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15. Shoulder Arthroplasty: Pain Management
15.1 Introduction
A pain management strategy depending on a single type of analgesic has been proven to be inadequate both because of the inadequate pain control and the side effects of that single type of analgesic depending on its rising dose. This strategy has also been shown to cause inadvertent effects such as nociception-induced central sensitization and secondary hyperalgesia, as well as the functional loss of related joint. The multimodal approach mainly depends on the use of additive and synergistic effects of various analgesics of different mechanisms, in order to provide a higher level of pain control with lower doses especially to reduce the side effects [1]. In order to achieve the goal; regional anaesthetic/analgesic techniques, local infiltration and systemic analgesics are employed simultaneously in the perioperative period. This multimodal pain management has also proven beneficial by reducing opioid consumption and shortening the length of hospital stay after shoulder arthroplasty [2, 3].
The pain management strategy should also include preemptive analgesia which describes the analgesic medication given before the noxious stimulus begins. This technique aims to prevent hypersensitivity via blocking sensory inputs caused by the inflammatory process. In a study by Kadum et al., the preoperative pain threshold and preoperative pain at rest were found to be significantly associated with functional status of the shoulder after arthroplasty surgery. The findings of this study have shown that the central sensitization which may develop prior to the surgery has a high impact on functional recovery [4]. Hence, the use of preemptive analgesia to prevent central sensitization leading to a high preoperative threshold and low sensitivity to pain may result in low pain scores, thus better functional status after surgery.
The postoperative pain control not only depends on the effective medications and techniques brought into clinical practice during the perioperative period, but also there are some other factors which were suggested to have impact on outcome. Patients’ expectations which may vary according to age, demographic characteristics and stage of the functional status of the joint were reported to independently predict outcome [5, 6]. The positive expectations from surgery were shown to be associated with better outcomes [7]. The anxiety and depression which may be interrelated with expectations were also suggested to have impact on outcome. Preoperative acknowledgement about the procedure and the awaiting postoperative period in terms of functional status and pain will decrease the anxiety level before the surgery. The higher pain scores and the worse baseline functional status of the joint enhance the preoperative opioid use, which cause a deliberate rise in both the dose and duration of the requirement for opioids in the postoperative period. These factors are all interrelated and may be minimized by employing a multidisciplinary approach by anaesthetist, surgeon, physiotherapist and algologist. Thus, a multidisciplinary approach is needed for adequate pain control, as well as a multimodal approach for pain management itself.
15.1.1 Regional Anaesthesia
Regional anaesthesia has proven to be beneficial both in the intraoperative and postoperative period. Advancement in regional anaesthesia techniques with the guidance of ultrasound improved the blockade of brachial plexus and identification of its branches. The motor and most of the sensory innervation of the shoulder are supplied by the brachial plexus. The cephalad cutaneous parts are innervated by the supraclavicular nerves, which originate from C3 to C4. The glenohumeral joint, the capsule, subacromial bursa and coracoclavicular ligament and various parts of the skin are innervated by the suprascapular nerve originating from the superior trunk of brachial plexus (C5, C6). The cutaneous innervation of the skin covering the deltoid muscle is innervated by the axillary nerve originating from the posterior cord of the brachial plexus (C5–C6) [1]. These nerves can be blocked by various approaches to brachial plexus.
15.1.1.1 Interscalene Block
Interscalene block is performed to obtain analgesia at the lateral two-thirds of the clavicle, the glenohumeral joint and proximal part of the humerus. The blockade includes the C5 and C6 nerve roots and superior trunk of the brachial plexus (suprascapular, axillary, musculocutaneous, radial, thoracodorsal, median, anterior interosseous), most commonly sparing the ulnar nerve (C8, T1), which limits its effect for distal procedures [1, 8].
The interscalene block which remains the ‘gold standard’ for shoulder surgeries can be performed by using either a single-injection technique or a continuous infusion. The single-injection technique has a limited duration of action, which can be prolonged by using adjuvants in combination with local anaesthetic agents. In a study by Desmet et al., the addition of either intravenous or perineural 10 mg dexamethasone to 0.5% ropivacaine for ISB in patients undergoing arthroscopic shoulder surgery was reported to have similar effect on prolonging the analgesic period [9]. However, in another study by Kawanishi et al., a low dose of dexamethasone (4 mg) either intravenous or perineural as a supplement to ISB with ropivacaine was not found to be similar; perineural low dose was found to be superior in prolonging the analgesic period [10]. In similar studies, buprenorphine was also found to prolong analgesic period when used both systemic and perineural, but perineural was reported to provide longer duration of analgesia [11, 12]. Clonidine is another adjuvant to provide longer analgesic periods; moreover it can be used perineurally in the absence of a local anaesthetic [13, 14]. In a study which used a multimodal perineural analgesia for patients undergoing shoulder arthroplasty, bupivacaine, clonidine, buprenorphine and dexamethasone were combined in a solution. Either 0.375 or 0.2% of ropivacaine combined with the aforementioned three adjuvants was found to provide superior analgesia [15]. In a study by Alemanno et al., tramadol was used as an adjuvant to 0.5% levobupivacaine for single-shot middle interscalene block for patients undergoing arthroscopic rotator cuff repair. This study differs from previous ones due to inclusion of a patient group receiving systemic tramadol. The use of tramadol perineurally as an adjuvant to levobupivacaine was found superior either to placebo plus interscalene block with levobupivacaine or to systemic tramadol plus interscalene block with levobupivacaine in terms of duration of analgesia [16].
