The statistical atlas is a 3D medical image analysis tool towards more patient-oriented and more ... more The statistical atlas is a 3D medical image analysis tool towards more patient-oriented and more efficient diagnosis. The atlas includes information on geometry and their variation across populations. The comparison and information from other patients is very useful for the objective quantitative diagnosis. The statistical atlas can also be used to solve other challenging problems such as image segmentation. As
Background The statistical shape atlas is a 3D medical image analysis tool that encodes shape var... more Background The statistical shape atlas is a 3D medical image analysis tool that encodes shape variations between populations. However, efficiency, accuracy, and finding the correct correspondence, are still unsolved issues during the construction of the atlas.
ABSTRACT Background: Ensuring optimal position of the acetabular component during total hip arthr... more ABSTRACT Background: Ensuring optimal position of the acetabular component during total hip arthroplasty is a complex problem. Although computer assisted techniques have been developed to achieve this, these systems may result in improper cup alignment caused by errors in registration of the anterior pelvic plane. Furthermore, set goals for cup placement do not reflect the variation in acetabular morphology. A need exists to develop a method for cup positioning that is patient specific and eliminates the need to register the anterior pelvic plane. It is our hypothesis that the transverse acetabular ligament can be used to do this. The objective of this study was to define the version of acetabular components placed using this technique. Methods: In this series of 40 consecutive primary hip replacements, the transverse acetabular ligament was used as the sole method to define cup version. Postoperative CT scans of the pelvis were analyzed to measure the anteversion of the acetabular component. Results: At a minimum follow-up of 12 months (range 12–18 months), none of the hips dislocated. Using the transverse acetabular ligament as the sole method to control the version of the acetabular component resulted in an average radiographic anteversion of 19.7° ± 8.1° (mean ± standard deviation) which equates to an operative anteversion of 28.1° ± 11.3° (mean ± standard deviation). Conclusions: This paper highlights the variation in cup version when the transverse acetabular ligament is used to establish and control cup placement. This questions the one-size- fits-all philosophy of a set goal for cup positioning.
Computer assisted surgery (CAS) systems have generated a great deal of interest in the research a... more Computer assisted surgery (CAS) systems have generated a great deal of interest in the research and medical communities due to their promise of improved results with less invasive access to the surgical site. While some systems have been checked against a minimum acceptable standard set by the system’s developers, no overall methodology is in place to insure that a system
KneeNavTMACL, a CT-based surgical navigation system, is used to demonstrate two fundamental requi... more KneeNavTMACL, a CT-based surgical navigation system, is used to demonstrate two fundamental requirements for a practical computer-assisted surgical device: 1) it can guide the surgeon with the accuracy required for successful graft placement, and 2) this guidance can be achieved through a simple and intuitive interface. A series of ACL reconstruction preparation procedures were performed on foambone models using traditional
Clinical Orthopaedics and Related Research, Feb 1, 2006
Instability is one of the most challenging complications of total hip arthroplasty. The cause of ... more Instability is one of the most challenging complications of total hip arthroplasty. The cause of instability is not always clear and treatment outcome is not always satisfactory. Treatment can be optimized by accurate identification of the cause of instability and precise surgical technique. In this case report, we illustrate the use of a three-dimensional (3-D) preoperative planner and virtual radiographic system to improve component position in revision total hip arthroplasty required because of recurrent dislocation. Using this technique, we identified common problems seen in patients with unstable hips after previous revision surgery including impingement, cup malpositioning, bone deficiency in the medial wall, and integrity of fixation screws. The computer-assisted system allowed preoperative planning with range of motion simulation and optimization of the acetabular cup position. The virtual radiographic system provided 3-D measurement of the cup position using a postoperative plane radiograph.
