine output and wound drainage for ongoing bleeding. Follow the neurologic examination closely.
- Traditionally systemic opioids, often by patient-controlled analgesia pump. Side effects are respiratory depression, sedation and a sluggish gut. These matter more after major spine surgery when breathing is already fragile. Enhanced recovery pathways use multimodal analgesia: several drugs with different actions. That cuts pain scores, opioid use, opioid side effects and hospital stay.
- Historically only local anesthetic in the wound, or intrathecal morphine. Field and fascial plane blocks are now being applied to spine surgery. These include transversus abdominis plane and erector spinae plane blocks. The thoracolumbar interfascial plane block is another option. Adding non-opioid drugs cuts opioid use and opioid side effects while improving relief.
- Consider anticonvulsant drugs case by case. Recent evidence shows harm without clear benefit in patients not already on them. NSAIDs were historically avoided because of worry about bone remodelling and fusion. Newer data suggest a short course of low-dose nonselective NSAID is reasonable. Always consult the surgical team before starting them.
- Reading the multimodal analgesia table
- Multimodal analgesia for orthopedic surgery: mechanism of action
- Multimodal analgesia for orthopedic surgery: common side effects
- Multimodal analgesia for orthopedic surgery: additional considerations
- Venous air embolism during spine surgery
- Prevent by expanding blood volume, positioning carefully, PEEP and jugular vein compression. Treat by flooding the wound with saline and controlling the site where air enters. Reposition so the surgical site sits below the right atrium. Aspirate air through a multiorifice central venous catheter. Stop nitrous oxide, give oxygen, fluids and inotropes. Massive embolism may need supine repositioning and cardiopulmonary resuscitation.
- Rare, not fatal, but catastrophic. Causes are optic neuropathy, retinal artery occlusion, or brain ischemia. Most cases follow complex instrumented fusions. Also sustained low blood pressure, anemia, large blood loss and long surgery. The ASA Postoperative Visual Loss Registry reported 93 cases after spine surgery. Ischemic optic neuropathy accounted for 83 of those 93 cases.
- Male sex. Obesity. Use of the Wilson frame for positioning. Long anesthetic duration. Large blood loss. Use of noncolloid fluids for resuscitation.
Upper Extremity Surgery
- Upper limb orthopedic surgery suits regional techniques particularly well. Adjuvants added to the block prolong it and give significant pain relief afterwards. Continuous catheter techniques keep the analgesia going and help early movement. The benefits of regional anesthesia here are well established.
- Brachial plexus roots, trunks, divisions and cords
- What the plexus diagram shows
- Many orthopedic patients already have central or peripheral nerve disease. Surgery on the arm may involve nerves that are already damaged. Double-crush syndrome: two insults on one nerve add up to injury. Here that means surgical trauma plus needle and local anesthetic. Decide case by case, after discussion with patient and surgeon. Ultrasound guidance, sensible local anesthetic, careful positioning and repeated exams lower risk.
- Pick the local anesthetic by how long and how dense a block is needed. Tell the patient before surgery how long it should last. Instruct them to protect the numb limb until sensation returns. If the block may wear off overnight, start oral painkillers at bedtime while still numb. That avoids waking to sudden severe pain.
- Supraclavicular, superior trunk and infraclavicular blocks rarely cause pneumothorax. It may not show up until 6 to 12 hours after surgery. These blocks are still routinely safe for inpatient and day-case work. Tell every patient to contact the surgeon immediately if breathing becomes difficult.
- Nerve injury rates in shoulder surgery
- Axillary nerve and brachial plexus injuries usually follow proximal humerus fractures. Radial nerve palsy is associated with humeral shaft fractures. So examine carefully and document deficits before any block is placed. Communicate the current evidence on risk and benefit clearly to the patient.
- Beach chair and lateral positions for the shoulder
- Lateral decubitus versus beach chair for shoulder surgery
- It carries a risk of lateral femoral cutaneous nerve injury. That risk is higher in patients with a higher body mass index. Blood pools in the legs, dropping blood pressure and cardiac output. Blood pressure at the head is lower than at the arm or leg. For every 20 cm the head sits above the heart, mean arterial pressure falls about 15 mmHg.
