Continuous Interscalene Block vs Liposomal Bupivacaine After Proximal Humerus Fracture Surgery

The purpose of this study is to compare the efficacy of continuous interscalene block (CISB) using standard bupivacaine versus a single interscalene injection of liposomal bupivacaine (LB) on pain control following surgical fixation of proximal humerus fractures.

Restricted range of motion following open reduction and internal fixation (ORIF) of proximal humerus fractures is a potential complication that severely limits functional outcomes . It must therefore be avoided by adequate pain control in order to allow for early mobilisation in addition to physiotherapy.

Interscalene block (ISB) is one of the most effective and widely used regional analgesic options shoulder surgeries. ISB can be delivered as a single injection or by continuous infusion via an indwelling catheter. While continuous interscalene block (CISB) offers a longer duration of analgesia as compared to a single injection of the same anaesthetic, it carries an inherent risk of catheter malposition, dislodgement, and infection.

As compared to standard bupivacaine (SB), liposomal bupivacaine (LB) is a formulation designed to prolong the duration of analgesia up to 72 hours via a single injection. While this could avoid the need for an indwelling catheter, results of studies comparing LB to CISB have been inconsistent.

The purpose of this is non-inferiority trial is to compare the effectiveness of a single injection of LB versus CISB with SB on pain control following ORIF of proximal humerus fractures. The study hypothesis is that LB is not unacceptably worse than CISB with regard to pain control in the first two postoperative days.

Patients providing informed consent will be screened for eligibility. All eligible patients will be randomly assigned in a double-blind manner (participant and investigator) and a 1:1 ratio to receive either LB or CISB.

Eligibility Criteria:
Inclusion Criteria:

* ASA I-III
* Age between 18 and 80
* Isolated Proximal humeral fracture (AO Types 31.A1-3 and B1-3 or Neer 2/3 part or greater tuberosity fracture equivalent)
* Locking Plate fixation
* Split deltoid minimal invasive approach

Exclusion Criteria:

* Revision surgery
* Impaired cognitive function (Abbreviated Mental Test Score (AMT score) \< 8)
* 4 part fractures
* Poor surgical reduction quality
* Unable to attend rehabilitation
* Preexisting shoulder problems
* Fracture fixation stability unable to tolerate early passive motion exercise
* Use of implants other than a locking plate for fracture fixation
* Activity of daily living is dependent on others
* Polytrauma
* Use of deltopectoral approach
* Patient unable to follow post-operative rehabilitation protocol with early mobilization
* Allergy to amide local anaesthetics, paracetamol, non-steroidal anti-inflammatory drugs (NSAIDS), opioids
* Respiratory Disease with limited respiratory reserve
* Cardiac Disease: Any degree of Heart Block, Heart Failure
* Neurological: Any Seizure Disorder
* Psychiatric illnesses affecting pain perception e.g. severe depression and anxiety disorder
* Alcohol or substance abuse
* Chronic Pain, other than chronic knee pain
* Daily use of strong opioids (morphine, fentanyl, hydromorphone, ketobemidone, methadone, nicomorphine, oxycodone, or meperidine)
* Impaired Renal Function (defined as preoperative eGFR \< 30ml /min /1.73 m2)
* Impaired Hepatic Function
* Pregnancy
* Inability to use PCA
* Patient refusal to ISB
* Patient refusal to study
* Patients do not understand Cantonese