Microendoscope-assisted posterior lumbar interbody fusion: a technical note

Hirohiko Inanami, Fumiko Saiki, Yasushi Oshima


Background: Various surgical options for lumbar interbody fusion have been reported. Minimally invasive techniques are widely used to reduce soft tissue damage. Here, we report our novel technique of microendoscope-assisted posterior lumbar interbody fusion (ME-PLIF) using an 18-mm tubular retractor system (METRx, Medtronic Sofamor Danek, Memphis, TN, USA) for lumbar spine degeneration treatment.
Methods: Between January 2011 and December 2011, 48 patients underwent one level ME-PLIF by a surgeon in our hospital. We followed up 46 patients (95.8%). A 20-mm skin incision was made in the craniocaudal direction at the level of the intervertebral disc, 15 mm outside the midline (symptomatic side). The surgeon placed the tubular retractor and performed decompression, thoroughly discarded the intervertebral disc, and then inserted the autologous crushed bone on the opposite side. Subsequently, a cage was inserted using fluoroscopic guidance. Following the end of the microendoscopic operation, pedicle screws (PS) were inserted percutaneously using fluoroscopic guidance. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and the Japanese Orthopedic Association (JOA) scores. For radiological outcomes, fusion rates based on the Bridwell fusion grading system were evaluated using plain radiography or a computed tomography scan at the most recent follow-up timepoint.
Results: The mean age was 61.4 (range, 36.0–86.0) years, the mean operation time was 102 (range, 59–162) min, and the mean blood loss was 86 (range, small amounts–315) mL. The average pre- and post-operative ODI scores were 22.1 and 9.7, respectively, with an improvement rate of 56.1%, and the pre- and post-operative JOA scores were 9.8 and 16.4, respectively, with an improvement rate of 50%. There were no cases of pseudarthrosis. One case (2.2%) had a deep wound infection that required total removal of the implants. Four (8.7%) cases had a dural tear and required dural sutures under microendoscopy, though they had good recovery.
Conclusions: This technique yielded good results. The advantages of using only the microendoscope were: (I) better visual field and (II) higher operability (it was possible to change the tubular retractor to various angles; this was difficult under direct viewing or under a microscope). These features are considered to lead to reduce soft tissue damage. Although long-term follow-up results are needed, this appears to be a safe and minimally invasive treatment option for lumbar spine degeneration.