- Beach chair position and the pressure gradient
- Hypotension in this position has been linked with falling cerebral oxygen saturation. Case reports describe catastrophic injuries: brain and cord ischemia, and vision loss. Studies suggest a mismatch of brain oxygen supply and demand in the beach chair. But a clear link between those oxygen measures and bad outcomes has not been shown. More research is needed on how often harm occurs and how best to monitor and prevent it.
- Up to 24% of beach chair patients have hemodynamically significant hypotensive bradycardic events. They occur under general or regional anesthesia. Usually brief and self-resolving, but they can progress to asystole without prompt treatment. The cause is unknown; underfilling of the ventricle may trigger the Bezold-Jarisch reflex. Epinephrine, fentanyl, hydralazine, propofol and dexmedetomidine are linked to increased risk. Ondansetron or metoprolol given before incision may significantly lower the risk.
- Ephedrine has been used successfully to treat these events. Atropine has been used successfully to treat these events. Glycopyrrolate has been used successfully to treat these events. All three should be immediately available whenever the beach chair position is used.
- A tourniquet cannot be used on the proximal upper limb, so bleeding can be significant. Patients also risk sudden instability from fat, air or cement emboli. Consider an arterial line for continuous direct blood pressure. Monitor haemoglobin concentration as well. This applies particularly to total shoulder arthroplasty and humeral fracture fixation.
- Regional alone, general alone, or both combined. With careful positioning and sedation, interscalene, superior trunk or supraclavicular block can carry the case. Consider general without a block if there is existing brachial plexopathy or major cervical spine disease. In those patients a block risks worsening the existing deficits. For general anesthesia, use a supraglottic airway or a tracheal tube. A supraglottic airway allows spontaneous breathing, which preserves venous return.
- Positive pressure ventilation reduces venous return and worsens hypotension. Spontaneous breathing through a supraglottic airway avoids that. The major drawback is difficult access to the airway during the case. If the device is dislodged, or breathing fails, reaching the airway is hard. The same problem applies to deep sedation with nasal cannula only.
- Use of regional techniques after shoulder surgery has grown over the past decade. It reduces opioid use and opioid-related side effects. It improves pain control after the operation. It speeds discharge, cuts complications and readmissions, and raises satisfaction. Combining regional with general secures the airway and gives muscle relaxation when needed. It also covers a surgical field extending beyond the block's dermatomes.
- Interscalene groove and the phrenic nerve
- The interscalene block and the diaphragm
- Low-volume interscalene block with general anesthesia gives good relief. Clinically significant phrenic palsy is then rare in healthy patients. Accessory and intercostal muscles take over the work of breathing. Use with caution in severe lung disease: they may need oxygen or ventilation afterwards. Also be careful in obesity or sleep apnea, where functional reserve capacity is already low. These patients are at higher risk of clinically significant loss of lung function.
- Transient Horner syndrome can occur on the blocked side. Horner syndrome = drooping eyelid, small pupil, no sweating, sunken eye. The recurrent laryngeal nerve may also be blocked, causing hoarseness. These can alarm the patient, so include them in the preoperative consent.
- Concerns about breathing and safety have driven the search for blocks further down the plexus. The supraclavicular block has fewer side effects than interscalene. But it may need larger local anesthetic volumes to give adequate analgesia. Smaller volumes may miss the more proximal suprascapular nerve. Phrenic palsy after supraclavicular block is still clinically significant, though less common.
- The superior trunk block targets C5 and C6 where they join to form the superior trunk. The trunk then branches into the major nerves supplying the shoulder. As a low-volume block just distal to the interscalene, it preserves diaphragm function. The suprascapular nerve supplies part of the sensation to the shoulder. In 136 patients, a subomohyoid anterior suprascapular block was noninferior to interscalene. Posterior suprascapular plus axillary nerve block is inferior for major shoulder surgery.
