The results indicate the CADISS® system may be an effective method for the dissection of fibrosis in revision spine surgery and could be quicker and easier compared to current practice. The 95.8% of successful dissections over all the operations and high satisfaction and usability scores suggest CADISS® may have advantages that could benefit both surgeons’ practice and patients’ surgery and post-surgery experience. However, there were some limitations to the study and understanding these will allow the indicated conclusions in this study to be further investigated in the future.
Surgery was only unsuccessful in one patient. It involved dissection of a neurinoma L4/L5 tissue. This unsuccessful dissection was the first patient to be operated on by this surgeon and the contact time between the MESNA solution and fibrosis seemed to be shorter. In addition, the surgeon may still have been unfamiliar with using the CADISS® system. This explains the lower score for global satisfaction that was observed, which is due to the low outlying score for this one operation. All other following dissections were successful, and all dissections performed by the other surgeon were also successful. As only one SAE was thought to be related to the use of CADISS®, it suggests the risk of additional complications would be low with this method.
Quickness of action was the only endpoint with a lower median score, with 7 on the Likert scale. This can be explained by the waiting time of around 5 minutes that is required for the chemical action of the MESNA to take effect on the fibrotic tissues (21). Although the score is lower than other endpoints, it is still above 5, which indicates an improvement of the speed of dissection in comparison to current practice, according to the surgeons’ subjective opinion. Therefore, although a lower score was observed here, it still suggests the CADISS® system may be a quicker method than the typical method in use for these kinds of spine surgery procedures.
Dural tears are one of the most common complications of spine surgery, particularly in the lumbar area and for revision surgeries (14,22–25). As previously mentioned, dural tear rates are usually between 7 and 17% for lumbar revision spine operations (14). Furthermore, dural tears sustained with posterior lumbar spinal decompression and/or fusion surgery can significantly increase the length of hospital stay, risk of readmission and the overall 90-day hospital cost (26). They have also been found to increase the risk of venothromboembolic events by 1.46 times and meningitis by 6 times, both of which can lead to patient morbidity (26). In the current study, no dural tears were observed meaning there was a complete absence of ID when using the CADISS® method. Considering the typical incidence of ID and associated risks, the absence seen here supports the suggestion CADISS® is a safe method for this kind of surgery and may even reduce normal rates of usually observed complications. This is also made apparent when looking at the individual case studies we reported, particularly the 46-year-old patient who had experienced multiple lumbar spine surgeries. This patient had numerous complications and continuing back pain after previous operations, but she had no intra or post-operative complications, including dural tears, after the operation with CADISS® up to hospital discharge. This is reflected in the case of the second patient we discussed as well. Although these are only two cases which have been discussed within the full study of 24 operations, the results are promising when considering typical dural tear rates.
The results are also in line with the conclusions of a previous study, discussed in our background, in which a chemically assisted mechanical dissection with MESNA was used (15). In comparison to this previous study using MESNA to chemically assist dissection in revision lumbar spine surgery, there were both differences and similarities. The previous study included a blinded control group, however, as already mentioned, it only used chemically assisted dissection. The current study used the CADISS® method, still using MESNA application but with a solution composition developed for surgical application and a more sophisticated operational system in a typical practice setting. The remote kit and foot pedal of the CADISS® system allowed the surgeons to decide more precisely the volume of MESNA that was appropriate to use for each operation and gave them more control over the release of MESNA. In the 2010 study, less dural tears (1/15) were observed in the MESNA-controlled compared with their control group (4/15), while none were observed in the current study. Alongside the high global satisfaction and usability scores in this study, this suggests CADISS may have an advantage.
There were a few limitations with the current study. Primarily, the small cohort size and the absence of a direct comparison mean concrete conclusions regarding the benefits of CADISS®-assisted dissection cannot yet be made. Further clinical studies using a larger cohort and a comparison group, using the CADISS® device in regular practice, are necessary to fully verify the advantages using of this system. As it stands, there is some potential for CADISS® System to improve current practices and it ought to be investigated further.
If further investigations are made, and the preliminary conclusions from this study are confirmed, it could be greatly beneficial to this surgical field. If the CADISS® method proves to be advantageous, it could improve surgical practice for surgeons and reduce costs to health services. In addition, patients undergoing spine surgery may be able to have a smoother operation and lower risks of complications and pain post-surgery. Therefore, further research into the CADISS® system for revision spine surgery, and in other surgical fields, is encouraged.