Pain Management in Foot and Ankle Trauma
Phillip Ross
Michael C. Harrington
Dana Perim
Injuries to the foot and ankle are often associated with motor vehicle collisions, industrial accidents, or falls from great heights. While injuries can be sometimes minor, they can quickly lead to impaired function of the lower extremity. In motor vehicle collisions, the lower extremities are still widely unprotected despite the effectiveness in airbags that decrease the blunt trauma to the victim’s vital structures.1,2 The ankle and foot account for nearly 33% of injuries in individuals involved in a car accident with an abbreviated injury scale (AIS) greater than 2.3 It is estimated that 8% to 12% of all injuries in moderate or severe frontal end vehicular crashes are sustained by the foot and ankle.4,5,6 In addition, the foot is one of the most frequently injured extremities in industrial accidents.7 Injuries to the foot are unique compared to other body extremities. The bony framework is closed in space surrounded by an abundance of soft tissue making injuries to this extremity particularly susceptible to swelling and pain.
In treating the patient, it is crucial to involve them in the pain assessment. Using a pain scale can help provide clarity to an often vague and varied patient interpretation.8,9 Examples of pain scales include numerical (0-10), descriptive (excellent-poor), faces (smiling-sad), and patient behavior (grimacing, vocalizations, resistance to care) which can be a helpful assessment tool for the cognitively impaired or the pediatric patient population. Orthopedic procedures can be the most painful surgeries performed, and injuries sustained that require orthopedic intervention can be devastating. Clear and transparent communication with the patient is key when discussing appropriate pain management goals in order to optimize outcomes. In this section, we will focus on the preoperative, intraoperative, and postoperative pain management therapies.
PREOPERATIVE PAIN MANAGEMENT THERAPIES
Nonsteroidal Anti-inflammatory Drugs
Use of nonsteroidal anti-inflammatory drugs (NSAIDs) in the preoperative setting is typically contraindicated. NSAIDs exhibit antiplatelet activity by inhibiting cyclooxygenase.10 In fact, indobufen and flurbiprofen have demonstrated to be effective antithrombotic agents in patients with coronary syndromes.11,12 Typically, nonselective NSAIDs are held before surgery as their antiplatelet effect can increase the risk of intraoperative and postoperative bleeding. In addition, NSAIDs should not be given to certain patients as it has been reported that NSAIDs can increase the risk of precipitating heart failure or acute renal failure.13 Patients at risk for these conditions would be those that have preexisting congestive heart failure, renal dysfunction, or liver disease with ascites.14 Celecoxib, however, does not seem to have any effect on platelet function, and could be considered as a potential agent for analgesia in the preoperative
setting for patients with foot and ankle trauma. While preemptive celecoxib has been shown to be helpful in mitigating postoperative pain in various orthopedic procedures,15,16 its role as a preoperative analgesic still needs further study.
setting for patients with foot and ankle trauma. While preemptive celecoxib has been shown to be helpful in mitigating postoperative pain in various orthopedic procedures,15,16 its role as a preoperative analgesic still needs further study.
Acetaminophen
Acetaminophen’s mechanism of action on pain control is not well understood. However, it can be used in the preoperative setting for effective analgesia. Sometimes, 1 g of acetaminophen can be used preemptively in the analgesia regimen.17 Acetaminophen can increase the International Normalized Ratio (INR) in patients who are already taking warfarin.18 Use of acetaminophen in this patient population should be monitored closely as an increased INR can complicate surgery. In addition, patients with liver dysfunction, chronic alcohol abusers, or those who take enzyme-inducing medications such as rifampin or carbamazepine can have increased risk of developing hepatotoxicity from acetaminophen. Therefore, its use is generally contraindicated in patients with pre-existing hepatic dysfunction. A thorough medical and medicinal history is critical to avoid these adverse outcomes.
GABA Agents
GABA agents decrease pain by reducing the hyperexcitability of voltage-dependent calcium channels in activated neurons. While little has been documented about the effectiveness of GABA agents in the preoperative setting for patients with foot and ankle trauma, preemptive GABA agents have been shown to reduce the amount of opioid consumption postoperatively in other orthopedic surgeries. However, preoperative GABA administration was shown to reduce the use of postoperative opioid use in other orthopedic procedures. A study by Montazeri et al demonstrated that administration of preoperative gabapentin was able to decrease the postoperative consumption of opioids in patients undergoing knee arthroscopy. The study divided patients into 2 groups of 35 patients each. The first group received a placebo while the second group received 300 mg of gabapentin 2 hours before the induction of anesthesia. The authors found that there was significantly lower visual analog scores at 2, 4, 12, and 24 hours after surgery as well as a significant decrease in the amount of morphine consumed after surgery.19 While further investigation is warranted with regard to its application to patients with foot trauma, GABA agents could have an effective role in preoperative pain control.
