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The surgical learning curve and accuracy of minimally invasive lumbar pedicle screw placement using CT based computer-assisted navigation plus continuous electromyography monitoring - a retrospective review of 627 screws in 150 patients.

Wood MJ, McMillen J - Int J Spine Surg (2014)

Bottom Line: With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients.Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit.Pedicle screw placement accuracy continues to improve as the surgeon becomes more experienced with the technique.

View Article: PubMed Central - PubMed

Affiliation: Mater Misericordiae Private Hospital, South Brisbane, Queensland, Australia.

ABSTRACT

Objective: This study retrospectively assessed the accuracy of placement of lumbar pedicle screws placed by a single surgeon using a minimally-invasive, intra-operative CT-based computer navigated technique in combination with continuous electromyography (EMG) monitoring. The rates of incorrectly positioned screws were reviewed in the context of the surgeon's experience and learning curve.

Methods: Data was retrospectively reviewed from all consecutive minimally invasive lumbar fusions performed by the primary author over a period of over 4 years from April 2008 until October 2012. All cases that had utilized computer-assisted intra-operative CT-based image guidance and continuous EMG monitoring to guide percutaneous pedicle screw placement were analysed for the rates of malposition of the pedicle screws. Pedicle screw malposition was defined as having occurred if the screw trajectory was adjusted intraoperatively due to positive EMG responses, or due to breach of the pedicle cortex by more than 2mm on intraoperative CT imaging performed at the end of the instrumentation procedure. Further analysis of the data was undertaken to determine if the rates of malposition changed with the surgeon's experience with the technique.

Results: Six hundred and twenty-seven pedicle screws were placed in one hundred and fifty patients. The overall rate of intraoperative malposition and subsequent adjustment of pedicle screw placement was 3.8% (24 of 627 screws). Screw malposition was detected by intraoperative CT imaging. Warning of potential screw misplacement was provided by use of the EMG monitoring. With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients. Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit.

Conclusion: The use of CT-based computer-assisted navigation in combination with continuous EMG monitoring during percutaneous transpedicular screw placement results in very low rates of malposition and neural injury that compare favourably with previously reported rates. Pedicle screw placement accuracy continues to improve as the surgeon becomes more experienced with the technique.

No MeSH data available.


Related in: MedlinePlus

Pedicle screw malposition and adjustment learning curve.
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Figure 0001: Pedicle screw malposition and adjustment learning curve.

Mentions: The incidence of screw malposition and subsequent intraoperative adjustment was analysed in the context of increasing familiarity and expertise of the surgeon with the technique. The rates of pedicle cannulation trajectory adjustment per surgical case fell from an initial incidence of 8 cases requiring intraoperative adjustment in the first 50 cases (16%) to a rate of 3 of the final 50 cases (6.0%). Similarly, the total rates of malpositioned pedicle cannulation or screw placement requiring adjustment related to the total number of screws placed fell from 11 of 216 screws (5.1%) in the first 50 cases, to 9 of 209 screws (4.3%) in the second 50 cases, and 4 of 202 screws (2.0%) in the final 50 cases. The rates of screw adjustment subsequent to both monitoring modalities, EMG and intraoperative CT, both showed reducing rates with increasing surgical expertise. Trajectories that were adjusted due to positive EMG signals decreased from 9 of 216 screws placed (4.2%) in the first 50 cases to 3 of 202 screws (1.5%) in the last 50 cases performed over the final 14 months of the study. Pedicle screws that were malpositioned on end-of-procedure intraoperative CT imaging fell from 4 of 216 screws (1.9%) to 1 of 202 screws (0.5%). A summary of these results appears in Figure 1.


The surgical learning curve and accuracy of minimally invasive lumbar pedicle screw placement using CT based computer-assisted navigation plus continuous electromyography monitoring - a retrospective review of 627 screws in 150 patients.

Wood MJ, McMillen J - Int J Spine Surg (2014)

Pedicle screw malposition and adjustment learning curve.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4325487&req=5

Figure 0001: Pedicle screw malposition and adjustment learning curve.
Mentions: The incidence of screw malposition and subsequent intraoperative adjustment was analysed in the context of increasing familiarity and expertise of the surgeon with the technique. The rates of pedicle cannulation trajectory adjustment per surgical case fell from an initial incidence of 8 cases requiring intraoperative adjustment in the first 50 cases (16%) to a rate of 3 of the final 50 cases (6.0%). Similarly, the total rates of malpositioned pedicle cannulation or screw placement requiring adjustment related to the total number of screws placed fell from 11 of 216 screws (5.1%) in the first 50 cases, to 9 of 209 screws (4.3%) in the second 50 cases, and 4 of 202 screws (2.0%) in the final 50 cases. The rates of screw adjustment subsequent to both monitoring modalities, EMG and intraoperative CT, both showed reducing rates with increasing surgical expertise. Trajectories that were adjusted due to positive EMG signals decreased from 9 of 216 screws placed (4.2%) in the first 50 cases to 3 of 202 screws (1.5%) in the last 50 cases performed over the final 14 months of the study. Pedicle screws that were malpositioned on end-of-procedure intraoperative CT imaging fell from 4 of 216 screws (1.9%) to 1 of 202 screws (0.5%). A summary of these results appears in Figure 1.

Bottom Line: With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients.Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit.Pedicle screw placement accuracy continues to improve as the surgeon becomes more experienced with the technique.

View Article: PubMed Central - PubMed

Affiliation: Mater Misericordiae Private Hospital, South Brisbane, Queensland, Australia.

ABSTRACT

Objective: This study retrospectively assessed the accuracy of placement of lumbar pedicle screws placed by a single surgeon using a minimally-invasive, intra-operative CT-based computer navigated technique in combination with continuous electromyography (EMG) monitoring. The rates of incorrectly positioned screws were reviewed in the context of the surgeon's experience and learning curve.

Methods: Data was retrospectively reviewed from all consecutive minimally invasive lumbar fusions performed by the primary author over a period of over 4 years from April 2008 until October 2012. All cases that had utilized computer-assisted intra-operative CT-based image guidance and continuous EMG monitoring to guide percutaneous pedicle screw placement were analysed for the rates of malposition of the pedicle screws. Pedicle screw malposition was defined as having occurred if the screw trajectory was adjusted intraoperatively due to positive EMG responses, or due to breach of the pedicle cortex by more than 2mm on intraoperative CT imaging performed at the end of the instrumentation procedure. Further analysis of the data was undertaken to determine if the rates of malposition changed with the surgeon's experience with the technique.

Results: Six hundred and twenty-seven pedicle screws were placed in one hundred and fifty patients. The overall rate of intraoperative malposition and subsequent adjustment of pedicle screw placement was 3.8% (24 of 627 screws). Screw malposition was detected by intraoperative CT imaging. Warning of potential screw misplacement was provided by use of the EMG monitoring. With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients. Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit.

Conclusion: The use of CT-based computer-assisted navigation in combination with continuous EMG monitoring during percutaneous transpedicular screw placement results in very low rates of malposition and neural injury that compare favourably with previously reported rates. Pedicle screw placement accuracy continues to improve as the surgeon becomes more experienced with the technique.

No MeSH data available.


Related in: MedlinePlus