An official journal of Neuro Spinal Surgeons Association, India

ISSN 0975-2625 Vol No. 3 Issue No. 2 An official journal of Neuro Spinal Surgeons Association, India Cervical disc arthroplasty Radiation exposure during MISS Spinal arachnoid webs in adults Lateral mass fusion (CD-ROM enclosed) Developed, Designed & Published by Neuro Spinal Surgeons Association, India Unit No.602, Opulence 6th Road, TPS III, Santacruz (E), Mumbai - 400 055. Contact : info@medulla.in Website : www.medulla.in

Fluoroscopic exposure during percutaneous insertion of Interspinous Process Devices (IPDs) Patrick Fransen, MD Department of Neurosurgery, Clinique du Parc Léopold CHIREC, Brussels, Belgium Abstract Objective: This prospective case control study documents the level of radiation expected during percutaneous implantation of Interspinous Process Devices (IPDs). Methods: Percutaneous implantation of IPDs for neurogenic claudication caused by degenerative spinal stenosis is a recent addition to spinal surgery. However, the level of radiation exposure for this technique has never been reported. We collected the exposure data [Fluoroscopy Time (FT) in seconds and Radiation Dose (RD) in mgycm2] of 22 patients using the dose report provided by the digital interface of the fluoroscope. Forty implants were inserted under biplanar fluoroscopy. The IPDs (Aperius, Medtronic Inc., and Inspace, Synthes Inc.) were implanted percutaneously through a lateral incision, targeting the anterior third of the interspinous space and the midline. Results: The mean FT/patient was 110 sec and 61 sec/implant. The mean RD/patient was 7115 mgycm2 and 3913 mgycm2/implant. The first 10 patients required 59.2 sec FT/operation and the last 10, 62.2 sec FT/operation. There was no significant surgical learning curve influencing the quantity of radiation used during surgery. There was a 1 to 3, 45 difference ratio in the use of the fluoroscope between the two surgeons. (1621 mgycm2/implant and 29 sec/level versus 5607 mgycm2/implant and 83 sec/level). Conclusion: This quantification of the dose and duration of radiation during percutaneous implantation of IPDs shows that a high amount of radiation is necessary, making lead-coated protection clothing and careful use of the fluoroscope mandatory. Despite an easy learning curve, striking differences in fluoroscopic exposure between operators reveal the need for surgeon awareness and training. Introduction Key Words Minimally invasive spine surgery Neurogenic claudication Lumbar spinal stenosis Percutaneous interspinous process device Perioperative imaging Percutaneous implantation of Interspinous Process Devices (IPDs) for the treatment of neurogenic claudication caused by degenerative spinal stenosis and resistant to conservative treatment is one of the latest additions to the armamentarium of spinal surgery. Although long term results are still missing, short term improvement of gait perimeter and leg pain have been 1,2 reported with this technique. Percutaneous implantation of this device however requires preoperative fluoroscopic control. As the level of radiation exposure is not known for this new technique, we decided to prospectively collect the data regarding the use of the fluoroscope during these operations. Trying to achieve norms It is not easy to establish norms for such a study. There is no easy answer. Although norms would be an elegant solution, it is more a question of awareness of the surgeons and of his anxiety level during surgery that will change the level of radiation exposure. It would be difficult to limit the fluoroscopy time of surgeons for a given operation, because the surgeon might feel less comfortable with the accuracy of the positioning of the implant. Also, these Received: 05-02-11; Revised: 28-02-11; Accepted:30-05-11 Disclosures: This article has not received any funding and has no vested commercial interest Acknowledgements: The authors would like to express their gratitude to Mrs Aurelie Valentin for her help in the collection of these data. No grant or financial support has been received for this study. 667

