What is the safe duration for prescribing a muscle relaxant after medial patellofemoral ligament reconstruction to treat significant postoperative cramping in the operative leg?

Duration of Muscle Relaxant Therapy After MPFL Reconstruction

For significant postoperative muscle cramping after MPFL surgery, prescribe muscle relaxants for 7-14 days maximum, with most patients requiring only 7 days of treatment. 1

Recommended Agents and Duration

First-Line Options

Cyclobenzaprine 5 mg three times daily for 7 days is the optimal choice based on the strongest evidence:

• Provides effective relief within 3-4 doses (12-16 hours) in acute musculoskeletal conditions 2
• The 5 mg dose is as effective as 10 mg but causes significantly less sedation 2
• Should be held on the day of any subsequent surgical procedures but can be continued throughout the postoperative recovery period otherwise 1
• Fair evidence supports efficacy in acute musculoskeletal pain conditions 3

Methocarbamol is an alternative option:

• Can be given orally or intravenously for acute postoperative use 1
• Demonstrated benefit in reducing opiate consumption and improving physical therapy progress after orthopedic surgery 1
• Should be held on day of operation if additional procedures are planned 1

Alternative Agents

Tizanidine may be continued throughout the perioperative period:

• Improves postoperative pain control and decreases opioid consumption 1
• Can be taken preoperatively and postoperatively without interruption 1
• Provides hemodynamic stability during recovery 1
• Critical warning: Must be tapered slowly if discontinued after long-term use to avoid withdrawal (rebound tachycardia, hypertension, hypertonia) 1

Baclofen is appropriate for continued use:

• Should be taken preoperatively including day of operation 1
• Severe withdrawal risk: Abrupt discontinuation causes visual/auditory hallucinations, anxiety, delirium, fever, tremors, tachycardia, and seizures 1
• Intrathecal baclofen withdrawal is potentially life-threatening with risk of rhabdomyolysis and multiorgan failure 1

Agents to Avoid

Carisoprodol should not be initiated postoperatively:

• Controlled substance with high abuse and addiction potential 1
• Should be held on day of operation and ideally tapered off before surgery if patient is already taking it 1
• Requires slow taper over 4-9 days to prevent severe withdrawal symptoms 1

Metaxalone should be held on day of operation and is not recommended for routine postoperative cramping 1

Duration Rationale

The 7-14 day timeframe is based on:

• Acute muscle spasm typically resolves within the first postoperative week with appropriate rehabilitation 2, 3
• Cyclobenzaprine trials demonstrate efficacy within 7 days for acute musculoskeletal conditions 2
• Prolonged use beyond 2 weeks increases risk of tolerance, dependence, and withdrawal symptoms 1
• Most postoperative cramping after MPFL reconstruction responds to early mobilization, cryotherapy, and short-term pharmacologic intervention 1

Critical Monitoring and Adjunctive Measures

Combine muscle relaxants with non-pharmacologic interventions:

• Apply cryotherapy immediately post-exercise to minimize reactive inflammation 1, 4
• Use compression therapy in conjunction with ice application 1
• Continue appropriate closed kinetic chain exercises as tolerated 1, 5

Discontinue muscle relaxants if:

• Cramping resolves before 7 days (most common scenario)
• Excessive sedation interferes with rehabilitation participation
• Patient develops anticholinergic symptoms (dry mouth, urinary retention, confusion) 1

Extend to 14 days only if:

• Cramping persists beyond 7 days despite adequate dosing
• Patient demonstrates clear benefit without adverse effects
• Rehabilitation progress is being limited by muscle spasm

Common Pitfalls

Avoid prolonged prescriptions beyond 14 days as this increases risk of:

• Physical dependence requiring slow taper 1
• Sedation interfering with rehabilitation and functional recovery 1, 2
• Masking underlying complications (infection, compartment syndrome, DVT) that may present with muscle cramping

Do not combine multiple muscle relaxants as this potentiates sedation and central nervous system depression, particularly when used with opioids 1

Ensure patients understand sedation risk and avoid driving or operating machinery, especially during the first 3-4 doses 2, 6