An interscalene nerve block has traditionally been used to minimize pain for patients having shoulder replacement surgery. However, nerve blocks are expensive and can cause complications such as hematoma, pneumothorax and peripheral nerve injuries. University of Missouri Health Care orthopaedic surgeon H. Mike Kim, MD, wondered if there was an equally effective but potentially safer and less expensive alternative.

H. Mike Kim, MD
H. Mike Kim, MD

"We took a cue from our hip and knee surgeon colleagues, because they've been using a so-called joint cocktail injection for a long time and they have had a great success with that method," Kim said. "That technique had not been used for shoulder replacement patients, so we conducted a randomized clinical trial."

Kim enrolled 74 patients, with about half receiving a nerve block and the other half getting a joint injection that contained ropivacaine, ketorolac, epinephrine and saline. For two weeks after surgery, he collected data on the patient's pain levels, their opioid medication consumption, length of hospital stay and any complications.

  • There was no significant difference in pain between the two groups except at eight hours after surgery, when the average pain score for the injection group was five, compared to three for the block group.
  • The opioid medication consumption after surgery was similar.
  • The average length of hospital stay for the block group was 1.2 days, compared to 0.9 days for the injection group.
  • Each group had one complication. A patient in the block group suffered a case of phrenic nerve palsy that caused postoperative hypoxemia and an extended hospital stay. A patient in the injection group developed a dislocation of a reverse shoulder replacement, although that was caused by not complying with postoperative restrictions and wasn't related to the injection.

Kim was encouraged by the effectiveness of the joint injection, which has an average cost of $150 compared to $1,700 for the nerve block.

"We found that the joint injection can be very safe, effective and low-cost alternative to the interscalene block," Kim said. "It is less than one-tenth the cost of the interscalene the block, and the patients had good success with pain control after surgery.

"At this point, pretty much all my shoulder replacement patients get joint cocktail injections, unless they have allergies to ketorolac, in which case we use interscalene block. Other than that, we use joint cocktail injections and have been very satisfied with the results."

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