This study compared the repeatability and reproducibility of acetabular component positioning usi... more This study compared the repeatability and reproducibility of acetabular component positioning using imageless and fluoroscopic-referenced navigation methods. A single cadaveric pelvis had a modular acetabular component securely fixed. Cup position was evaluated using imageless and fluoroscopic registration techniques. These were compared to measurements of a coordinate measuring machine (CMM) and a validated CT scan protocol. The CMM-determined anatomical acetabular inclination measurement was 46.02 degrees (SD = 1.07), while the CMM-determined anatomical anteversion (pubic symphysis) was 15.79 degrees (SD = 0.41). Computed tomography revealed inclination of 42.2 degrees (SD = 0.65); anteversion with pubic tubercle referencing of 12.1 degrees (SD = 0.14); and anteversion with pubic symphysis referencing of 14.3 degrees (SD = 0.89). Evaluation of repeatability (one surgeon; n = 8) with the imageless system (pubic tubercle) revealed inclination of 41.8 degrees (SD = 0.46) and anteversion of 11.2 degrees (SD = 0.8). For the fluoroscopic system (pubic symphysis), inclination was 42.8 degrees (SD = 1.6) and anteversion was 17.6 degrees (SD = 3.1). Evaluation of reproducibility (three surgeons; n = 24) with the imageless system revealed inclination of 41.8 degrees (SD = 0.82) and anteversion of 15.2 degrees (SD = 1.06). For the fluoroscopic system, inclination was 48.5 degrees (SD = 0.9) and anteversion was 17.8 degrees (SD = 2.5). Imageless referencing of cup inclination and anteversion were found to be process capable using the Six Sigma Cp and Cpk capability indices. Fluoroscopic referencing was process capable for cup inclination but not for cup anteversion (Cp - 1.1; Cpk - 1.0). An F-test revealed significantly greater variance with fluoroscopic referenced anteversion (p < 0.002). Imageless referencing was process capable for computer navigation of cup placement in the ex-vivo setting. Fluoroscopic referencing for pelvic landmarks is problematic as locating points from radiographic images is difficult, especially for cup anteversion.
The statistical atlas is a 3D medical image analysis tool towards more patient-oriented and more ... more The statistical atlas is a 3D medical image analysis tool towards more patient-oriented and more efficient diagnosis. The atlas includes information on geometry and their variation across populations. The comparison and information from other patients is very useful for the objective quantitative diagnosis. The statistical atlas can also be used to solve other challenging problems such as image segmentation. As
Background The statistical shape atlas is a 3D medical image analysis tool that encodes shape var... more Background The statistical shape atlas is a 3D medical image analysis tool that encodes shape variations between populations. However, efficiency, accuracy, and finding the correct correspondence, are still unsolved issues during the construction of the atlas.
ABSTRACT Background: Ensuring optimal position of the acetabular component during total hip arthr... more ABSTRACT Background: Ensuring optimal position of the acetabular component during total hip arthroplasty is a complex problem. Although computer assisted techniques have been developed to achieve this, these systems may result in improper cup alignment caused by errors in registration of the anterior pelvic plane. Furthermore, set goals for cup placement do not reflect the variation in acetabular morphology. A need exists to develop a method for cup positioning that is patient specific and eliminates the need to register the anterior pelvic plane. It is our hypothesis that the transverse acetabular ligament can be used to do this. The objective of this study was to define the version of acetabular components placed using this technique. Methods: In this series of 40 consecutive primary hip replacements, the transverse acetabular ligament was used as the sole method to define cup version. Postoperative CT scans of the pelvis were analyzed to measure the anteversion of the acetabular component. Results: At a minimum follow-up of 12 months (range 12–18 months), none of the hips dislocated. Using the transverse acetabular ligament as the sole method to control the version of the acetabular component resulted in an average radiographic anteversion of 19.7° ± 8.1° (mean ± standard deviation) which equates to an operative anteversion of 28.1° ± 11.3° (mean ± standard deviation). Conclusions: This paper highlights the variation in cup version when the transverse acetabular ligament is used to establish and control cup placement. This questions the one-size- fits-all philosophy of a set goal for cup positioning.
