Biomedical subjects

Kort Eckman

Publications and source records attributed to Kort Eckman.

4 recordsLinked to original sources

PubMed2006

Virtual reality simulation of fluoroscopic navigation.

Surgical navigation systems assist surgeons by tracking targets attached to the patient's bones and to the surgical tools. Fluoroscopic navigation is a technology that adds "live" imaging to surgical navigation. In order to identify the limitations and potential sources of errors in fluoroscopic navigation, a virtual environment is created in which all the key steps of fluoroscopic navigation can be rehearsed. This provides a low-cost, highly portable, and radiation-free training environment with the ability of instant accuracy validation and reliable measurement of trainee progress. This virtual environment also is suitable for comparing different fluoroscopic registration techniques and protocols. Although the imaging component of the navigation is simulated, physical interaction with the environment can be modeled at different levels; from a fully virtual environment, to miniature models, to life-size dummies and cadavers. Each of these options satisfies different specific training needs, such as the need for portability and easy setup to the need for a completely realistic simulation of the entire clinical environment and operating procedure. In this study, we present the example of a system based on a scaled-down model with a specific focus on analyzing and training bony landmark localization using fluoroscopic navigation.

Computer Simulation↗

PubMed2006

Accuracy of pelvic flexion measurements from lateral radiographs.

Variations in pelvic orientation affect preoperative planning decisions, intraoperative navigation, and postoperative measurements. By providing the means to measure pelvic flexion at low cost and reporting pelvic flexion using the standard reference system, a lateral radiograph technique based on the pubic tubercles and anterior superior iliac spines may be useful for studying functional pelvic orientation and functional alignment and for improving accuracy of postoperative measurement. We evaluated the accuracy of this method by synthesizing 50 lateral pelvic radiographs. Six observers performed manual landmark-based pelvic flexion measurements on the resultant radiographs. Pelvic flexion measurement errors were small (0.004 masculine +/- 1.38 masculine). Apart from one outlier with an error of 12.4 masculine, the errors ranged from -4.0 masculine to 3.0 masculine. The data suggest that accurate measurements of pelvic flexion can be made from lateral radiographs with respect to the standard anatomic reference system. However, failure to correctly observe a landmark can introduce large errors. Therefore, the clarity of the relevant landmarks should be considered carefully before applying this technique. Lateral radiographs can be easily acquired and analyzed, making this technique convenient and inexpensive.

Body Weights and Measures↗

PubMed2006

Three-dimensional planning and virtual radiographs in revision total hip arthroplasty for instability.

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.

Aged↗

PubMed2005

Measurements of acetabular cup position and pelvic spatial orientation after total hip arthroplasty using computed tomography/radiography matching.

This study presents a clinical validation of postoperative measurements of acetabular cup alignment following total hip arthroplasty (THA). The methodology was based on concurrent anatomic three-dimensional (3D) measurements of both the acetabular cup alignment and pelvic orientation, using an original CT/X-ray matching algorithm named Xalign. The subjects were 19 patients who had undergone bilateral THA using CT-based surgical navigation. All patients had postoperative pelvic CT scans and multiple antero-posterior (AP) pelvic X-rays. Using a proprietary software algorithm, the X-rays included in the study were matched with the corresponding postoperative CT scans. The goal of this method was to allow 3D anatomic pelvic and acetabular measurements on two-dimensional AP X-rays. The postoperative cup abduction, version and pelvic flexion angles were determined in three different ways: using CT images directly, applying the Xalign method, and finally by performing conventional (abduction only) measurements on AP pelvic X-rays. The cup orientation measured on CT images was taken as the ground truth. The Xalign measurement errors were defined as the difference between the CT cup values and those obtained by applying the matching method. The mean cup abduction error was 0.85 degrees +/- 1.3 degrees (+/- standard deviation) and the mean version error was 0.01 degrees +/- 1.99 degrees . Conventionally measured cup abduction ranged from 44 degrees to 62 degrees and correlated significantly (p = 0.001, r = -0.5) with pelvic flexion angle, proving the linear negative correlation between pelvic flexion and the error in conventional radiographic cup measurements. The Xalign method offered reasonable accuracy for cup orientation, and allowed cup and pelvic 3D anatomic measurements at different times.

Acetabulum↗