Assessment of CAOS as a training model in spinal surgery: a randomised study

Abstract

The objectives of this study were (1) to quantify the benefit of computer assisted orthopaedic surgery (CAOS) pedicle screw insertion in a porcine cadaver model evaluated by dissection and computed tomography (CT); (2) to compare the effect on performance of four surgeons with no experience of CAOS, and varying experience of pedicle screw insertion; (3) to see if CT with extended windows was an acceptable method to evaluate the position of the pedicle screws in the porcine cadaver model, compared to dissection. This was a prospective, randomised, controlled and blinded porcine cadaver study. Twelve 6-month-old porcine (white skinned Landrace) lumbar spines were scanned pre-operatively by spiral CT, as required for the CAOS computer data set. Computer randomisation allocated the specimens to one of four surgeons, all new to CAOS but with different levels of experience in spinal surgery. The usual anatomical landmarks for the freehand technique were known to all four surgeons. Two pedicles at each vertebral level were randomly allocated between conventional free hand insertion and an electromagnetic image guided surgery (NAVITRAK Ò ) and 6.5 mm cancellous AO screws inserted. Post-operatively, spiral CT was blindly evaluated by an independent radiologist and the spine fellow to assess the accuracy of pedicle screw placement, by each method. The inter-and intra-observer reliability of CT was evaluated compared to dissection. The pedicle screw placement was assessed as perfect if within the pedicle along its central axis, or acceptable (within < 2 mm from perfect), and measured in millimetres from perfect thereafter. One hundred and sixty-six of 168 pedicles in 12 porcine spines were operated on. Complete data were present for 163 pedicles (81 CAOS, 82 freehand). In the CAOS group 84% of screws were deemed acceptable or perfect, compared to 75.6% with the freehand technique. Screw misplacement was significantly reduced using CAOS (P = 0.049). Seventy-nine percent of CAOS screws were ideally placed compared with 64% with a conventional freehand technique (P = 0.05). A logistic linear regression model showed that the miss placed pedicle screw rate was significantly reduced using CAOS (P = 0.047). CAOS benefited the least experienced surgeons most (the research registrars acceptable rate increased from 70 to 90% and the spine fellow from 76 to 86%). CAOS did not have a statistically significant effect on the experienced consultant spine surgeon increasing from 70 to 79% (P = 0.39). The experienced general orthopaedic surgeon did not benefit from CAOS (P = 0.5). CT compared to dissection showed an intra-observer reliability of 99.4% and inter-observer reliability of 92.6%. The

"Free-hand" technique for thoracolumbar pedicle screw instrumentation: Critical appraisal of current "State-of-Art"

“…Therefore, it could be argued that it would not be advisable to learn procedures which employ all these technological apparatus which would probably never be useful in real situations. [29] A critical review on the topic has recognized that computer-assisted operations (CAOS) involve additional surgical steps which take both time and manpower: Operations usually take longer; some products require additional imaging; all systems need to have infrared beacons anchored to bone and which produce significant further morbidity and risks, besides being very expensive (for some center almost prohibitive), has almost the same size as an image intensifier, taking up space in the operating suite and requiring specialized nursing support; and finally, the software contracts associated with each system, may be exorbitant. [30] Conclusions…”

Significance of Preoperative Planning Simulator for Junior Surgeons’ Training of Pedicle Screw Insertion

“…[5][6][7][8] Simulation offers an opportunity for surgical trainees to gain experience carrying out difficult procedures with complex anatomy in a safe environment.…”

“…3 The potential of 3-dimensional software simulation in numerous areas of surgical training is well recognized. [5][6][7][8] The simulator is playing an increasingly important role in surgical training. Surgical trainees new to this operative technique can learn to appreciate the complex 3-dimensional anatomy of the spine, and the implications of small errors in insertion point placement, screw choice, angulation, and depth of insertion.…”

Image-Guided Surgery in the Spine: Neuronavigation vs. Fluoroscopy

“…This is only possible as the instrument applied is equipped with LEDs or reflector elements that are captured by a system of cameras which are connected to the computer that processes the images. 6,[11][12][13][14][15] Cadaveric [16][17][18][19][20][21][22][23] and clinical 8,[24][25][26][27][28][29] studies have demonstrated that neuronavigation in the vertebral column is a safe and accurate method that is more effective than conventional methods for implanting pedicle screws. In a clinical study comparing the precision of the positioning of pedicle screws in the thoracic and lumbosacral spine between the two methods, the authors found an error in the positioning of screws of 13.4% in the conventional surgery group and only 4.6% in the group that used neuronavigation.…”