Total shoulder arthroplasty, also known as total shoulder replacement, is the treatment for the end stage of shoulder joint disability. These patients often have pain in and dysfunction of their shoulder, and have a tried a variety of treatments, including oral pain relievers and steroid injections, without relief. This surgery is often performed in older patients, who may potentially have cardiac or pulmonary co-morbidities. Given the elective nature of this surgery, the plan for post-operative pain control is usually developed prior to the surgical procedure.
Total shoulder arthroplasty is almost exclusively an elective surgical procedure.
Emergent: Cases of emergent total shoulder arthroplasty are rare, if any.
Urgent: There are rare, if any, cases of urgent total shoulder arthroplasty. Any urgent shoulder surgery, which is usually related to proximal humerus fracture, would likely result in a hemi-arthroplasty.
Elective: Total shoulder arthroplasty is most often performed as an elective surgical procedure, and therefore a patient’s coexisting medical conditions are often able to be optimized prior to surgery.
Most patients receiving total shoulder arthroplasty are in their 60s – 70s and tend to have other arthritic joints. Shoulder pathology, requiring total shoulder arthroplasty, is usually secondary to osteoarthritis or pre-existing massive rotator cuff tears. Given the age of these patients, it is possible for co-existing cardiac disease to be present.
Medically unstable conditions warranting further evaluation include: As in any other elective surgery performed in this age group, common medically unstable conditions warranting further evaluation include: unstable angina, reversible cardiac wall-motion abnormalities, uncontrolled hypertension, congestive heart failure, and active infection.
Delaying surgery may be indicated if: There are head and neck issues if the procedure is performed using beach chair positioning. Given the elective nature of this surgery, any medically unstable conditions should be treated or optimized. If controlled hypotension is planned, cardiac and cerebral vessel patency should be evaluated.
Basic pre-operative evaluations include EKG (in men over the age of 40 and women over the age of 50), chemistry, and hematocrit. If the patient is on any anti-coagulation therapy, coagulation status should be evaluated. Exercise tolerance should be ascertained, which may be challenging if arthritis in other joints limits activity. Preoperative pain control with oral medications will also need to be examined, to predict the method and amount of pain medications that will be required in the post operative period.
Any medically unstable condition needs to be addressed and treated and all coexisting medical conditions optimized prior to proceeding with this elective surgery.
Examples of unstable cardiac conditions that need to be treated prior to proceeding with this elective surgery include: unstable angina, reversible cardiac wall-motion abnormalities, uncontrolled hypertension, and congestive heart failure. Absolute contraindications to elective surgery include myocardial infarction less than one month prior to surgery, active heart failure, and severe aortic stenosis.
Goals of management of cardiac conditions include optimizing blood pressure and heart rate prior to surgery.
If the patient is to receive an interscalene peripheral nerve block, pulmonary status will need to be assessed. Hemi-diaphragmatic paralysis, which is common for this particular block, needs to be anticipated. Patients with severe COPD may not be able to tolerate this loss of diaphragm movement, and individual risks and benefits need to be weighed in these cases.
Peripheral nerve blockade is an appropriate post-operative pain management choice, as it will likely decrease the amount of oral or IV opiate required by the patient. It is often systemic pain medications that can worsen a patient’s obstructive apnea, and interscalene nerve block is not known to worsen this condition in at-risk patients. If the peripheral nerve block is used as part of the surgical anesthesia, it will also likely lessen the amount of inhalational or IV agent required to keep a patient under general anesthesia. This can often lessen the effects of these agents in the recovery room in patients with obstructive sleep apnea.
As for any surgery, reactive airway disease needs to be anticipated and treated with an agent such as nebulized albuterol.
Patients with renal and/or hepatic impairment may tolerate a single-injection peripheral nerve block without difficulty. However, caution is warranted when infusing local anesthetics through a perineural catheter to provide postoperative analgesia if there is concern that the patient may not be able to adequately metabolize the local anesthetic and/or excrete any active metabolites.
In patients with long standing hypertension, cerebral auto-regulation may be compromised. These patients will not be able to tolerate extreme arterial blood pressure changes, and controlled hypotension of more than 20% of baseline should not be planned.For patients with multiple arthritic joints or a long standing arthritic shoulder, there is the possibility of chronic pain and opiate tolerance. This tolerance needs to be considered and treated with higher opiate doses or regional anesthesia in the post-operative period.
