The Morphologic Patella Entry Point Into The Proximal Trochlea Is More Lateral in Recurrent Dislocators Than Controls as Measured by Entry Point-Trochlear Groove Angle.

PURPOSE: The purpose of this work is to create a metric for evaluating the degree of laterality of the patella's entry into the trochlea, the entry point-trochlear groove (EP-TG) angle, and to evaluate if this laterality is associated with recurrent patella instability. METHODS: The time frame of the study was January 2020 to February 2023. The inclusion criteria were patients treated by the senior author (JPF) (with the exception of two patients who were treated by another provider at the institution who was aware of the study) who have been diagnosed with recurrent atraumatic patellar dislocations. Controls without knee pathology were selected from the New Mexico Decedent Imaging Database (NMDID). Simpleware ScanIP was used to create three-dimensional (3D) models of the distal femurs from CT scans. AP images of these 3D models were uploaded to a custom EP-TG angle measuring tool. Three measurers used the tool to measure the EP-TG angle of the distal femurs. RESULTS: 28 patients were included for the recurrent dislocator group. 24 decedents from NMDID were selected for the control group, each with a left or right knee chosen randomly for measurement. A one-sided Mann-Whitney U test, used to evaluate whether the recurrent dislocators had higher EP-TG angle values, yielded a p value <0.001, demonstrating a high level of significance. A Bayesian mixed effect model, used to determine how different the EP-TG angles are between the two groups, gave a posterior predictive interval (PPI) of [11.93, 19.12] degrees for the EP-TG angle shift of dislocators. The intraclass correlation coefficient was 0.648. CONCLUSIONS: The morphological entry point of the patella into the proximal trochlea is more lateral in recurrent patella dislocators than in controls. This increased laterality can be measured by EP-TG angle, which may be useful information for optimizing treatment of recurrent patella instability. LEVEL OF EVIDENCE: Level III Case Control Study.

A review of the design, manufacture, and outcomes of custom total joint replacement implants available in the United States.

Custom total joint replacement (TJA) implants, specifically designed and manufactured for each patient, have emerged as surgeons seek to improve functional outcomes of primary total joint replacement, as well as treat patients with complex primary deformities, bone defects, and revision surgeries. The purpose of this review is to present the various custom total hip and knee arthroplasty implants available in the United States for primary and revision cases, so that surgeons can understand the design considerations and manufacturing processes of custom implants, as well as their performance compared to standard implants.

Three-Dimensional Printing of Models of Patellofemoral Joint Articular Cartilage in Patients With Patella Instability for Observing Joint Congruity.

Three-dimensional (3D) modeling and printing are increasingly used in the field of orthopaedic surgery for both research and patient care. One area where they are particularly helpful is in improving our understanding of the patellofemoral (PF) joint. Heretofore, morphological studies that use 3D models of the PF joint have primarily been based on computed tomography imaging data and thus do not incorporate articular cartilage. Here, we describe a method for creating 3D models of the articular surfaces of the PF joint based on magnetic resonance imaging. Models created using this technique can be used to improve our understanding of the morphology of the articular surfaces of the PF joint and its relationship to joint pathologies. Of particular interest is our finding of articular congruity in printed articular cartilage surfaces of dysplastic PF joints of recurrent patella dislocators.

Three-Dimensional Printing of the Patellofemoral Joints of Patellar Instability Patients.

Three-dimensional (3D) modeling and printing comprise an important tool for orthopaedic surgeons. One area in which 3D modeling has the potential to dramatically improve our understanding of biomechanical kinematics is pathologies of the patellofemoral joint, in particular trochlear dysplasia. We describe a method for creating 3D printed models of the patellofemoral joint, including computed tomography image acquisition, image segmentation, model creation, and 3D printing. The models created can help surgeons understand and plan surgery for recurrent patellar dislocations.

Improving acetabular shell deformation testing.

BACKGROUND: To be FDA approved, acetabular shells must undergo rigorous testing. To prevent implant failure, acetabular shells must be able to tolerate peak loads during impaction with minimal deformation. The implants must therefore be validated in order to ensure that their structural integrity can tolerate peak loads. The current ISO 7206-12 recommends manufacturing an expensive single-purpose testing device to measure the deformation of acetabular shells. In the article, we provide an open access methodology, that can be conducted with minimal expense, for testing acetabular shell deformation. METHODS: We designed our experimental setup to utilize a servohydraulic materials testing device (Instron) commonly found in biomechanics laboratories and then validated the measurements optically with optical data. Furthermore, we designed an inexpensive acetabular screw fastener which acts as an adaptor that can be used to mount a variety of acetabular shell types just as effectively as current methods and is in compliance with the standards outlined in ISO 7206-12:2016. RESULTS: A Bland-Altman plot comparing the Instron and optical displacement measurements found the standard deviation of bias to be 0.046 mm and an insignificant systemic bias. CONCLUSION: We have developed and validated a low-cost open-source system that can effectively test acetabular shell deformation that meets ISO standards.

Mini-Blade Plate to Obtain Length Across Lateral Malleolus Fractures: Surgical Technique and Biomechanical Evaluation.

Background: Restoration of fibular length is the main determinant in preventing mal-union and early ankle arthritis in lateral malleolus fractures. A 1/3 tubular plate fashioned into a mini-blade plate can be used to distract the distal fragment and achieve length in a controlled fashion over time. The purpose of this study was to describe the surgical technique and perform a biomechanical comparison of the blade plate to a locking plate. Methods: A 1/3 tubular plate is fashioned into a 135° blade plate. Blades are seated into the lateral malleolus and a distally directed force is applied on the plate to obtain length.A lateral malleolus fracture was created in 20 cadaveric ankles. The distal fragment was fixed with either a blade plate (BP, n = 10) or a locking plate (LP, n = 10). A distally directed force was applied by an Instron machine and fracture distraction, maximal load and construct stiffness were measured and compared. Results: The average maximal load was 262.06 N compared to 255.52 N for the BP and LP groups, respectively. The maximal distraction was 3.57 mm compared to 4.57 mm for the BP and LP groups, respectively. The loading pattern of the blade plate over time differed from that of a locking plate as the blades seat into bone. Conclusion: A 1/3 tubular mini-blade plate demonstrates biomechanical similarities in terms of load and distraction to the more expensive locking plate. We recommend using this technique for fractures with late presentation or with significant shortening. Level of Evidence: Level V-Mechanism-based reasoning.

Interpretation of regulatory factors for 3D printing at hospitals and medical centers, or at the point of care.

3D printing is revolutionizing the medical device landscape through its ability to rapidly create patient-specific anatomic models, surgical instruments, and implants. Recent advances in 3D printing technology have allowed for the creation of point-of-care (PoC) 3D printing centers. These PoC centers blur the line between healthcare provider, medical center, and device manufacturer, creating regulatory ambiguity. The United States Food & Drug Administration (FDA) currently regulates 3D printed devices through existing medical device regulations. However, the FDA is increasingly interested in developing guidelines and regulations specifically for PoC 3D printing due to its rapid adoption across the healthcare institutions. In this article, we review the regulatory framework that governs medical devices, discuss how PoC 3D printing falls within this framework, and describe a novel conceptual framework that the FDA has proposed. Finally, through analysis of the aforementioned regulations and discussions with industry medical 3D printing regulatory experts, we provide recommendations for PoC medical 3D printing best practices so that institutions are best positioned to utilize this revolutionary technology safely and effectively.