Ultrasound-Guided Obturator Nerve Block for Ambulatory Hip Arthroscopy

RESEARCH DESIGN AND METHODS Patient selection The proposed study will be a prospective
randomized placebo-controlled trial. Eligibility criteria will include patients having
primary unilateral ambulatory hip arthroscopy for femoral acetabular impingement, age 18 to
65 years, ASA physical status I to III, and ability to follow the protocol.

Exclusion criteria: patient refusal, inability to comprehend the consent form, age < 18, and
> 65 years of age; contraindications to obturator nerve blockade (pre-existing neuromuscular
or peripheral nerve disorder, localized infection, or bleeding disorder); allergy to opioids
or local anesthetics; allergy to celecoxib or sulfa medications or nonsteroidal
anti-inflammatory medications (NSAIDs); chronic opioid use (> 1 month of 60 mg morphine PO
equivalents daily); and, women who are pregnant or breastfeeding.

Consent Patients will be enrolled preoperatively in either the orthopedic surgery clinic or
through the anesthesia preoperative clinic after the hip arthroscopy surgery is scheduled

Randomization, Blinding, and Allocation

Study medications will be administered by the primary investigator who will perform or
closely supervise all ultrasound-guided obturator nerve blocks. Randomization will be
performed with use of computerized random number generator and then each assignment will be
placed into an opaque sealed envelope. Upon enrollment into the study and consent obtained,
the next sealed envelope (numbered sequentially) will be opened and the patient allocated to
either:

- Group 1 (Treatment), Ultrasound-guided obturator nerve block: 20 ml ropivacaine 0.5%

- Group 2 (Placebo), Ultrasound-guided saline placebo block: 5 mL sterile saline 0.9% The
primary investigator will not be involved in any subsequent postoperative data
collection. The sub-investigators will perform all subsequent data collection and will
be blinded to group allocation.

Intervention Following randomization, the principle investigator will perform the block
procedure 30 minutes prior to expected transfer back to the operating room.

Anesthetic care All intraoperative anesthetic care will be standardized as well, including
general endotracheal anesthesia induction using propofol 1.5-2mg/kg IV, succinylcholine
1-1.5mg/kg IV or rocuronium 0.6-1mg/kg IV (based on the clinical discretion of the blinded
anesthesia provider). In order to provide adequate intraoperative analgesia for both groups
for the expected duration of the procedure, 1 mg of intravenous hydromorphone will be
administered 10 minutes prior to surgical incision.

No further intraoperative opioids will be administered. Neuromuscular blockade will be
maintained with rocuronium as indicated by surgical requirements and titrated by
neuromuscular monitoring, and reversed in standard fashion prior to emergence from general
anesthesia. At the end of the procedure, the surgeon will inject ropivacaine 0.25% 30 mL in
each of the 2 arthroscopic portal sites for a total of 60 ml ropivacaine 0.25% in all
subjects as is standard practice for all hip arthroscopy patients.

Subjects will be given a log to record their postoperative pain scores and oxycodone
consumption for the 1st 24 hours after discharge.

Outcomes The primary outcome will be the pain immediately upon arrival to the post
anesthesia care unit. This will be measured by an 11-point numerical rating scale (NRS 0 =
no pain, and 10 = worst pain imaginable).

Secondary outcomes will include NRS pain scores at additional time frames for pain score
self-assessments will include:

1. 3-4 hours after arriving home

2. Within 1 hour prior to going to sleep

3. Within 1 hour after waking up the following day.

4. 24 hours after surgery

Additional secondary outcomes will also include: cumulative 24-hour postoperative opioid
consumption, percentage of patients with postoperative nausea and vomiting, sleep
disturbance (difficulty going to sleep or waking up from sleep due to postoperative pain).

Expected Time Frame

Typically, 4-5 hip arthroscopies per week are performed. Thus the expected timetable for
recruitment will take at least 6-12 months

Inclusion Criteria:

- Primary unilateral ambulatory hip arthroscopy

- Age 18 to 65 years

- ASA physical status I to III

- Ability to follow the protocol.

Exclusion Criteria:

- Age <18 or >65 years of age

- Contraindications to peripheral nerve blockade

- Allergy to opioids or local anesthetics

- Allergy to sulfa medications or nonsteroidal anti-inflammatory medications

- Chronic opioid

- Patient refusal