Additional care must be taken in patients with Diabetes Mellitus, as patients with this condition are thought to have nerves that are extra sensitive to ischemia. This is more evident in lower extremity nerves, although the same could potentially be true in upper extremity nerves as well. Practitioners have tried to improve safety by decreasing the amount or concentration of local anesthetic placed around these nerves, or decreasing the amount or use of epinephrine in the local anesthetic solution.
If a patient has multiple arthritic joints requiring surgery, usually the joint causing the most disability is addressed and corrected first. This often affects recovery, as disability in one joint can influence how a patient participates in physical therapy.
Immediately prior to surgery, patients are likely receiving oral pain relievers (excluding NSAIDS); these medications can be continued peri-operatively. Alternatively, NSAIDS (eg. aspirin, ibuprofen, naproxen, indomethacin) should be discontinued 7-10 days prior to surgery.
Older patients are often treated for hypertension, and oral antihypertensives (eg. beta blockers, calcium channel blockers, diuretics) should be continued. Occasionally ACE inhibitors are held due to the risk of hypotension during general anesthesia. Risks of continuing anticoagulation for other medical reasons should be weighed against the risk of bleeding.
Patients with chronic pain associated with multiple joint pain are often on opiates. These patients may have a relative tolerance to these medications, which needs to be taken into consideration when treating post-operative pain.
Anti-hypertensives should be continued peri-operatively, if the patient’s blood pressure tolerates it.
The risks of discontinuing anti-platelet medications need to be weighed against the risk of bleeding in individual patients. If this medication is being given because of a recent intracoronary stent, consultation with the patient’s cardiologist about optimal perioperative management is warranted.
A true allergy to amide local anesthetics is exceedingly rare. An allergy to ester local anesthetics is much more common. There is no reported cross-reactivity between these two classes, and thus the potential benefits greatly outweigh the potential risks of administering an amide local anesthetic to a patient with a history of an ester allergy.
Patients who have an allergy to third generation cephalosporins should receive vancomycin or clindamycin.
If a patient has an allergy to a specific local anesthetic, it is best to avoid that particular class of local anesthetics in the peri-operative period. This includes peripheral nerve blocks.
Coagulation panel: Patients who have recently discontinued Coumadin (for other vascular issues, such as Atrial Fibrillation or a history of deep vein thrombosis) prior to surgery or those with known liver disorders should have their coagulation panel checked. For total shoulder arthroplasty, one should expect 200 ml EBL, but this amount varies.
Imaging: Prior to surgery, the orthopedic surgeon will have likely diagnosed the shoulder disorder with x-rays, while occasionally an MRI or CT will be performed.
There are various methods of surgical anesthesia for total shoulder arthroplasty. Patient and surgeon preference often dictate the plan, but the anesthesiologist ultimately determines that the plan is a safe one. Regional and general anesthesia and sedation are all options, and an anesthetic plan often includes a combination of these techniques.
Brachial plexus nerve block at the interscalene site is the most common location for regional anesthesia for total shoulder arthroplasty. The brachial plexus is anesthetized at the root and/or trunk level. This provides surgical anesthesia to the entire shoulder joint as well as most of the skin overlying the area.
Electro-stimulation or ultrasound guidance are common techniques for locating the correct site for local anesthetic deposition. The brachial plexus runs between the anterior and middle scalene muscles, just deep to the posterior border of the sternocleidomastoid muscle. 20-30 ml of local anesthetic (1.5% mepivacaine for catheter placement, or 0.5% ropivacaine for long acting single-injection blocks) is deposited, with most of it located near the C5 or C6 nerve roots.
Given the level of post-operative pain for this procedure, it is common for the anesthesia provider to leave a peripheral catheter at that site for 2-3 days of continuous local anesthetic infusion.
Benefits of interscalene nerve block: Shoulder muscle relaxation, reduces the amount of general anesthetic required during surgery, provides post-operative pain control.
Drawbacks: Side effects of interscalene nerve block- diaphragmatic paralysis (100% incidence), Horner’s syndrome, decreased chest wall sensation, and hoarse voice. Rare complications of this nerve block are pneumothorax, spinal or epidural spread, and vertebral artery injection.
Issues: Localized infection at the site of needle insertion for interscalene nerve block is an absolute contraindication, systemic infection or infection at another anatomic site is a relative contraindication to block placement.
Benefits: Given the positioning required for surgery (beach-chair or lateral with shoulder extended) patients are often more comfortable during surgery with a general anesthesia, even if a surgical block is present.
Drawbacks: Post-op nausea and vomiting are more common after general anesthesia in susceptible patients.
Airway concerns: The airway needs to be protected during positioning, especially if the patient is placed in the beach-chair.
