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Regional blocks in orthopaedics
ORTHOPAEDIC ANAESTHESIA
Regional blocks in orthopaedics
Learning objectives After reading this article, you should be able to: C list ten advantages of regional anaesthetic techniques over general anaesthesia C name the different types of upper limb nerve blocks C name the different types of lower limb nerve blocks
Cyrus Lee Wing Wai Michael G Irwin
Abstract Furthermore, regional techniques offer several advantages over general anaesthesia (Box 1). Regional techniques are not without risk. Apart from local anaesthetic toxicity, they can lead to delayed diagnosis of acute compartment syndrome, nerve injury, and paraplegia. Concomitant sedation should also be carefully administered to avoid respiratory and cardiovascular problems. Proper positioning and adequate cushioning are necessary to minimize positional discomfort and prevent iatrogenic injury.
Effective postoperative pain management plays a significant role in decreasing hospital stay and has a positive effect on functional recovery and patient satisfaction. Orthopaedic surgery is an expanding surgical specialty with a potentially difficult patient population. Regional anaesthesia is becoming increasingly popular as it offers several advantages over general anaesthesia. The aim of analgesic protocols is not only to reduce pain intensity but also to decrease the incidence of side effects from analgesic agents and to improve patient comfort. Moreover, adequate pain control is a prerequisite for rehabilitation programmes to accelerate functional recovery and may have economic benefits. Recently there has been resurgence in the use of regional anaesthesia with advanced techniques for nerve localization and visualization of needle and local anaesthetic spread. The use of peripheral nerve blocks has been associated with earlier discharge in ambulatory orthopaedic surgery when compared to general anaesthesia and neuraxial blockade.
Role of ultrasound in regional anaesthesia Neural blockade has evolved from using anatomical knowledge and eliciting paraesthesia to using nerve stimulators for electrolocation and now sonolocation for direct visualization of the peripheral nerves. Peripheral nerve stimulators can only confirm that the needle tip is within the proximity of the nerve and the success rate in the best hands peaks around 95%. High-resolution
Keywords Catheter; neuraxial block; perioperative; peripheral nerve block; plexus; postoperative; regional anaesthesia; ultrasound guidance
Advantages of regional anaesthesia versus general anaesthesia
Benefits of regional anaesthesia
C
The number of elderly population is increasing in many developed as well as developing countries. They often present for surgery with concomitant diseases, such as ischaemic heart disease and diabetes. Obesity is also a frequent co-morbidity with its attendant problems. The aim of regional anaesthetic techniques is to improve patients’ comfort and reduce pain intensity and also to decrease the incidence of side effects from analgesic agents. Adequate pain control is a prerequisite for the use of rehabilitation programmes to accelerate recovery from surgery. Postoperative symptoms and complications can be prevented by a suitable choice of anaesthetic and analgesic techniques for specific procedures. Combining regional anaesthetic techniques with systemic analgesics not only improves analgesic efficacy but also reduces opioid demand and side effects. Virtually all types of orthopaedic surgeries can be conducted using various regional anaesthetic techniques. The exceptions include spine surgery.
C C
C
C
C
C
C
C
Cyrus Lee Wing Wai MBBS is an Anaesthetist at Queen Mary Hospital, Hong Kong, China. Conflict of interest: none declared. C
Michael G Irwin MBChB (Glas) MD FRCA FANZCA FHKAM (Anaesthesiology) is Professor and Head of the Department of Anaesthesiology at Queen Mary Hospital, Hong Kong, China. Conflict of interest: none declared.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Reduction of nausea and vomiting A decreased stress response Excellent quality of analgesia both perioperatively and postoperatively, avoiding the systemic side effects associated with other analgesics Possible pre-emptive analgesia and, theoretically, a reduction in sensitization of nerve endings after surgery with a reduction in chronic pain syndromes Earlier patient discharge owing to improved analgesia and earlier mobilization Reduction of blood loss because of relative hypotension with central neural blockade Economic benefit to the hospital, as drug and equipment costs are consistently lower for regional anaesthesia and patients have shorter in-hospital stay Enhanced communication and easier positioning of the patient, who will be conscious throughout the surgery Avoidance of airway instrumentation and cervical movement during the operation, which is particularly important for patients with rheumatoid arthritis and ankylosing spondylitis Reduced environmental exposure to anaesthetic gases
Box 1
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
portable ultrasound now allows visualization of the perineural distribution of local anaesthetic and may, therefore, achieve greater nerve selectivity with a quicker onset, longer duration and improved quality of the block compared with use of a peripheral nerve stimulator. Ultrasound-guided regional anaesthesia also allows the anaesthetist to visualize complex and varied neural and vascular anatomy prior to needle insertion, which should theoretically reduce the risks of intravascular injection or nerve damage. Although ultrasound is no substitute for detailed anatomical knowledge, with appropriate training and experience, ultrasound techniques have the potential to reduce onset time volume of local anaesthetics used, and improve the success rates of peripheral nerve blocks. For adequately imaged nerves, a positive motor response to nerve stimulation does not improve the success of the block. A block could be successful without positive nerve stimulation. Muscle stimulation and paraesthesia may not occur even when ultrasound confirms the correct needle position. The needle can be intraneural and there can still be failure to provoke muscle contractions by the nerve stimulator. In diabetic patients, nerve stimulation and paraesthesia may be impossible to elicit at currents below 2.4 mA. Contrary to conventional belief, nerve puncture and intraneural injection of LA does not always lead to nerve injury. In practice, the choice of regional or general anaesthesia in orthopaedics will depend on factors such as patient preference, the patient’s co-morbidities, the expertise of the anaesthetist, the duration of the procedure, the surgeon’s preference and the practice pattern of the hospital. Effective intraoperative and postoperative pain management is important and is an integral part of the perioperative care. Selection of patients is key to successful regional anaesthesia and requires understanding and cooperation from the patient (Box 2).
