Rationale

Total knee arthroplasty (TKA) is associated with significant pain postoperatively.¹ Poorly controlled pain following TKA can not only lead to impaired mobilization and rehabilitation but also increase the likelihood of complications.² Severity of acute pain is also known to be an independent predictor of chronic postsurgical pain after TKA.³ Ideal perioperative analgesic technique should provide excellent analgesia, limit opioid consumption, and facilitate early mobilization and rehabilitation.

Clinical comment

Broadly, the analgesic options following TKA include pharmacological and nonpharmacological techniques. In clinical practice, these options tend to be used either alone or in combination.

• Systemic options include: (1) opioid‐based intravenous PCA and (2) multimodal oral analgesia, including acetaminophen, nonsteroidal anti‐inflammatory drugs (NSAIDs) +/− opioid analgesics.
  
• Regional options include: (1) local anesthetic infiltration techniques, including periarticular infiltration, intra‐articular infiltration, and infiltration between the popliteal artery and the capsule of knee (IPACK); (2) peripheral nerve blocks (+/− continuous catheter techniques), including femoral nerve block (FNB) or adductor canal block (ACB) +/− sciatic nerve block (SNB); and (3) neuraxial techniques, including continuous epidural analgesia and intrathecal morphine.
  
• Nonpharmacological options include: continuous passive motion (CPM), preoperative exercise, cryotherapy, electrotherapy, including transcutaneous electrical nerve stimulation (TENS), and acupuncture.

Available literature and quality of the evidence

As we included systematic reviews and meta‐analyses of randomized controlled trials (RCTs) for all interventions except the use of cannabis were level I. Only three studies were found with regards to cannabis, all of which were level III or IV.

Findings

NSAIDS

COX‐2 inhibitors are preferred over nonselective NSAIDS because of the lower risk of perioperative bleeding. A meta‐analysis of eight small RCTs showed that the perioperative administration of selective COX‐2 inhibitors reduces postoperative pain, opioid consumption, and postoperative nausea vomiting (PONV) after TKA without increasing the risk of perioperative bleeding.⁶ Furthermore, perioperative use of selective COX‐2 may improve postoperative knee function.⁶

Acetaminophen

Two recent systematic reviews show that intravenous acetaminophen added to multimodal analgesia leads to reduced pain and opioid consumption after total joint arthroplasty with few adverse effects.⁷,⁸ Further, no difference has been observed between oral and intravenous acetaminophen.⁹

Gabapentinoids (gabapentin and pregabalin)

Although one review with meta‐analysis did not find clinically important effect with gabapentin for the management of acute pain following TKA,¹⁰ another review with meta‐analysis observed that it decreases opioid requirements at 24 and 48 hours.¹¹ Small (probably clinically insignificant) analgesic efficacy, antiemetic and opioid‐sparing effects of gabapentinoids need to be balanced against a significant increase in the risk of sedation.

Ketamine

There is limited evidence on the use of ketamine for TKA. Three small RCTs showed that adding intraoperative small‐dose intravenous ketamine infusion to multimodal analgesic regimen decreased morphine consumption and improved early rehabilitation without increasing the incidence of side effects.¹²–¹⁴

Cannabis

As there has been renewed interest in looking at the effect of cannabis on pain and other outcomes in TKA patients, we performed a specific search to identify any such literature. In general, substance abuse increased the risk of complications including infection and prolonged discharge.¹⁵,¹⁶ Another retrospective study using the Medicare database suggests that the risk of revision surgery is significantly increased among cannabis users.¹⁷

Steroids

At least six different groups have reviewed the evidence on use of systemic steroids for TKA.¹⁸–²³ The included studies had marked heterogeneity regarding the type and dose of steroid used. The reviews either show an analgesic benefit of steroid use or no difference in pain compared to control patients. In particular, steroid use was associated with reduced pain at rest and activity and lower opioid use during the first 24 hours after operation. Additionally, patients given perioperative steroids had a lower incidence of nausea and vomiting.¹⁹ Generally, no significant adverse effects were observed in the outcomes, such as superficial or deep infections. However, perioperative steroid use was associated with clinically nonsignificant increase in blood glucose for the first six hours. The analgesic benefits of systemic steroids were more apparent in patients undergoing TKA compared to total hip arthroplasty.¹⁸

Femoral nerve block (FNB)