On the other hand, continuous infusion is another way to prolong the duration of action. In shoulder arthroplasties, the continuous infusion was reported to decrease the time to discharge, increase the passive range of motion in early period and reduce the opioid requirements [17]. Aside from the advantages of placing continuous indwelling catheters, there are certain factors which may limit its use. The most common failure of a continuous interscalene block (CISB) was reported to be the displacement of the catheter [18]. The catheter may also cause adverse events, especially infection, related to the leakage of solution from insertion site into the operative field in patients undergoing shoulder surgery in sitting position [19]. Aside from catheter-related adverse events, continuous infusion provided by catheter in patients undergoing upper extremity arthroplasty was reported to have higher rate of pulmonary and neurologic barriers to discharge leading to a longer length of hospital stay compared to single-shot injection [20]. The inadvertent effects of continuous brachial plexus block related to these barriers may be overcome by modifying the catheter insertion site. In a study by Auyong et al., interscalene, suprascapular nerve and supraclavicular nerve levels of brachial plexus were compared as different catheter insertion sites. The level of suprascapular nerve which is more distally located along the brachial plexus, sparing the phrenic nerve, resulted in less pulmonary adverse events compared to the continuous block at the interscalene level. A selective suprascapular nerve block catheter may prove to be beneficial in patients with pulmonary co-morbidities when compared to CISB [21].
Despite the efforts to overcome adverse events related to ISB, the technique still has some drawbacks due to the inadvertent effects on the nervous system (central blocks, brachial plexopathy, recurrent laryngeal nerve palsy, Horner syndrome) and respiratory (pneumothorax, phrenic nerve palsy) and cardiovascular complications (arrhythmias). The implementation of ultrasound guidance was reported to reduce the complication rates especially that of Horner syndrome [22]. However, the vital structures such as vertebral and carotid arteries, internal jugular vein, lungs and neuroaxial compartments surrounding the plexus at the interscalene level as well as the close proximity to the phrenic nerve remain to be the major concerns limiting the use of the technique [23].
15.1.1.2 Suprascapular Nerve Block
The shoulder is innervated mainly by suprascapular nerve, which can be blocked in suprascapular fossa by using either an anatomical landmark, nerve stimulator or ultrasound-guided technique in order to provide blockade of the distal branch of C5 and C6 roots [1, 21, 23]. The nerve originates proximally from the superior trunk of the brachial plexus and gives off an articular branch innervating especially the posterior glenohumeral joint capsule and runs with this branch through suprascapular notch beneath the transverse scapular ligament [24]. The primary goal in employing suprascapular nerve block (SSNB) as an alternative to interscalene block is to spare phrenic nerve in order to prevent respiratory complications caused by diaphragmatic paresis. Thus, this block can be preferred in patients who have higher risk of developing morbidity due to respiratory complications [1, 23]. In a case report, the bilateral use of continuous suprascapular nerve block was reported to provide beneficial effects on analgesia for bilateral hemiarthroplasty [25]. The block may also be considered as a rescue technique in case of an unsuccessful interscalene block.
The suprascapular nerve block may require the supplementary blockade of axillary nerve (ANB), which also supplies the sensory innervation of the shoulder to a lesser extent. The suprascapular nerve block without axillary nerve block was reported to reduce morphine consumption, nausea and length of hospital stay after arthroscopic shoulder surgery compared to placebo; however, it was reported to have lower impact on pain control compared to single-injection interscalene block [1, 26]. The suprascapular nerve is the branch of superior trunk and the axillary nerve is the branch of the posterior cord of the brachial plexus; thus the combination of these nerve blocks requires a two-step approach including the suprascapular nerve block at the level of suprascapular notch and axillary nerve block at the quadrangular space [27]. Despite the minority of the contribution, the lateral pectoral, subscapular and musculacutaneuos nerves also innervate the shoulder and surrounding tissues. Thus, the combination of SSNB and ANB, which spares the blocks of those aforementioned nerves, may provide insufficient analgesia leading to a need for local infiltration analgesia (LIA) in order to provide a complete pain control (see Sect. 15.1.2).