Opioids
Many patients may be using opioids for pain control for other pain related issues prior to surgery. For a patient who is found to be consuming opioids before surgery, prescribing opioid analgesia as needed may not adequately control the patient’s pain. In addition, these patients may require higher doses of opioids to control their pain compared to those who are opioid naive. There are several effective opioids to choose from. The gold standard for opioid analgesia is morphine. It is available in multiple forms for ease of administration. These include liquids, suppositories, injectables, and immediate and long-acting tablets. A drawback to the use of morphine is the production of morphine-6-glucuronide, a metabolite that is a more potent analgesic than morphine itself. Care must be taken when administering morphine in the elderly or those with impaired renal clearance, as accumulation of the metabolite can cause sedation, confusion, and respiratory depression.20
Hydromorphone has become increasingly popular because of its versatility and decreased incidence of side effects when used in the elderly or those with renal impairment. It also has multiple forms of administration and can be given orally, intramuscularly, intravenously, and subcutaneously. However, a drawback to using hydromorphone is its poor bioavailability; 1 mg of parenteral hydromorphone is equipotent to 4 mg of oral hydromorphone.20
Oxycodone is another opioid option. It is also safe to use in patients with renal insufficiency, making it a popular drug of choice for pain control. Multiple forms are available and include liquids and immediate and sustained released tablets. In addition, oxycodone-acetaminophen combinations are available. Typically, combinations that include a low dose of acetaminophen, such as 325 mg per tablet, are effective and avoid the risk of developing acetaminophen toxicity.20
Tramadol has also become increasingly popular and is thought to have a dual mechanism of action; one being from tramadol itself, and the other from its metabolite. First, tramadol inhibits the reuptake of norepinephrine and serotonin. The metabolite that is produced, desmethyltramadol, binds to the mu-opioid receptor. Two main strengths of tramadol exist: 50 mg tablet and 37.5 mg tablet. There is also a sustained release tablet available in 100, 200, and 300 mg tablets. To avoid side effects of sedation, nausea, and dizziness, slow upward titrations of the drug is helpful. In addition, it is important to identify patients that are also taking certain antidepressant medications, as the combination of the drugs may cause seizures or serotonin syndrome.20
Opioids are known to have common side effects but can be effectively mitigated if recognized early. Antiemetics such as metoclopramide and promethazine can treat nausea and vomiting often associated with opioid use. In addition, lowering the dose, changing the route of administration, or increasing the time of infusion can be effective. Constipation is another common side effect, and patients should be started on a laxative that is both a stool softener and a stimulant. Senokot-S, MiraLax, and lactulose can be effective forms of treatment.20
As a cautionary note, patients with traumatic injuries to the foot and ankle can be at risk of developing compartment syndrome. Opioids should be given judiciously to these individuals as excessive amounts of opioids can quickly alter the patient’s mentation, making a thorough extremity examination and evaluation difficult. Using lower doses of opioids, increasing the interval between doses, or implementing an alternative analgesia, such as Toradol, can provide the patient with pain relief while still allowing them to fully participate in the neurovascular examination.
Rest, Ice, and Elevation
Rest, ice, and elevation are well known to most people as the basic first steps for pain relief for minor strains and sprains in an extremity. Even in traumatic injuries, these same simple maneuvers can have profound effects on alleviating pain. After a trauma, inflammation quickly develops at the injury site. This inflammation can stretch the soft tissue which in turn causes pain. Resting, icing, and elevating the extremity can all help decrease the amount of inflammation, and thus, alleviate pain. Resting an extremity can decrease its metabolic demands. By doing so, blood flow is decreased which can lead to decreased swelling of the tissues. Ice acts as a form of cryotherapy.21 Application of ice to the extremity will cool it. By cooling the tissues, it further decreases metabolic demand and induces vasoconstriction of the vessels, thereby decreasing inflammation. In addition, application of the ice can increase pain threshold levels at nerve synapses as well as increasing the latency of or nerve conduction, which can induce analgesia.21 Elevation can allow gravity to increase inflammatory exudate flow through the lymph vessels allowing excess fluid to drain out of the soft tissues, helping to reduce the swelling and pain in the extremity.21
PERIOPERATIVE PAIN MANAGEMENT THERAPIES
Perioperative pain control for patients undergoing orthopedic surgery is complex, requiring multimodal therapies to achieve adequate analgesia.22 Pain from surgery of the foot and ankle can be particularly difficult to manage, as demonstrated by Gerbershagen whose study showed patients undergoing calcaneal open reduction internal fixation to have the highest numerical pain scale rating of all surgeries surveyed.23
Management of pain in the intraoperative setting is imperative to ensuring patients continue to remain comfortable in the postoperative setting. Perioperative pain management, particularly with multimodal therapies, has demonstrated shorter lengths of stay,24 and with the increased use of peripheral nerve blocks, many procedures can now be accomplished on an outpatient basis.25
There are several intraoperative factors cited as the primary cause of increased pain in the immediate postoperative period. These factors include inflammatory mediators released at the wound site and direct damage to peripheral neurons. The inflammatory mediators augment
the local peripheral nerves, leading to increased nociceptive sensitivity. However, it is not only the peripheral nerves that can influence the patient’s sensation pain. The surge of afferent stimulation throughout surgery modulates the neurons of the CNS to become hyperexcitable in a process called central sensitization.26 The increased excitability is due to changes in a cell’s membrane excitability, as well as reduced nociceptive signal inhibition. Central sensitization leads to unprovoked pain at rest, as well as increased sensitivity to inputs which are not normally nociceptive in the postoperative period.27 These findings suggest that management of pain intraoperatively could lead to reduced discomfort in the postoperative period.
the local peripheral nerves, leading to increased nociceptive sensitivity. However, it is not only the peripheral nerves that can influence the patient’s sensation pain. The surge of afferent stimulation throughout surgery modulates the neurons of the CNS to become hyperexcitable in a process called central sensitization.26 The increased excitability is due to changes in a cell’s membrane excitability, as well as reduced nociceptive signal inhibition. Central sensitization leads to unprovoked pain at rest, as well as increased sensitivity to inputs which are not normally nociceptive in the postoperative period.27 These findings suggest that management of pain intraoperatively could lead to reduced discomfort in the postoperative period.
