Postoperative Pain Management in Orthopaedics

1. Assessment of Postoperative Pain

• The Numeric Rating Scale (NRS) or Visual Analogue Scale (VAS) should be used and documented periodically; The Joint Commission mandates a documented pain score with an acceptable discharge threshold.
• Staff estimation of pain is unreliable - inexperienced nurses tend to overestimate, experienced nurses tend to underestimate; patient self-report is the gold standard.
• Signs such as tachycardia, hypertension, sweating, or PONV may indicate pain but their absence does not exclude it.
• In a haemodynamically unstable (e.g. hypovolaemic) patient, assess carefully before giving analgesics that may precipitate hypotension through vasodilation.

Barash Clinical Anesthesia 9e, p.4565-4566

2. Principles of Multimodal Analgesia

Campbell's Operative Orthopaedics 15th Ed 2026; Morgan & Mikhail's Clinical Anesthesiology 7e, p.2117

3. Individual Drug Classes

A. NSAIDs and COX-2 Inhibitors

• NSAIDs reduce postoperative pain intensity, decrease opioid consumption, and reduce opioid-related side effects (PONV, sedation, urinary retention).
• Non-selective NSAIDs (naproxen, ibuprofen, diclofenac) inhibit both COX-1 and COX-2. Selective COX-2 inhibitors (celecoxib) reduce platelet dysfunction and GI bleeding risk but preserve renal concerns.
• IV ketorolac and IV diclofenac are well-validated for acute postoperative pain.
• Cautions: active peptic ulcer, bleeding risk, cardiovascular disease, CKD, and hepatic impairment.
• Bone healing concern: Earlier concerns about NSAIDs impairing bone healing have not been confirmed in high-quality studies (meta-analysis of observational studies found no correlation when only high-quality studies were analysed).

Miller's Anesthesia 10e, p.10023-10024; Morgan & Mikhail 7e, p.2117

B. Acetaminophen (Paracetamol)

• Can be given orally, rectally, or intravenously.
• Analgesic effect is ~20-30% less than NSAIDs, but has a safer pharmacological profile.
• Significantly reduces pain intensity and spares opioid consumption after orthopaedic and abdominal surgery specifically.
• Most effective when combined with NSAIDs (additive effect).
• Allows NSAIDs to be reserved for breakthrough pain, limiting NSAID-related side effects.

Morgan & Mikhail 7e, p.2117

C. Opioids

• Remain a cornerstone for managing surgical pain, especially for transitional phase from parenteral to oral analgesia.
• Common agents: morphine, fentanyl, hydromorphone, oxycodone, hydrocodone.
• Patient-Controlled Analgesia (PCA) provides better pain control, greater patient satisfaction, and fewer side effects vs. nurse-administered PRN dosing. PCA can be used in children as young as 5 years.
  • Morphine PCA: interval dose 20 mcg/kg (paediatric), 10-min lockout; continuous infusion 0-12 mcg/kg/h.
  • Hydromorphone PCA: 5 mcg/kg interval dose; 0-3 mcg/kg/h continuous infusion.
• Oral opioids (oxycodone, hydrocodone) combined with NSAIDs or acetaminophen are common in the perioperative period.
• Opioid-sparing is a key goal - excessive opioids cause PONV, sedation, respiratory depression, urinary retention, and ileus.

Morgan & Mikhail 7e, p.2119; Barash Clinical Anesthesia 9e

D. Gabapentinoids (Gabapentin / Pregabalin)

• A single preoperative oral dose reduces postoperative pain and opioid consumption in the first 24 hours.
• Evidence for optimal dose and duration of perioperative use is still debated.
• May reduce risk of chronic post-surgical pain.
• Side effects: sedation and dizziness, especially in elderly patients - risk of falls.
• Pregabalin specifically has been shown to reduce opioid consumption and improve outcomes after total knee arthroplasty (TKA).

Morgan & Mikhail 7e, p.2118; Campbell's 2026 (Sawan et al., TKA reference)

E. Ketamine (NMDA Antagonist)

• Low-dose perioperative ketamine (0.5-1 mg/kg bolus followed by 2-10 mcg/kg/min infusion) significantly reduces pain, opioid consumption, and PONV.
• Particularly beneficial in patients on chronic opioids (reduces opioid-induced hyperalgesia).
• Analgesic efficacy confirmed in orthopaedic surgery.
• Monitor for CNS effects (sedation, nystagmus, hallucinations) and cardiovascular effects.

