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Real time noninvasive assessment of external trunk geometry during surgical correction of adolescent idiopathic scoliosis.

Duong L, Mac-Thiong JM, Labelle H - Scoliosis (2009)

Bottom Line: At last, a minor increase of the spinal length can be noticed.Moreover, this technique can used be used to reach the optimal configuration on the operating frame before proceeding to surgery.It could therefore become relevant for computer-assisted guidance of surgical maneuvers when performing posterior instrumentation of the scoliotic spine, provide important insights during positioning of patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Center, Hôpital Sainte-Justine, Montréal, Québec, Canada. duongluc@hotmail.com

ABSTRACT

Background: The correction of trunk deformity is crucial in scoliosis surgery, especially for the patient's self-image. However, direct visualization of external scoliotic trunk deformity during surgical correction is difficult due to the covering draping sheets.

Methods: An optoelectronic camera system with 10 passive markers is used to track the trunk geometry of 5 scoliotic patients during corrective surgery. The position of 10 anatomical landmarks and 5 trunk indices computed from the position of the passive markers are compared during and after instrumentation of the spine.

Results: Internal validation of the accuracy of tracking was evaluated at 0.41 +/- 0.05 mm RMS. Intra operative tracking during surgical maneuvers shows improvement of the shoulder balance during and after correction of the spine. Improvement of the overall patient balance is observed. At last, a minor increase of the spinal length can be noticed.

Conclusion: Tracking of the external geometry of the trunk during surgical correction is useful to monitor changes occurring under the sterile draping sheets. Moreover, this technique can used be used to reach the optimal configuration on the operating frame before proceeding to surgery. The current tracking technique was able to detect significant changes in trunk geometry caused by posterior instrumentation of the spine despite significant correction of the spinal curvature. It could therefore become relevant for computer-assisted guidance of surgical maneuvers when performing posterior instrumentation of the scoliotic spine, provide important insights during positioning of patients.

No MeSH data available.


Related in: MedlinePlus

A) View from the camera system, with the mounting post on landmark 1–9 to track the spine during and after instrumentation. Landmark 10 is identified using the triangular frame. B) Visualization of the markers in 3-D using positions given by the camera system.
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Figure 6: A) View from the camera system, with the mounting post on landmark 1–9 to track the spine during and after instrumentation. Landmark 10 is identified using the triangular frame. B) Visualization of the markers in 3-D using positions given by the camera system.

Mentions: Continuous tracking for evaluation of the trunk geometry is performed during the surgery. Two sets of data acquisition were retained for each patient for the purpose of this study. A first data acquisition (stage I) was performed after insertion of the first rod before the rod rotation maneuver. Stage I therefore corresponds to the state prior to curve correction. A second data set (stage II) was acquired after fixation of both rods before wound closure, and is used to characterize the trunk geometry after final curve correction. 3-D positions were collected for a 10 second interval at 10 Hz for each stage. Since the patient is still breathing during continuous data acquisition, 3-D tracking was visually gated to select only the frames at the end of the respiratory cycle, to ensure a reproducible protocol across patients. Data collection was performed using 3-D visualization software that displays the position of all markers and a schematic representation of the trunk (Figure 6). The optical tracking system gathers 3-D position relative to a global reference frame relative to the camera fixed on the ceiling. The raw data, recorded in the axis system of the camera, are rotated and translated into the coordinate axis system defined by the Scoliosis Research Society (SRS) [13]. This reference frame is defined as follow: the X axis follows the gravity line, which is directed anteriorly with respect to the prone patient, and the Y- and Z-axes point toward left and cephalad directions, respectively. The origin of the axis system is at the spinous process of S1. The orientation of X, Y and Z axis from the origin is identified using the passive markers on the triangular frame defining a local reference frame, including which axis correspond to the left and cephalad directions. The initial orientation of the triangular frame, to ensure proper identification of the reference frame, is set by aligning two of the triangular frame's passive markers, with the markers on the pelvis (landmark 8–9) and this procedure is assisted using the software. The software also computes in real-time five geometric indices of the trunk based on the 3D position of the sensors in the SRS axis system (Figure 2B). A positive value for a linear index (in mm) is directed along the X-, Y- or Z-axis whereas a positive value for an angular index (in degrees) indicates a counterclockwise rotation with respect to an X-, Y- or Z- positive axis. The position of the markers as well as the trunk indices and the Cobb angles were compared between the two stages of surgery for each patient.


