Common Peroneal Nerve Analgesia Considerations During Knee Posterolateral Corner Reconstruction.

Peripheral nerve blockade is commonly employed as perioperative pain management for posterolateral corner (PLC) knee reconstructions. However, common peroneal nerve (CPN) analgesia limits immediate postoperative assessment (within 0.5-2 hours of surgery) for iatrogenic injury and may further cause a "second hit" injury in cases of preoperative CPN trauma. Meanwhile, lack of lateral knee analgesia may result in intractable pain and the need for postoperative "rescue block." The incidence of iatrogenic peroneal nerve injury (from nerve block and/or surgical exploration) and frequency of "rescue blockade" remains unknown after PLC reconstruction. This study aims to identify the incidence of these events to inform the ideal perioperative anesthesia protocol. Patients who underwent PLC reconstruction at a single Level 1 academic institution were identified over a 4-year period. Medical records were queried for demographics, injury patterns, nerve blockade, surgical interventions, and perioperative nerve injury. Fifty knees were identified: 30 (60%) underwent preoperative CPN block, and 20 (40%) underwent CPN-sparing analgesia. Preoperative CPN injury was present in 20% of the cohort. Forty percent of these neurological injuries experienced improvement of symptoms shortly after neurolysis, while another 40% required further intervention. Factors determining avoidance of CPN analgesia were preoperative CPN injury (p = 0.030) and low-energy injury mechanism (p = 0.038). Of the CPN-sparing cohort, nine (45%) underwent a postoperative rescue block. Risk factors for rescue block were younger age (25.3 years vs. 39.8 years; p = 0.007) and lower BMI (26.5 kg/m2 vs. 33.0 kg/m2; p = 0.035). Incidence of iatrogenic CPN palsy following PLC reconstruction was 6%, all of which were incomplete and did not require operative intervention. Incidence of iatrogenic CPN injury was low, with only incomplete nerve palsies that did not necessitate operative intervention. Avoidance of preoperative CPN blockade allowed for immediate postoperative neurologic evaluation. However, nearly half of the CPN-sparing cohort did require a postoperative "rescue block." This risk was higher among younger patients with lower BMIs.