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

Recent Trends, Technical Concepts and Components of Computer-Assisted Orthopedic Surgery Systems: A Comprehensive Review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.

Using Porcine Cadavers as an Alternative to Human Cadavers for Teaching Minimally Invasive Spinal Fusion: Proof of Concept and Anatomical Comparison

Training surgeons to perform minimally invasive spinal (MIS) surgery is difficult because there are few realistic alternatives to human cadavers which are expensive and require special handling. In this study we report a protocol for performing an MIS training course on a fresh porcine cadaver. We find that the porcine lumbar spine closely resembles the human spine in terms of the vertebral and discal anatomy. Notable differences include a lower disc height and shallower diameter. We obtained fresh porcine cadavers weighing 40-70 kg from local farmers that had been gutted and bled. We position the cadaver prone on a backboard and set up the operating room with biplanar fluoroscopy. During approach and cage insertion, we found that the tactile feedback obtained is realistic and allows surgeons to familiarize themselves with the procedure. Porcine cadavers were also an excellent tool for practicing pedicle screw fixation due to the larger pedicles. Five training courses involving eight surgeons noted that except for anatomical differences the training course was equivalent to training on human cadavers and unanimously preferred training on porcine cadavers to synthetic foam models. We conclude that porcine cadavers are a useful model for training surgeons in MIS surgery. Routine use of porcine cadavers may increase the availability of MIS surgery training.

A low invasiveness patient’s specific template for spine surgery

Free-hand pedicle screw placement is still conventional in surgery, although it has potentially high risks. The surgical procedures such as pedicle screw placement are usually designed based on medical imaging, but during surgery, the procedures are not normally followed due to the fact that some points are missed in two-dimensional images and seen only during surgery. In this regards, some highly accurate computer-assisted systems have been proposed and are currently used. Moreover, it is possible to reduce or completely avoid hand working by applying modern digital technology. Therefore, using these technologies has remarkable advantages. In this study, we have presented a new approach of pedicle screw placement in the lumbar and sacral regions using a specific drill guide template. The template was created by additive manufacturing technology and was verified in a clinical study as well. The main aim of this research includes the following: design, analyze, manufacture and evaluate the accuracy of a new patient-specific drill guide template, for lumbar pedicle screw placement, and compare the template to the free-hand technique under fluoroscopy supervision. Our results show that the incidence of cortex perforation is substantially reduced compared to existing methods. Finally, we believe that this approach remarkably lowers the incidence of cortex perforation and could be potentially used in clinical applications, particularly in certain selected cases.

IMAGE-GUIDED SURGERY IN THE SPINE: NEURONAVIGATION VS. FLUOROSCOPY

Objectives:To evaluate the accuracy and the operative complications of implanting pedicle screws in the thoracic and lumbar spine, using computer-assisted surgery compared to the implantation technique using fluoroscopy.Methods:A retrospective study was conducted at the Hospital Universitário Cajuru PUC-PR from January 2000 to January 2009. Two groups of patients undergoing implant pedicle screws were analyzed (n=80). Group I received implant pedicle screws through fluoroscopy technique and group II, through neuronavigation technique. The accuracy of positioning of pedicle screws was evaluated using rating scales.Results:The accuracy was higher in group II, where 77.5% of the screws were correctly positioned, whereas there were only 28.5% in group I (p=0.001). There was a reduction of 95% (CI: 80-97%) in the risk of screws misplacement in group II. The average operation time was 312.2±78.1 minutes in group I and 270.3±41.4 in group II (p=0.004). Blood transfusion was needed in 28 patients in group I and 10 patients in group II (p=0.005), resulting in 64% risk reduction of blood transfusion in group II. Eight patients in group I underwent revision surgery whereas only one patient in the group II, that is, 75% of surgical revision risk reduction.Conclusion:The implantation technique of pedicle screws using neuronavigation is a more accurate method and has less operative complications compared with the technique that uses fluoroscopy.

Significance of preoperative planning simulator for junior surgeons' training of pedicle screw insertion

STUDY DESIGN

A prospective study to access the significance of preoperative planning simulator for junior surgeons' training of pedicle screw insertion.

SUMMARY OF BACKGROUND DATA

Pedicle screw insertion is particularly challenging to carry out on patients with abnormal spine morphology, especially for the doctors who lack experience. Currently, preoperative planning for pedicle screw insertion is carried out using patient computed tomography and magnetic resonance imaging scans. In addition, there is no projection fluoroscopy provided to the user.

OBJECTIVE

The aim of this study was to investigate the feasibility and efficacy of a 3-dimensional, patient-specific volume rendering combined with the projection fluoroscopy simulator for training junior surgeons with no experience of pedicle screw insertion, and to help identify the role such simulation has in surgical education.

METHODS

Two junior surgeons with no experience of pedicle screw insertion were trained on the technique through the preoperative planning simulator; the operative time and the position of the pedicle screws were assessed before training (control group 1) and after training (experimental group) and compared with 2 senior spine surgeons with >10 years' experience of pedicle screw insertion (control group 2).

