Thermomechanical damage in cortical bone caused by margins of surgical drill bit: A finite element analysis.

BACKGROUND AND OBJECTIVE: Conventional surgical drill bits suffer from several drawbacks, including extreme heat generation, breakage, jam, and undesired breakthrough. Understanding the impacts of drill margin on bone damage can provide insights that lay the foundation for improvement in the existing surgical drill bit. However, research on drill margins in bone drilling is lacking. This work assesses the influences of margin height and width on thermomechanical damage in bone drilling. METHODS: Thermomechanical damage-maximum bone temperature, osteonecrosis diameter, osteonecrosis depth, maximum thrust force, and torque-were calculated using the finite element method under various margin heights (0.05-0.25 mm) and widths (0.02-0.26 mm). The simulation results were validated with experimental tests and previous research data. RESULTS: The effect of margin height in increasing the maximum bone temperature, osteonecrosis diameter, and depth were at least 19.1%, 41.9%, and 59.6%, respectively. The thrust force and torque are highly sensitive to margin height. A higher margin height (0.21-0.25 mm) reduced the thrust force by 54.0% but increased drilling torque by 142.2%. The bone temperature, osteonecrosis diameter, and depth were 16.5%, 56.5%, and 81.4% lower, respectively, with increasing margin width. The minimum thrust force (11.1 N) and torque (41.9 Nmm) were produced with the highest margin width (0.26 mm). The margin height of 0.05-0.13 mm and a margin width of 0.22-0.26 produced the highest sum of weightage. CONCLUSIONS: A surgical drill bit with a margin height of 0.05-0.13 mm and a margin width of 0.22-0.26 mm can produce minimum thermomechanical damage in cortical bone drilling. The insights regarding the suitable ranges for margin height and width from this study could be adopted in future research devoted to optimizing the margin of the existing surgical drill bit.

Primary Antiphospholipid Antibody Syndrome Presenting as Acute Myocardial Infarction.

A 46-year-old woman with no significant past history presented to the emergency department with history of sudden-onset central chest discomfort and diaphoresis. With a preliminary diagnosis of acute myocardial infarction, she was subjected to coronary angiography, which showed occlusion of the distal left anterior descending artery with otherwise normal epicardial coronary arteries. Aspiration was performed in the vessel and yielded pinkish friable tissue. The histopathological examination revealed fibrin-rich thrombus. The patient was treated with enoxaparin and switched to oral anticoagulation with warfarin. On follow-up, the nodular mass on the mitral valve reduced considerably in size and she was advised that life-long anticoagulation was necessary.

Surgical Drill Bit Design and Thermomechanical Damage in Bone Drilling: A Review.

As drilling generates substantial bone thermomechanical damage due to inappropriate cutting tool selection, researchers have proposed various approaches to mitigate this problem. Among these, improving the drill bit design is one of the most feasible and economical solutions. The theory and applications in drill design have been progressing, and research has been published in various fields. However, pieces of information on drill design are dispersed, and no comprehensive review paper focusing on this topic. Systemizing this information is crucial and, therefore, the impetus of this review. Here, we review not only the state-of-the-art in drill bit designs-advances in surgical drill bit design-but also the influences of each drill bit geometries on bone damage. Also, this work provides future directions for this topic and guidelines for designing an improved surgical drill bit. The information in this paper would be useful as a one-stop document for clinicians, engineers, and researchers who require information related to the tool design in bone drilling surgery.

An unusual shot-retrograde transthoraco-abdominal venous bullet embolization.

A 72-year-old gentleman was brought to the emergency department, after sustaining an allegedly accidental airgun-shot injury to the right side of his neck. A chest radiograph and plain CT chest revealed the bullet lodged deeply in the soft tissues of the right side of the neck. He was taken up for an emergency neck exploration for foreign body removal. Peroperatively, the bullet was observed to be lodged in the right internal jugular vein. During the attempt to retrieve the bullet, it inadvertently migrated downstream. An intraoperative fluoroscopy revealed the bullet in the thorax near the level of the diaphragm. A subsequent CT chest revealed an intracardiac location of the bullet in the right atrium, at its junction with the inferior vena cava. When it was decided to attempt a percutaneous endovascular retrieval strategy, fluoroscopic imaging of the chest in the cardiac catheterization lab, revealed that the bullet was no longer in the thorax, and had migrated again, and was found to be located in the left side of the pelvis. A subsequent venogram showed the bullet to be lodged in a tributary of the left external iliac vein. It was then snared percutaneously, through the left femoral vein, and delivered through a venotomy. Vascular bullet embolization is a rare phenomenon, especially, as in this case, a retrograde venous embolization with a transthoraco-abdominal course. The treatment of bullet embolization, whether surgical or endovascular, depends on the final destination site, symptomatic status and propensity for complications.

Optimization of drilling parameters for thermal bone necrosis prevention.

