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11 Articles in Volume 14, Issue #4
Recognizing and Treating Concussions Related to Sports Injuries
CDC Initiative: Concussion in Sports and Play
Pain Management After ACL Surgery
Risk Assessment in the Digital Age: Developing Meaningful Screening Tools for Opioid Prescribers
Testosterone Replacement: Essential in Pain Management
Why Is There Hydromorphone In My Patient’s Urine?
Benzodiazepines in Pain Practice: Necessary But Troubling
Commentary: Risk Assessment in the Digital Age
Zohydro Debate: Drug Hysteria or True Concern
Benefit of Long-acting Versus Short-acting Opioids?
Epidural Steroid Injections, Coping Skills, Medical Marijuana

Pain Management After ACL Surgery

Women more likely to tear the anterior cruciate ligament than men, especially younger athletes.

Knee injuries are the most common musculoskeletal complaint reported to health care providers. The number of patients visiting their physicians for knee symptoms and complaints has risen dramatically over the past decade, from approximately 12.5 million per year in 2000 to over 18.6 million in 2010.1

The knee is a complex joint with multiple components, making it vulnerable to injury. As a hinge joint, the knee is held together by two pairs of ligaments, which include ligaments on each side of the knee, known as collateral ligaments, and two ligaments inside the knee, known as the posterior cruciate ligament (PCL) and anterior cruciate ligament (ACL). These ligaments both hold the knee bones together and help control the movements of the knee.

One of the most common injuries to the knee is an ACL sprain or tear (Figure 1, above). This most often occurs during vigorous physical exercises, automobile accidents, and work injuries.2 Athletes who participate in high demand sports like soccer, football, and basketball (rapid stopping, changing directions, indirect contact from a hit) are more likely to injure their ACL (Table 1). Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes.1

Signs and Symptoms

The signs and symptoms of an ACL injury or tear are severe pain and swelling (sometime accompanied by a popping sound and buckling of the knee), making it difficult for the patient to move or walk. If untreated, the swelling and pain may resolve on its own, however, the knee will probably remain unstable and the patient risks causing further damage to the cushioning cartilage (meniscus) of the knee. Other symptoms include:

  • Loss of full range of motion
  • Tenderness along the joint line
  • Discomfort while walking

The diagnosis of an ACL injury can be confirmed by physical examination, which includes comparing the injured to the uninjured knee to help determine the state of the ACL. Although magnetic resonance imaging (MRI) creates better images of soft tissues like the ACL, according to the American Association of Orthopedic Surgeons, it is usually not required to make the diagnosis of a torn ACL.1

Treatment

ACL injuries can be managed non-operatively or operatively. According to 2 new prospective studies (MOON and KANON), both ACL reconstruction and rehabilitation treatment strategies “are likely to yield high-quality, low-cost care when performed for the appropriate candidates.”3 For patients who are not good candidates for surgical repair (elderly, non-active older person), nonsurgical treatment may be effective. If the overall stability of the knee is intact, bracing and physical therapy may be recommended—and the patients is given specific exercises to strengthen the muscles around the knee and help restore the function of the knee.

If a patient opts to treat a complete ACL rupture non-operatively, it is important for them to understand the possible consequences. The ACL deficient knee may place the patient at increased risk for further injury such as meniscal tears, chronic pain, and decreased level of activity. Fewer than 50% of patients treated non-operatively return to their pre-injury level of sports participation.4 A number of studies suggest that the ACL injury alone, regardless of the treatment, predisposes the patient to developing osteoarthritis.5

Active, younger patients, and high-level athletes often opt for surgical reconstruction. The decision to have surgery is based upon several factors including age, level of activity, functional demands, and the presence of associated injuries (meniscal tear.) Patients with associated injuries must have surgical reconstruction. ACL reconstruction is generally performed with arthroscopy using a graft to replace the ruptured ACL. The 3 most common grafts include the patellar tendon, the allograft, and the semitendonosus graft. While each surgeon has their own preference, no particular graft has demonstrated superior functional outcome, and each has it’s own advantages and disadvantages.6

Pain Management

Immediately after injury and surgery, when indicated, the patient will experience pain and swelling around the knee. There are a number of techniques that can be used to reduce the pain.

