Miniature robotic guidance for spine surgery--introduction of a novel system and analysis of challenges encountered during the clinical development phase at two spine centres.

BACKGROUND

Instrumented spinal fusion surgery is increasingly performed. Breaching of the pedicle occurs in 3-55% of screws; clinically significant screw misplacements occur in 0-7% of all transpedicular screw placements. Several techniques have reduced this incidence but none gained popularity due to cost as well as staff issues. Surgical robots offer distinct added value in accuracy and minimal invasiveness. The aim of this study is to introduce the SpineAssist--a novel spine surgery miniature robot, to discuss the various reasons that had prevented full success with its use, to identify patients related, technical related, and surgeon related issues, and to offer ways to avoid them.

METHODS

The SpineAssist miniature robotic system is presented, including a short description of the system, its mode of action and a short summary of the surgical procedure.15 patients had undergone lumbar fusion procedures using the robotic system as part of clinical trials in two Israeli spine centres. A group of 9 procedures was identified within this prospective cohort. This group represents a wide array of technical challenges and human errors which were encountered during the clinical development phase of the SpineAssist. These 9 cases were conducted in two different sites by different surgical teams, over a period of 9 months, with an average interval of 7 weeks between consecutive cases. The cases were analysed for patient, system, surgeon and technical issues causing the difficulty. Conclusions were drawn as to how to avoid these hurdles in the future.

RESULTS

In six cases the system operated smoothly, resulting in accurate screws placement according to the pre-operative plan, this was confirmed by a post-operative CT scan. Technical and surgical challenges which are associated with the system early development stage were encountered during 9 procedures. On the technical side, the following phenomena were evident: 1) failure of the software to automatically achieve satisfying CT-to-fluoro image registration and 2) failure of the hospital's peripheral equipment/logistics preventing registration. On the clinical side of things, the following issues were encountered: 1) failure to avoid excessive pressure on the guiding arm caused by surrounding soft tissues, leading to a shift in the entry point and trajectory of the tool guide. 2) a surgeon applying too much force on the tool guide at the tip of the robotic arm, causing deviation from plan. 3) pre-operative plan out of the reach of the robot arm and 4) attachment of the clamp to the spinous process in a suboptimal orientation.

CONCLUSIONS

It is expected that following a steep learning curve in the range of 5-10 cases, recommended to take place within 2-3 weeks time, the surgical team will gain sufficient experience in operating the SpineAssist miniature robotic device in order to achieve excellent surgical results. The system may be used for wide range of applications including but not limited to pedicle screws, trans-facet and trans-laminar screws, biopsy needles, vertebroplasty or kyphoplasty tools and more. The preoperative plan has to be logical, intraoperative fluoro images taken with care, gentle surgical technique must be kept - maintaining the integrity of the posterior elements, and avoiding pressure between the robot arms and the soft tissues. During the clinical development phase discussed in this study, both teams used an early version of the system. Based on the results of this study several significant software and hardware improvements have already been implemented. It is our hope that describing and analysing our findings will help in planning and preparing for the clinical utilization of the SpineAssist system in future sites and will shorten their learning curve. By the time this article is published wider clinical experience will have been gathered and we expect to soon follow up with an analysis of clinical utilization of this system in a larger study group.