Morgan & Mikhail 7e, Table 48-4

F. IV Lidocaine

• Systemic IV lidocaine has confirmed analgesic efficacy in orthopaedic surgery (among other settings).
• Dosing: 1.5 mg/kg bolus, then 1.5-2 mg/kg/h intraoperatively, then 1 mg/kg/h postoperatively.
• Monitor for local anaesthetic systemic toxicity (CNS and cardiovascular signs).

Morgan & Mikhail 7e, Table 48-4

G. Dexamethasone

• Acts as an anti-inflammatory adjuvant, reduces pain, PONV, and swelling.
• Single perioperative dose commonly used in multimodal regimens.

4. Regional Anaesthesia and Analgesia Techniques

A. Neuraxial Analgesia

• Spinal (intrathecal) analgesia: Intrathecal morphine or opioids provide excellent analgesia post-op, used commonly after hip and knee arthroplasty, hip fracture surgery.
• Epidural analgesia: Combination of local anaesthetic (bupivacaine 0.1-0.125% or ropivacaine 0.1-0.2%) + opioid (fentanyl 2-2.5 mcg/mL or morphine/hydromorphone equivalent) via continuous epidural infusion. Effective for bilateral/major lower limb and spine surgery.

B. Peripheral Nerve Blocks

• Continuous nerve block catheters (perineural infusion with local anaesthetic) extend analgesia beyond single-shot block duration, particularly valuable for major reconstructions.
• Femoral nerve block vs. adductor canal block for TKA: The adductor canal block is now preferred because it provides equivalent analgesia to femoral nerve block but with less quadriceps weakness, enabling earlier ambulation and physiotherapy.

Barash 9e (sciatic nerve block + FNB for TKA systematic review); Miller's Anesthesia 10e (ACB vs FNB for TKA); Campbell's 2026

C. Local Infiltration Analgesia (LIA) / Periarticular Injection

• Surgeon-administered technique where a multimodal cocktail is injected around the joint during closure.
• Typical LIA mixture: ropivacaine or bupivacaine (often liposomal bupivacaine) + ketorolac + epinephrine ± morphine.
• Liposomal bupivacaine (extended-release formulation) prolongs local anaesthetic effect; studies in TKA show it may be equivalent or superior to traditional periarticular injection.
• Comparative studies show LIA and femoral nerve block have similar efficacy for TKA early pain; combining both may offer superior results.
• Particularly useful when regional blocks are contraindicated or not feasible.

Campbell's 2026 (TKA pain management section)

5. Pain Management by Specific Orthopaedic Procedure

Total Knee Arthroplasty (TKA)

• Preferred approach: Spinal/epidural anesthesia + adductor canal block (single shot or continuous) + multimodal oral/IV analgesia (acetaminophen + celecoxib + pregabalin) + periarticular LIA.
• Periarticular injection vs. epidural vs. femoral nerve block: all have evidence; current preference is adductor canal block for early ambulation.
• Celecoxib + muscle relaxants combination improves early recovery scores in RCT data.

Total Hip Arthroplasty (THA)

• Spinal anaesthesia + fascia iliaca / PENG block + multimodal oral analgesia.

Spine Surgery

• IV ketamine efficacy for spine surgery is mixed (+/-); epidural or intrathecal analgesia post-spinal surgery.

Amputations

• Continuous nerve block catheters at the amputation stump level.
• Rigid stump dressing post-amputation: decreases postoperative pain, allows earlier mobilisation, prevents knee flexion contractures in transtibial amputations, and reduces hospital stay.

Campbell's Operative Orthopaedics 15th Ed 2026, p.842

6. Enhanced Recovery Programs (ERPs) in Orthopaedics

• Pre-emptive/preventive analgesia (starting analgesics before incision)
• Aggressive multimodal analgesia throughout the perioperative period
• Early ambulation and physiotherapy (facilitated by opioid-sparing analgesia)
• Early oral feeding and early catheter removal
• Goal-directed fluid therapy

Morgan & Mikhail 7e, p.2125

7. Special Considerations

8. Complications of Analgesic Agents

Recent Evidence (PubMed 2024-2026)

Primary sources: Campbell's Operative Orthopaedics 15th Ed 2026; Morgan & Mikhail's Clinical Anesthesiology 7e; Miller's Anesthesia 10e; Barash Clinical Anesthesia 9e