Jorge A. Ochoa

Purpose Accelerating development of new therapeutic cardiac devices remains a clinical and technical priority. High-performance computing and the emergence of functional and complex in silico models of human anatomy can be an engine to accelerate the commercialization of innovative, safe, and effective devices. Methods An existing three-dimensional, nonlinear model of a human heart with flow boundary conditions was evaluated. Its muscular tissues were exercised using electrophysiological boundary conditions, creating a dynamic, electro-mechanical simulation of the kinetics of the human heart. Anatomic metrics were selected to characterize the functional biofidelity of the model based on their significance to the design of cardiac devices. The model output was queried through the cardiac cycle and compared to in vivo literature values. Results For the kinematics of mitral and aortic valves and curvature of coronary vessels, the model’s performance was at or above the 95th percentile range of the in vivo data from large patient cohorts. One exception was the kinematics of the tricuspid valve. The model’s mechanical use environment would subject devices to generally conservative use conditions. Conclusions This conservative simulated use environment for heart-based medical devices, and its judicious application in the evaluation of medical devices is justified, but careful interpretation of the results is encouraged.

Retrieving and analyzing medical devices from revision or removal surgeries are critical activities for understanding device failures. However, the role of retrieval analysis should not be limited to the investigation of individual failures and subsequent root cause analysis. Implementation of retrieval programs that operate throughout the commercial life of devices can be a means by which manufacturers inform product development, augment regulatory submissions, evaluate and mitigate risks, implement continuous improvement, and develop new designs or product enhancements. Understanding how retrieval analysis can contribute to the Total Product Life Cycle of a device will enhance a manufacturer’s ability to address regulatory requirements and U.S. Food and Drug Administration inquiries, identify and respond to unanticipated failure modes, evaluate successful in vivo performance of its devices, and to improve the quality, safety, effectiveness, and performance of new devices. We will review some of the basic scientific and regulatory requirements that apply to devices in the context of retrievals. We will also examine the role of retrieval analysis during device development within the design control framework and will provide guidelines for implementing a formal program that will allow manufacturers to realize the benefits of retrieval analysis throughout the Total Product Life Cycle of a medical device.

This study was designed to evaluate treatment patterns in open treatment and percutaneous fixation of distal radius fractures, compare morbidity rates for the 2 types of treatment, and compare costs associated with the procedure and treatment of complications up to 1 year after surgery. From a 5% sample of nationwide Medicare claims records (1997–2009), patients with distal radius fractures were identified withInternational Classification of Diseases, 9th revision, Clinical Modification(ICD-9-CM), codes. Patients who underwent percutaneous fixation and open treatment were tracked with appropriate Current Procedural Terminology codes. Complications were identified at 3 and 12 months. Medicare charges and payments associated with the treatment groups were compiled from the claims data. The rate of surgical treatment increased from 44.7 to 82.0 surgeries per 100,000 persons (+83.0%) over the study period. A total of 9343 procedures met the inclusion criteria between 1998 and 2008. The proportion of open treatment procedures increased from 25.5% in 1998 to 73.4% in 2008. Percutaneous fixation was associated with lower adjusted risk of carpal tunnel syndrome and release and mononeuritis at 3 and 12 months. The percutaneous fixation group had lower adjusted risk of malunion/nonunion at 3 months and tendon rupture at 12 months. Average charges were lower in the percutaneous fixation group for the index operation as well as for treatment of morbidities at 3 and 12 months. The operative fixation rate for distal radius fractures in the Medicare population continues to rise, with a significant trend toward open fixation. Charges and payments associated with open treatment are significantly higher than those for percutaneous fixation.

Object: The purpose of this study was to quantify the perioperative outcomes, complications, and costs associated with posterolateral spinal fusion (PSF) among Medicare enrollees with lumbar spinal stenosis (LSS) and/or spondylolisthesis by using a national Medicare claims database. Methods: A 5% systematic sample of Medicare claims data (2005–2009) was used to identify outcomes in patients who had undergone PSF for a diagnosis of LSS and/or spondylolisthesis. Patients eligible for study inclusion also required a minimum of 2 years of follow-up and a claim history of at least 12 months prior to surgery. Results: A final cohort of 1672 patients was eligible for analysis. Approximately half (50.7%) had LSS only, 10.2% had spondylolisthesis only, and 39.1% had both LSS and spondylolisthesis. The average age was 71.4 years, and the average length of stay was 4.6 days. At 3 months and 1 and 2 years postoperatively, the incidence of spine reoperation was 10.9%, 13.3%, and 16.9%, respectively, whereas readmissions for complications occurred in 11.1%, 17.5%, and 24.9% of cases, respectively. At 2 years postoperatively, 36.2% of patients had either undergone spine reoperation and/or received an epidural injection. The average Medicare payment was $36,230 ± $17,020, $46,840 ± $31,350, and $61,610 ± $46,580 at 3 months, 1 year, and 2 years after surgery, respectively. Conclusions: The data showed that 1 in 6 elderly patients treated with PSF for LSS or spondylolisthesis underwent reoperation on the spine within 2 years of surgery, and nearly 1 in 4 patients was readmitted for a surgery-related complication. These data highlight several potential areas in which improvements may be made in the effective delivery and cost of surgical care for patients with spinal stenosis and spondylolisthesis.

Objective: The design and implementation of skin flaps remains a puzzle for the reconstructive surgeon. The objective of the present study is to use finite element (FE) analysis to characterize and understand the biomechanics of the monopedicle skin flap design.Study Design: The current study uses a nonlinear hyperelastic FE model of the human skin to understand the biomechanics of monopedicle‐based flap designs as geometric flap parameters are varied.Setting: In silico.Subjects and Methods: The simulation included the displacement loading, stitching, and relaxation of various forms of the flap design. Stress and strain outcomes, previously correlated with scarring, necrosis, and blood perfusion, are reported for a basic monopedicle design as well as a number of modifications to this design.Results: The results suggest that the length of the monopedicle flap should not exceed 3 times the size of the defect, as the benefit in reducing principal strain (deformation) is diminished beyond this point. Further, to minimize skin strain, the ideal Burrow's triangle size can be described as proportional to flap length and inversely proportional to defect height, according to a linear function.Conclusion: The ideal flap design should attempt to minimize not only the stress in the skin, but the size of the incisions and the degree of undermining. The results of our analyses provide guidance to increase the general understanding of monopedicle flap mechanics and provide context for the clinician and insight into designing a better monopedicle flap for individual situations.