Percutaneous full-endoscopic anterior transcorporeal cervical discectomy and channel repair: a technique note report

This study was approved by local institutional review board (IRB) and the informed consent was acquired from all the patients. In our study, PEATCD with CR was performed for 4 consecutive patients, including 1 female and 3 males with an age range of 41 to 46 years old, with soft CDH from Jul. 2016 to Sep. 2016. The duration of neck pain ranged from 14 to 26 weeks. The demographic characteristics, clinical data, and treatment level are shown in Table 1. The visual analog score (VAS) was used to record the neck pain scores during the postoperative periods. The clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) scores and modified Macnab criteria (Table 2).

The following were indications for PEATCD and CR. (1) The patient had experienced failure of strict conservative treatment for at least 12 weeks. In our study, 3 patients accepted drug therapy and physical treatment, the left one was treated with epidural ejection; (2) single-level central or mediolateral soft herniation; (3) herniated disc fragment that migrated upward or downward but not free; (4) the symptom or discomfort was caused by the CDH. and (5) there is no evidence of instability in the cervical spine. The contraindications were as follows: (1) Patients with multiple-levels CDH or cervical spinal canal stenosis; (2) posterolateral herniation or foraminal stenosis; (3) previous surgery at the same segment; (4) calcification of the herniated disc or posterior osteophytes of the vertebral body; (5) obesity, (6) the herniation was induced by trauma.

The spinal endoscopy system (SPINENDOS GmbH., Munich, Germany) was comprised of a 4.3 mm working channel, an outer sheath with a 6.9 mm diameter, a 30°-angled scope with a continuous water irrigation system, a trephine with a 6.6 mm inner diameter and a 7.6 mm outer diameter, and a low-temperature radiofrequency ablation system (ArthroCare Co., Sunnyvale, CA, USA). The drill was made by NOUVAG AG, Goldach, Switzerland.

Under general anesthesia, the patient was placed in a supine position with the neck in slight extension. The caudal vertebra was chosen to be drilled for all patients. The entire process was monitored with C-arm fluoroscopy. We used a trephine to directly create the bony channel, which proceeded towards the posterosuperior edge of the targeted vertebra. We primarily confirmed the anterior surface of the drilled vertebra and then selected the channel position with a K-wire under C-arm fluoroscopy (Fig. 1). With the help of two-finger technique (The surgeon located the carotid artery as indicated by its pulsation with the index finger of the left hand and pushed it aside laterally. The tracheoesophagus was then pushed to the medial side with the middle finger), a safe window was created for the insertion of the K-wire and the following operations. The ultrasound examination intraoperative was beneficial if we couldn’t ensure that the vessels had been pushed aside. And the iohexol contrast agent was helpful for confirming the position of the esophagus under C-arm fluoroscopy. We made an approximately 8 mm incision, after which the serial dilators, working cannula and trephine were introduced. We turned the trephine gradually until its tip was located at the posterosuperior border of the vertebra (Fig. 2a and b). Then, the bone plug that was prepared for subsequent CR could be removed together with the trephine by moving it gently in all directions (Fig. 2c). We inserted the working cannula into the bony channel and then inserted the endoscopic system. Bleeding from soft tissues and the channel was resolved by radiofrequency ablation. We could observe some residual bone at the bottom of the channel due to the non-parallel plane between the posterior wall of the vertebra and the bottom of the channel (Fig. 2d). We used a diamond high-speed burr and rongeur to clear these remnants and make a consistent channel towards the herniated lesion. A blunt hook could be used to confirm the posterior wall of the vertebra when a satisfactory channel was established (Fig. 2e). Then, decompression was conducted. To ensure sufficient intraoperative decompression, a small window was made on the posterior longitudinal ligament to directly observe the pulse of the spinal cord (Fig. 2f). When the dural sac re-expansion became apparent, we removed the working cannula from the channel and ensured that no active bleeding was present in the channel. Then, bone grafting was conducted in the channel, in which prior shortening and pruning for the harvested bone had been performed. The insertion process was intently observed via an endoscopy, and the process was terminated when the surfaces of the vertebra and implant were parallel (Fig. 3a and b). We again examined the area for active bleeding before the working cannula and endoscopy were removed. A drainage tube was not necessary. Finally, the residual fluid in the cervical tissues was drained, and the incision was sutured.

Patients could manage their daily activities 1 day after the operation and could return to general office work 1 week postoperatively. All 4 patients underwent follow-up observation at 1, 3, 6, 12, and 22 months after surgery. At each follow-up stage, the results of the VAS, JOA score, modified Macnab criteria, and neurologic examinations were recorded. MRI was conducted 1 week after the operation to confirm decompression, and CT images were used to observe the bony channel at 1 week and 3 months after the operation.