Upper limb blocks: anterior CUTANEOUS INNERVATION
DERMATOMES
Lateral cutaneous nerve of arm
C3 C4
Intercostobrachial
C5
Medial cutaneous nerve of arm
C6
T2
T1
Medial cutaneous nerve of forearm Lateral cutaneous nerve of forearm
Radial Median Ulnar
C7 C8
Figure 1
different benefits and limitations. Brachial plexus block has the potential to provide surgical anaesthesia and prolonged postoperative analgesia to most of the upper limb. Five major terminal nerves come from the plexus (axillary, musculocutaneous, median, ulnar and radial) and these can be blocked individually or in combination to provide analgesia. The selection of regional technique will be dependent on the anticipated site of surgery as well as the site of the tourniquet. The interscalene approach is well suited for proximal surgery on the shoulder joint and upper arm; the supraclavicular approach is preferable for the upper arm, elbow and radial side of the
Regional anaesthetic techniques for the upper limb Orthopaedic procedures in the arm may be performed under a variety of brachial plexus blocks, with intravenous regional anaesthesia or by a combination of individual nerve blocks in the arm (Figures 1 and 2). The upper extremity is well suited to peripheral nerve blockade because the entire arm and shoulder is innervated by the brachial plexus and blockade is easily accomplished with a single injection. The brachial plexus is relatively superficial and may be approached at the interscalene, supraclavicular, infraclavicular or axillary level, each having
Upper limb blocks: posterior CUTANEOUS INNERVATION
DERMATOMES
Supraclavicular Lateral cutaneous nerve of arm
C4
Posterior cutaneous nerve of arm
Contraindications to regional anaesthesia C C C
C C C
C
C5 T2
Medial cutaneous nerve of arm
Patient’s refusal despite adequate explanation Confused, uncooperative or uncommunicative patient Systemic infection, trauma/burns/local infection over the site of injection Pre-existing neurological deficit (relative) Raised intracranial pressure (central neural blocks) Untreated hypovolaemia, hypotension or heart failure (central neural blocks) Anticoagulated/coagulopathic patient
T1
Posterior cutaneous nerve of forearm Lateral cutaneous nerve of forearm Radial
C6 Medial cutaneous nerve of forearm C7 C8
Ulnar Median
Box 2
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Figure 2
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
forearm and can provide a dense block of the arm providing optimal tourniquet coverage as well; the infraclavicular and axillary approaches are best for the hand, wrist and forearm. A major advance is the placement of indwelling brachial plexus catheters to provide prolonged analgesia at home, thereby allowing operations that would have traditionally required 2e3 days of hospitalization to be performed as day-stay or short-stay surgery. Indeed, both total elbow and shoulder arthroplasty have been performed as day-stay procedures with analgesia primarily provided by a perineural catheter.
ultrasound guidance than the axillary approach for inexperienced clinicians. The correct identification of the four nerves with ultrasound takes practice and also carries a risk of pneumothorax. An axillary approach may not be adequate for surgery to the mid- or distal humerus because of the close proximity of the level of blockade to the site of surgery and difficulty in blocking the posterior cord of the brachial plexus.
Hand and forearm Axillary blocks are ideal for hand and forearm surgery because the four main nerves (median, ulnar, radial, musculocutaneous) can all be selectively identified using ultrasound guidance and/or peripheral nerve stimulation. Multiple-stimulation techniques are associated with a greater success rate than single injection techniques. It is the most commonly used technique for surgery below the shoulder and is relatively safe, easy to perform and is ideal for surgery on the hand, forearm and elbow. The analgesia produced is usually effective for tourniquets applied to the upper arm. Peripheral nerve blocks at the elbow, wrist and hand may be performed (either individually or in combination) to provide discrete, distal nerve blockade or to supplement brachial plexus blocks. A short-duration brachial plexus block combined with a long-lasting peripheral nerve block is useful as it allows early mobilization and limb protection, while maintaining good peripheral analgesia.