RESULTS

The time of per pedicle screw insertion was 43.5±3.9 seconds in control group 1, 31.6±2.9 seconds in control group 2, and 50.8±3.7 seconds in experimental group. The relative position of the screw to the pedicle was graded regarding pedicle breach (I, no breach; II, <2 mm; III, 2-4 mm; IV, >4 mm). The pedicle breach grading I and II was 20 pedicle screws (20/56, 35.7%) in control group 1, 54 pedicle screws (54/56, 96.4%) in control group 2, and 44 pedicle screws (44/56, 78.6%) in the experimental group. There were significant differences between control group 1 and experimental group in the time of per pedicle screw insertion (P<0.001) and the rate of pedicle breach grading I and II (P<0.001). There were significant differences between control group 2 and experimental group in the time of per pedicle screw insertion (P<0.001) and the rate of pedicle breach grading I and II (P=0.004).

CONCLUSIONS

The simulator offers many helpful features to the surgeon with respect to the surgical trainee learning the basic technique of pedicle screw insertion, using free-hand technique or under the guiding of intraoperative fluoroscopy. The surgical skills of the junior surgeons can be significantly improved through the training of simulator.

A multi-level rapid prototyping drill guide template reduces the perforation risk of pedicle screw placement in the lumbar and sacral spine

INTRODUCTION

The method of free-hand pedicle screw placement is generally safe although it carries potential risks. For this reason, several highly accurate computer-assisted systems were developed and are currently on the market. However, these devices have certain disadvantages. We have developed a method of pedicle screw placement in the lumbar and sacral region using a multi-level drill guide template, created with the rapid prototyping technology and have validated it in a clinical study. The aim of the study was to manufacture and evaluate the accuracy of a multi-level drill guide template for lumbar and first sacral pedicle screw placement and to compare it with the free-hand technique under fluoroscopy supervision.

MATERIALS AND METHODS

In 2011 and 2012, a randomized clinical trial was performed on 20 patients. 54 screws were implanted in the trial group using templates and 54 in the control group using the fluoroscopy-supervised free-hand technique. Furthermore, applicability for the first sacral level was tested. Preoperative CT-scans were taken and templates were designed using the selective laser sintering method. Postoperative evaluation and statistical analysis of pedicle violation, displacement, screw length and deviation were performed for both groups.

RESULTS

The incidence of cortex perforation was significantly reduced in the template group; likewise, the deviation and displacement level of screws in the sagittal plane. In both groups there was no significantly important difference in deviation and displacement level in the transversal plane as not in pedicle screw length. The results for the first sacral level resembled the main investigated group.

CONCLUSIONS

The method significantly lowers the incidence of cortex perforation and is therefore potentially applicable in clinical practice, especially in some selected cases. The applied method, however, carries a potential for errors during manufacturing and practical usage and therefore still requires further improvements.

Image guidance shortens the learning curve for K-wire placement - an experimental study

BACKGROUND

Computer assisted systems in orthopaedic trauma depend in most cases on fixed reference markers. This work evaluated a reference-free image-based guidance system. Outcome parameters were the number of trials needed to achieve an optimal wire position, the radiation and procedure time, and the learning curve.

METHODS

Forty artificial proximal femora covered in polyurethane foam were used and randomized in two groups. Each bone was equipped with a target marker at the fovea capitis femoris. Two surgeons each inserted 20 K-wires, 10 with and 10 without assistance from the guidance system. The aim was to bring the tips of the K-wires as close as possible to the target marker. Both procedures were performed under fluoroscopic control. The new guidance system is based on 2D-C-arm images. Following the procedure the result was determined using computed tomography.

RESULTS

The same accuracy (P = 0.34) was achieved with less time (P = 0.0008) and less radiation (P = 0.0002) with the guidance system. However, use of the guidance system did shorten the learning curve of both surgeons, leading to a reduced number of trials (P <0.0001). The learning curve of both surgeons was strongly correlated. From the first trial, the performance of both surgeons while using the guidance system, improved over their performance without the guidance system.

CONCLUSIONS

The guidance system helped to achieve an optimal K-wire position with less radiation and less time. The major advantage is the ability of the guidance system to be integrated into the workflow and the short and flat learning curve.

The rate of screw misplacement in segmental pedicle screw fixation in adolescent idiopathic scoliosis

BACKGROUND AND PURPOSE

There are no reports in the literature on the influence of learning on the pedicle screw insertion. We studied the effect of learning on the rate of screw misplacement in patients with adolescent idiopathic scoliosis treated with segmental pedicle screw fixation.

METHOD

We retrospectively evaluated low-dose spine computed tomography of 116 consecutive patients (aged 16 (12-24) years, 94 females) who were operated during 4 periods over 2005-2009 (group 1: patients operated autumn 2005-2006; group 2: 2007; group 3: 2008; and group 4: 2009). 5 types of misplacement were recorded: medial cortical perforation, lateral cortical perforation, anterior cortical perforation of the vertebral body, endplate perforation, and perforation of the neural foramen.

RESULTS

2,201 pedicle screws were evaluated, with an average of 19 screws per patient. The rate of screw misplacement for the whole study was 14%. The rate of lateral and medial cortical perforation was 7% and 5%. There was an inverse correlation between the occurrence of misplacement and the patient number, i.e. the date of operation (r = -0.35; p < 0.001). The skillfulness of screw insertion improved with reduction of the rate of screw misplacement from 20% in 2005-2006 to 11% in 2009, with a breakpoint at the end of the first study period (34 patients).

INTERPRETATION

We found a substantial learning curve; cumulative experience may have contributed to continued reduction of misplacement rate.