Perthes disease is a childhood disorder often resulting in femoral head deformity. Categorical/dichotomous outcomes of deformity are typical clinically, however quantitative, continuous measures, such as Sphericity Deviation Score (SDS), are critical for studying interventions. SDS uses radiographs in two planes to quantify femoral head deformity. Limitations of SDS may include non-orthogonal planes and lost details due to projections. We applied this method in 3D, with specific objectives to: 1. Develop SDS-like sphericity measures from 3D data 2. Obtain 2D and 3D sphericity for normal and Perthes hips 3. Compare slice-based (3D) and projection-based (2D) sphericity CT images of 16 normal (8 subjects) and 5 Perthes hips (4 subjects) were segmented to create 3D hip models. Ethics board approval was obtained for this study. SDS consists of roundness error (RE) in two planes and ellipsoid deformation (ED) between planes. We implemented a modified SDS which was applied to (a) orthogonal projections simulating radiographs (sagittal/coronal; 2D-mSDS), and (b) largest radii slices (sagittal/coronal; 3D-mSDS). Mean 2D-mSDS was higher for Perthes (27.2 (SD 11.4)) than normal (11.9 (SD 4.1)). Mean 3D-mSDS showed similar trends, but was higher than 2D (Perthes 33.6 (SD 5.3), normals 17.0 (SD 3.1)). Unlike 2D-mSDS, 3D-mSDS showed no overlap between groups. For Perthes hips, 2D-mSDS was consistent with SDS. For normal hips, 2D-mSDS was higher than expected (similar to Stulberg II). Projection-based (2D) measures may produce lower mSDS due to spatial averaging. Slice-based (3D) measures may better distinguish between normal and Perthes shapes, which may better differentiate effectiveness of treatments.
This paper presents a methodology for measuring the femoro-pelvic joint angle based on We scanned a healthy subject in a lying position in a 3T MRI scanner to obtain high resolution (HR) images including two transverse T1-weighted TSE sequence scans at the pelvis and knee and a sagittal T1-weighted dual sense scan at the hip joint. We then scanned the same subject in a weight-bearing configuration in a 0.5T open MRI scanner to obtain related low resolution (LR) images of the femur and acetabulum. Four scan cycles were obtained with the subject being removed and reinserted between cycles in the Open MRI scanner. In each cycle, a block was inserted (up position) and removed (down position) under the subject's foot. The femur and acetabulum bone models were manually segmented and the models from the LR (sitting) images were registered to the HR (supine) images. The femoroacetabular angles relative to the LR scanning plane for four cycles were calculated. The femoral angle relative to the scanner were quite repeatable (SD < 0.9°), the pelvic angles less so (SD ∼2.6–4.3°). The hip flexion angle ranged from 23°–34° in the down and up positions, respectively, so the block induced a mean angle change in the flexion direction of approximately 11° (SD = 1.7°). We found that the femoral position could be accurately re-acquired upon repositioning, while the pelvic position was notably more variable. Limb position changes induced by inserting a block under the subject's foot were consistent (standard deviations in the relative attitude angles under 2°). Overall, our measurement method produces plausible measures of both the femoroacetabular angles and the changes induced by the block, and the reproducibility of relative joint changes is good. ACKNOWLEDGMENTS: Dr. Kang was supported by the National Science and Engineering Research Council of Canada (NSERC) through a Postdoctoral Fellowship and conducted her research at the Centre for Hip Health and Mobility at Vancouver General Hospital, Canada.