Shoulder In order to provide anaesthesia for shoulder procedures, a block of at least the upper two roots (C5 and C6) or the superior trunk of the brachial plexus is necessary. In addition, blockade of the supraclavicular nerve is needed, as this covers the ‘cape’ of the shoulder e the skin overlying the superior aspect of the shoulder. The interscalene approach is, therefore, best suited for shoulder joint and upper arm surgery. Blockade occurs at the level of the roots as they exit between the middle and anterior scalene muscles at the C6 level (identified by the cricoid cartilage). The brachial plexus is quite spread out at this level, and even with large doses of LA the lower roots (C8 and T1) may be left unblocked. This approach can lead to a variety of complications ranging from blockade of the cervical sympathetic chain, recurrent laryngeal nerve and phrenic nerve blockade, through hypotension and bradycardia that is blamed on the Bezolde Jarisch reflex, via accidental epidural and spinal injection, and all the way to permanent damage to the spinal cord in patients who had undergone attempted interscalene block when under general anaesthesia. Catheter placement into the brachial plexus allows continuous local anaesthetic infiltration for painful procedures, such as shoulder arthroplasties, and allows earlier mobilization. This technique, however, does not provide a more superior postoperative analgesia than infusion through intra-articular cathether placement. Regional analgesia for arthroscopy for the shoulder can be achieved by means of a suprascapular nerve block, but this is not adequate as a sole technique and will need to be combined with a general anaesthetic. The degree of discomfort following a shoulder arthroscopy is dependent on the surgeon’s expertise, the operation performed, the length of surgery and the amount of irrigation fluid absorbed into the soft tissues.
The lower limbs The lumbar and sacral nerve roots of the spinal cord provide the nerve supply to the lower extremity by forming two plexuses (lumbar and sacral), which in turn produce five major terminal nerves (Figure 3). The femoral, obturator and lateral cutaneous nerve of thigh are terminal nerves of the lumbar plexus and the sciatic plexus produces the sciatic nerve and posterior cutaneous nerve of thigh.
Central neuraxial blocks Lower extremity surgery may be performed under a spinal, epidural, combined spinal epidural (CSE) or continuous spinal catheter anaesthetic. They are relatively easy techniques to perform with a high success rate but are associated with significant complications and the disadvantages of unpredictable onset and regression, bilateral lower limb blockade, cardiovascular instability, bladder and bowel disturbance and bilateral limb immobility. Plain solutions of local anaesthetic are preferable to hyperbaric as the duration of action is longer and there is less propensity for high block with its attendant problems.
Elbow Surgery on an elbow may be performed with an interscalene, supraclavicular, infraclavicular, or axillary brachial plexus block or a mid-humeral block in conjunction with cutaneous infiltration of the medial cutaneous nerve of the arm. Selection of the appropriate technique is determined by the innervation of the surgical site, specific patient anatomy and co-morbidities, whether a tourniquet will be used, the experience of the anaesthetist and the associated anaesthetic and surgical complications. For example, patients with significant pulmonary disease may not be suitable for a supraclavicular approach due to the potential for pneumothorax. Likewise interscalene and supraclavicular block are likely to cause phrenic nerve paresis. An infraclavicular approach is more difficult to perform on
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Peripheral nerve blocks The advance of the popularity of peripheral nerve blocks for lower limb surgery has been in the effective management of pain and in accelerating postoperative mobility. These have the advantages of providing long-lasting analgesia and improved mobility, but may be more difficult to perform technically than central neuraxial techniques. This is because the nerves supplying the lower extremity are not anatomically clustered where they can be easily blocked with a relatively superficial injection of local anaesthetic. Because of anatomic
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
Lower limb blocks: cutaneous innervation
Lateral cutaneous branch of subcostal nerve
Lateral cutaneous branch of subcostal nerve
Femoral branch of genitofemoral nerve Lateral femoral cutaneous nerve
Lateral femoral cutaneous nerve Anterior femoral cutaneous nerves
Obturator nerve Posterior cutaneous nerve of thigh Medial femoral cutaneous
Obturator nerve
Common fibular nerve Common fibular nerve Saphenous nerve Saphenous nerve Superficial fibular nerve Sural nerve Calcaneal branch of tibial nerve
Sural nerve Deep fibular nerve ANTERIOR
POSTERIOR
Plantar branches of the tibial nerve
Figure 3
considerations, lower extremity blocks are technically more difficult and require more training and practice before expertise is acquired. They are usually performed for postoperative analgesia rather than used as the primary anaesthetic technique. Many of these blocks were classically performed using paraesthesia, loss of resistance or field block techniques that result in variable success. Advances in needles, catheters and nerve stimulator technology have facilitated the localization of nerves and improved success rates. Peripheral nerve blocks lead to faster mobilization through better postoperative pain management, less postoperative nausea and vomiting, and decreased overall hospital stay. They can avoid many side effects of parenteral opioids such as hypotension, confusion, constipation, urinary retention, pruritis, sedation and respiratory depression.
anaesthetic is injected within the neurovascular sheath with the needle directed cranially, in the hope that the anaesthetic spreads proximally. This idea is not supported by dye injection studies. It may work in some cases because of lateral spread of the anaesthetic but may also fail even if a large volume of anaesthetic is injected. The fascia iliaca compartment block is a hybrid anterior lumbar plexus approach with a puncture point relatively distant from the neurovascular sheath. A nerve stimulator is not necessary for this procedure. It provides a faster and more consistent blockade of the lateral cutaneous nerve of the thigh and femoral nerve than the ‘three-in-one’ block. A lumbar plexus block can provide complete analgesia of the lower limb when combined with a sciatic nerve block when central neuraxial block is contraindicated. The combination of general anaesthesia and lumbar plexus block is particularly useful in revision joint replacement where the surgery is likely to be prolonged.