- It does not adequately cover the lateral pectoral nerve. It does not adequately cover the subscapular nerves. It does not adequately cover the musculocutaneous nerve. That is why it is inferior to interscalene block for major shoulder surgery.
- Blocks for the elbow, wrist and hand
- Carpal tunnel release, phalanx fracture reduction and superficial debridement are minor. Without a tourniquet, local infiltration alone may be enough. Or block the nerve at midhumeral, elbow or wrist level. Intravenous regional anesthesia (Bier block) uses a double tourniquet. It suits short hand and forearm surgery but gives no pain relief afterwards.
- Reading the upper extremity block table
- Regional techniques for upper extremity surgery: nerves blocked
- Regional techniques for upper extremity surgery: applications
- Regional techniques for upper extremity surgery: comments
- Regional techniques for upper extremity surgery: comments (continued)
- Peripheral nerve blocks bring earlier discharge after rotator cuff repair. They also lower the risk of hospital admission after that operation. For total shoulder arthroplasty, blocks improve pain control without added complications. Brachial plexus catheters can go in by interscalene, infraclavicular or axillary route. They are typically left in for 2 to 3 days without adverse effects. Indwelling catheters cut opioid needs and side effects and improve rehabilitation.
Lower Extremity Surgery
- Lower limb orthopedic operations are among the commonest surgeries in the United States. Demand for hip and knee replacement is rising with longer life and quality-of-life expectations. Either general or regional anesthesia can be used. The mortality and morbidity benefit of neuraxial technique is somewhat controversial. With the move to day-case joint replacement, regional improves readiness for discharge. It improves same-day discharge and can reduce readmissions.
- A large database study of hip and knee replacement favoured neuraxial technique. It found lower 30-day mortality and fewer clot events. Also less blood loss and fewer transfusions. Plus shorter stay, lower cost and fewer in-hospital complications. However a systematic review and a hip fracture trial found no morbidity or mortality difference. Peripheral nerve blocks are associated with better outcomes after knee and hip replacement.
- Deep vein thrombosis and venous thromboembolism are major complications after lower limb surgery. Epidural haematoma after a neuraxial block is rare but devastating. It happens when the block is placed or removed too close to an anticoagulant dose. So the dose and timing of every anticoagulant must be known before any needle goes in.
- Reading the lower extremity technique table
- Anesthetic techniques and nerve blocks for lower extremity surgery: anesthetic (optimal anesthetic)
- Anesthetic techniques and nerve blocks for lower extremity surgery: nerve block options (preferred blocks)
- Hip replaced on one side, seen on an AP pelvis radiograph
- Hip arthroplasty: scale and patient profile
- The anterior approach is gaining favour because it spares tissue. It allows a smaller incision, possibly less pain, faster recovery and better mobility. But most hip and femur surgery still uses a posterior approach. For that the patient lies lateral, arms neutral, abducted or flexed under 90 degrees. An axillary roll stops compression of the brachial plexus and axillary artery. Secure the airway supine before turning, and keep the neck and head neutral.
- Positioning for hip surgery
- Patient on the traction table for anterior hip arthroplasty
- Lateral position with an inflatable axillary roll
- General anesthesia is still commonly used, but evidence supports neuraxial technique here. It offers potentially better morbidity and readiness for discharge. Done properly and within anticoagulation guidelines, it is low risk. Exact complication rates are elusive because practice and patients vary so much. Higher risk after neuraxial: clotting abnormalities, spinal stenosis and older age. Haematomas are less likely with subarachnoid (spinal) than with epidural technique.
- Neuraxial technique may shorten hospital stay in hip fracture. Its overall mortality benefit remains controversial. These patients are frail with conditions that are hard to optimise. Surgery within 48 hours of admission lowers inpatient mortality and pressure sores. So operate as soon as it is safely possible.
