An ankle-foot orthosis (AFO) is an L-shaped orthotic device supporting the lower leg and foot. AFOs are used to remedy abnormal gait patterns, control ankle movement, and compensate for muscle weakness in patients experiencing drop foot. They are also used to treat patients with arthritis, adult acquired flatfoot deformity, and fractures. A junior biomedical engineering student was tasked to develop a custom fit AFO after she had independently gained 3D scanning and modeling experience. The following outlines the development process and pedagogical conclusions from the experience: • 3D Scanning: Utilizing a FARO Arm laser scanner, a point cloud replica of the lower leg and foot anatomy was generated. Multiple scans were manually registered and merged to create a single model, then globally registered to fine tune the anatomical data. • 3D Data Manipulation: Geomagic Studio software was used to reduce noise and outlying points while retaining the scanned detail. The Points Wrap command helped reduce the points and generate a uniform .wrap file. The Polygon Phase capabilities of Geomagic Studio were then used to repair intersections, fill holes, and refine floating data and edges. The Select by Curvature command was employed to relax the structure while retaining detail. A NURBS (Non-Uniform Rational B-Spline) surface was created to finalize the mesh structure and export it as an .stl file. Once the 3D mesh is generated, the number of triangles comprising the mesh must be reduced in order to lower computing lag. MeshLab software was utilized to reduce the number of triangles below 8,000. Autodesk Meshmixer allows for simple, yet detailed modification of .stl files through direct editing of a mesh geometry, a feature that is not available in SolidWorks. SolidWorks requires a subtraction command to generate the scanned structure onto a part. With Meshmixer, the AFO is produced directly from the patient's original scan without losing much detail or accuracy. After the .stl was imported, the Extrude command was used to produce depth for the 3D Printing Process. Next, the data was modified by removing excess material and utilizing smoothing and sculpting commands to produce a clean and detailed structure. • 3D Printing: The final .stl file was printed in scale for form checking in a UPrint SE machine. This lean process results in a custom-fitted AFO matching the patient's lower limb anatomy. The use of safe laser scanning technology produces data that will remain available for future reprints of the custom device in case of wear or lost equipment. The student was presented a set of Geomagic Tutorials and supplementing data after a FARO Arm demonstration. No further instructions were given. The student faced a large time commitment over several months but acquired strong background knowledge and great amount of skills in 3D Scanning, 3D Data Manipulation, and 3D Printing, along with AFO design knowledge while successfully completing the task. The student's competency and confidence also improved. After completing this pr...

Background: Abnormalities in size and position of the acetabulum have been linked to both developmental dysplasia of the hip and femoroacetabular impingement. Owing to its 3-dimensional (3D) complexity, plain radiography and cross-sectional studies [computed tomography (CT) and magnetic resonance imaging] have limitations in their ability to capture the complexity of the acetabular 3D anatomy. The goal of the study was to use 3D computed tomography reconstructions to identify the acetabular lunate cartilage and measure its size at varying ages of development and between sexes. Methods: Patients aged 10 to 18 years with asymptomatic hips and a CT pelvis for appendicitis were reviewed. Patients were stratified by sex and age: preadolescent (10 to 12), young adolescent (13 to 15), and old adolescent (16 to 18) in equal proportions. Materialise 3-matic was used to generate a 3D pelvic model, and the acetabular lunate cartilage surface area was calculated. The lunate cartilage was divided into anatomic segments: superior (11:00 to 1:00), anterior (1:00 to 4:00), and posterior (8:00 to 11:00). The femoral head surface area was calculated to control for patient size. Mixed effects models were generated predicting segment size where side was treated as a repeated measure. Absolute and relative (lunate cartilage to femoral head) models were generated. Results: Sixty-two patients (124 hips) were included. Females showed a significant decrease in femoral head coverage as age increased overall and in the 3 subsegments. The majority of changes occurred between the preadolescent and young adolescent groups. Males did not show an overall change, but the superior and anterior anatomic subgroups showed a significant decrease in coverage between the young and old adolescent groups. Male lunate cartilages were absolutely, but not relatively, larger than females. No clinically significant side-to-side differences were noted. Conclusions: The relative femoral head coverage by the acetabular lunate cartilage reduced with increasing age, suggesting the growth of the femoral head outpaces the acetabular lunate cartilage’s growth. This was more prominent in females. This study has important implications for expected acetabular coverage changes in the latter aspects of pediatric and adolescent development. Level of Evidence: Level III—diagnostic study.

Bone morphology has been increasingly recognized as a significant variable in the evaluation of non-arthritic hip pain in young adults. Increased availability and use of multidetector CT in this patient population has contributed to better characterization of the osseous structures compared to traditional radiographs. Femoral and acetabular version, sites of impingement, acetabular coverage, femoral head–neck morphology, and other structural abnormalities are increasingly identified with the use of CT scan. In this review, a standard CT imaging technique and protocol is discussed, along with a systematic approach for evaluating pelvic CT imaging in patients with non-arthritic hip pain.