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Residual Neurological Symptoms After Peripheral Nerve Blocks for Pediatric Knee Surgery

Background: Peripheral nerve blocks (PNBs) provide excellent pain control and reduce the need for systemic analgesics in orthopaedic surgery. PNBs rarely cause complications; however, a few studies of adults have reported neurological complications during the early postoperative period. We investigated complications associated with the use of PNBs during pediatric knee surgery. Methods: We reviewed the medical records of all 121 children (aged ⩽18 y) who underwent knee surgery by 1 orthopaedic surgeon between October 2014 and September 2016. One hundred of these patients had PNBs. The primary outcome of interest was postoperative neurological symptoms. Other study parameters were patient characteristics, surgical details, tourniquet use/duration of use, PNB guidance method and anatomic location, and PNB-associated procedural complications (eg, blood loss, anesthetic neurotoxicity). Data were analyzed using Student t tests and Fisher exact tests, with significance at P<0.05. Results: Of the 100 patients with PNBs, 23 had persistent lower-extremity paresthesias postoperatively. Most paresthesias were attributed to the surgical procedure; however, at first follow-up (mean, 1.6±0.4 wk) 6 patients had paresthesias and other neurological symptoms proximal to the knee in a distribution pattern consistent with the PNB. Three of these were unresolved at last follow-up (mean, 56±37 wk). All neurological symptoms were associated with femoral nerve blocks. The 6 patients with suspected PNB-associated neurological symptoms had a significantly higher mean BMI (31±5.5) than the 94 patients without symptoms (23±6.1; P=0.002). Obesity was associated with PNB-associated neurological symptoms (P=0.002), as was female sex (P<0.001). No significant differences were found in terms of age, surgery duration, or tourniquet use/duration of use. Most PNB procedures used ultrasound guidance, and no procedural complications were reported. Conclusions: Compared with previous studies, we report a higher rate (6%) of PNB-associated neurological symptoms in children after knee surgery with PNBs. Obesity and female sex were associated with persistent neurological symptoms in the distribution pattern of the PNB. Level of Evidence: Level III (retrospective comparative study).