Ultrasound-Guided Interscalene Block for Arthroscopic Bankart Repair
A pure ultrasound-guided interscalene block is safe and effective as the sole anesthetic technique for isolated arthroscopic Bankart repair in healthy adults with normal pulmonary function, using 20-25 mL of long-acting amide local anesthetic (ropivacaine 0.5% or levobupivacaine 0.5%). 1, 2
Safety and Efficacy Profile
The interscalene block is the first-choice regional analgesic technique for shoulder surgery, with high success rates and low complication rates when performed under ultrasound guidance. 1 For arthroscopic procedures in healthy patients, this approach provides:
- Complete surgical anesthesia without requiring general anesthesia conversion when combined with monitored anesthesia care 3
- Reliable blockade of the suprascapular and axillary nerves, which are the primary nerves innervating the glenohumeral joint during Bankart repair 1, 4
- Effective postoperative analgesia lasting 6-8 hours with single-shot technique, with significantly lower pain scores and opioid consumption compared to systemic analgesia alone 5
Recommended Local Anesthetic Volume and Concentration
Use 20-25 mL of ropivacaine 0.5% or levobupivacaine 0.5% for single-shot interscalene block in healthy adults. 2, 6 This volume provides:
- Adequate spread to cover C5-C6 nerve roots (and often C7) for complete shoulder anesthesia 6
- Predictable onset time of 14-22 minutes to achieve complete motor and sensory blockade 2, 3
- Duration of 6-8 hours of surgical anesthesia and postoperative analgesia 5
For patients where minimizing phrenic nerve involvement is desired despite normal pulmonary function, low-volume techniques (5-10 mL) can be considered but may have slightly delayed onset. 7
Technical Optimization
Add 4 mg intravenous dexamethasone at the time of block performance to prolong analgesic duration and reduce supplemental analgesic requirements in the first 48 hours postoperatively. 5, 1 This is preferred over perineural dexamethasone as it provides equivalent benefit without theoretical risks of perineural injection. 5
Target the superior trunk or C5-C6 nerve roots at the level where they lie between the anterior and middle scalene muscles, using an extraplexus approach (injection anterior and posterior to the brachial plexus sheath rather than between nerve roots). 8, 6 The extraplexus technique results in:
- Lower incidence of transient paresthesia during needle placement (14.5% vs 35.9%) 6
- Equivalent block efficacy with slightly longer onset time (6 minutes vs 4 minutes) 6
- Reduced theoretical risk of intraneural injection 6
Expected Side Effects in Healthy Patients
Hemidiaphragmatic paralysis occurs in nearly 100% of patients receiving standard interscalene blocks, but this is well-tolerated in healthy adults with normal baseline pulmonary function. 2, 3 Other common but benign side effects include:
- Horner's syndrome (approximately 19% of patients) 3, 6
- Transient hoarseness from recurrent laryngeal nerve involvement (less common with lower volumes) 6
- Subjective dyspnea (approximately 10% even in healthy patients, though objective respiratory function remains adequate) 3
Multimodal Analgesia Protocol
Initiate scheduled acetaminophen and NSAIDs (or COX-2 inhibitors) preoperatively or intraoperatively and continue postoperatively to prevent rebound pain when the block resolves. 1 This is imperative because single-shot interscalene blocks have limited duration and can result in significant rebound pain at 24 hours if multimodal analgesia is not in place. 5
Reserve opioids for rescue analgesia only, as the combination of interscalene block with scheduled non-opioid analgesics minimizes opioid requirements. 1
Alternative Considerations
If you wish to avoid hemidiaphragmatic paralysis entirely (even though it's clinically insignificant in healthy patients), consider costoclavicular block as an alternative that provides equivalent postoperative analgesia with 0% incidence of phrenic nerve involvement. 2, 3 However, the costoclavicular block may have slightly longer onset time (21.6 minutes vs 14 minutes) and requires additional validation for providing complete surgical anesthesia rather than just analgesia. 2
Continuous interscalene block is superior to single-shot for reducing rebound pain and providing analgesia on postoperative days 1-3 and beyond, but adds complexity for outpatient procedures. 5, 1 If the patient will be discharged the same day, ensure robust multimodal analgesia is prescribed for home use.
Critical Pitfall to Avoid
Do not rely on interscalene block alone without establishing a multimodal analgesic regimen. The most common error is failing to initiate scheduled acetaminophen and NSAIDs before block resolution, leading to severe rebound pain at 12-24 hours postoperatively when patients are at home. 1 This undermines the quality of life benefit that the block was intended to provide.