Hip surgery Lumbar paravertebral or lumbar plexus block can be used when the use of a spinal or epidural is contraindicated. A femoral nerve block can provide analgesia for fracture neck of femur or total hip replacement and femoral shaft fracture. A ‘three-in-one’ block and the fascia iliaca block are techniques that target the lateral cutaneous nerve of the thigh and the obturator, in addition to the femoral nerve. It is a technique where a large volume of local
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Knee surgery Total knee replacement is associated with significantly more pain than total hip replacement and the use of continuous passive motion devices or early mobilization of the knee will increase the patient’s pain. For knee joint surgery, femoral and sciatic nerve
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
blocks provide intraoperative and postoperative analgesia and improve early rehabilitation by effectively controlling the pain compared with intravenous morphine given via a patientcontrolled analgesia system. The psoas compartment block can provide anaesthesia and analgesia to the entire lumbar plexus and has been used for knee arthroscopy. However, due to the relatively low pain scores after minor knee arthroscopy and the risk profile associated with psoas blockade (epidural spread, weak hip flexors), this block may not be justified in the ambulatory population. The more distal femoral nerve block provides anaesthesia and analgesia to the anteromedial thigh, anterior knee and medial calf. This broad coverage combined with the relative ease of block placement makes the femoral nerve block one of the most common lower extremity blocks. Intra-articular injection of a combination of ropivacaine or levobupivacaine, adrenaline, morphine, and methylprednisolone is rapidly gaining popularity. It may improve the outcomes after total knee replacement. However, further studies on the optimal volume and concentration of the drugs used are needed. This technique is also used in total hip replacement. The evidence is not as convincing as in total knee replacement. An indwelling catheter can also be put in place for top-ups or continuous infusion. This obviously raises the concern of infection.
combined with either a saphenous or femoral nerve block allows the use of a calf tourniquet and provides anaesthesia comparable with neuraxial techniques, but without urinary retention and longer postoperative analgesia (12e24 hours of analgesia when used with long-acting local anaesthetics such as ropivacaine or bupivacaine). Compared with the more proximal blocks, the ankle block will have little effect on postoperative ambulation (no foot drop, hamstring, or quadriceps weakness) while providing prolonged postoperative analgesia if a long-acting local anaesthetic is used. However, it can be uncomfortable as it requires several injections and often provides incomplete operative analgesia; therefore, it is often combined with a general anaesthetic. For most surgical procedures on the foot, it is not necessary to block more than one or two nerves together. If the intended surgery is particularly extensive, a more proximal technique is appropriate.
Postoperatively Following surgery, the positioning and protection of the anaesthetized limb is of paramount importance. In order to make the patient as comfortable as possible, analgesics should be given prior to the offset of the regional block. The insertion of epidural, spinal and peripheral nerve catheters can prolong the effectiveness of a block over several days by using intermittent bolus injections or a continuous infusion. Patient-controlled central and peripheral regional block infusions, which reduce the drug volume but give good-quality analgesia, are becoming increasingly popular. A
Ankle/foot surgery The popliteal block is an effective block for foot and ankle surgery; if the surgery involves the medial aspect of the foot and ankle a saphenous nerve block should also be included. This combination is adequate for a calf tourniquet in a conscious patient, but if a thigh tourniquet is required during surgery the anaesthetist should use a sciatic and femoral nerve block. The popliteal sciatic nerve block is generally good for surgical anaesthesia as well as long-lasting postoperative pain control for foot and ankle procedures. Posterior and lateral approaches to the sciatic nerve at the level of the popliteal fossa have both been shown to provide safe, efficient and reliable anaesthesia. A popliteal sciatic nerve block
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
FURTHER READING Griffin J, Nicholls B. Ultrasound in regional anaesthesia. Anaesthesia 2010; 65(suppl 1): 1e12. Kopp SL, Horlocker TT. Regional anaesthesia in day-stay and short-stay surgery. Anaesthesia 2010; 65(suppl 1): 84e96. Murray JM, Derbyshire S, Shields MO. Anaesthesia 2010; 65(suppl 1): 57e66. Russon K, Pickworth T, Harrop-Griffiths W. Upper limb blocks. Anaesthesia 2010; 65(suppl 1): 48e56.
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Ó 2011 Elsevier Ltd. All rights reserved.
