Objective:

Detection of neurologic injury utilizing a novel intraoperative neuromonitoring (IONM) protocol for distal femoral extension osteotomies (DFEOs).

Background:

DFEOs treat knee flexion contractures but have a high rate of neurologic injury up to 40%, yet IONM is not standard of care.

Design/Methods:

A retrospective review of pediatric patients undergoing DFEOs utilizing our novel IONM protocol with a single surgeon from 2017-2024.  Somatosensory evoked potentials (SSEPs) of the peroneal and posterior tibial nerves are recorded from the popliteal fossae, lumbar and cervical regions.  Transcranial electrical motor evoked responses (TcMEPs) are produced by stimulation of the motor cortex and recorded from the abductor pollicis brevis, abductor hallucis, extensor digitorum brevis and abductor hallucis.  Critical changes are noted by the application of standard critical values in addition to comparison of the operative and non-operative leg. All cases utilized total intravenous anesthesia.

Results:

Seventeen patients undergoing 25 DFEO surgeries, average age of 13 years (9-17 years) were included. Nine patients had cerebral palsy from neonatal periventricular leukomalacia, stroke, intraventricular hemorrhage, or hypoxic ischemic encephalopathy.  Two patients had genetic disorders leading to spasticity and 6 had other pathologies. Six of 25 cases (24%) had critical changes.  3 of these occurred after osteotomy and improved after surgical adjustment.  2 cases were due to positioning and 1 from tourniquet use.  All cases had IONM potentials return to baseline at the close of surgery.  No patient awoke with neurologic impairment.

Conclusions:

IONM during DFEO detects the risk of neurologic injury postoperatively.  In addition, SSEP recording during peripheral procedures is improved with lumbar recording.