Investigation of Cumulative Fatigue Damage as a Cause for Fracture of Swanson Finger Joint Prostheses

In this project, I have developed a realistic model of the currently best-selling finger\ud joint prosthesis--the Swanson Finger Joint manufactured by Wright Medical Technologies--to\ud create a finite element model which could be subjected to loading conditions which are more\ud representative of the normal function of a metacarpophalangeal joint than any of the simple\ud flexion-extension tests previously performed on these joints. By doing so, I can identify\ud regions of high stress, determine whether mechanical fatigue alone is sufficient explanation for\ud their history of premature fracture, and design a modified joint with improvements in joint\ud geometry, articulation, or other factors to help improve fatigue life of the joints.\ud Research was done on the mechanical and material properties of the joint prostheses,\ud physiological data, and expected forces and moments on the hand during "typical" daily\ud activities ranging from piano-playing to simple pinching activities. I then developed a number\ud of finite element models of the Swanson joint, of variable fineness, using solid elements for the\ud joint itself and uniaxial link elements to represent tendons.\ud The most significant finding from my results was that, in all loading conditions,\ud analysis showed that fatigue fracture should occur at the base of the proximal stem, not the\ud distal stem as is seen in clinical fractures. Time until fracture varied depending on the S-N\ud fatigue curve I used, but the most liberal estimate predicted a lifetime of approximately six\ud years, which fits in well with reported fracture times. Because I am confident that my model\ud gives an accurate representation of the Swanson prosthesis with no fundamental errors, I\ud conclude from my results that mechanical fatigue is not responsible for the clinical fractures\ud which have been seen to occur at the base of the distal stem. These fractures are probably due\ud to other problems with the joint and material, including low tear resistance, or inadequate\ud protection of the joint from surrounding bone. Those problems must be confronted before\ud mechanical fatigue if the current premature fractures are to be avoided. If and when those\ud problems are solved, fatigue must then be addressed to avoid the fractures at the proximal\ud stem which my results show will occur within approximately six years

Failure of a metal-on-metal total hip arthroplasty from progressive osteolysis

Abstract: Uhra-high-molecular weight polyethylene (UHMWPE) wear, debrisinduced osteolysis is a frequent cause of failure of total hip arthroplasty. Metal-onmetal total hip arthroplasty eliminates the generation of UHMWPE particulate debris. Although the volumetric wear of a metal-on-metal articulation may be lower than a metal-UHMWPE articulation, the number of particles may be higher. Osteolysis can deve|op in response to metallic and UHMWPE debris. The following case of massive osteolysis associated with large amounts of cobalt-chrome wear debris shows adhesive and abrasive wear mechanisms, as well as wear caused by third-body cobalt-chrome debris and impingement of the femoral component against the rim of the acetabular cup, which led to failure of a metal-on-metal total hip arthroplasty. Key words: wear, metal, hip, arthroplasty, cobalt-chrome. Polyethylene wear and osteolysis can limit the longevity of total hip arthroplasty (THA). It has been suggested that metal-on-metal articulations may generate less wear and perform more favorably than metal-on-polyethylene articulations Case Report A 76-year-old man complained of left hip pain i4 years after THA with a Sivash metal-on-metal prosthesis (Joint Medical Products, Port Washington, NY) 87

The Value of Cytochrome P450 2C19 Pharmacogenomic Information for Patients Receiving Clopidogrel Therapy Following a Major Cardiovascular Event: Evidence from Geisinger

Dual antiplatelet therapy, combining a P2Y12 inhibitor and aspirin, is central to the management of patients with acute coronary syndromes. Clopidogrel is a commonly prescribed thienopyridine P2Y12 inhibitor used to prevent secondary events following a myocardial infarction / percutaneous coronary intervention. Clopidogrel effectiveness has been linked to proper function of metabolic enzyme cytochrome P450 2C19 (CYP2C19). Testing for CYP2C19 genetic changes that result in decreased activity has been proposed as a mechanism by which to identify clopidogrel non-responders a priori. Robust real-world studies evaluating the impact of genotype-guided antiplatelet selection on clinical, utilization and outcome metrics are lacking. Approach: We linked clinical and financial data on a cohort of 2,595 Geisinger patients who were prescribed antiplatelet therapy without pharmacogenomic insight. Leveraging post-hoc, research-generated pharmacogenomic information, we describe the potential value of pharmacogenomic information in the selection of clopidogrel as the P2Y12 inhibitor therapy. Major Results: Among patients examined, CYP2C19 loss of function did not predict the probability of follow-on adverse events, clinical utilization or total medical costs within the 12 months after clopidogrel initiation in adjusted or crude analysis. Conclusion: Universal CYP2C19 pharmacogenomic testing to inform P2Y12 selection following an MI/PCI index event within the Geisinger patient population studied would not have led to improved clinical outcomes, decreased health care utilization or lower total medical cost

PS1-06: Increased Incident Renal Disease with ACE-1 + Thiazide Therapy for Hypertension: The Geisinger Clinic Population

Background and Aims: Thiazide diuretics are recommended alone or in combination for uncomplicated hypertension (HTN). Most patients require treatment with 2 or more drugs. Based on studies of mono-therapy, ACE-I are recommended for patients at risk of renal disease, including diabetics. Data are sparse regarding thiazide plus ACE-I combination therapy. We hypothesized that thiazide plus ACE-I is associated with a lower incidence of renal disease compared with other common thiazide combinations, but that confounding by indication for diabetes might attenuate this effect

Pediatric all-terrain vehicle (ATV) injuries: An epidemic of cost and grief

Objective: Evaluate cost of care of all-terrain vehicle (ATV) related injuries sustained by riders 16 years and younger in Pennsylvania. Methods: Population-based retrospective cohort design reviewing costs of care of 78 patients (≤16 years), admitted (01/01/2007–12/31/2009) to our institution for injuries sustained during an ATV accident. Results: Cost of care varied from $322 to$310,435. Mean and median costs for all patients were $25,760 and$8,066, respectively. Average costs increased with increasing age. Patients wearing helmets or driving the ATV had lower mean costs, but these trends were not statistically significant. Crashes with stationary objects not involving rollover or ejection had significantly lower mean costs than other crash types (p = 0.01). Patients involved in rollover accidents were significantly more likely to require an overnight hospital stay (OR = 3.45, p = 0.02). Patients wearing helmets were marginally less likely to require an overnight admission (OR = 0.34, p = 0.07). Conclusion: ATV crashes involving unhelmeted riders and rollover accidents result in significant medical costs. Interventions to increase helmet use and measures to improve stability are likely to reduce these costs and shorten hospital stays. Level of evidence: Level IV, Economic study

DS_10.1177_1558944718788687 – Supplemental material for Incidence and Reason for Readmission and Unscheduled Health Care Contact After Distal Radius Fracture

<p>Supplemental material, DS_10.1177_1558944718788687 for Incidence and Reason for Readmission and Unscheduled Health Care Contact After Distal Radius Fracture by Kirsten Sumner, Louis C. Grandizio, Max D. Gehrman, Jove Graham and Joel C. Klena in HAND</p