Regional blocks in orthopaedics
Learning objectives After reading this article, you should be able to: C list ten advantages of regional anaesthetic techniques over general anaesthesia C name the different types of upper limb nerve blocks C name the different types of lower limb nerve blocks
Cyrus Lee Wing Wai Michael G Irwin
Abstract Furthermore, regional techniques offer several advantages over general anaesthesia (Box 1). Regional techniques are not without risk. Apart from local anaesthetic toxicity, they can lead to delayed diagnosis of acute compartment syndrome, nerve injury, and paraplegia. Concomitant sedation should also be carefully administered to avoid respiratory and cardiovascular problems. Proper positioning and adequate cushioning are necessary to minimize positional discomfort and prevent iatrogenic injury.
Effective postoperative pain management plays a significant role in decreasing hospital stay and has a positive effect on functional recovery and patient satisfaction. Orthopaedic surgery is an expanding surgical specialty with a potentially difficult patient population. Regional anaesthesia is becoming increasingly popular as it offers several advantages over general anaesthesia. The aim of analgesic protocols is not only to reduce pain intensity but also to decrease the incidence of side effects from analgesic agents and to improve patient comfort. Moreover, adequate pain control is a prerequisite for rehabilitation programmes to accelerate functional recovery and may have economic benefits. Recently there has been resurgence in the use of regional anaesthesia with advanced techniques for nerve localization and visualization of needle and local anaesthetic spread. The use of peripheral nerve blocks has been associated with earlier discharge in ambulatory orthopaedic surgery when compared to general anaesthesia and neuraxial blockade.
Role of ultrasound in regional anaesthesia Neural blockade has evolved from using anatomical knowledge and eliciting paraesthesia to using nerve stimulators for electrolocation and now sonolocation for direct visualization of the peripheral nerves. Peripheral nerve stimulators can only confirm that the needle tip is within the proximity of the nerve and the success rate in the best hands peaks around 95%. High-resolution
Keywords Catheter; neuraxial block; perioperative; peripheral nerve block; plexus; postoperative; regional anaesthesia; ultrasound guidance
Advantages of regional anaesthesia versus general anaesthesia
Benefits of regional anaesthesia
C
The number of elderly population is increasing in many developed as well as developing countries. They often present for surgery with concomitant diseases, such as ischaemic heart disease and diabetes. Obesity is also a frequent co-morbidity with its attendant problems. The aim of regional anaesthetic techniques is to improve patients’ comfort and reduce pain intensity and also to decrease the incidence of side effects from analgesic agents. Adequate pain control is a prerequisite for the use of rehabilitation programmes to accelerate recovery from surgery. Postoperative symptoms and complications can be prevented by a suitable choice of anaesthetic and analgesic techniques for specific procedures. Combining regional anaesthetic techniques with systemic analgesics not only improves analgesic efficacy but also reduces opioid demand and side effects. Virtually all types of orthopaedic surgeries can be conducted using various regional anaesthetic techniques. The exceptions include spine surgery.
C C
C
C
C
C
C
C
Cyrus Lee Wing Wai MBBS is an Anaesthetist at Queen Mary Hospital, Hong Kong, China. Conflict of interest: none declared. C
Michael G Irwin MBChB (Glas) MD FRCA FANZCA FHKAM (Anaesthesiology) is Professor and Head of the Department of Anaesthesiology at Queen Mary Hospital, Hong Kong, China. Conflict of interest: none declared.
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Reduction of nausea and vomiting A decreased stress response Excellent quality of analgesia both perioperatively and postoperatively, avoiding the systemic side effects associated with other analgesics Possible pre-emptive analgesia and, theoretically, a reduction in sensitization of nerve endings after surgery with a reduction in chronic pain syndromes Earlier patient discharge owing to improved analgesia and earlier mobilization Reduction of blood loss because of relative hypotension with central neural blockade Economic benefit to the hospital, as drug and equipment costs are consistently lower for regional anaesthesia and patients have shorter in-hospital stay Enhanced communication and easier positioning of the patient, who will be conscious throughout the surgery Avoidance of airway instrumentation and cervical movement during the operation, which is particularly important for patients with rheumatoid arthritis and ankylosing spondylitis Reduced environmental exposure to anaesthetic gases
Box 1
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
portable ultrasound now allows visualization of the perineural distribution of local anaesthetic and may, therefore, achieve greater nerve selectivity with a quicker onset, longer duration and improved quality of the block compared with use of a peripheral nerve stimulator. Ultrasound-guided regional anaesthesia also allows the anaesthetist to visualize complex and varied neural and vascular anatomy prior to needle insertion, which should theoretically reduce the risks of intravascular injection or nerve damage. Although ultrasound is no substitute for detailed anatomical knowledge, with appropriate training and experience, ultrasound techniques have the potential to reduce onset time volume of local anaesthetics used, and improve the success rates of peripheral nerve blocks. For adequately imaged nerves, a positive motor response to nerve stimulation does not improve the success of the block. A block could be successful without positive nerve stimulation. Muscle stimulation and paraesthesia may not occur even when ultrasound confirms the correct needle position. The needle can be intraneural and there can still be failure to provoke muscle contractions by the nerve stimulator. In diabetic patients, nerve stimulation and paraesthesia may be impossible to elicit at currents below 2.4 mA. Contrary to conventional belief, nerve puncture and intraneural injection of LA does not always lead to nerve injury. In practice, the choice of regional or general anaesthesia in orthopaedics will depend on factors such as patient preference, the patient’s co-morbidities, the expertise of the anaesthetist, the duration of the procedure, the surgeon’s preference and the practice pattern of the hospital. Effective intraoperative and postoperative pain management is important and is an integral part of the perioperative care. Selection of patients is key to successful regional anaesthesia and requires understanding and cooperation from the patient (Box 2).