– this is only an option with a complete interscalene block; local anesthesia alone is not effective.
Benefits: Regional anesthesia plus sedation results in less post-operative nausea and sleepiness.
Drawbacks: Positioning may be uncomfortable for the patient.
The combination of an interscalene block (preferably with a catheter) combined with general anesthesia as described above is our preference.
– A third generation cephalosporin (eg. cefazolin) is generally used for prophylactic antibiotics, but if a patient caries MRSA, vancomycin in generally used.
– It is often helpful to keep the patient sedated until the shoulder immobilizer is in place in order to protect the rotator cuff repair.
Since it is not possible to decrease blood loss with the use of a tourniquet, the anesthesiologist can often assist with decreasing blood loss by controlled hypotension. Using anesthetic agents, or antihypertensives (sympathetic antagonists, calcium channel blockers, peripheral dilators), the arterial blood pressure can be decreased to around 20% of baseline blood pressure, but usually not lower than a mean arterial pressure of 50 mmHg.
Prioritize them by urgency. Fracture of the humerus can occur when stem placement or preparation occurs, which can prolong surgery or increase blood loss.
Cement implantation syndrome is a rare but serious complication of total shoulder arthroplasty. Hardening of the methylmethacrylate cement produces an exothermic reaction that can cause dislodgement of bone elements, such as fat and bone marrow, and cement into systemic circulation. Cardiac symptoms include hypotension, dysrhythmias, and decreased cardiac output. Pulmonary symptoms include pulmonary hypertension, which can manifest as a decreased oxygen saturation. Treatment is mainly supportive in these cases.
Venous air embolism is another rare but serious complication that can occur if the patient is positioned in the beach chair, since the patient’s head is positioned above the patient’s heart.
Unique to Procedure: Given that many of the total shoulder arthroplasties completed today are done in a sitting or semi-recumbent position, and surgeons are requesting controlled hypotension for decreasing blood loss, there is an added concern for hypotensive central nervous system problems. While these occurrences are rare, they are particularly devastating.
If interscalene block is performed and general anesthesia is used, these patients have less stimulation and often have moderate hypotension from anesthetic effects and venous pooling in the lower extremities. Care needs to be taken to recognize that the cerebral perfusion pressure can be much less (7-23 mm Hg) than the bracheal blood pressure, or much less than the lower extremity blood pressure measured by the non-invasive cuff.
Care also needs to be taken while positioning a patient’s head in the sitting positions, as extreme head manipulations can affect cerebral and cord blood flow.
While the incidence of peripheral nerve injury is low, the issue should still be addressed and considered. Meta-analysis puts the incidence of any nerve injury, most commonly short-term neuropraxia, at around 3%. In many of these cases, it was unknown if the nerve injury was caused by the peripheral nerve block, the surgical procedure itself, positioning, or ischemia.
Compared to other peripheral nerve blocks, the incidence of nerve injury from interscalene nerve block may be slightly higher. This risk must be weighed against the benefits in each individual case, and should be addressed and considered by the surgeon, anesthesiologist, and patient.
Post-operative pain control can be managed using IV, oral, or regional analgesia modalities, or a combination of the three. Often patients who receive interscalene nerve block catheters can wake up from general anesthesia comfortably, requiring only minimal supplemental IV pain medication. These patients are placed on continuous dilute infusions of either bupivacaine (0.1-0.25%) or ropivacaine (0.15-0.4%) at an initial rate of 6-8 ml/hr. This rate can be titrated to proper pain control with minimal motor weakness.
In addition to the continuous infusion, patients can be given the ability to bolus their own catheters through a bolus function located on most peripheral nerve block pain pumps. A recommended starting bolus is 4 ml every 30 minutes, but a number of regimens are available, depending on the pain pump used.
Patients on chronic preoperative opiates will often need to be placed on their preoperative dose and regimen during their perioperative period. Most often patients with opiate tolerance will need additional opiates and other modes of pain relief to control pain during the postoperative period. Long acting opiates, given as a scheduled medication with a PRN option of a shorter duration opiate, often works best in these patients.
For patients with no outstanding baseline medical issues, a floor bed is adequate after total shoulder arthroplasty.
For patients who receive peripheral nerve block catheters, the amount of oral and IV opiates is generally minimal. This decreases the risk of falls from disorientation and sedation. One must take precaution from the numbness and weakness that occurs after an interscalene nerve block. These patients are often in a supportive sling for the surgery itself, but this sling needs to remain in place for the duration of the infusion.
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