Survival and failure modes of the Compress® spindle and expandable distal femur endoprosthesis among pediatric patients: A multi-institutional study.

BACKGROUND: Expandable endoprostheses can be used to equalize limb length for pediatric patients requiring reconstruction following large bony oncologic resections. Outcomes of the Compress® Compliant Pre-Stress (CPS) spindle paired with an Orthopedic Salvage System expandable distal femur endoprosthesis have not been reported. METHODS: We conducted a multi-institutional retrospective study of pediatric patients with distal femoral bone sarcomas reconstructed with the above endoprostheses. Statistical analysis utilized Kaplan-Meier survival technique and competing risk analysis. RESULTS: Thirty-six patients were included from five institutions. Spindle survivorship was 86.3% (95% confidence interval [CI], 67.7-93.5) at 10 years. Two patients had a failure of osseointegration (5.7%), both within 12 months. Twenty-two (59%) patients had 70 lengthening procedures, with mean expansions of 3.2 cm (range: 1-9) over 3.4 surgeries. The expandable mechanism failed in eight patients with a cumulative incidence of 16.1% (95% CI, 5.6-31.5) at 5 years. Twenty-nine patients sustained International Society of Limb Salvage failures requiring 63 unplanned surgeries. Periprosthetic joint infection occurred in six patients (16.7%). Limb preservation rate was 91% at 10 years. CONCLUSIONS: There is a high rate of osseointegration of the Compress® spindle among pediatric patients when coupled with an expandable implant. However, there is a high rate of expansion mechanism failure and prosthetic joint infections requiring revision surgery. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Perceptions of a Remote Learning Pathology Elective for Advanced Clinical Medical Students.

In mid-March 2020, our institution removed most medical students from in-person clinical clerkships due to the COVID-19 pandemic. The Department of Pathology responded by transitioning a fourth-year clinical elective to an all-remote format composed of synchronous didactics, daily clinical sign-out utilizing digital microscopy, and asynchronous learning materials. Thirty-seven medical students completed 2- or 4-week anatomic pathology electives tailored to meet their career goals and allowing them to progress toward graduation. Institutional Review Board approval was granted to survey students' perceptions of engagement in the remote learning environment. Quantitative and qualitative data were collected using a standardized school-wide end-of-rotation survey, an online survey developed by the authors, and students' self-directed learning goals. End-of-rotation data showed the remote pathology course performed well (4.88 of possible 5) when compared to all advanced clinical clerkships (4.51, n = 156 courses), all elective rotations (4.41, n = 50 courses), and the traditional in-person pathology elective (4.73). Core strengths in the virtual environment included high educational value, flexibility of content and schedule, organization, tailoring to an individual's learning goals, and a positive education environment. Deficits included the inability to gross surgical specimens, inadequate observation or feedback about students' skills, and impaired social connections. Areas for improvement included requests for in-person experiences and development of themed tracks for career exploration. Many aspects of anatomic pathology appear well-suited to the remote learning environment. While the remote model may not be sufficient for students pursuing careers in pathology, it can be adapted to increase nonpathologists' understanding of interdisciplinary clinical collaboration with pathologists.

Identifying a commercially-available 3D printing process that minimizes model distortion after annealing and autoclaving and the effect of steam sterilization on mechanical strength.

BACKGROUND: Fused deposition modeling 3D printing is used in medicine for diverse purposes such as creating patient-specific anatomical models and surgical instruments. For use in the sterile surgical field, it is necessary to understand the mechanical behavior of these prints across 3D printing materials and after autoclaving. It has been previously understood that steam sterilization weakens polylactic acid, however, annealing heat treatment of polylactic acid increases its crystallinity and mechanical strength. We aim to identify an optimal and commercially available 3D printing process that minimizes distortion after annealing and autoclaving and to quantify mechanical strength after these interventions. METHODS: Thirty millimeters cubes with four different infill geometries were 3D printed and subjected to hot water-bath annealing then immediate autoclaving. Seven commercially available 3D printing materials were tested to understand their mechanical behavior after intervention. The dimensions in the X, Y, and Z axes were measured before and after annealing, and again after subsequent autoclaving. Standard and strength-optimized Army-Navy retractor designs were printed using the 3D printing material and infill geometry that deformed the least. These retractors were subjected to annealing and autoclaving interventions and tested for differences in mechanical strength. RESULTS: For both the annealing and subsequent autoclaving intervention, the material and infill geometry that deformed the least, respectively, was Essentium PLA Gray and "grid". Standard retractors without intervention failed at 95 N +/- 2.4 N. Annealed retractors failed at 127.3 N +/- 10 N. Autoclave only retractors failed at 15.7 N +/- 1.4 N. Annealed then autoclaved retractors failed at 19.8 N +/- 3.1 N. Strength-optimized retractors, after the annealing then autoclaving intervention, failed at 164.8 N +/- 12.5 N. CONCLUSION: For 30 mm cubes, the 3D printing material and infill geometry that deformed the least, respectively, was Essentium PLA and "grid". Hot water-bath annealing results in increased 3D printed model strength, however autoclaving 3D prints markedly diminishes strength. Strength-optimized 3D printed PLA Army-Navy retractors overcome the strength limitation due to autoclaving.

The Use of Photogrammetry for Interactive, Three-Dimensional Modeling of an Open Reduction and Internal Fixation of the Elbow.

We present our step-by-step guide to acquire and combine intraoperative photographs into three-dimensional models of surgical anatomy. We then apply our technique to model six steps in an open reduction and internal fixation of the elbow. Our protocol can be done with equipment and software retailing for under $500.

Advances in 3D-Printed Pediatric Prostheses for Upper Extremity Differences.

➤The prohibitive cost of cutting-edge prostheses prevents many children with a limb difference from obtaining them; however, new developments in 3-dimensional (3D) printing have the potential to increase the accessibility, customization, and procurement of such devices.➤Children with upper limb differences are ideal candidates for currently available 3D-printed devices because they quickly damage and outgrow prostheses, and the low cost of 3D printing makes repairs and upgrades substantially more affordable.➤Physicians and medical practitioners should become familiar with the possibilities of 3D-printed devices in order to determine the benefits and utility for their patients.