- Neuraxial block causes sympathectomy: blood vessels relax and pressure falls. Take extra care in patients with significant other diseases. Severe aortic stenosis is the particular concern, since output cannot rise to compensate. Give a fluid bolus before the spinal or epidural to blunt the drop. Dose an epidural catheter slowly and in stages rather than all at once.
- The lumbar plexus (psoas compartment) block is deep and gives potent hip analgesia. The needle goes deep, so vascular puncture risk is higher; avoid it in anticoagulated patients. It can rarely lead to unintended intrathecal or intravascular injection. Femoral nerve block is a useful alternative. But quadriceps weakness from it may raise the risk of falls during rehabilitation. Catheters for either block can reduce opioid needs and opioid side effects.
- Fascial plane blocks add further options for hip analgesia. The quadratus lumborum block is one of them. The pericapsular nerve group (PENG) block is another. So is the suprainguinal fascia iliaca block. All are fully or partly motor sparing compared with lumbar plexus and femoral blocks. They are new and the evidence is contradictory, so their final place is unclear.
- Hip replacement now uses smaller implants, smaller cuts and less cement. Recovery is therefore faster and less painful. Some surgeons inject a cocktail into the tissue around the joint. It may contain local anesthetic, epinephrine, an NSAID, a corticosteroid or an antibiotic. These infiltrations beat placebo. But they do not appear to outperform peripheral nerve blocks.
- Deliberate hypotension under neuraxial block cuts blood loss and transfusion versus general anesthesia. However the practice remains controversial. Tranexamic acid, given intravenously or topically, is safe and widely used. It reduces blood loss and transfusion in joint arthroplasty, even in high-risk patients. Keeping the patient warm improves clotting during the operation.
- Hip arthroscopy
- Arthroscopy fluid can leak out of the joint into the abdominal cavity. In extreme cases this causes abdominal compartment syndrome. That leads to hemodynamic instability, cardiovascular collapse, and rarely death. Iliopsoas tenotomy with high pump pressures is a risk factor. Suspect it in an unstable patient with severe abdominal or pelvic pain after surgery. Treatment ranges from observation to diuresis, and in severe cases laparotomy.
- Intra-abdominal fluid extravasation after hip arthroscopy
- Point-of-care ultrasound can diagnose the fluid leak at the bedside. It uses the FAST examination: focused assessment with sonography in trauma. Fascial plane blocks such as quadratus lumborum and PENG show mixed results in hip arthroscopy.
- Knee replacement seen on a radiograph
- Total knee arthroplasty: scale and pain
- Knee arthroplasty and arthroscopy are done supine for easy access to the joint. That allows the knee to be checked in both extension and flexion. A thigh tourniquet reduces bleeding and improves the surgeon's view. It may not compress arteries properly in severe atherosclerosis. Use it cautiously with active leg infection or thrombosis: emptying the limb can spread them. Tranexamic acid is safe here and cuts blood loss and transfusion.
- Regional anesthesia improves pain outcomes over traditional opioid regimens. Epidural infusion of dilute local anesthetic with low-dose opioid gives excellent control. It works particularly well with patient-controlled epidural analgesia. Managing an epidural for analgesia must fit around clot prophylaxis drugs. Intrathecal morphine can be added, but needs prolonged monitoring. That is because respiratory depression from it can be delayed.
- Ultrasound guidance has greatly increased use of nerve blocks and catheters. A balanced multimodal regimen includes anti-inflammatories and acetaminophen. It also includes opioids where needed. Drugs for the neuropathic component of pain, such as pregabalin, may be added. Multimodal treatment maximises pain relief while minimising side effects.
- The femoral, sciatic and obturator nerves supply sensation to the knee joint. The commonest blocks are lumbar plexus, fascia iliaca (3-in-1), femoral, and adductor canal. The adductor canal block is also called the saphenous nerve block. These can be combined with sciatic or obturator block. Or with an IPACK block: infiltration between the popliteal artery and the posterior knee capsule. Evidence keeps evolving on which combination best supports rehabilitation and discharge.
