Microsurgical Wiltse Paraspinal Approach Using a Low-Budget Exoscope

Abstract

Access to microneurosurgical care in low- and middle-income countries remains limited mainly due to a lack of equipment. High purchasing and maintenance costs hinder the use of operating microscopes in low-resource facilities. The authors present an improved version of their previously introduced low-cost exoscope to achieve high magnification and illumination in low-resource environments. The setup included a 48-megapixel two-dimensional digital microscope camera, a wide field C-mount lens, ring light, and a two-link cantilever with a screw terminal. The surgical field was projected to a portable 17.3-inch 2K resolution monitor. Ten patients underwent exoscope-assisted transforaminal lumbar interbody fusion via the Wiltse paraspinal approach. The simple construction allowed a fast and intuitive preoperative setup. The in-plane switching type display provided a clear and bright image regardless of the viewing angle. The two-link arm of the cantilever allowed smooth positioning of the camera, overcoming the cumbersome up and down movements needed to zoom in and out with the previous prototype. Industrial microscope cameras are effective low-budget alternatives to conventional operating microscopes in lumbar microdiscectomy. The improved system is superior compared to the authors' previous prototype with regard to affordability, image quality, and adjustability of position and angle.

Keywords: exoscope; low-cost; minimally-invasive spine surgery; paarspinal approach; transforaminal lumbar interbody fusion; wiltse approach.

Figure 1. (A) The previously published prototype was composed of a 16-megapixel industrial microscope camera, a wide field C-mount lens and an LED ring light attached to an intravenous pole via a heavy-duty support arm. To zoom in and out, the support arm was loosened and moved down or up along the pole, respectively. (B) The improved version of the low-cost exoscope includes a 48-megapixel digital microscope camera and a two-link cantilever that can be attached to the operating table via a screw terminal. The two-link arm allows seamless adjustment of zoom and angle with a wide range of motion.

Figure 2. (A) Cables and microscope cameras were covered with sterile drapes. The remaining components were sterilized with ethylene oxide. The cantilever was attached to the contralateral side of the operating table. The ring light was secured at the upper edge of the microscope tube. The lower half of the microscope tube allowed a firm grip to adjust the camera's position and angle. (B) The exoscope provided sufficient magnification and illumination of the surgical field despite a narrow surgical corridor.

Figure 3. (A) The Wiltse approach begins with a paravertebral incision 4 cm lateral to the midline. Using blunt dissection, the natural corridor between the multifidus and longissimus muscles is opened. (B) The junction between the facets and the transverse process is exposed.

Figure 4. (A) Sagittal and (B) coronal x-ray images of the lumbosacral spine after bilateral pedicle screw placement at the L4/L5 segments in a 44-year-old male patient.

Figure 5. Graphical illustration of the operating room setup during the exoscope-assisted phase of the surgery.