What is the best course of action for a patient one day post knee replacement surgery, complaining of low back and buttock pain unrelieved by 5mg oxycodone (oxycodone) and 10mg cyclobenzaprine (flezeril)?

Immediate Management of Inadequate Post-Operative Pain Control

This patient requires immediate dose escalation of oxycodone to 10-15 mg every 4-6 hours, discontinuation of cyclobenzaprine (which has shown no benefit in this context), and addition of scheduled naproxen 500 mg twice daily. 1, 2

Rationale for Medication Adjustment

Opioid Dose Optimization

• The current 5 mg oxycodone dose is at the lower end of the FDA-approved initial dosing range of 5-15 mg every 4-6 hours for acute pain 2
• Titrate to 10-15 mg every 4-6 hours based on pain severity, as FDA labeling emphasizes individualizing doses based on severity of pain and patient response 2
• Post-surgical pain one day after knee replacement typically requires around-the-clock scheduled dosing rather than as-needed administration to prevent pain recurrence 2
• Monitor closely for respiratory depression, especially within the first 24-72 hours of dose increases 2

Discontinue Cyclobenzaprine

• High-quality evidence demonstrates cyclobenzaprine provides no additional benefit when combined with NSAIDs for acute low back pain 1, 3
• A randomized trial of 323 patients showed naproxen plus cyclobenzaprine produced identical functional improvement (10.1 points) compared to naproxen plus placebo (9.8 points) at one week, with no statistically significant difference (P=0.77) 1, 3
• Cyclobenzaprine increases adverse effects including drowsiness and dizziness without improving analgesia 1

Add Scheduled NSAID Therapy

• NSAIDs are first-line pharmacologic treatment for acute musculoskeletal pain and should be added if not contraindicated 1
• Naproxen 500 mg twice daily provides superior analgesia compared to opioids alone for acute musculoskeletal pain 1, 3
• The combination of NSAID plus opioid is more effective than either agent alone for post-operative pain 1
• Screen for contraindications: cardiovascular disease, chronic renal failure, or previous gastrointestinal bleeding 1

Critical Differential Diagnosis Considerations

Rule Out Surgical Complications First

• Buttock pain one day post-knee replacement raises concern for positioning-related nerve injury, compartment syndrome, or referred pain from surgical site 4, 5
• Examine for signs of compartment syndrome: severe pain out of proportion to exam, pain with passive stretch, paresthesias, pallor, pulselessness 6
• Assess for sciatic nerve injury from surgical positioning or retractor placement 4
• Check surgical site for hematoma or infection 6

Piriformis Syndrome Consideration

• Buttock pain with tenderness in the sciatic notch suggests possible piriformis syndrome, which can be exacerbated by prolonged surgical positioning 4
• Pain typically worsens with prolonged sitting and hip flexion, adduction, and internal rotation (FADIR test) 4
• This diagnosis should be considered if pain persists beyond expected post-operative course 4

Multimodal Analgesia Protocol

Pharmacologic Approach

• Scheduled oxycodone 10-15 mg every 4-6 hours (not as-needed) for around-the-clock coverage 2
• Scheduled naproxen 500 mg twice daily with food 1
• Acetaminophen 1000 mg every 6 hours can be added for additional analgesia 1
• Discontinue cyclobenzaprine immediately 1, 3

Non-Pharmacologic Interventions

• Ice application to surgical site for 20 minutes every 2-3 hours 6
• Early mobilization as tolerated per orthopedic protocol 1
• Physical therapy consultation for positioning and gentle range of motion 1

Red Flags Requiring Urgent Evaluation

• Progressive neurologic deficits (foot drop, numbness, weakness) 1
• Severe pain out of proportion to examination 6
• Signs of infection (fever, wound drainage, erythema) 6
• Inability to void or loss of bowel/bladder control 1
• Compartment syndrome signs (pain with passive stretch, tense compartments) 6

Follow-Up and Reassessment

• Reassess pain scores and functional status within 2-4 hours of medication adjustment 2
• If pain remains uncontrolled after optimizing oral regimen, consider consultation with acute pain service for regional anesthesia techniques (femoral nerve block, epidural) 1
• Plan for opioid taper beginning 48-72 hours post-operatively as pain improves, reducing dose by 25-50% every 2-4 days 2
• Transition to non-opioid regimen (NSAIDs plus acetaminophen) by post-operative day 5-7 if pain trajectory is appropriate 1

Common Pitfalls to Avoid

• Do not continue ineffective muscle relaxants - cyclobenzaprine has no proven benefit in this setting and only adds side effects 1, 3
• Do not use as-needed dosing for severe acute post-operative pain - scheduled dosing prevents pain recurrence 2
• Do not prescribe opioids without concurrent NSAID therapy unless contraindicated - combination therapy is superior 1
• Do not attribute all post-operative pain to expected surgical pain - maintain high suspicion for complications 4, 6