Upper limb blocks: anterior CUTANEOUS INNERVATION
DERMATOMES
Lateral cutaneous nerve of arm
C3 C4
Intercostobrachial
C5
Medial cutaneous nerve of arm
C6
T2
T1
Medial cutaneous nerve of forearm Lateral cutaneous nerve of forearm
Radial Median Ulnar
C7 C8
Figure 1
different benefits and limitations. Brachial plexus block has the potential to provide surgical anaesthesia and prolonged postoperative analgesia to most of the upper limb. Five major terminal nerves come from the plexus (axillary, musculocutaneous, median, ulnar and radial) and these can be blocked individually or in combination to provide analgesia. The selection of regional technique will be dependent on the anticipated site of surgery as well as the site of the tourniquet. The interscalene approach is well suited for proximal surgery on the shoulder joint and upper arm; the supraclavicular approach is preferable for the upper arm, elbow and radial side of the
Regional anaesthetic techniques for the upper limb Orthopaedic procedures in the arm may be performed under a variety of brachial plexus blocks, with intravenous regional anaesthesia or by a combination of individual nerve blocks in the arm (Figures 1 and 2). The upper extremity is well suited to peripheral nerve blockade because the entire arm and shoulder is innervated by the brachial plexus and blockade is easily accomplished with a single injection. The brachial plexus is relatively superficial and may be approached at the interscalene, supraclavicular, infraclavicular or axillary level, each having
Upper limb blocks: posterior CUTANEOUS INNERVATION
DERMATOMES
Supraclavicular Lateral cutaneous nerve of arm
C4
Posterior cutaneous nerve of arm
Contraindications to regional anaesthesia C C C
C C C
C
C5 T2
Medial cutaneous nerve of arm
Patient’s refusal despite adequate explanation Confused, uncooperative or uncommunicative patient Systemic infection, trauma/burns/local infection over the site of injection Pre-existing neurological deficit (relative) Raised intracranial pressure (central neural blocks) Untreated hypovolaemia, hypotension or heart failure (central neural blocks) Anticoagulated/coagulopathic patient
T1
Posterior cutaneous nerve of forearm Lateral cutaneous nerve of forearm Radial
C6 Medial cutaneous nerve of forearm C7 C8
Ulnar Median
Box 2
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Figure 2
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
forearm and can provide a dense block of the arm providing optimal tourniquet coverage as well; the infraclavicular and axillary approaches are best for the hand, wrist and forearm. A major advance is the placement of indwelling brachial plexus catheters to provide prolonged analgesia at home, thereby allowing operations that would have traditionally required 2e3 days of hospitalization to be performed as day-stay or short-stay surgery. Indeed, both total elbow and shoulder arthroplasty have been performed as day-stay procedures with analgesia primarily provided by a perineural catheter.
ultrasound guidance than the axillary approach for inexperienced clinicians. The correct identification of the four nerves with ultrasound takes practice and also carries a risk of pneumothorax. An axillary approach may not be adequate for surgery to the mid- or distal humerus because of the close proximity of the level of blockade to the site of surgery and difficulty in blocking the posterior cord of the brachial plexus.
Hand and forearm Axillary blocks are ideal for hand and forearm surgery because the four main nerves (median, ulnar, radial, musculocutaneous) can all be selectively identified using ultrasound guidance and/or peripheral nerve stimulation. Multiple-stimulation techniques are associated with a greater success rate than single injection techniques. It is the most commonly used technique for surgery below the shoulder and is relatively safe, easy to perform and is ideal for surgery on the hand, forearm and elbow. The analgesia produced is usually effective for tourniquets applied to the upper arm. Peripheral nerve blocks at the elbow, wrist and hand may be performed (either individually or in combination) to provide discrete, distal nerve blockade or to supplement brachial plexus blocks. A short-duration brachial plexus block combined with a long-lasting peripheral nerve block is useful as it allows early mobilization and limb protection, while maintaining good peripheral analgesia.
