Epidural analgesia for pain relief following hip or knee replacement

P T Choi, M Bhandari, J Scott, J Douketis, P T Choi, M Bhandari, J Scott, J Douketis

Abstract

Background: Hip and knee replacement are common operative procedures to improve mobility and quality of life. Adequate pain relief is essential in the postoperative period to enable ambulation and initiation of physiotherapy. Lumbar epidural analgesia is a common modality for pain relief following these procedures. However, there is no systematic review of the evidence comparing the efficacy of epidural analgesia with other postoperative analgesic modalities. As the use of epidural analgesia may delay the initiation of anticoagulant thromboprophylaxis due to the potential risk of epidural hematoma, a synthesis of the evidence is necessary to determine whether or not alternative analgesic modalities are worse, equivalent, or better than epidural analgesia.

Objectives: Our objective is to answer the question: "Is lumbar epidural analgesia more efficacious than systemic analgesia or long-acting spinal analgesia for postoperative pain relief in patients after elective hip or knee replacement?"

Search strategy: MEDLINE, EMBASE, CINAHL, LILACS, and the Cochrane Controlled Trials Register were searched from their inception to June 2001. Reference lists of review articles and included studies were also reviewed for additional citations.

Selection criteria: A study was included if it was a randomized or pseudo randomized controlled clinical trial of patients undergoing hip or knee replacement, in which postoperative lumbar epidural analgesia was compared to other methods for pain relief. Study selection was performed unblinded in duplicate.

Data collection and analysis: Data were collected unblinded in duplicate. Information on the patients, methods, interventions, outcomes (pain relief, postoperative function, length of stay) and adverse events were recorded. Methodological quality was assessed using a validated 5-point scale. Meta-analysis was conducted when sufficient data existed from two or more studies. Heterogeneity testing was performed using the Breslow-Day method. The fixed effects model was used unless heterogeneity was present, in which case, a random effects model was used. Continuous data were summarized as weighted mean differences (WMD) or standardized mean differences (SMD) with 95% confidence intervals (CI). Dichotomous data were summarized as odds ratios (OR) and numbers-needed-to-treat (NNT) or numbers-needed-to-harm (NNH) with their respective 95% CI. Graphical representation of continuous data used the MetaView program.

Main results: In the first four to six hours after surgery, patients receiving epidural analgesia had less pain at rest, based on visual analog scores (VAS), than patients receiving systemic analgesia (SMD -0.77; 95% CI -1.24 to -0.31). This effect was not statistically significant by 18 to 24 hours (SMD -0.29; 95% CI -0.73 to 0.16). These observations were based only on studies evaluating populations consisting of total knee replacements alone or mixed populations of total hip or total knee replacements. For pain relief with movement after surgery, patients receiving epidural analgesia reported lower pain scores than patients receiving systemic analgesia in all four studies examining these outcomes. The choice of epidural agents may also influence the extent to which epidural analgesia differs from systemic analgesia. The differences between epidural analgesia and systemic analgesia in the frequency of nausea and vomiting (OR 0.95; 95% CI 0.60 to 1.49) or depression of breathing (OR 1.07; 95% CI 0.45 to 2.54) were not statistically significant. Sedation occurred less frequently with epidural analgesia (OR 0.30; 95% CI 0.09 to 0.97) with a number-needed-to-harm of 7.7 (95% CI 3.5 to 42.0) patients for the systemic analgesia group. Retention of urine (OR 3.50, 95% CI 1.63 to 7.51; NNH 4.5, 95% CI 2.3 to 12.2), itching (OR 4.74, 95% CI 1.76 to 12.78; NNH 6.8, 95% CI 4.4 to 15.8), and low blood pressure (OR 2.78, 95% CI 1.15 to 6.72; NNH 6.7, 95% CI 3.5 to 103) were more frequent with epidural analgesia compared to systemic analgesia. There were insufficient numbers to draw conclusions on the edural analgesia compared to systemic analgesia. There were insufficient numbers to draw conclusions on the effect of epidural analgesia on serious postoperative complications, functional outcomes, or length of hospital stay.

Reviewer's conclusions: Epidural analgesia may be useful for postoperative pain relief following major lower limb joint replacements. However, the benefits may be limited to the early (four to six hours) postoperative period. An epidural infusion of local anesthetic or local anesthetic-narcotic mixture may be better than epidural narcotic alone. The magnitude of pain relief must be weighed against the frequency of adverse events. The current evidence is insufficient to draw conclusions on the frequency of rare complications from epidural analgesia, postoperative morbidity or mortality, functional outcomes, or length of hospital stay.

Conflict of interest statement

The authors of this Cochrane review have never received any honoraria or consulting fees from pharmaceutical companies that produce anticoagulants or analgesics. The authors do not have any commercial interest in anticoagulant thromboprophylaxis or postoperative analgesia and they do not hold any patents related to these fields.

Figures

1.1. Analysis
1.1. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 1 Early (4‐6 hours) postoperative pain relief at rest.
1.2. Analysis
1.2. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 2 Late (18‐24 hours) postoperative pain relief at rest.
1.3. Analysis
1.3. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 3 Early (4‐6 hours) postoperative dynamic pain relief.
1.4. Analysis
1.4. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 4 Nausea or vomiting.
1.5. Analysis
1.5. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 5 Sedation.
1.6. Analysis
1.6. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 6 Urinary retention.
1.7. Analysis
1.7. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 7 Pruritis.
1.8. Analysis
1.8. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 8 Respiratory depression.
1.9. Analysis
1.9. Analysis
Comparison 1 Epidural analgesia versus systemic analgesia, Outcome 9 Hypotension.

References

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Grace 1995 {published data only}
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Kampe 1999 {published data only}
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Kohro 1998 {published data only}
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Kopacz 1999 {published data only}
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Lauretti 1999a {published data only}
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Lauretti 1999b {published data only}
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Markel 1997 {published data only}
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Mauerhan 1997 {published data only}
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McBeath 1995 {published data only}
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Mitchell 1991 {published data only}
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Modig 1976 {published data only}
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Mollmann 1999 {published data only}
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Murphy 1984 {published data only}
    1. Murphy DF, MacGrath P, Stritch M. Postoperative analgesia in hip surgery. A controlled comparison of epidural buprenorphine with intramuscular morphine. Anaesthesia 1984;39(2):181‐3.
Nielsen 1990 {published data only}
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Nielson 1990 {published data only}
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Pati 1994 {published data only}
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Segstro 1991 {published data only}
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Sharrock 1992 {published data only}
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Silvasti 2000 {published data only}
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Tsueda 1998 {published data only}
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Weir 1998 {published data only}
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