Todays, anterior cruciate ligament (ACL) reconstruction is a common operation. After surgery, there is sever pain in the knee region [1] which interfere with rehabilitation program of patient and can delay returning him or her to daily living or sport [2]. If patient cannot participate in rehabilitation program in post operative period, some complications like muscle spasm, anterior knee pain and complex regional pain syndrome (CRPS) and delay in regaining preoperative muscle strength are anticipated [3-7].

Post operative pain may change from acute to chronic pain. Appropriate pain control in acute phase can inhibit formation of chronic pain [8,9]. Also, during operation pain impulses which received by pain centers in brain may the source of chronic pain in postoperative periods [10]. Transient and short time pain relief is reported after administration of opiates during operation [11]. The goal of some preventive regimens is eliminating pain during surgery and postoperative period not only during skin incision [12]. Appropriate pain control can prevent both acute and chronic pain in postoperative period [13,14]. The aim of this study is evaluation of effectiveness celecoxib as a part of multimodal pain control on long term results of ACL reconstruction surgery.

It is a double blind clinical trial study. All patients who undergone fully arthroscopic ACL reconstruction with hamstring graft in 2010 in Sina hospital (Tehran , Iran) after a written consent based on Helsinki rules , enter this study (inclusion criteria). Previous knee surgery, osteotomies around knee, bilateral operations, chondral lesions, heart diseases, preoperative addiction to opiates and hypersensitivity to nonstriodal anti inflammatory drugs (NSAIDS) are exclusion criterias.

These patients are divided randomly to two groups. One group named case group receive 400 mg celecoxib and 750 mg acetaminophen 1 hour before operation. The other group named control group receive 750 mg acetaminophen and placebo 1 hour before surgery. Anesthesia induced with propofol (2 mg/kg) and fentanyl (2 micro gram/kg) and ketamin 30 mg and maintain with 30-50% NO2 gas inhalation. All of the patients receive 20cc intraarticular bupivacain 0.25% before skin suture. After operation, case group receive 200 mg celecoxib each 12 hours but in control group, they receive placebo in the same time intervals. Both groups receive 750 mg acetaminophen each 6 hours. This regimen continues for 2 weeks. All of them had rapid rehabilitation program. At the end of 2^nd week and 6^th month, patients are evaluated for patellofemoral complications (anterior knee pain, flexion contracture, quadriceps weakness and) and pain (Table 1). Patients are requested to clarify their pain in the first 2 weeks from 0 to 10 and bring the results in the first visit in the 2^nd week with themselves. Examination in 2^nd week and 6^th month were about anterior knee pain, flexion contracture, quadriceps strength, knee range of motion and sign and symptoms of CRPS (Table 2). Results and findings are evaluated with chi-square and t- test with SPSS soft ware.

Table 1: Patellofemoral complications.

Table 2: Knee range of motion.

90 patients entered this study (43 in case group and 47 in control group). Average age in case and control groups were 33.9 year and 32.8year respectively. There were 5 female (11.6%) in case group and 7 female (14.9%) in control group. Average weight was 68.3 kg in case group and 68.4 kg in control group. So, there were no statistical meaningful difference regard age, sex, weight between two groups. Also, mechanism of injury was the same in both groups and average operation time in case group was 102 minutes and in control group was 102.9 minutes with no statistical difference (p=0.795).

Post operative patellofemoral complications were reported in 13 patients (30.2%) in case group and 39 patients (83%) in control group with a meaningful difference (p=0.000).

Patients who cannot participate in post operative rehabilitation program after arthroscopic ACL reconstruction are prone to complications such as anterior knee pain, knee stiffness, quadriceps weakness and chronic pain.

Studies documented that receiving pain killers in post operative period can decrease not only acute pain but also chronic pain [15]. In 2007, Reabon SS et al. in a similar study on 200 patients showed that patellofemoral complications like anterior knee pain, flexion contracture and CRPS are lower in the group which received celecoxib and they return to athletic activity sooner [16].

Acute postoperative pain may remain as chronic postoperative pain so appropriate management of acute postoperative pain can eliminate chronic pain syndrome [8,9].

Because single drug therapy for pain control has little role in controlling pain so there is more trend toward multi modal pain control regimens like NSAIDS, intraarticular anesthetics, cryotherapy and regional blocks [3-7].

In our study , there were no difference regard to confounding parameters such as age, sex, preoperative activity level and time of operation between case and control groups, so it can be concluded that difference between results (patellofemoral complications, anterior knee pain, quadriceps atrophy, restricted range of motion) are duo to celecoxib in case group.

Acetaminophen with cox2 inhibitors (like celecoxib) has synergistic effect on pain control and on the other hand, although opiates are useful in this manner, but there may be nausea in postoperative period with opioids.

So, it is safe and wise to use combination of acetaminophen and celecoxib before and after ACL reconstruction surgery.