Microendoscopic Surgery for Degenerative Disorders of the Cervical and Lumbar Spine: The Influence of the Tubular Workspace on Instrument Angulation, Clinical Outcome, Complications, and Reoperation Rates

Abstract

Background: Long-term clinical outcomes with microendoscopic spine surgery (MESS) are poorly investigated. The effect of instrument angulation on clinical outcomes has yet to be assessed.

Methods: A total of 229 consecutive patients operated on via two MESS systems were analyzed. Instrument angulation for both MESS systems, which differ from each other regarding the working space for instruments, was assessed using a computer model. Patients' charts and endoscopic video recordings were reviewed to determine clinical outcomes, complications, and revision surgery rates. At a minimum follow-up of two years, clinical outcomes were assessed employing the Neck Disability Index (NDI) and Oswestry Disability Index (ODI).

Results: A total of 52 posterior cervical foraminotomies (PCF) and 177 lumbar decompression procedures were performed. The mean follow-up was six years (range 2-9 years). At the final follow-up, 69% of cervical and 76% of lumbar patients had no radicular pain. The mean NDI was 10%, and the mean ODI was 12%. PCF resulted in excellent clinical outcomes in 80% of cases and 87% of lumbar procedures. Recurrent disc herniations occurred in 7.7% of patients. The surgical time and repeated procedure rate were significantly lower for the MESS system with increased working space, whereas the clinical outcome and rate of complication were similar.

Conclusions: MESS achieves high success rates for treating degenerative spinal disorders in the long term. Increased instrument angulation improves access to the compressive pathology and lowers the surgical time and repeated procedure rate.

Keywords: cervical spine; clinical outcome; complication; degenerative disc disease; endoscopy; instrument angulation; lumbar spine; microendoscopic; reoperation.

Figure 1

Shown is the EasyGO system view from above, illustrating the available workspace (red circled area) within the tubular retractor for the instrument workspace. The first-generation EasyGO™ system (a) is shown in the left panel, and the second in the right panel (b). The retractor system has a tubular retractor holder (white arrow) and another holder to insert the endoscope (white arrowhead).

Figure 2

Shown is the instrument angulation simulation through the tubular retractor, demonstrating the four depths of instrument tips and two different angulations. The angulation at the center of the trocar of the first generation EasyGO™ is shown in the upper row: (a) 0 mm of the trocar edge, (b) 5 mm of the trocar edge, (c) 10 mm of the trocar edge, and (d) 15 mm of the trocar edge. The angulation at the rim of the trocar of the second generation EasyGO™ is shown in the lower row: (e) 0 mm of the trocar edge, (f) 5 mm of the trocar edge, (g) 10 mm of the trocar edge, and (h) 15 mm of the trocar edge.