Neurological complications using a novel retractor system for direct lateral minimally invasive lumbar interbody fusion

• Lateral interbody fusion is safe and effective.
• It can be used to treat multiple structural pathologies of the lumbar spine.
• Neural complications are most common.
• This is mainly altered thigh sensation that recovers within a few weeks of surgery.
• Triggered electromyography (tEMG) is utilised to determine proximity to the plexus branches.

We describe our experience using the RAVINE retractor (K2M, Leesburg, VA, USA) to gain access to the lateral aspect of the lumbar spine through a retroperitoneal approach. Postoperative neurological adverse events, utilising the mentioned retractor system, were recorded and analysed. We included 140 patients who underwent minimally invasive lateral lumbar interbody fusion (MI-LLIF) for degenerative spinal conditions between 2011 and 2015 at two major spinal centres. A total of 228 levels were treated, 35% one level, 40% two level, 20% three level and 5% 4 level surgeries. The L4/5 level was instrumented in 28% of cases. 12/140 patients had postoperative neurological complications. Immediately after surgery, 5% of patients (7/140) had transient symptoms in the thigh ranging from sensory loss, pain and paraesthesia, all of which recovered within 12 weeks following surgery. There were five cases of femoral nerve palsy (3.6% — two ipsilateral and three contralateral), all of which recovered completely with no residual sensory or motor deficit within 6 months. MI-LLIF done with help of the described retractor system has proved a safe and efficient way to achieve interbody fusion with minimal complications, mainly nerve related, that recovered quickly. Judicious use of the technique to access the L4/5 level is advised.