Icing and Compression

The most effective technique to adopt is R.I.C.E. This is an acronym for Rest, Ice, Compression, and Elevation. Icing reduces the flow of blood from vessels surrounding the knee and compression decrease the fluid hemorrhaging resulting from the surgery.7 The technique has proven to be more effective and applicable immediately after the ACL surgery. It helps to reduce pain, facilitate recovery, and improve knee range of motion.

Weight Bearing

After the ACL surgery, the patient experiences a lot of pain when they apply weight on the leg. Depending on the type of reconstructive surgery, the patient is required to use crutches for a specified period. Walking with some weight on the repaired leg reduces atrophy, maintains proper blood circulation, and maintains knee flexibility. Lengthening the leg by use of full weight bearing technique also helps the knee to recover more quickly. When using the weight bearing technique patients are advised to use walking crutches to prevent the pain that results from knee strain.2

Bracing

Almost all surgeons who perform ACL surgery provide the patients with a brace that is intended to limit knee movement during the patient’s recovery from the surgery. The brace can also be used during sports to prevent any pain that might be caused during vigorous physical movements. Bracing also prevents subsequent knee injury that would cause a lot of pain on the operated part of the knee. According to the surgeons, bracing improves the outcome of ACL surgery by reducing pain and graft strain.8

Elevation

It is advisable to elevate the leg on which ACL surgery has been performed. When the patient is lying down or sleeping, the leg should be lifted higher than the hips. This can be done by putting a couple of pillows under the leg to prop it up. This technique of elevating the leg will reduce the pain on the patient’s knee. Figure 2, page 52, illustrates the proper position the leg should be elevated to avoid pain on the knee when lying down or sleeping.7

 

Physical Exercises

Again, the patient is encouraged by the physical therapist to exercise to increase walking stability and speed the healing process. During the first week after the surgery the therapist advises the patient on the kind of gentle exercises that the patient should undergo to enhance movement of the knee and reduce pain in case of full movement. The exercises may focus on restoring the strength of the quadriceps and the therapists might adopt an electrical stimulation technique to quicken the recovery from ACL surgery.

Pharmaceutical Pain Management

It is imperative to control postoperative pain. Pain can inhibit movement, thereby hampering rehabilitation, physical therapy, and recovery. The most common medications used to manage pain are a combination of non-steroidal anti-inflammatory drugs (NSAIDs), local anesthetics, and opioids.9

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

NSAIDs are administered to patients after ACL surgery to help reduce swelling and manage both mild to moderate pain. The most commonly prescribed NSAIDs include ibuprofen, naproxen, and aspirin. NSAIDs stop the body from producing prostaglandin, making it an effective pain medication that enables the patients to recover quickly.10

Oral NSAIDs are associated with a dose-dependent risk of gastrointestinal, cardiovascular, hematologic, hepatic, and renal adverse events (AEs).11 The risk of gastrointestinal side effects can be lessened by using a cyclooxygenase (COX)-2 selective NSAID (Celebrex) or by combining non-
selective NSAIDs with proton pump inhibitors.11 Concerns about cardiovascular events with COX-2 selective NSAIDs have limited the use of this class of medications in patients who have cardiovascular risk factors.12

Local and Regional Anesthetics

Local infiltration at the incision site, as well as intra-articular and peri-articular injections of local anesthetic mixtures are often used during and after ACL surgery as part of the pain management protocol. When the local anesthetics are injected, they block the pain signals that send pain messages to the brain. On the other hand, regional anesthetics are more effective in pain management during and after an ACL surgery. This is because the medication relieves pain for several hours after the surgery.13