Shoulder In order to provide anaesthesia for shoulder procedures, a block of at least the upper two roots (C5 and C6) or the superior trunk of the brachial plexus is necessary. In addition, blockade of the supraclavicular nerve is needed, as this covers the ‘cape’ of the shoulder e the skin overlying the superior aspect of the shoulder. The interscalene approach is, therefore, best suited for shoulder joint and upper arm surgery. Blockade occurs at the level of the roots as they exit between the middle and anterior scalene muscles at the C6 level (identified by the cricoid cartilage). The brachial plexus is quite spread out at this level, and even with large doses of LA the lower roots (C8 and T1) may be left unblocked. This approach can lead to a variety of complications ranging from blockade of the cervical sympathetic chain, recurrent laryngeal nerve and phrenic nerve blockade, through hypotension and bradycardia that is blamed on the Bezolde Jarisch reflex, via accidental epidural and spinal injection, and all the way to permanent damage to the spinal cord in patients who had undergone attempted interscalene block when under general anaesthesia. Catheter placement into the brachial plexus allows continuous local anaesthetic infiltration for painful procedures, such as shoulder arthroplasties, and allows earlier mobilization. This technique, however, does not provide a more superior postoperative analgesia than infusion through intra-articular cathether placement. Regional analgesia for arthroscopy for the shoulder can be achieved by means of a suprascapular nerve block, but this is not adequate as a sole technique and will need to be combined with a general anaesthetic. The degree of discomfort following a shoulder arthroscopy is dependent on the surgeon’s expertise, the operation performed, the length of surgery and the amount of irrigation fluid absorbed into the soft tissues.
The lower limbs The lumbar and sacral nerve roots of the spinal cord provide the nerve supply to the lower extremity by forming two plexuses (lumbar and sacral), which in turn produce five major terminal nerves (Figure 3). The femoral, obturator and lateral cutaneous nerve of thigh are terminal nerves of the lumbar plexus and the sciatic plexus produces the sciatic nerve and posterior cutaneous nerve of thigh.
Central neuraxial blocks Lower extremity surgery may be performed under a spinal, epidural, combined spinal epidural (CSE) or continuous spinal catheter anaesthetic. They are relatively easy techniques to perform with a high success rate but are associated with significant complications and the disadvantages of unpredictable onset and regression, bilateral lower limb blockade, cardiovascular instability, bladder and bowel disturbance and bilateral limb immobility. Plain solutions of local anaesthetic are preferable to hyperbaric as the duration of action is longer and there is less propensity for high block with its attendant problems.
Elbow Surgery on an elbow may be performed with an interscalene, supraclavicular, infraclavicular, or axillary brachial plexus block or a mid-humeral block in conjunction with cutaneous infiltration of the medial cutaneous nerve of the arm. Selection of the appropriate technique is determined by the innervation of the surgical site, specific patient anatomy and co-morbidities, whether a tourniquet will be used, the experience of the anaesthetist and the associated anaesthetic and surgical complications. For example, patients with significant pulmonary disease may not be suitable for a supraclavicular approach due to the potential for pneumothorax. Likewise interscalene and supraclavicular block are likely to cause phrenic nerve paresis. An infraclavicular approach is more difficult to perform on
ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:3
Peripheral nerve blocks The advance of the popularity of peripheral nerve blocks for lower limb surgery has been in the effective management of pain and in accelerating postoperative mobility. These have the advantages of providing long-lasting analgesia and improved mobility, but may be more difficult to perform technically than central neuraxial techniques. This is because the nerves supplying the lower extremity are not anatomically clustered where they can be easily blocked with a relatively superficial injection of local anaesthetic. Because of anatomic
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Ó 2011 Elsevier Ltd. All rights reserved.
ORTHOPAEDIC ANAESTHESIA
Lower limb blocks: cutaneous innervation
Lateral cutaneous branch of subcostal nerve
Lateral cutaneous branch of subcostal nerve
Femoral branch of genitofemoral nerve Lateral femoral cutaneous nerve
Lateral femoral cutaneous nerve Anterior femoral cutaneous nerves
Obturator nerve Posterior cutaneous nerve of thigh Medial femoral cutaneous
Obturator nerve
Common fibular nerve Common fibular nerve Saphenous nerve Saphenous nerve Superficial fibular nerve Sural nerve Calcaneal branch of tibial nerve
Sural nerve Deep fibular nerve ANTERIOR
POSTERIOR
Plantar branches of the tibial nerve
Figure 3
considerations, lower extremity blocks are technically more difficult and require more training and practice before expertise is acquired. They are usually performed for postoperative analgesia rather than used as the primary anaesthetic technique. Many of these blocks were classically performed using paraesthesia, loss of resistance or field block techniques that result in variable success. Advances in needles, catheters and nerve stimulator technology have facilitated the localization of nerves and improved success rates. Peripheral nerve blocks lead to faster mobilization through better postoperative pain management, less postoperative nausea and vomiting, and decreased overall hospital stay. They can avoid many side effects of parenteral opioids such as hypotension, confusion, constipation, urinary retention, pruritis, sedation and respiratory depression.
anaesthetic is injected within the neurovascular sheath with the needle directed cranially, in the hope that the anaesthetic spreads proximally. This idea is not supported by dye injection studies. It may work in some cases because of lateral spread of the anaesthetic but may also fail even if a large volume of anaesthetic is injected. The fascia iliaca compartment block is a hybrid anterior lumbar plexus approach with a puncture point relatively distant from the neurovascular sheath. A nerve stimulator is not necessary for this procedure. It provides a faster and more consistent blockade of the lateral cutaneous nerve of the thigh and femoral nerve than the ‘three-in-one’ block. A lumbar plexus block can provide complete analgesia of the lower limb when combined with a sciatic nerve block when central neuraxial block is contraindicated. The combination of general anaesthesia and lumbar plexus block is particularly useful in revision joint replacement where the surgery is likely to be prolonged.