Computer assisted surgery (CAS) systems have generated a great deal of interest in the research a... more Computer assisted surgery (CAS) systems have generated a great deal of interest in the research and medical communities due to their promise of improved results with less invasive access to the surgical site. While some systems have been checked against a minimum acceptable standard set by the system’s developers, no overall methodology is in place to insure that a system
KneeNavTMACL, a CT-based surgical navigation system, is used to demonstrate two fundamental requi... more KneeNavTMACL, a CT-based surgical navigation system, is used to demonstrate two fundamental requirements for a practical computer-assisted surgical device: 1) it can guide the surgeon with the accuracy required for successful graft placement, and 2) this guidance can be achieved through a simple and intuitive interface. A series of ACL reconstruction preparation procedures were performed on foambone models using traditional
Clinical Orthopaedics and Related Research, Feb 1, 2006
Instability is one of the most challenging complications of total hip arthroplasty. The cause of ... more Instability is one of the most challenging complications of total hip arthroplasty. The cause of instability is not always clear and treatment outcome is not always satisfactory. Treatment can be optimized by accurate identification of the cause of instability and precise surgical technique. In this case report, we illustrate the use of a three-dimensional (3-D) preoperative planner and virtual radiographic system to improve component position in revision total hip arthroplasty required because of recurrent dislocation. Using this technique, we identified common problems seen in patients with unstable hips after previous revision surgery including impingement, cup malpositioning, bone deficiency in the medial wall, and integrity of fixation screws. The computer-assisted system allowed preoperative planning with range of motion simulation and optimization of the acetabular cup position. The virtual radiographic system provided 3-D measurement of the cup position using a postoperative plane radiograph.
This study compared the repeatability and reproducibility of acetabular component positioning usi... more This study compared the repeatability and reproducibility of acetabular component positioning using imageless and fluoroscopic-referenced navigation methods. A single cadaveric pelvis had a modular acetabular component securely fixed. Cup position was evaluated using imageless and fluoroscopic registration techniques. These were compared to measurements of a coordinate measuring machine (CMM) and a validated CT scan protocol. The CMM-determined anatomical acetabular inclination measurement was 46.02 degrees (SD = 1.07), while the CMM-determined anatomical anteversion (pubic symphysis) was 15.79 degrees (SD = 0.41). Computed tomography revealed inclination of 42.2 degrees (SD = 0.65); anteversion with pubic tubercle referencing of 12.1 degrees (SD = 0.14); and anteversion with pubic symphysis referencing of 14.3 degrees (SD = 0.89). Evaluation of repeatability (one surgeon; n = 8) with the imageless system (pubic tubercle) revealed inclination of 41.8 degrees (SD = 0.46) and anteversion of 11.2 degrees (SD = 0.8). For the fluoroscopic system (pubic symphysis), inclination was 42.8 degrees (SD = 1.6) and anteversion was 17.6 degrees (SD = 3.1). Evaluation of reproducibility (three surgeons; n = 24) with the imageless system revealed inclination of 41.8 degrees (SD = 0.82) and anteversion of 15.2 degrees (SD = 1.06). For the fluoroscopic system, inclination was 48.5 degrees (SD = 0.9) and anteversion was 17.8 degrees (SD = 2.5). Imageless referencing of cup inclination and anteversion were found to be process capable using the Six Sigma Cp and Cpk capability indices. Fluoroscopic referencing was process capable for cup inclination but not for cup anteversion (Cp - 1.1; Cpk - 1.0). An F-test revealed significantly greater variance with fluoroscopic referenced anteversion (p < 0.002). Imageless referencing was process capable for computer navigation of cup placement in the ex-vivo setting. Fluoroscopic referencing for pelvic landmarks is problematic as locating points from radiographic images is difficult, especially for cup anteversion.
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Papers by Branislav Jaramaz