Fransen P norms or guideline would need to be result of a consensus; which is always difficult to reach. In my eyes, the purpose of this article is about increasing the awareness amongst surgeons, and for the younger ones, about including this awareness in their surgical training and education. Materials and methods The study design is a prospective case control study. We collected the data of 22 patients, 14 men and 8 women, aged 42 to 77 (mean age 60 years-old) between March 2007 and April 2009. The data were collected at the time of surgery, using the dose report provided by the digital interface of the fluoroscope. Fluoroscopy Time (FT) was measured in seconds and radiation dose (RD) in mgycm2 (Figure 1 and 2). 22 patients were operated by two surgeons (12 and 10 operations respectively). Forty implants were inserted under biplanar surgeon controlled fluoroscopy. The implanted IPDs (Aperius Medtronic Inc, Memphis USA, and Inspace Synthes Inc., Solothurn, Switzerland) were implanted percutaneously through a lateral incision. The target area was the anterior third of the interspinous space as seen on the lateral view and the midline as seen on the antero-posterior view. Results The mean fluoroscopy time/patient was 110 sec and 61 sec/implant. The mean radiation dose/patient was 7115 mgycm2 and 3913 mgycm2/implant. The first 10 patients required an average 59.2 sec FT/operation and the last 10, 62.2 sec FT/operation. There was no significant influence of the surgical learning curve on the quantity of radiation used during surgery. There was a 1 to 3, 45 difference ratio in the use of the fluoroscope between the two surgeons. One surgeon used an average 1621 mgycm2 and /implant and 29 sec/level, whereas the second surgeon used an average 5607 mgycm2/implant and 83 sec/level. Discussion Figure 1 Percutaneous procedure under fluoroscopic guidance Protection Glasses Thyroid shield Hand gloves or hand should be held behind Body protection gown Figure 2 Steps taken for radiation protection during fluoroscopy The implementation of a new surgical technique implies that surgeons should not only monitor clinical results, but also prospectively collect the data of all the specific 3 requirements of this technique. This is particularly crucial with Minimally Invasive Spinal Surgery (MISS) that systematically requires an increased use of preoperative fluoroscopic controls. The radiation exposure to the patient and to the surgeon has been addressed in several publications regarding 4 5 kyphoplasty, vertebroplasty, percutaneous placement of 6 cervical screws or minimally invasive transforaminal 7 interbody fusion. All these studies show that although perioperative imaging is often the key for MISS, it is associated with a nonnegligible increase in radiation exposure when compared to open surgery. They praise the use of preventive measures such as leaded coats, thyroid protection, radio-protective gloves and glasses and the use of a source-inferior position of the C-arm. We present the first evaluation of radiation during percutaneous interspinous device implantation. Our results 668

Fluoroscopic exposure in OT confirm the previously mentioned studies, stressing the fact that efforts to reduce fluoroscopy time and radiation exposure should be made particularly as fluoroscopy time and radiation exposure varies widely between surgeons for the same procedures. Awareness of the surgeon and radioscopy focused training should certainly be encouraged. We also found in our department that monitoring the radiation exposure allowed us improve and standardize the visualization technique and so, to reduce the dose delivery to the patient. In the future, three-dimensional imaging as offered by navigation assisted fluoroscopy systems may help to decrease the radiation exposure, but very little literature 8,9 has been published to this date. Also, the accuracy of such systems to position implants in the soft tissue between the vertebrae still has to be proven as the navigation systems have been designed to position rigid implants in fixed structures, not between them. Conclusion This first ever quantification of the dose and duration of radiation during the implantation of percutaneous interspinous devices shows that this technique requires a non negligible amount of radiation. Therefore lead-coated protection clothing and careful use of the fluoroscope are mandatory. Although the learning curve is very flat, striking differences between operators reveal the need for awareness and education during fluoroscopically controlled MISS. References 1. Collignon F, Fransen P. Traitement de la sténose lombaire dégénérative symptomatique par mise en place percutanée d implants interépineux. Expérience préliminaire avec l implant APERIUS. Neurochirurgie 56 (1) : 3-7, 2010 2. Nardi P, Cabezas D, Rea G, Pettorini BL. Aperius perclid stand alone interspinous system for the treatment of degenerative lumbar stenosis: experience on 152 Cases. J Spinal Disord Tech. 23(3):203-7, 2010 3. Fransen P. Les techniques minimalement invasives en chirurgie rachidienne : introduction ; table ronde de la réunion de la société de neurochirurgie de langue française du 5 novembre 2008. Neurochirurgie 56 (1) : 1-2, 2010 4. Mroz TE, Yamashita T, Davros WJ, Lieberman IH. Radiation exposure to the surgeon and the patient during kyphoplasty. J Spinal Disord Tech. 21(2) :96-100, 2008 5. Fitousi NT, Efstathopoulos EP, Delis HB, Kottou S, Kelekis AD, Panayiotakis GS. Patient and staff dosimetry in vertebroplasty. Spine (Phila Pa 1976). 31(23): E884-9; discussion in E890, 2006 6. Holly LT, Foley KT. Percutaneous placement of posterior cervical screws using three-dimensional fluoroscopy. Spine (Phila Pa 1976). 31(5):536-40; discussion 541, 2006 7. Bindal RK, Glaze S, Ognoskie M, Tunner V, Malone R, Ghosh S : Surgeon and patient radiation exposure in minimally invasive transforaminal lumbar interbody fusion. J Neurosurg Spine 9(6): 570-3, 2008 8. Nakashima H, Sato K, Ando T, Inoh H, Nakamura H. Comparison of the percutaneous screw placement precision of isocentric C- arm 3-dimensional fluoroscopy-navigated pedicle screw implantation and conventional fluoroscopy method with minimally invasive surgery. J Spinal Disord Tech. 22(7) :468-72, 2009 9. Kim CW, Lee YP, Taylor W, Oygar A, Kim WK.: Use of navigationassisted fluoroscopy to decrease radiation exposure during minimally invasive spine surgery. Spine J. 8(4): 584-90. Epub 2007 Feb 20, 2008 Address for correspondence: Dr. Patrick Fransen: Email: p.fransen@neurobrussels.be 669