Real time noninvasive assessment of external trunk geometry during surgical correction of adolescent idiopathic scoliosis.

Duong L, Mac-Thiong JM, Labelle H - Scoliosis (2009)

A) View from the camera system, with the mounting post on landmark 1–9 to track the spine during and after instrumentation. Landmark 10 is identified using the triangular frame. B) Visualization of the markers in 3-D using positions given by the camera system.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651122&req=5

Figure 6: A) View from the camera system, with the mounting post on landmark 1–9 to track the spine during and after instrumentation. Landmark 10 is identified using the triangular frame. B) Visualization of the markers in 3-D using positions given by the camera system.
Mentions: Continuous tracking for evaluation of the trunk geometry is performed during the surgery. Two sets of data acquisition were retained for each patient for the purpose of this study. A first data acquisition (stage I) was performed after insertion of the first rod before the rod rotation maneuver. Stage I therefore corresponds to the state prior to curve correction. A second data set (stage II) was acquired after fixation of both rods before wound closure, and is used to characterize the trunk geometry after final curve correction. 3-D positions were collected for a 10 second interval at 10 Hz for each stage. Since the patient is still breathing during continuous data acquisition, 3-D tracking was visually gated to select only the frames at the end of the respiratory cycle, to ensure a reproducible protocol across patients. Data collection was performed using 3-D visualization software that displays the position of all markers and a schematic representation of the trunk (Figure 6). The optical tracking system gathers 3-D position relative to a global reference frame relative to the camera fixed on the ceiling. The raw data, recorded in the axis system of the camera, are rotated and translated into the coordinate axis system defined by the Scoliosis Research Society (SRS) [13]. This reference frame is defined as follow: the X axis follows the gravity line, which is directed anteriorly with respect to the prone patient, and the Y- and Z-axes point toward left and cephalad directions, respectively. The origin of the axis system is at the spinous process of S1. The orientation of X, Y and Z axis from the origin is identified using the passive markers on the triangular frame defining a local reference frame, including which axis correspond to the left and cephalad directions. The initial orientation of the triangular frame, to ensure proper identification of the reference frame, is set by aligning two of the triangular frame's passive markers, with the markers on the pelvis (landmark 8–9) and this procedure is assisted using the software. The software also computes in real-time five geometric indices of the trunk based on the 3D position of the sensors in the SRS axis system (Figure 2B). A positive value for a linear index (in mm) is directed along the X-, Y- or Z-axis whereas a positive value for an angular index (in degrees) indicates a counterclockwise rotation with respect to an X-, Y- or Z- positive axis. The position of the markers as well as the trunk indices and the Cobb angles were compared between the two stages of surgery for each patient.

Bottom Line: At last, a minor increase of the spinal length can be noticed.Moreover, this technique can used be used to reach the optimal configuration on the operating frame before proceeding to surgery.It could therefore become relevant for computer-assisted guidance of surgical maneuvers when performing posterior instrumentation of the scoliotic spine, provide important insights during positioning of patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Center, Hôpital Sainte-Justine, Montréal, Québec, Canada. duongluc@hotmail.com

ABSTRACT

Background: The correction of trunk deformity is crucial in scoliosis surgery, especially for the patient's self-image. However, direct visualization of external scoliotic trunk deformity during surgical correction is difficult due to the covering draping sheets.

Methods: An optoelectronic camera system with 10 passive markers is used to track the trunk geometry of 5 scoliotic patients during corrective surgery. The position of 10 anatomical landmarks and 5 trunk indices computed from the position of the passive markers are compared during and after instrumentation of the spine.

Results: Internal validation of the accuracy of tracking was evaluated at 0.41 +/- 0.05 mm RMS. Intra operative tracking during surgical maneuvers shows improvement of the shoulder balance during and after correction of the spine. Improvement of the overall patient balance is observed. At last, a minor increase of the spinal length can be noticed.

Conclusion: Tracking of the external geometry of the trunk during surgical correction is useful to monitor changes occurring under the sterile draping sheets. Moreover, this technique can used be used to reach the optimal configuration on the operating frame before proceeding to surgery. The current tracking technique was able to detect significant changes in trunk geometry caused by posterior instrumentation of the spine despite significant correction of the spinal curvature. It could therefore become relevant for computer-assisted guidance of surgical maneuvers when performing posterior instrumentation of the scoliotic spine, provide important insights during positioning of patients.

No MeSH data available.


Related in: MedlinePlus