The main disadvantage of this block is that it requires the additional axillary nerve block in order to provide a complete analgesia; moreover, it has a limited duration of action with still remaining adverse events such as nerve damage, Horner syndrome and respiratory complications [1].
15.1.1.3 Supraclavicular Nerve Block
The supraclavicular nerve block is achieved at the level of brachial plexus between anterior and middle scalene muscles at the first rib, lateral and posterior to the subclavian artery [1, 28]. At this level the target nerves would be suprascapular (if the block is too caudal, then the proximally originating suprascapular nerve would not be blocked), axillary, musculocutaneous, radial, thoracodorsal, median, anterior interosseous and ulnar nerves [28]. The major adverse event associated with this block has been reported to be pneumothorax, which actually limited the use of this block. Because the cupula of the lung is immediately medial to the first rib very close to the plexus, towards which the needle is advanced from the mid-point of clavicle. The risk is higher especially on the right side, because cupula is higher on this side [28]. However, the rate of pneumothorax was reported to be reduced by using the ultrasound guidance during the block [1, 24]. Aside from pneumothorax, which was minimized by the use of ultrasound, there still remain some major complications such as intravascular injection, Horner syndrome, nerve injury and diaphragmatic paresis.
15.1.2 Periarticular Injection
The local anaesthetic injection into the periarticular area and the wound has been suggested to be a complementary technique in multimodal analgesia regimens. The injections into the subacromial or intraarticular space are no longer considered for pain control both due to the insufficient analgesia and the adverse effects such as chondrolysis, although chondrolysis is not much of a concern in arthroplasty surgeries [1]. In a study by Bjornholdt et al., the patients undergoing shoulder replacement under general anesthesia were addressed to compare the effectiveness of local infiltration analgesia (LIA) and continuous interscalene block. Local infiltration analgesia, which included axillary and suprascapular nerve blocks, was provided by using 150 ml 0.2% ropivacaine with epinephrine, whereas the continuous analgesia via catheter was provided by using 0.75% ropivacaine with 7 ml of bolus followed by 5 ml/h infusion for 48 h postoperatively. The continuous infusion of ropivacaine was reported to be superior in terms of opioid consumption and pain scores after shoulder replacement, when compared to local infiltration technique [29]. However, a combination of both techniques was suggested to improve the pain control after shoulder arthroplasty [27]. In a case report by Panchamia et al., the selective blocks of suprascapular and axillary nerves combined with local anaesthetic infiltration of periarticular area and incision were reported to provide sufficient analgesia when supplemented by scheduled multimodal systemic analgesic use after shoulder arthroplasty [27].
Liposomal bupivacaine, which uses a carrier matrix encapsulating and slowly releasing (over 72–96 h) bupivacaine, was reported to have a similar effect on pain management after shoulder arthroplasty with interscalene block by reducing the opioid requirements [30, 31]. The duration of effect of local anaesthetics may be relatively shorter, besides the ideal agent and its volume has not been established clearly yet. Hannah et al. addressed patients undergoing shoulder arthroplasty surgery to compare the effectiveness of local injection of liposomal bupivacaine with preoperative single-injection interscalene block (ISB). The investigators used 30 ml of 5% ropivacaine for ISB before surgery and used liposomal bupivacaine (266 mg diluted in 40 ml of NS) near the end of the procedure infiltrated into the pericapsular area and layers of the wound. The postoperative pain management was provided by paracetamol and patient-controlled analgesia (PCA) for each and every patient enrolled in the study. The investigators added standard bupivacaine to liposomal bupivacaine injections to provide the pain control in the early postoperative period. Liposomal bupivacaine was found to decrease pain scores at 18–24 h and reduce opioid consumption on the second postoperative day. Local liposomal bupivacaine injection was suggested to provide superior or similar pain control compared to ISB and also proved to be beneficial in shortening the length of hospital stay [30]. In another study by Sabesan et al., the ‘gold standard’ CISB was compared with a combination of single-injection ISB and periarticular infiltration of liposomal bupivacaine in patients undergoing shoulder arthroplasty [18]. The patients in CISB group received a 20 ml single bolus 0.5% of bupivacaine followed by 0.125% of bupivacaine at a rate of 6 ml/h, whereas the liposomal bupivacaine group received a 20 ml single bolus 0.5% of bupivacaine as the single-injection ISB in combination with intraoperative periarticular infiltration of LB. The standard recommended dose of 266 mg (20 ml) LB was diluted to 80 ml with NS and administered by the recommended moving needle technique. The LB was administered in 48 ml around the bone prior to the implantation of the prosthesis, in 16 ml into the capsule and deep and superficial muscular structures after implantation, followed by the remaining 16 ml into the wound both subcutaneous and into the incision [31–33]. LB administration was performed intraoperatively due to the delay in its efficacy caused by its pharmacokinetic profile. The investigators used a standard postoperative pain management consisted of 20 mg celecoxib and 650 mg acetaminophen, whereas rescue medication was provided by opioids. The patient-reported outcomes measured by Penn Shoulder Score (PSS) and American Shoulder and Elbow Surgeons (ASES) scores were reported to be better in LB group than CISB. Periarticular infiltration of LB in combination with a single-injection ISB was suggested to be a useful pain management technique for patients undergoing shoulder arthroplasty [18].