Hip surgery Lumbar paravertebral or lumbar plexus block can be used when the use of a spinal or epidural is contraindicated. A femoral nerve block can provide analgesia for fracture neck of femur or total hip replacement and femoral shaft fracture. A ‘three-in-one’ block and the fascia iliaca block are techniques that target the lateral cutaneous nerve of the thigh and the obturator, in addition to the femoral nerve. It is a technique where a large volume of local
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Knee surgery Total knee replacement is associated with significantly more pain than total hip replacement and the use of continuous passive motion devices or early mobilization of the knee will increase the patient’s pain. For knee joint surgery, femoral and sciatic nerve
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ORTHOPAEDIC ANAESTHESIA
blocks provide intraoperative and postoperative analgesia and improve early rehabilitation by effectively controlling the pain compared with intravenous morphine given via a patientcontrolled analgesia system. The psoas compartment block can provide anaesthesia and analgesia to the entire lumbar plexus and has been used for knee arthroscopy. However, due to the relatively low pain scores after minor knee arthroscopy and the risk profile associated with psoas blockade (epidural spread, weak hip flexors), this block may not be justified in the ambulatory population. The more distal femoral nerve block provides anaesthesia and analgesia to the anteromedial thigh, anterior knee and medial calf. This broad coverage combined with the relative ease of block placement makes the femoral nerve block one of the most common lower extremity blocks. Intra-articular injection of a combination of ropivacaine or levobupivacaine, adrenaline, morphine, and methylprednisolone is rapidly gaining popularity. It may improve the outcomes after total knee replacement. However, further studies on the optimal volume and concentration of the drugs used are needed. This technique is also used in total hip replacement. The evidence is not as convincing as in total knee replacement. An indwelling catheter can also be put in place for top-ups or continuous infusion. This obviously raises the concern of infection.
combined with either a saphenous or femoral nerve block allows the use of a calf tourniquet and provides anaesthesia comparable with neuraxial techniques, but without urinary retention and longer postoperative analgesia (12e24 hours of analgesia when used with long-acting local anaesthetics such as ropivacaine or bupivacaine). Compared with the more proximal blocks, the ankle block will have little effect on postoperative ambulation (no foot drop, hamstring, or quadriceps weakness) while providing prolonged postoperative analgesia if a long-acting local anaesthetic is used. However, it can be uncomfortable as it requires several injections and often provides incomplete operative analgesia; therefore, it is often combined with a general anaesthetic. For most surgical procedures on the foot, it is not necessary to block more than one or two nerves together. If the intended surgery is particularly extensive, a more proximal technique is appropriate.
Postoperatively Following surgery, the positioning and protection of the anaesthetized limb is of paramount importance. In order to make the patient as comfortable as possible, analgesics should be given prior to the offset of the regional block. The insertion of epidural, spinal and peripheral nerve catheters can prolong the effectiveness of a block over several days by using intermittent bolus injections or a continuous infusion. Patient-controlled central and peripheral regional block infusions, which reduce the drug volume but give good-quality analgesia, are becoming increasingly popular. A
Ankle/foot surgery The popliteal block is an effective block for foot and ankle surgery; if the surgery involves the medial aspect of the foot and ankle a saphenous nerve block should also be included. This combination is adequate for a calf tourniquet in a conscious patient, but if a thigh tourniquet is required during surgery the anaesthetist should use a sciatic and femoral nerve block. The popliteal sciatic nerve block is generally good for surgical anaesthesia as well as long-lasting postoperative pain control for foot and ankle procedures. Posterior and lateral approaches to the sciatic nerve at the level of the popliteal fossa have both been shown to provide safe, efficient and reliable anaesthesia. A popliteal sciatic nerve block
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FURTHER READING Griffin J, Nicholls B. Ultrasound in regional anaesthesia. Anaesthesia 2010; 65(suppl 1): 1e12. Kopp SL, Horlocker TT. Regional anaesthesia in day-stay and short-stay surgery. Anaesthesia 2010; 65(suppl 1): 84e96. Murray JM, Derbyshire S, Shields MO. Anaesthesia 2010; 65(suppl 1): 57e66. Russon K, Pickworth T, Harrop-Griffiths W. Upper limb blocks. Anaesthesia 2010; 65(suppl 1): 48e56.
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