BACKGROUND: Bone drilling is a mandatory process in orthopedic surgery to fix the fractured bones. Excessive heat is generated due to the shear deformation of bone and friction energy during the drilling process. OBJECTIVE: This paper is carried out to optimize the bone drilling parameters to prevent thermal bone necrosis. The main contribution of this work is instead of only consider the influence of rotational speed and feed rate, the effect of tool diameter and drilling hole depth are also incorporated for optimization study. METHODS: Response surface methodology (RSM) was used to develop a temperature prediction model. Drilling experiments were performed using finite element software DEFORM-3D. Analysis of variance (ANOVA) was conducted to investigate the drilling parameters' effect. Desirability function in RSM was used to determine the optimum combination of drilling parameters. RESULTS: Results indicated that one applicable combination of drilling parameters could increase the bone temperature by less than 0.03%. To avoid thermal bone necrosis, eight reasonable combinations of drilling parameters were proposed. 3.3∘C residuals between in-vitro experiments and predicted values were demonstrated. CONCLUSIONS: It is envisaged that finite element simulation with RSM can simplify tedious experimental works and useful in the clinical application to avoid bone necrosis.

Aspirin and clopidogrel resistance using the cone and plate(let) analyser in Indian patients with coronary artery disease.

BACKGROUND: Resistance to antiplatelet drugs is a well-known entity. However, data for aspirin and clopidogrel resistance, and its clinical significance, in Indian patients are meagre. AIMS AND OBJECTIVES: We sought to determine the prevalence of resistance to aspirin and clopidogrel in Indian patients with stable coronary heart disease (CHD), using the cone and plate(let) analyser (CPA) technology. SETTING AND DESIGN: A single centre prospective study in a cohort of patients with stable CHD on chronic aspirin and clopidogrel therapy attending the cardiology outpatient clinic of a tertiary care hospital in Southern India. METHODS: Platelet function was measured using the Impact-R device (DiaMed, Cressier, Switzerland). Resistance to aspirin and clopidogrel was measured in a cohort of 100 patients with stable documented CHD. Relation of antiplatelet resistance to various clinical comorbidities was also assessed. RESULTS: Of the 100 patients, 85% were men, and 15% were above 65 years of age. 47% patients had diabetes, 29% of patients were hypertensive and 16% were smokers. Using the CPA, 12 patients (12%) were found to be resistant to aspirin and 19 patients (19%) were clopidogrel resistant. In addition, 10 patients (10%) were resistant to both aspirin and clopidogrel. There was no significant correlation between the presence of antiplatelet resistance and several baseline clinical variables, including age, sex, diabetes, hypertension and smoking. CONCLUSIONS: Resistance to aspirin and clopidogrel and dual antiplatelet resistance are prevalent in Indian patients, comparable with the prevalence worldwide. The CPA is a feasible assay to determine antiplatelet resistance.

Penile Augmentation with Resultant Foreign Material Granuloma and Sequalae

Throughout history, a proportion of men appear to correlate penis size and dimensions directly with physical fitness and sexual prowess. Foreign materials, such as paraffin oil, paraffin balm, mineral oils, and silicone, have been used to promise an improvement in penile shaft contour and dimensions. These materials are injected directly into the penis; inducing granuloma formation to achieve increased penis length and girth. However, the result is a severely disfigured and swollen penis, which cannot achieve erection. Local complications of penile lipogranuloma include infection, ulceration, local migration, and cavernosal invasion; leading to functional impairment. Meanwhile, systemic complications include foreign body embolization, organ infarct, and death. Penile lipogranuloma is best treated surgically. Granulomatous skin needs to be completely excised; wound closure with a scrotal skin flap, Cecil’s inlay operation and split thickness skin graft commonly used options. Our case series has shown that penile lipogranuloma, induced by subcutaneous foreign body injections into the penile shaft, and its subsequent adverse outcomes to patients and their partners.

Soft tissue cover for an exposed transplanted kidney with a pedicled myocutaneous anterolateral thigh perforator and vastus lateralis flap.

Surgical wound infection after a renal transplant procedure can lead to graft loss in the presence of host immunosuppression and graft exposure to the environment. Early cover of the wound with well-vascularized tissue will facilitate early wound healing and preservation of the graft. The pedicle anterolateral thigh perforator flap is a popular flap used for soft tissue reconstruction in the groin and perineum. We present a case of an anterolateral thigh flap used to cover an exposed transplanted kidney after surgical wound breakdown.

Right pulmonary artery-to-left atrial fistula.

Right pulmonary artery-to-left atrial fistula is a rare congenital anomaly. Contrast echocardiography and cardiac catheterization diagnosed a right pulmonary artery-to-left atrial fistula in a 24-year-old female with a history of cyanosis since childhood, and recurrent thromboembolism. She underwent successful surgical closure of the fistula.