Clinical framing for
the OPERA Method.

Positioning

After confirming cervical alignment on a preoperative lateral X-ray, the head is fixed with a Mayfield clamp in a neutral to slightly flexed position. Both shoulders are taped downward so that the operative level can be checked more easily.

Instruments and imaging

The technique uses a blunt right-angle Gelpi retractor, a compact high-speed burr with an irrigation nozzle, 3 mm and 1.5 mm diamond burrs, and a blunt right-angle suction tube. Preoperative axial CT is used to understand laminar thickness and adjust the depth of the lateral gutter. Three-dimensional CT is used to review spinous process shape and facet osteophytes before planning the working corridor.

Technical note

Positioning is especially important in a small-incision procedure. If the preoperative alignment is straight or kyphotic, routine slight flexion may create excessive kyphosis and make exposure through a small incision difficult.

Incision and exposure

The surgeon stands on the patient's left side. After palpating the C2 and C7 spinous processes, a two-fingerbreadth incision, about 35 mm for the authors, is designed. In many cases the incision is placed from the C3 spinous process caudally, roughly over C3 to C5. The midline nuchal ligament is opened precisely, the C3 to C6 midline is reached, and the level is confirmed by X-ray. A blunt right-angle Gelpi retractor is placed. The tips of the C3 to C6 spinous processes are split with a high-speed diamond burr while preserving the semispinalis cervicis attachments, and the laminae are exposed only as far laterally as needed for the lateral gutters.

C2/3 fenestration

The C2 semispinalis cervicis is fully preserved. The lower edge of the C2 lamina and the upper edge of the C3 lamina are exposed with a high-speed burr to identify the C2/3 ligamentum flavum. If there is no C2/3 stenosis, the ligamentum flavum is detached from the C3 lamina with a curved curette. If C2/3 stenosis is present, a 3 to 4 mm domeplasty of the lower C2 lamina is performed until the ligament can be detached from the C2 side. During this step the exoscope camera is tilted most cranially.

Technical notes

• The C3 lamina and lateral mass are deep and angled cranially, so plate placement tends to be difficult. Setting the incision closer to the C3 lamina can make C3 plate placement easier.
• Instead of completely removing the interlaminar ligamentum flavum, cutting or partially detaching it with a curette can reduce bleeding. Bleeding from the fenestration or epidural venous plexus can usually be controlled with flowable hemostatic material.

Lateral gutters and C6/7 fenestration

The lateral gutters of the C3 to C5 laminae are made with a high-speed burr. The authors use the right side as the hinge side and the left side as the open side. On the open side, the bone is cooled intermittently with saline to avoid thermal injury; when operating alone, a burr with a saline-drip nozzle is preferred. For C6, only the hinge-side gutter is first created, and the procedure then moves to C6/7 fenestration. Because the C6/7 view looks caudally, the lower edge of C6 can obstruct access to the ligamentum flavum. Removing a few millimeters of the distal C6 lamina makes the C6/7 ligamentum flavum easier to identify. The upper edge of C7 is exposed, and the ligamentum flavum is detached from C7 with a curved curette. If C6/7 stenosis is present, the upper C7 lamina is removed sufficiently with a burr or 2 mm Kerrison rongeur. The open side of C6 is cut only after the C6/7 fenestration is complete.

Plate-supported elevation

Because the field is limited, conventional suture-only fixation or hydroxyapatite spacer fixation can be difficult. The authors use the OPERA SYSTEM, which is compact and suited to minimally invasive manipulation. The laminar side of the plate can be bent to fit individual laminar shape. Each lamina is lifted with a curved curette and supported with a plate. The open-side ligamentum flavum is usually not cut. If elevation is stiff, additional drilling is performed on the hinge-side gutter; the lamina should not be forced upward. Each screw hole is prepared with a 1 to 2 mm burr, and the plate is fixed with two screws on the lateral mass side and two screws on the laminar side.

Technical notes

• The authors create the gutters in a continuous motion, moving from the hinge side C2 to C6 and then from the open side C6 to C2 after C2/3 fenestration.
• C6/7 fenestration is performed before cutting the open side of C6, because an early C6 cut may allow the lamina to move toward closure and compress the spinal cord.
• With preserved posterior cervical muscles and higher postoperative activity, the opened lamina may tend to reclose. Stable plate fixation is therefore important; a hinge plate may be preferred when the lamina is unstable.

Plate fixation and closure

The laminar side of the plate can be bent to match laminar shape. After the lamina is raised with a curved curette, the plate is inserted and fixed without looseness because preserved soft tissue can promote reclosure. Unlike conventional suture fixation, this technique generally does not require passing sutures behind the lamina, cutting the open-side ligamentum flavum, or dissecting between the lamina and dura. Direct contact with the epidural venous plexus is reduced, making bleeding control easier.

After thorough irrigation, a 3.5 mm closed continuous suction drain is placed and the muscle layer is closed. Retraction of the Gelpi retractor by an assistant or scrub nurse allows the cranial and caudal ends of the muscle layer to be sutured under direct vision even through a small incision. Subcutaneous closure is followed by skin strips. Rehabilitation begins the day after surgery in the authors' department.

Intraoperative CT navigation and XR

Because exoscope video is converted into digital data, integration with support devices such as XR is expected. CT navigation images can be displayed picture-in-picture on the exoscope monitor, allowing the surgeon to check the magnified surgical field and navigation image at the same time with less eye movement and improved operative efficiency.