Lumbar disc herniation (LDH), with the disc material extruded outside the normal intervertebral space, is the main cause of low back and lower extremity pain. Although conservative care remains the main strategy for treatment, discectomy is required when clinical symptoms cannot be resolved via nonsurgical treatment.

    With advances in medical technology, open discectomy has been gradually replaced by minimally invasive spine surgery, and microdiscectomy has become an important part of the treatment of LDH. Facilitated by the development of endoscopic equipment and techniques, a variety of modified minimally invasive lumbar surgical techniques have been developed.Few studies have directly compared PTED and UBE for the treatment of LDH. 

    The objective is to compare the clinical outcomes of percutaneous transforaminal endoscopic discectomy (PTED) and unilateral biportal endoscopic discectomy (UBE) for the treatment of single level lumbar disc herniation (LDH).

    From January 2020 to November 2021, 62 patients with single-level LDH were retrospectively reviewed. All patients underwent spinal surgeries at the Affiliated Hospital of Chengde Medical University and Beijing Tongren Hospital, Capital Medical University. Among them, 30 patients were treated with UBE, and 32 were treated with PTED. The patients were followed up for at least one year. Patient demographics and perioperative outcomes were reviewed before and after surgery. The Oswestry Disability Index (ODI), visual analog scale (VAS) for back pain and leg pain, and modified MacNab criteria were used to evaluate the clinical outcomes. X-ray examinations were performed one year after surgery to assess the stability of the lumbar spine.

    For the UBE group, the surgical procedure (based on the L4-L5 segment of LDH) was performed following methods reported in the literature. After successful general anesthesia with tracheal intubation, the patient was placed in a prone position with the abdomen draped, and the L4-L5 intervertebral space was marked with X-ray fluoroscopy. The initial target point is located at the junction of the inferior lamina and the spinous process of L4. The surgical bed is adjusted until the responsible intervertebral space is vertical to the floor to make the first horizontal line, and the second line is drawn along the inner edge of the pedicles of L4-L5. The observation and operation incision points on the body surface along the second line were approximately 0.5-1.0 cm from the intersection of the two lines. Two incisions were made, 0.8-1.0 cm long, in the skin and subcutaneous fascia. Then, we bluntly expanded and separated the soft tissue covering the surface of the lamina to form the working and observation portals. With irrigation, the arthroscopic system was inserted into the observation portal. The soft tissue on the surface of the intervertebral space was removed by the plasma scalpel in the working portal. Next, the ipsilateral spinolaminar junction at the L4-L5 level was identified, laminotomy was performed with part of the inferior lamina of L4, and the superior lamina of L5 was removed with a drill. After the exposed ligamentum flavum was removed, the discectomy was conducted with Kerrison forceps. Finally, a drainage tube was placed after hemostasis. X-ray, CT and MRI were performed after surgery.

    For the PTED group, the following steps (based on the L4-L5 segment of LDH) were performed following methods reported in the literature that we have published: A soft pillow was placed under the patient's waist while the patient was in the lateral decubitus position with their knee and hip flexed. The incision was located 8-12 cm from the midline horizontally and 2-4 cm above the iliac on the side with leg pain. A mixed local anesthetic, which consisted of 30 mL 1:200000 epinephrine and 20 mL 2% lidocaine, was used. After 5 mL of the mixed anesthetic was inserted into the skin at the entry point, 20 mL was inserted into the trajectory, 15 mL was inserted into the articular process, and 10 mL was inserted into the foramen. Then, 0.8-1.0 cm of skin and the subcutaneous fascia were incised. Drills were used to resect the ventral osteophytes on the superior articular process of L5. The PTED system (Hoogland Spine Products, Germany) was inserted. Parts of the ipsilateral ligamentum flavum and the extruded lumbar disc were completely resected with endoscopic forceps. The drainage tube was placed after hemostasis. X-ray, CT and MRI were performed after surgery.

    The mean ages in the UBE and PTED groups were 46.7 years and 48.0 years, respectively. Compared to the UBE group, the PTED group had better VAS scores for back pain at 1 and 7 days after surgery  (3.06±0.80 vs 4.03±0.81 P<0.05; 2.81±0.60 vs 3.70±0.79 P<0.05). The UBE and PTED groups demonstrated significant improvements in the VAS score for leg pain and ODI score, and no significant differences were found between the groups at any time after the first month (P>0.05). Although the good-to-excellent rate of the modified MacNab criteria in the UBE group was similar to that in the PTED group (86.7% vs. 87.5%, P>0.05), PTED was advantageous in terms of the operation time, estimated blood loss, incision length, and length of postoperative hospital stay.

    Both UBE and PTED have favorable outcomes in patients with single-level LDH. However, PTED is superior to UBE in terms of short-term postoperative back pain relief and perioperative quality of life.