Perioperative and Intraoperative Pain Management in Total Knee Arthroplasty

Anesthesia Modalities: Neuraxial Dominance

• Nearly 100% of patients receive neuraxial anesthesia (spinal or epidural) unless clear medical contraindications exist.

• Contraindications: Extensive lumbar spine instrumented fusion, severe uncorrected coagulopathy, or pulmonary hypertension (which may necessitate controlled general anesthesia).

• Clinical Benefits of Neuraxial Anesthesia:

  • Reduced operative time.

  • Decreased intraoperative blood loss and transfusion rates.

  • Significant reduction in postoperative deep vein thrombosis (DVT).

  • Lower early postoperative pain scores.

Periarticular Multimodal Injections (The Ranawat Cocktail)

• Pioneered by Dr. Chitranjan Ranawat over 20 years ago; local infiltration targets periosteum, posterior capsule, and surrounding capsular sleeves.

• Safety of Steroids in the Cocktail: Inclusion of methylprednisolone acetate (Depo-Medrol) in hundreds of thousands of cases has shown no increased risk of periprosthetic joint infection (PJI).

• Non-Steroidal Alternatives: Ketorolac is widely used as a substitute for corticosteroid agents.

• Liposomal Bupivacaine (Exparel): Clinical utility has leveled off; studies demonstrate high cost without superior analgesia compared to traditional bupivacaine mixtures. Modern research is evaluating extended-release bupivacaine combined with meloxicam.

• Anatomical Safety Warning:

  • Exercise extreme caution during infiltration of the posterolateral corner of the knee.

  • Deep extravasation around the fibular neck risks transient common peroneal nerve palsy.

  • While typically non-permanent, it causes an acute postoperative foot drop that creates significant clinical anxiety over the first 24 hours.

Peripheral Regional Nerve Blocks

• Femoral Nerve Block (FNB) Obsolescence: Previously standard of care at Hospital for Special Surgery (HSS), FNBs cause extensive quadriceps motor block, increasing the incidence of postoperative patient falls.

• Adductor Canal Block (ACB):

  • Ultrasound-guided block within the subsartorial (Hunter’s) canal targeting the saphenous nerve and branches of the anterior femoral cutaneous nerve.

  • Provides dense sensory analgesia to the anterior and medial knee while sparing quadriceps motor function.

  • Achieves equivalent pain relief to femoral nerve blocks with superior early ambulatory capacity.

• Combined ACB and Periarticular Cocktail: HSS clinical trials confirm that combining an adductor canal block with intraoperative periarticular injection yields superior analgesia compared to either technique alone.

• IPAC Block (Infiltration between Popliteal Artery and Capsule of the Knee):

  • Targets sensory articular branches supplying the posterior knee capsule without motor block of the tibial or peroneal nerves.

  • Combining ACB + IPAC + Periarticular Injection provides complete 360-degree pain coverage (anterior, medial, and posterior joint compartments).

Pharmacological Adjuncts, Cryotherapy, and Early Rehabilitation

• Duloxetine (Cymbalta) Protocol:

  • Dose: Once-daily oral administration for 2 weeks postoperatively.

  • Trial outcomes (160 patients): Reduced total postoperative narcotic consumption by nearly 50%.

  • Precaution: Monitor baseline serum sodium; duloxetine can induce or exacerbate hyponatremia.

• Cold Therapy (Cryotherapy):

  • Protocol: Apply ice for 20 minutes at least 4 times daily (up to 10 times daily as needed).

  • Safe, non-pharmacologic modality that effectively reduces postoperative edema and secondary hyperalgesia.

• Evolution of Early Physical Therapy:

  • High-intensity, aggressive early passive range-of-motion protocols have been abandoned.

  • Current practice focuses on gentle mobilization, unassisted gait re-education, and protected functional movement during the first postoperative week, preventing arthrogenic muscle flare-ups.

Summary Protocol: The Modern Multimodal Pathway

• Anesthesia: Neuraxial spinal or epidural block.

• Regional Blocks: Combined ultrasound-guided Adductor Canal Block (ACB) + IPAC block.

• Intraoperative Infiltration: Wide periarticular cocktail (avoiding the deep posterolateral corner).

• Systemic Non-Opioid Adjuncts: Oral duloxetine for 14 days; pre-existing hyponatremia screening.

• Physical Modalities: Regular scheduled cryotherapy (20-minute sessions) and gentle, non-aggressive functional mobilization during week one.