To the best of our knowledge, this is the first report on the evaluation of the clinical results of a 3D exoscope for decompression of massive LDH. In the present study, with the help of a clear and deep surgical field visualized by the 3D exoscope, the decompression process could be performed under the condition of minimally invasive exposure. As it was easy to operate under a 3D exoscope, there was no need for excessive traction of the patient’s incision. The internal vertebral venous plexus clearly displayed in the eyepiece is also conducive to timely hemostasis. However, in consideration of the differences in surgical techniques, habits of the surgeons and routine operations, the operation time and EBL were reported differently. Kim M et al. reviewed 748 Korean subjects and reported that the open lumbar microdiscectomy group’s average operation time was 83.99 min and the average hospital stay was 7.47 days [17]. Liu et al. reported that the mean EBL in microdiscectomy was 26 ± 15 ml [18]. Results of our present study demonstrated functional improvement with significantly improved VAS scores for back and leg pain and ODI score postoperatively. For the LOVE surgery, the mean decompression time was 15.50 ± 5.84 min, which is shorter compared with results of Kim M et al. The mean EBL during decompression was 24.32 ± 8.61 ml, which is resemble to results of Liu et al. Compared with LOVE surgery, additional procedures such as removing of cartilaginous end plates and inserting of cage for LIF led to increased decompression time (28.35 ± 8.93 min) and mean EBL (42.65 ± 12.42 ml) during the operation.
In our department, the length of stay is sometimes lengthened by some preoperative examinations such as MRI, lung function and echocardiography. However, PLS is closely related to the operation effect, complication rate and side effects. Therefore, we investigated the PLS and results showed the mean PLS was 4.56 ± 0.82 days (LIF) and 2.00 ± 0.65 days (LOVE surgery).
Gupta A reported that complications observed in the discectomy of massive LDH were 11% [2]. Dural tear and infection are the common complications during decompression. According to a review conducted by the British Association of Spinal Surgeons, the incidence of cerebrospinal fluid leakage was 3.5% in primary discectomy and 13.2% in revision discectomy, while the infection rate was as high as 3% [19]. In most cases, the dural tear is small in size, and therefore, conservative treatment is adopted. In our study there were no complications such as cerebrospinal fluid leakage, nerve root injury or epidural hematoma. With the assistance of the 3D exoscope, the surgeon and the assistant could more accurately identify the adhesion of the nerve root, dural sac, and the adhesion between the protruding nucleus pulposus and the surrounding tissue. Intraoperative explorations were reduced, which greatly decreased the pulling time of the nerve root during decompression and accidental injury of the nerve root caused by the nerve root retractor due to the poor visual field of the assistant. Hence, less damage occurred to the dural sac and nerve root when the adhesion site was peeled off. A 3D exoscope not only makes the field of vision for this form of minimally invasive spinal surgery clearer but also enlarges it, which improves 3D spatial recognition. This enables surgeons to maneuver with precision and ease especially in high-risk patients with massive LDH or anatomical difficulties.
It is well known that patients who fail to respond to conservative treatment are treated with surgery. The aim is to remove the herniated nucleus pulposus and relieve nerve compression [20]. There are many surgical strategies for massive lumbar disc herniation, such as decompressive laminotomy; discectomy; endoscopic lumbar discectomy and transforaminal lumbar interbody fusion [2, 4, 21, 22]. There is a learning curve for any surgical procedure, but open discectomy is mastered by the vast majority of spinal surgeons. Presently, spine surgery has become minimally invasive by using a microscope or an endoscope, and effective postoperative results have been reported [23]. Chiu RG et al. concluded that patients who underwent endoscopic decompression were less likely to experience postoperative complications and surgical site infection [24]. Additionally, when the surgeons used the binocular microscope for viewing the operating field, they were required to stand higher and observe from an upward viewing angle in order to adapt to the position of the microscope oculars. A 3D exoscope negates the use of the traditional eyepiece to observe the anatomical regions and thus frees the surgeon from adopting the non-upright posture for observation, thereby relieving fatigue during long-term surgery. Joachim M. Oertel interviewed 15 surgeons in Saarland University Medical Center (Homburg-Saar, Germany) for evaluation of their intraoperative posture comfort, and all of them rated their comfort as excellent [25].
More surgical equipment and instruments will be required if interbody fusion needs to be performed in some cases; for such situations, it is necessary to optimize the operation plan and the space layout of the operating room in advance in order to avoid unnecessary prolongation of surgical time because of space congestion due to several instruments. Frykman PK believes that the exceptional intraoperative images provided by a 3D exoscope are more valuable for scrub and itinerant nurses, because these images allow them to understand better the operative process, facilitate surgical cooperation, and shorten the surgical time [26]. The 3D exoscope system allows both the surgeon and the remaining operating room team members to experience the surgical process while viewing through conveniently positioned high-definition video monitors as compared with the traditional endoscope. Our experience is consistent with the above reports.
Spinal surgery teaching often requires the adoption of the one-to-one apprenticeship mode because of small incision and narrow surgical field. Moreover, clinical skills can be directly acquired under the supervision of experienced spinal surgeons. This teaching method, however, has limitations because of high cost and work timings. Spinal surgery teaching also has related constraints due to the increased cost of surgical training on cadavers and animals and the increased risk of contracting infectious diseases. A 3D exoscope allows surgeon and resident doctors to observe the surgical area from the same view interactively and immersively, thereby making the traditional, single, and dull teaching method more flexible and interesting. The video recording system of a 3D exoscope can simultaneously record the operation process, which is significantly helpful for the training of junior spinal surgeons. Thus, the use of a 3D exoscope can enable the resident doctors to observe and learn how experienced surgeons handle the instruments and to obtain better understanding of the operative process. Although quantitative assessments are lacking, resident doctors have reported to make progress in their understanding of the operative technique.
Several limitations to this study existed. As this study was designed as a preliminary application of a 3D exoscope for assistance during surgery of patients with spinal degenerative diseases, the sample size was small and the study was retrospective in nature with no control group for comparison. Further studies with a large sample size and multicenter studies are warranted to confirm the findings of the present study. All operations were performed by spinal surgeons with abundant clinical experience in our hospital, and the final conclusions may vary according to the experience of surgeons in different hospitals.