A Cochrane review observed that FNB provided more effective analgesia than PCA opioid alone with less nausea and vomiting, and it was as effective as epidural analgesia.²⁴ Although continuous FNB can provide superior pain relief and fewer side effects, local infiltration analgesia (LIA) can potentially provide similar outcomes of analgesia with earlier mobilization.²⁵ More recently, another review with meta‐analysis showed that ACB provides equally effective analgesia with early ambulation.²⁶

Intrathecal morphine

A meta‐analysis showed that FNB provides equal postoperative pain control with similar morphine consumption compared with intrathecal morphine following TKA, although there were fewer side effects in the FNB groups.²⁷ Particularly, the incidence of itching in the intrathecal morphine group was higher than in the FNB group.²⁸ Postoperative urinary retention is also a potential concern.²⁹

FNB + SNB

Five different systematic reviews support the analgesic benefits of adding SNB to FNB following TKA. SNB added to FNB reduces postoperative opioid consumption and reduces pain scores after TKA.³⁰–³³ However, SNB is not routinely used in clinical practice, as it interferes with the postoperative assessment of potential nerve injury and impedes early mobilization.³⁴

Periarticular local infiltration analgesia (LIA)

There is significant heterogeneity in the mixture and technique of LIA used across the studies which makes the comparisons with other modalities difficult.³⁵ When compared to placebo, LIA appears to reduce pain scores and opioid consumption in the first 24 hours (but not 48 hours) postoperatively. Another systematic review suggested that intraoperative periarticular but not intra‐articular injection may be helpful in pain control up to 24 hours after TKA.³⁶ Overall, LIA reduces short‐term pain compared to placebo and provides improved early postoperative pain relief compared to FNB.³⁷ Multiple reviews comparing LIA with FNB found that LIA was as effective as FNB in terms of 24‐ to 48‐hour pain scores, total morphine consumption, and range of motion.²⁵,³⁸–⁴⁰ However, two systematic reviews found that single‐injection FNB was associated with reduced pain upon movement compared with single‐injection LIA.⁴¹,⁴²

Intra‐articular local anesthetics

Compared with the placebo group, the single local anesthetic group had a significantly lower pain score at rest, less opioid consumption, and greater range of motion at 24, 48, and 72 hours postoperatively. There were no significant differences in side effects or length of hospital stay.⁴³ Considering other effective treatment modalities that are available, intra‐articular LA is not a popular option.

Adductor canal block (ACB)

• ACB vs. FNB: most studies have found no significant differences in pain scores at rest or mobilization at 24 and 48 hours between ACB group and FNB group. While Dong et al. found no significant differences in the strength of quadriceps and adductors between ACB and FNB groups,⁴⁴ multiple different systematic reviews have shown early sparing of quadriceps strength and enhanced ambulation ability with ACB.⁴⁵–⁵²
  
• ACB vs. LIA: evidence suggests that LIA is more effective than ACB regarding pain control and opioid use following TKA. However, no clear difference has been observed regarding short‐term functional outcomes when the two modalities are compared.⁵³
  
• ACB + LIA: evidence suggests that adding ACB to LIA is more effective than single therapy within the first 48 hours following TKA.⁵⁴,⁵⁵ Combining the two modalities was associated with statistically significant lower pain scores, opioid consumption, and more distance walked on postoperative day 1. These differences were not significant on postoperative day 2.⁵⁶

Epidural analgesia

As peripheral nerve blocks⁵⁷ and LIA⁵⁸ are as effective as epidural analgesia for postoperative pain management in TKA, the role of continuous epidural analgesia is limited considering the higher risk of complications associated with epidural and the common use of anticoagulants for thromboprophylaxis after TKA.

Liposomal bupivacaine (LB)

LB is intended to prolong the action of bupivacaine employed for regional analgesia. It has been shown that LIA with LB is better than placebo for analgesia;⁵⁹ it provides similar pain relief as FNB with decreased opioid requirements,⁶⁰ and with shorter length of hospital stay than FNB.⁶¹ However, considering that other meta‐analyses have shown equivalent analgesia between LIA and FNB (without any LB), its superiority is uncertain.

IPACK

IPACK

Related posts:

The Direct Anterior Approach Patient‐Specific Instrumentation in Total Knee Arthroplasty Management of Glenoid Bone Loss Distal Femur Fractures Periprosthetic Fractures: Knee Lisfranc Injuries

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