UBE Microdiscectomy: A Surgical Technique Guide – Orthopedics Today

A minimally invasive approach to spine surgery, unilateral biportal endoscopy (UBE) is gaining traction as a viable alternative to traditional methods for treating lumbar disc herniation. This technique integrates principles of both microscopic and endoscopic surgery, offering potential benefits in terms of reduced tissue trauma and faster recovery times. The procedure utilizes two independent portals – one for visualization and one for instrumentation – allowing for greater maneuverability and improved ergonomics for the surgeon.

UBE is indicated for symptomatic lumbar disc herniation, radiculopathy, or neural compression that hasn’t responded to conservative management. However, it’s not suitable for all patients. Contraindications include spinal instability, active infection, prior fusion at the operative level, and significant spinal deformity. Careful patient selection is crucial for optimal outcomes.

Patient Positioning and Setup

Successful UBE relies on precise positioning. Patients are positioned prone on a Jackson table, allowing for optimal spinal alignment and exposure. A slight reverse Trendelenburg position – tilting the head down slightly – is often employed (Figure 1). Leg slings are used to increase the interlaminar window, the space between the vertebrae, reducing the amount of bone resection needed during the procedure.

The surgical setup includes a Mayo stand positioned at the foot of the bed, equipped with essential instruments like shavers, radiofrequency wands, endoscopes, and micro-instruments for easy access. Additional equipment includes a Bair Hugger for temperature regulation, a Bovie electrocautery unit, a headlight, and a Neptune manifold for fluid management. A C-arm fluoroscopy unit is essential for real-time imaging and guidance during portal placement.

Portal Placement: A Critical Step

Accurate portal placement is paramount for a successful UBE microdiscectomy. The midline and medial pedicle lines are first marked using C-arm fluoroscopy. A slight-gauge needle is then inserted to identify the optimal entry point just lateral to the spinous process. For a right-handed surgeon performing a left-sided discectomy, the initial needle is inserted at the proximal portion of the distal pedicle, with a second needle placed 2-3 cm proximally to mark the viewing portal (Figure 4). The C-arm is used to confirm alignment with the affected pathology.

Source: Kern Singh, MD

The portals are mirrored for a right-handed surgeon performing a right-sided discectomy. A lateral radiograph can be obtained to ensure the working portal trajectory aligns with the disc herniation.

Creating the Surgical Workspace

A 7-mm incision is made at the working portal site, followed by blunt dissection to the lamina. At the viewing portal site, sequential dilators are inserted, gently elevating the paraspinal musculature. The endoscope sheath is then carefully inserted, ensuring it remains outside the interlaminar space. Irrigation is initiated, typically using gravity, with suction open to maintain clear visualization. The irrigation pump pressure should be kept below 30 mm Hg to minimize complications.

Initial tissue removal is performed with a radiofrequency wand, followed by bone removal with a high-speed burr to expose the ligamentum flavum. Constant suction is maintained to prevent fluid accumulation and ensure a clear visual field (Figure 5). A small flavotomy – an opening in the ligamentum flavum – is then created using a ball-tip probe or curved micro-curette, exposing the epidural fat (Figure 6).

Microdiscectomy and Decompression

With the thecal sac exposed, the surgeon carefully accesses the disc space and uses a micro-pituitary rongeur to remove the herniated disc material. The amount of disc material removed is determined by the surgeon to ensure adequate decompression of the nerve root. Loose fragments are removed, and hemostasis – control of bleeding – is confirmed (Figure 8).

Advantages and Considerations

UBE microdiscectomy offers several potential advantages. Its minimally invasive nature leads to greater preservation of bone and surrounding tissues, potentially reducing the risk of infection and accelerating recovery. Many patients are able to return home the same day of the operation.

However, the technique presents challenges. It requires advanced surgical proficiency and extensive training to achieve proper triangulation and maintain a clear visual field. Dependence on the endoscope for visualization also means potential issues with the technology could arise. As with any surgery, there are risks of recurrent herniation, postoperative fluid accumulation, and dural tears, which may require further intervention.

Tips for Successful UBE Microdiscectomy

Surgeons considering UBE should have a strong foundation in traditional open and microscopic discectomy. Creating the initial working space efficiently is key, and maintaining a clear visual field through continuous irrigation is essential. Consistent endoscopic orientation is crucial, and fluoroscopic imaging can be helpful for beginners. Proper ergonomics – a comfortable surgeon position – are also important for prolonged procedures (Figure 9).

Postoperative Care

Following surgery, the incisions are closed with absorbable sutures, Dermabond, and skin glue. Patients are encouraged to walk as tolerated and are restricted from bending, twisting, squatting, and lifting more than 10 pounds for the first six weeks. Submersion in water is also restricted for six weeks. Postoperative medications typically include pain relievers, muscle relaxants, and a stool softener.

Illustrative Case

A 43-year-old man with severe lower extremity radiculopathy and weakness underwent a left-sided biportal endoscopic discectomy at L4/5 for a large central herniated nucleus pulposus with a left paracentral component causing significant thecal sac compression (Figures 10a and 10b). A video of the procedure is available.

UBE microdiscectomy represents a promising advancement in minimally invasive spine surgery. By adhering to the principles of accurate portal placement, careful tissue management, and meticulous technique, surgeons can optimize outcomes and offer patients a potentially less invasive and faster recovery option.

For more information:

Puranjay Gupta, BS; Aimen A. Khan, BS; Aryan Patel, BS; Noah A. Pogonitz, BS; and Kern Singh, MD, can be contacted at Rush University Medical Center’s department of orthopedic surgery in Chicago. Sehajvir Singh, BA, can be contacted at Drexel University College of Medicine in Philadelphia.