Bupivacaine Infusion

The increasing trend of ACL surgery has stimulated the development of intra-articular bupivacaine infusion as a method of managing pain. Bupivacaine is a local anaesthetic that is used during medical procedures and is very effective in controlling postoperative pain. This method has been very efficient and is safe in the outpatient setting since it makes use of several devices that help in pain management. Infusion pumps that dispense bupivacaine to the fat pad after an ACL surgery is used.14 The femoral sheath is infiltrated and blocks the femoral nerve and this aids in relieving the initial pain after the ACL surgery. A recent survey of patients who have undergone ACL surgery found that blocking of the femoral nerve is very beneficial in managing pain after surgery.15

The use of bupivacaine infusion has also been shown to result in less need for postoperative opioid therapy. In studies of patients undergoing total knee arthroplasty, injections of a local anesthetic mixture (ropivacaine with epinephrine and ketorolac) combined with patient-controlled analgesia (PCA) morphine significantly reduced opioid consumption over 48 hours postoperatively compared to patient receiving morphine alone (P=0.003). The local anesthetic group also reported lower mean visual analog pain scores (VAS) at rest (P=0.01) and during exercise on postoperative day (POD) 1 (P=0.008) and on POD 2 (P=0.02), as well as less postoperative nausea (P=0.011) compared to the control group.16

Intra-articular injection of ropivacaine with morphine and ropivacaine alone, however, did not significantly affect pain scores or narcotic consumption. Similarly, ropivacaine injection—when compared with placebo injection—had no significant effects on pain scores or narcotic consumption.17,18

These local anesthetic injection mixtures can also be administered periarticularly. Periarticular injection of a
steroid-containing local anesthetic mixture (bupivacaine, morphine, epinephrine, and methylprednisolone) resulted in lower pain scores and higher patient satisfaction (P=0.05 for both), in addition to lower opioid consumption when compared to patients receiving PCA with or without femoral nerve block (FNB). Also, patients receiving the injections achieved active straight leg raise sooner and had a shorter mean length of stay (LOS).19

Periarticular injection of bupivacaine and epinephrine with triamcinolone acetonide was compared with bupivacaine and epinephrine alone. Pain scores were lower with the steroid-containing injection (P=0.02) along with decreased cumulative morphine consumption (P=0.03). The steroid-containing injection also resulted in a shorter LOS (P=0.02) and achieved greater range of motion (ROM) on POD 2 up to 6 months postoperatively (P=0.01).20

 

Nerve Blocks

A less localized method of multimodal analgesia is the placement of a peripheral nerve block, with the most common site being the femoral nerve. This type of medication is more appropriate to be administered immediately after carrying out the ACL surgery. It reduces the amount of opioid medication, hence, reducing the side effects of opioids such as vomiting, nausea, drowsiness, and itching. Femoral nerve block is not only used as pain management medication after ACL surgery but it can also be used during the surgery. It is administered during the surgery because it makes the patient feel sleepy, comfortable, and relaxed.21

In patients undergoing athroplasty, a continuous ropivacaine FNB with a fentanyl PCA was compared with PCA alone. The control had a higher total opioid consumption (P<0.001) and required more PCA dose increases compared to the FNB group. Those with an FNB, however, experienced lower ROM in both flexion and extension (P<0.006 and P<0.04, respectively).22

Similarly, when levobupivacaine FNB with patient-controlled epidural analgesia (PCEA) was compared with PCEA alone, the FNB group had lower VAS scores from 0 to 24 hours (P<0.001), and 24 to 48 hours (P=0.025). Patients receiving FNB also experienced significantly less nausea (P <0.001), vomiting (P=0.033), and demand for rescue antiemetics (P=0.037) in the 0- to 6-hour period, as well as required significantly less meperidine (P=0.005).23

Opioids Analgesics

Opioids analgesics are the most commonly used medicines for managing both moderate and severe pain following ACL surgery. They bind to the opioid receptors in the brain, gastrointestinal tract, and spinal cord. After they are completely attached to the opioid receptors, they obstruct the transmission of pain to the brain. The medication can be administered either orally or through PCA devices.7

