Postoperative Pain Relief After Knee and Hip Replacement: A Review

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In 2010, an estimated 50 million American adults were diagnosed with some form of arthritis, with osteoarthritis (OA) being the most common.1 Concurrent with the increasing diagnosis of OA, the demand for total joint arthroplasty (TJA) has also risen steadily over the past decade. In 2004, there were a reported 454,652 total knee arthroplasties (TKAs) and 232,857 total hip arthroplasties (THAs) performed primarily for the treatment of arthritis.1 In the past, many patients have elected not to undergo lower extremity arthroplasty procedures due to the fear of severe postoperative pain and prolonged periods of rehabilitation. Fortunately, in recent years, our understanding of how to properly manage postoperative pain has grown immensely.2-7

There exist numerous protocols for the management of postoperative pain in patients undergoing elective lower extremity arthroplasty (ELEA). In this article, we review a number of pain management methods to determine which method is most efficacious in reducing postoperative pain, length of hospital stay (LOS), and effectiveness of rehabilitation.

Noninvasive Pharmaceutical Management
The most commonly used pharmaceuticals for postoperative pain management are some combination of nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics. A number of other pharmaceutical agents have been used as adjuncts to NSAIDs and opioids, including propacetamol, acetaminophen, gabapentin, duloxetine (Cymbalta), and the cyclooxygenase (COX)-2 inhibitor celecoxib (Celebrex). We reviewed 6 studies illustrating the efficacy of these agents in managing postoperative pain following ELEA. The results of the studies are summarized in Table 1.

Table 1. Noninvasive Pharmaceutical Management Studies

Propacetamol is the more soluble pro-drug of paracetamol (acetaminophen), which is given intravenously. When compared to intravenous (IV) ketorolac, IV propacetamol resulted in a similarly shorter time to onset of analgesia versus control.8 More recently, IV propacetamol and IV acetaminophen were compared to placebo. Both acetaminophen and propacetamol resulted in both higher pain relief scores (P<0.05) and lower morphine consumption (P<0.01) than placebo over a 6-hour period and continuing over the 24-hour study interval. Patients’ global evaluations of satisfaction with treatment after the initial dose and at 24 hours were higher for both acetaminophen and propacetamol (P<0.01). Patients receiving acetaminophen and placebo, however, experienced fewer adverse effects compared with propacetamol (P<0.05).9

Gabapentin, a drug traditionally used for the relief of neuropathic pain, was compared in variable doses to placebo in relieving postoperative pain. Gabapentin resulted in less total patient-controlled analgesia (PCA) morphine use over 48 hours postoperatively (P<0.05), better active knee flexion on postoperative days (PODs) 2 and 3 (P<0.05 for both), and less pruritus (P<0.05) than placebo.10

Duloxetine, a serotonin-norepinephrine reuptake inhibitor, has also been administered to manage postoperative pain. Duloxetine combined with traditional opioid analgesia was compared to placebo in managing postoperative pain. Duloxetine treatment resulted in lower morphine consumption in the first 24 hours postoperatively than placebo (P=0.017).11

Selective COX-2 inhibitors such as celecoxib have classically been used in postoperative pain management. Celecoxib, when compared with IV PCA alone, resulted in improved visual assessment scale (VAS) scores over a 72-hour period (P=0.02), and higher active range of motion (ROM) over 72 hours (P=0.004). Also, opioid requirements were lower in the celecoxib-treated group by 40% (P=0.03).12

Periarticular and Intra-Articular Injections
Another multimodal approach to managing postoperative pain following ELEA involves the use of local anesthetic injection mixtures containing a variety of agents including corticosteroids, opioids, epinephrine, and clonidine. When periarticular injections of a local anesthetic mixture (ropivacaine with epinephrine and ketorolac) combined with PCA morphine were compared with morphine alone, the local anesthetic mixture significantly reduced opioid consumption over 48 hours postoperatively (P=0.003). The local anesthetic group also reported lower mean VAS pain scores at rest (P=0.01) and during exercise on 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.13

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.14,15

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 LOS.16

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 ROM on POD 2 up to 6 months postoperatively (P=0.01).17

Peripheral Femoral Nerve Block
A less localized method of multimodal analgesia is the placement of a peripheral nerve block, with the most common site being the femoral nerve. 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).18

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 in the 0- to 6-hour period (P=0.005).19

First published on: December 1, 2012