Preoperative intraarticular injection for pain relief after outpatient arthroscopic knee surgery

OBJECTIVES: Injection of intraarticular local anesthetics to provide post-operative pain relief after knee surgery has been described.(l) The presence of inflammatory induced peripheral opioid receptors in the articular space has also been documented.(2) We hypothesized that a pre-surgical, intraarticular injection of local anesthetics, morphine and epinephrine may provide prolonged pain relief after arthroscopically guided Anterior Cruciate Ligament (ACL) reconstruction with minimal side effects. METHODS: IRB approval was obtained. Twenty-three patients, ASA Nil, ages 16-70, were randomized to one of three groups in a prospective, double-blinded randomized fashion. All groups had 60 ml injected intraarticularly 20 minutes prior to incision by the same surgeon. Group I received normal saline with 1:200,000 epinephrine, Group II received.25% bupivacaine with 1:200,000 epinephrine, and Group III received.25% bupivacaine with 1:200,000 epinephrine and 1 mg morphine sulfate. There was no premedication. All patients received general anesthesia with intravenous propofol 1.82 mg/kg and fentanyl up to 5 ug/kg prior to incision, and endotracheal intubation facilitated with succinylchoSne 1.5 mg/kg and d-tubocurare 3 mg. Maintenance was with NîO/Oj (70%/30%) and propofol 3.6 mg/kg/hr. Ketorolac 30 mg IM was given at the conclusion of the surgical procedure. In the recovery room visual analog pain scores were obtained upon arrival and after 30,60,120,240,360, and 480 minutes. Personnel performing the pain assessment of the patients were blinded to the treatment protocol. Supplemental opioids were given in the Post Anesthesia Care Unit (PACK) or the phase II recovery area for pain scores greater than 5. Each patient was given hydrocodone and acetaminophen (5/500) to be taken at home as needed. Use of supplemental opioids, nausea, vomiting, pruritus, and respiratory depression were also noted. Opioids usage in the first 24 hours was obtained by telephone interview. Data was analyzed with ANOVA and the Kruskal-Wallis test. Values are presented as mean ±SO. RESULTS: The groups were similar demographically. GROUP III patients had significantly lower pain scores up to 30 minutes after arrival in the PACU with a mean of 3.1 ±2.7 (p<0.001}. The patients in GROUPS I and II clearly had higher pain scores on arrival and in the first 30 minutes (p<0.001) but these differences were less significant over time. This may be attributed to the use of supplemental opioids in the recovery room. Rescue doses of fentanyl (M±SO) were 115+53.9,83.3±69.6,6.25±17.7 ug for GROUPS I, II, and III respectively. The rescue dose for GROUP III was significantly lower than for GROUPS I and II (p=0.0023, p=0.0087respectively).(Fig. 1} DISCUSSION: The presurgical blockade of peripheral opioid receptors with morphine provided significant pain relief with only 1 mg of morphine. The administration of local anesthetic, opioid, and epinephrine prior to surgical trauma provided significant pain relief. The use of ketorolac in all of the patients may have minimized the effect and may be due to the synergistic activity of NSAIDS and opiates in preventing nociception. Epinephrine may also have a role in the prevention of peripheral hypersensitivity. In conclusion the intraarticular injection of bupivacaine with epinephrine and morphine provides superior pain relief after arthroscopically assisted ACL repair. (RgufcD Supplemental narcotic use In PACU Group P Value IvsII.26 I vs III.0023 IIvsIII.0087 Kruskal-Wallis.