The most commonly practiced method for analgesia is a combination of NSAIDs and opioids, and while this has proven effective, the inclusion of opioids does predispose the patient to numerous side effects including nausea, vomiting, pruritus, sedation, constipation, and urinary retention. In a retrospective study, investigators found that constipation (P<0.0001), emesis (P<0.001), and confusion (P<0.01) are associated with an increased LOS in patients receiving opioids following orthopedic surgery. Nausea and vomiting occurred in 36.1% of patients, constipation in 6.5%, and emesis in 3.7% of patients, with more than half of patients experiencing at least one adverse effect.24 In light of these adverse effects, many of the authors in this review have sought reduction in opioid consumption as a primary outcome measure by which to gauge the efficacy of their respective pain management protocols. Despite the effectiveness of this traditional analgesia combination, the addition of other non-opioid pharmaceutical agents has been proven to be more effective than NSAIDs and opioids alone.

Alternative Methods

After the surgery, doctors make every effort to control the pain and there are alternative methods that clincians use to manage pain. The alternative methods have proved effective because they are combined approaches that are tailored according to each patient. The alternative methods are listed below.

Transcutaneous Electrical Nerve Stimulation

The transcutaneous electrical nerve stimulation (TENS) is a special devise that transmits low-level electrical charges into the area that is in pain. It has a small battery powered machine that is connected to the electrodes by a pair of wires. The electrodes are connected to the area in pain, which in this case is the knee, and current travels through the skin along the nerve fibers causing a tingling sensation.13 Studies conducted have shown that TENS is effective in managing pain after an ACL surgery. This method is generally considered safe and a routine use is recommended to the patients. TENS works by forcing the nerve cells in the knee to release endorphins causing the patient to feel less pain. TENS also works within the brain, changing the way the brain perceives pain.13

Continuous Passive Motion

Continuous passive motion is used to flex and extends the knee joint to improve ROM after the ACL surgery. Continuous passive motion (CPM) is a method in which the knee joint is moved in a mechanical splint to prevent stiffness and increase motion.25 Through the CPM machine the joint moves without any extra effort. Immobilization is the main cause of pain after an ACL surgery so early motion is needed to ease pain to many patients. CPM enhances the mobility and circulation within the knee joint, discourages the formation of a scar tissue, and prevents shortening of the knee muscles that surround the knee joint.15

Acupuncture

The World Health Organization has endorsed acupuncture in relieving pain after an ACL surgery. This is because several case studies on this method have shown that it relieves pain in an effective manner. Acupuncture is effective in reducing intensified knee pain after surgery. Needles are placed in the skin that contains many nerve endings that feed the muscles like the knee. The procedure is performed for 30 minutes and swelling and pain is relieved. There is also a feeling of relaxation after the acupuncture procedure because endorphins are released.26 While the AAOS does not endorse the use of acupuncture, it is an effective treatment.

Supplements

Clinicians should ask their patients about what supplements they are taking, especially pain-relieving agents. A thorough patient history is necessary to rule out potential drug-drug interactions or adverse side effects.

Omega-3 Fatty Acids

One supplement that is endorsed by the AAOS is omega-3 fatty actid. After ACL surgery, controlling inflammation is very important in reducing pain. Omega-3 fatty acids that are found in fish oil, cod liver oil, and flaxseed oil have properties that are anti-inflammatory. The fatty acids, including the decosahexaenoic acid and aicosapentaeonic acid, helps to diminish pain and inflammation. Adding omega-3 fatty acids in the postoperative diet is important because it will help ease knee soreness and pain that is caused by ACL surgery.27

Summary

An ACL injury is a serious health issue and a common injury that requires surgery. Once the ACL repair is done, patients often suffer from pain and inflammation. In the past, ice packs were the only cold treatment techniques that were available to help in reducing inflammation and pain management. However, recently the trend has changed and there are now better solutions for managing pain. The techniques, medications, and supplements that have been discussed here are convenient and have been used by many people who have undergone ACL surgery—with positive results. Even so, scientists continue to carrying out research to come up with new techniques and method to improve the management of pain after ACL surgery.

Last updated on: May 8, 2014
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