- Femoral nerve block versus adductor canal block
- Femoral nerve block was historically the block of choice for knee replacement analgesia. It has a low complication profile and is easy with nerve stimulator or ultrasound. Its drawback is quadriceps weakness, reported up to 80%, and the fall risk that follows. The correlation with falls is disputed. Adductor canal block gives a similar analgesic profile with better mobility. Low local anesthetic volume inside the canal minimises block of the vastus medialis.
- The sciatic nerve supplies sensation to the back of the knee. Combined with a femoral block, it reduces opioid use after knee replacement. But sciatic block causes foot drop, which raises fall risk. Foot drop also delays diagnosis of common peroneal nerve palsy. That palsy is seen after large valgus corrections of the knee. A selective tibial nerve block gives similar relief without the foot drop.
- IPACK is a motor-sparing alternative to sciatic block for pain at the back of the knee. It targets the 12 articular branches of the anterior and posterior knee capsule. It works well when added to an adductor canal block or periarticular injection. Transient foot drop is rare, but happens if local anesthetic reaches the sciatic nerve.
- Surgeons can inject drug cocktails around the joint. This shortens stay and improves resting pain scores compared with placebo. But it does not seem better than regional anesthesia techniques. Liposomal bupivacaine can be added to prolong the local anesthetic effect. Its benefit over standard local anesthetic is not conclusive. Weigh both its safety profile and its cost.
- Anesthesia for ambulatory knee surgery
- Use a short-to-intermediate acting local anesthetic for ambulatory spinal anesthesia. Intrathecal lidocaine causes a high rate of transient neurologic symptoms and is rarely used. Mepivacaine 1.5% historically also had a significant rate. With routine ketorolac and dexamethasone use, that rate is now quite low. Transient neurologic symptoms are rare with 2% chloroprocaine and 0.5% bupivacaine. Bupivacaine may still be unsuitable for day cases because it lasts too long.
- Short-acting narcotics such as fentanyl can be added to increase spinal potency. The itching they cause may not be tolerated. A large multicenter retrospective study of ambulatory knee replacement found no complication difference by anesthetic type. Neuraxial anesthesia was linked with higher same-day discharge. It was also linked with lower pain, lower opioid use, and less nausea and vomiting.
- ACL reconstruction is a common day-case procedure. The graft is cadaveric allograft, or autograft from patellar tendon or hamstring. Autograft is preferred in younger, more active patients. But patellar tendon and hamstring grafts hurt significantly afterwards. Epidural or spinal block gives the anesthesia, with a femoral or adductor canal block for pain. Catheters can also be used for continuing analgesia.
- Femoral nerve block is not superior to multimodal analgesia here and may delay discharge. Quadriceps weakness is itself a complication of ACL reconstruction. It comes from muscle wasting and failure of activation. A femoral block may then confuse the clinical picture. Adductor canal block gives similar analgesia without causing quadriceps weakness. The IPACK block may help too, but more randomized trials are needed.
- Innervation of the foot and ankle
- A neuraxial or general anesthetic may be needed to stop movement and allow a thigh tourniquet. Foot and ankle surgery can be severely painful. Regional anesthesia gives the best pain relief afterwards, especially in day cases. Bupivacaine and ropivacaine can give up to 24 hours of analgesia. Preservative-free dexamethasone as an adjuvant consistently extends it beyond 24 hours. A catheter infusion prolongs relief further with few opioid-related side effects.
- Catheters may not suit noncompliant patients. Nor patients with limited access to follow-up care. Outpatients must be protected from injuring an anesthetised limb. Teach the patient how to protect the limb before they go home.
- Pediatric orthopedic anesthesia
Special Considerations in Orthopedics
- Amputation and phantom limb pain
- Microvascular surgery: goals
- Keeping the patient warm is essential, because cold constricts vessels. Volume replacement is recommended at 3.5 to 6 mL/kg per hour. Permissive hemodilution to a hematocrit of 30% can be considered. That balances blood thickness against oxygen-carrying capacity. Vasopressors may help maintain flap flow but risk flap ischemia. Discuss their use with the surgical team before starting them.