The undulating pattern of the distal femur is well recognized. Radiographs do not always represent the full extent of the undulations. With recent increasing use of guided growth technique in the distal femur, it is important to define safe zones for screw placement. We performed an anatomical study on 26 cadaveric distal femoral epiphyses, ages 3–18 years. High resolution three-dimensional surface scans were obtained with a laser scanner, and were analyzed to determine the absolute height of the central physeal ridge, and the central physeal ridge height with respect to the highest points medially and laterally.Purpose
Method
Measurements of patellar kinematics are essential to investigate the link between anterior knee pain following knee arthroplasty and patellar maltracking. A major challenge in studying the patellofemoral (PF) joint postoperatively is that the patellar component is only partially visible in the sagittal and close-to-sagittal radiographs. The narrow angular distance between these radiographs makes the application of conventional bi-planar fluoroscopy impossible. In this study a methodology has been introduced and validated for accurate estimation of the 3D kinematics of the PF joint post-arthroplasty using a novel multi-planar fluoroscopy approach. An optoelectronic camera (Optotrak Certus) was used to track the motion of an ISO-C fluoroscopy C-arm (Siemens Siremobil) using two sets of markers attached to the X-ray source and detector housings. The C-arm was used in the Digital Radiography (DR) mode, which resembles an ordinary X-ray fluoroscopy image. A previously-developed technique (Cho et al., 2005; Daly et al., 2008) was adapted to find the geometric parameters of the imaging system. Thirty-eight DRs of the calibration phantom were obtained for the 190 of rotation of the C-arm at 5 rotational increments while data from motion markers were recorded continuously at a frequency of 100 Hz. A total knee replacement prosthesis was implanted on an artificial bone model of the knee, and the implant components and bones were rigidly fixed in place using a urethane rigid foam. For the purpose of validation, positions of the implant components were determined using a coordinate measuring machine (CMM). Sagittal and obliquely sagittal radiographs of the model were taken where the patellar component was most visible. For each DR the geometric parameters of the system were interpolated based on the location of the motion markers. The exact location of the projection was then determined in 3D space. JointTrack Bi-plane software (Dr. Scott Banks, University of Florida, Gainesville) was used to conduct 2D-3D registration between the radiographs and the reverse-engineered models of the implant components. Results of the registration were directly compared to the ground-truth obtained from the CMM to calculate the accuracies.Purpose
Method
Primary internal fixation of uncomplicated scaphoid fractures offers many advantages compared to conventional casting. However, ideal fixation placement along the central scaphoid axis can be challenging, especially if the procedure is performed percutaneously. Because of the lack of direct visualization, percutaneous procedures demand liberal use of imaging, thereby increasing exposure to harmful radiation. It has been demonstrated that computer-assisted navigation can improve the accuracy of guidewire placement and reduce X-ray exposure in procedures such as hip fracture fixation. Adapting the conventional computer-assist paradigm, with preoperative imaging and intraoperative registration, to scaphoid fixation is not straightforward, and thus a novel tactic must be conceived. Our navigation procedure made use of a flatpanel C-arm (Innova, GE Healthcare) to obtain a 3D cone-beam CT (CBCT) scan of the wrist from which volumetrically-rendered images were created. The relationship between the Innova imager and an optical tracking system (OptoTrak Certus, Northern Digital Inc.) was calibrated preoperatively so that an intraoperatively-acquired image could be used for real-time navigation. Optical markers fitted to a drill guide were used to track its orientation, which was displayed on a computer monitor relative to the wrist images for navigation. Randomized trials were conducted comparing our 3D navigated technique to two alternatives: one using a standard portable C-arm, and the other using the Innova flatpanel C-arm with 2D views and image intensification. A model forearm with an exchangeable scaphoid was constructed to provide consistency between the trials. The surgical objective was to insert a K-wire along the central axis of a model scaphoid. An exposure meter placed adjacent to the wrist model was used to record X-ray exposure. Procedure time and drill passes were also noted. CT scans of the drilled scaphoids were used to determine the shortest distance from the drill path to the scaphoid surface.Purpose
Method
Introduce an Integrated Approach for Orthopedic-Sports Medicine Practice and Patient Care Management that Is built around effective and efficient surgical techniques, and patient care management processes Integrates Operations and Service Excellence best practices with patient care management processes Integrates orthopedic care delivery between outpatient clinic, pre-surgery, surgery, inpatient, (acute care) and post acute care settings Delivers exceptional clinical, patient satisfaction and financial outcomes as validated by independent national healthcare benchmarking organization Helps position Ortho-Sports medicine services for strategic growth Is replicable to develop Ortho-Sports Medicine Centers of Excellence Presentation illustrates the ‘Ten Elements’ approach to implement the Ortho-Sports Medicine Centers of Excellence and demonstrate the effectiveness of the approach with an outcomes study from over 1000 total knee arthroplasty (TKA) procedures. During the presentation, the speakers would share the key clinical, patient satisfaction, and financial outcomes achieved by the implementation of the best practices defined in our ‘Ten Elements’ approach. All performance data elements are collected, validated and analyzed by an independent third party, national healthcare benchmarking company. During the presentation Dr. Bramlett would elaborate on the surgical protocol, and the key differentiating steps in procedure technique from traditional approach that significantly enhances procedure effectiveness, efficiency and lowers the patient complication rate as demonstrated by benchmarking data. Speakers would further present the key elements of Total Knee Arthoplasty procedure that focus on patient education, patient participation in pre-surgical weight loss and pre-habilitation program, anesthesia approach, avoiding tourniquet use and deep veen thrombosis (DVT) risk reduction, early post operative patient ambulation and weight bearing, and post operative patient management approach. On average the ortho-sports medicine clinical of Alabama TKA patients are disharged from the hospital in 2.6 days, and experience 65 percent less complications than expected for a similar patient population and assume early control of their independent functionality.Purpose