Yet, it should be kept in mind that the long-acting local anaesthetics have a peak plasma level after 24 h of injection without covering the early postoperative period. Aside from this ineffective period, nausea, vomiting and dizziness with more serious but rare complications such as myocyte toxicity, chondrotoxicity and inflammation may also be encountered with local anaesthetic injections. The efficacy and safety of liposomal bupivacaine and its combinations with adjuvants such as dexamethasone and its use in regional anaesthesia are to remain the main goals for future research.
15.1.3 Oral and Parenteral Medications
Oral and parenteral medications acting systemically are often not preferred as sole analgesic techniques mainly due to their side effect profile. However, the multimodal pain management protocols all include those medications in pre-, intra- and postoperative period. The primary goal in using regional anaesthetic and analgesic techniques is to reduce the consumption of those systemic medications to minimize their side effects. These medications include non-opioids such as acetaminophen, nonsteroid anti-inflammatory drugs (NSAID) and gabapentinoids, which are administered according to a scheduled protocol both prior to surgery and after surgery. In addition, opioids remain in pain management protocols mainly for rescue medications. The studies investigating the patients undergoing shoulder arthroplasty in terms of pain scores and opioid consumption in the postoperative period mostly employed multimodal analgesic techniques. In a study by McLaughlin et al., all patients received ISB with 15–20 ml of 0.5% ropivacaine prior to surgery and enrolled into two groups to receive the standard and multimodal pain management protocols. The standard approach included scheduled acetaminophen and opioid medications, whereas the multimodal approach included preoperative and postoperative scheduled non-opioid medications. All the patients received opioid as rescue medication. The multimodal approach in shoulder arthroplasty was reported to reduce opioid consumption and shorten the length of hospital stay [3]. In a similar study by Auyong et al., brachial plexus block was performed by using 6 ml/h 0.2% ropivacaine for infusion after shoulder arthroplasty [21]. All patients received multimodal analgesic protocol both in the preoperative (975 mg acetaminophen, 200 mg celecoxib and 600 mg gabapentin) and postoperative (650 mg/6 h acetaminophen and 200 mg/12 h celecoxib) period. Oral oxycodone was administered at a dose according to the severity of pain measured by numeric rating scale (NRS) as the rescue medication [21]. Hence, these systemic medications maintain their role in these pain management protocols as complementary to regional anaesthetic and analgesic techniques.
15.1.4 Cryotherapy
Cryotherapy is another adjuvant method that can be used as complementary to other pain management techniques. The technique alters the inflammatory process in cells leading to a better oxygenation, lower metabolic rate and lower oxygen demand, as well. It decreases the sensitivity leading to higher thresholds and slower synaptic activity. Extended exposures should be avoided [1]. In a systematic review evaluating the effectiveness and safety of cryotherapy in patients undergoing anterior cruciate ligament reconstruction, the cold compression devices were reported to reduce the pain scores for 48 h postoperatively [34]. In a recent systematic review addressing the randomized-controlled trials investigating the effect of pain management techniques in patients undergoing anterior cruciate ligament reconstruction, the cryotherapy was reported to be beneficial [35]. In a very recent study by Boddu et al., the use of cryotherapy was included in a multimodal analgesia regimen for patients undergoing total shoulder arthroplasty. The regimen consisted of a combination including ISB with 0.25% bupivacaine combined with 4 mg dexamethasone, LIA with 20 ml liposomal bupivacaine diluted in 40 ml of NS, scheduled acetaminophen and ketorolac, and immediate cryotherapy was suggested to be considered for selected patients undergoing shoulder arthroplasty [36].
15.2 Conclusion
Pain management strategy for shoulder arthroplasty surgery includes pre-, intra- and postoperative period. Since the main indication for surgery is the pain on the joint, analgesic medications should start in the preoperative period to prevent central sensitization. The analgesia should be maintained by peripheral nerve blocks and local infiltration techniques to cover both the intraoperative and the postoperative period which is important especially for the early rehabilitation in order to facilitate functional recovery of the joint. In the late postoperative period, during which the effect of local anaesthetics and adjuvant agents wares off, oral or parenteral medications should cover the remaining period with pain. The use of such multimodal analgesia helps pain control in the perioperative period and functional recovery after shoulder arthroplasty.