- Local anesthetic infusions after surgery help maintain flap blood flow. These may be neuraxial, perineural, or both. Antithrombotics are often given to prevent graft thrombosis. These include unfractionated and low-molecular-weight heparins. Their timing must be factored into catheter insertion and removal.
- Acute compartment syndrome
- Acute compartment syndrome mechanism
- Discuss regional use with the surgical team and the patient when the risk exists. Use the minimum effective dose and concentration of local anesthetic. Recent guidelines name surgeries needing particular vigilance. Tibial shaft fractures, and high tibial or low femoral osteotomies. High-energy tibial plateau fractures. Dual midshaft forearm fractures and high-energy single-bone forearm fractures.
- Tourniquet cuff and pressure
- Safe inflation time is generally considered to be 2 hours. If longer is needed, allow a perfusion break then re-exsanguinate the limb. Breakthrough bleeding usually comes from marrow blood flow inside long bones. Or from small arteries running between the two bones of a distal limb. Overinflating the cuff will not stop that bleeding.
- Tourniquet pain grows significant over time. It can be blunted with opioids or hypnotics. The definitive treatment is deflating the tourniquet. Deflation brings transient metabolic acidosis, higher arterial carbon dioxide and a pressure drop. Healthy patients tolerate these changes well. Take special care in patients with significant comorbidities.
- Fat embolism syndrome
- Diagnostic criteria were set out by Gurd and by Schonfeld. Early fixation of the fracture may help prevent the syndrome. Corticosteroid use in long-bone fracture patients may also be beneficial. Management is largely supportive. Early mechanical ventilation may be needed. Mortality is high, with estimates of 10% to 20%.
- Reading the fat embolism criteria table
- Criteria for fat embolism syndrome: major
- Criteria for fat embolism syndrome: minor
- Criteria for fat embolism syndrome: laboratory
- Bone cement implantation syndrome is a poorly defined syndrome after cemented implants. It combines low oxygen, low blood pressure and altered mental state. It is defined by these events occurring close in time to a specific step. That step is cementation, prosthesis insertion, joint reduction or tourniquet deflation. Severity is graded by how low the oxygen and blood pressure fall. It was blamed on methyl methacrylate monomer, but monomer levels are too low to explain it.
- Mechanism shared by fat embolism and bone cement syndromes
- The syndrome overlaps heavily with fat embolism syndrome. It results from embolized fat and debris, worsened by cement expanding the marrow cavity. An arterial line speeds detection of significant hemodynamic change during cementation. Central venous pressure monitoring may be considered in fragile patients. So may a pulmonary artery catheter, where cementation cannot be avoided.
- Scale of venous thromboembolism risk
- Venous thromboembolism without chemical prophylaxis
- Many societies have issued guidelines for prophylaxis after orthopedic surgery. These include the American Academy of Orthopedic Surgeons. Also the American College of Chest Physicians and the American Society of Hematology. All recommend some form of prophylaxis, but they do not agree on type or duration. All recommend stronger prophylaxis where risk factors exist, especially a prior clot. All suggest mechanical prophylaxis with intermittent pneumatic compression unless contraindicated.
- Take care with regional technique in patients on preoperative anticoagulation. The same applies to those needing postoperative anticoagulation for clot prevention. The American Society of Regional Anesthesia updated its practice advisory in 2018. It aims to minimise clinically significant haematoma in at-risk patients. The International Consensus Meeting has also produced multispecialty guidelines. Follow the same rules for deep plexus blocks and blocks near poorly compressible vessels.
- Reading the ASRA anticoagulation table
- Summary of ASRA practice advisory guidelines for neuraxial anesthesia and antithrombotics
- Summary of ASRA practice advisory guidelines for neuraxial anesthesia and antithrombotics (continued)
- Summary of ASRA practice advisory guidelines for neuraxial anesthesia and antithrombotics (continued)
Key Points and References
- Key points: technique and positioning
- Key points: spine surgery
- Key points: nerves, blocks and clots
- References
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- Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Edition