Oral narcotics have to be broken down by the digestive tract. They differ in activation time and in the blood concentration. Controlled release oral narcotics may be more effective than immediate release narcotics, particularly in the immediate postoperative period. Reuben et al. (5) compared controlled release to immediate release oxycodone in patients undergoing ACL reconstruction. Less pain and vomiting, better sedation scores, and greater satisfaction were reported in patients receiving controlled release oxycodone. Popp et al. (6) found fewer side effects with a regimen of oral oxycodone and ketorolac versus morphine in patients undergoing ACL reconstruction. The morphine was delivered by a patient controlled analgesia device (PCA). According to visual analog scores, the pain control was identical between methods. Intra-articular morphine could theoretically block pain receptor sites in the knee thus providing a direct relief from painful surgery.

Meperidine should be used with caution in the elderly because one of its metabolites, normeperidine, is toxic to the central nervous system. This drug also has anticholinergic side effects.

Intra-articular morphine has been used extensively to aid in postoperative pain control. It theoretically blocks pain receptor sites in the knee and thus provides direct relief from painful surgery. It has been found to provide analgesia in arthroscopic knee surgery as well as patients undergoing ACL reconstruction (7). A needle is typically placed within the knee joint preoperatively or postoperatively. The mu-receptors of opoids have been found on articular cartilage, which is a possible explanation for the benefit of intra-articular morphine (8). Lawrence et al. (9) performed a study on biopsied synovium. They found evidence for the presence of opoid binding receptor sites in this tissue.

In a canine study inflamed articular cells were found to have increased opoid binding sites (10). This upregulation of opoid receptors on inflamed tissues likely validates the use of intra-articular opoid usage in postoperative patients. Brandsson et al. (11) compared intra-articular morphine to a placebo in patients undergoing ACL reconstruction. In a double blinded placebo controlled study the authors showed that the group of patients receiving morphine had lower pain scores than those in the placebo groups.

Karlsson et al. (12) found that a combination of bupivicaine and morphine given in an intra-articular fashion reduced pain scores after ACL reconstruction. In a previous study, authors had similar conclusions when patients undergoing ACL reconstruction received intraarticular morphine (13). In a multimodal study these results were somewhat refuted. Reuben et al. (14) looked at patients undergoing ACL reconstruction who received a placebo, bupivicaine, and/or morphine. Patients receiving bupivicaine had prolonged analgesia and decreased postoperative analgesia requirements. The addition of intra-articular morpine did not provide added benefit to these patients.

Tourniquet release may have an effect on the benefit of intra-articular morphine. In a study looking at the time to deflation of the tourniquet Whitford et al. (15) showed that when the tourniquet was maintained for 10 minutes after injection, pain scores were lower compared to a group of patients who had immediate release of their tourniquet. Another study looked at the concentration of the medicine delivered into the knee. The authors found no difference in pain relief when different concentrations of bupivicaine were delivered to the knee in an intra-articular fashion.

Preoperative anesthesia has the theoretical benefit of interrupting the pain cycle before it begins. A study looking at preemptive intra-articular morphine showed lower analgesic usage and greater duration of analgesia in patients undergoing arthroscopic knee surgery (16). McCarty et al. (17) performed a prospective randomized double blind study comparing a preoperative injection of morphine (5 mg) to a placebo. Sixty-two patients underwent arthroscopically assisted ACL reconstruction using the central third of the patella as an autograft. There was no significant difference between the two groups in their Visual Analog Scale (VAS) scores or their postoperative narcotic requirements. Hoher et al. (18) found a reduction in VAS scores in patients receiving a preoperative intra-articular injection of bupivacaine on the day after their ACL reconstruction surgery. Tetzlaff et al. (19) found a reduction in the need for postoperative opoid usage in a group of patients who received a preoperative intra-articular injection of bupivacaine and morphine.

A study looking at patients undergoing ACL reconstruction did not show a great benefit for the use of preemptive intra-articular analgesia. In this study 30 patients were placed into three groups: one group had a preoperative placebo, one group had a preoperative injection with bupivicaine, and a third group had an injection with bupivicaine and morphine. Postoperative pain was significantly greater in the placebo group. However this difference became less apparent with time and after one hour there was no significant difference. Another finding
of the study was that patients in the third group used significantly less narcotic than the other groups; the authors recommended the use of preemptive analgesia (20). Based on the available literature, an intra-articular injection of bupivacaine and morphine should be carried out prior to ligament reconstruction.

An intra-articular infusion of analgesia medication may be given as a bolus. This is given as a one time injection either before or after the procedure. This one time injection has the theoretical benefit of a lower chance for infection versus the prolonged placement of the catheter for the infusion pump. The medication typically used is bupivicaine. This medicine has a longer half life than lidocaine and thus provides longer analgesia. The one time bolus may be given preoperatively or postoperatively. Studies have validated the use of a one time bolus of bupivacaine but have not shown a benefit of a preoperative over a postoperative injection.

Intra-articular pain infusion pumps using anesthetic have the theoretical advantages of administering analgesia directly to the site of injury. However, this theoretical advantage may be only theoretical. Alford and Fadale (21) did an excellent prospective, randomized, placebo-controlled, double-blinded study examining the use of a bupivacaine infusion pump in patients undergoing ACL reconstruction. One group had infusion with normal saline and a second group had infusion with bupivacaine. There was no significant difference in the median pain rating between the two groups, though the maximum pain rating was better in the bupivacaine group. Narcotic usage was lower in both groups when compared with a group that did not have an infusion catheter. There was also no difference in the ability to progress with therapy between the two groups. The authors felt the catheter may have provided a psychological difference and thus the reason for lower narcotic usage.

A study done by Chew et al. (21a) examined infusion into the infrapatellar fat pad in patients undergoing ACL reconstruction using autograft central third of the patellar tendon. Opioid usage was decreased compared to historic controls in the bupivicaine group. The authors felt the fat pad infusion provided significant enhancement of pain relief after surgery. Dauri et al. (22) compared epidural analgesia, continuous femoral nerve blocks, and intra-articular infusion in patients undergoing ACL reconstruction. The patients receiving an intra-articular infusion required more ketorolac to help them cope with the pain and their pain as measured by the VAS was higher. Potential side effects of intra-articular anesthesia include the risk of infection.

Femoral nerve blocks are a method of anesthetizing the lower limb. They have the advantage of delivering analgesia in a safe and effective way without the side effects of narcotics. They are particularly useful in the acute postoperative period, but their long term benefit has not been proven. The femoral sheath is infiltrated with an anesthetic agent which blocks the femoral nerve. There is some controversy as to whether the obturator and lateral femoral cutaneous nerves are blocked as well (23). Potential side effects include incomplete anesthesia, hematoma, and infection.

Preoperative femoral nerve blocks may aid in the amount of anesthesia during the operative procedure. Postoperative blocks probably aid in the initial pain after surgery but do not aid in the rehab after surgery. Edkin et al. (24) retrospectively reviewed their charts in 161 patients undergoing outpatient ACL reconstruction using patellar tendon autograft. Ninety-eight percent of patients surveyed found femoral nerve blocks to be beneficial in helping to control the post surgical pain. Williams et al. (25) found a 2.5 fold reduction in unplanned hospital admissions in patients undergoing ACL reconstruction using patellar tendon autograft and femoral nerve block versus a control group. Several other studies have documented the effectiveness of femoral nerve blocks in this patient population as well (26,27,28). Another study in patients undergoing ACL reconstruction found femoral nerve blocks with bupivicaine 0.5% found lower pain scores and lower narcotic usage compared to a placebo group however there was no difference in time to discharge between the two groups (29).