Finite Element Analysis: A Maxillofacial Surgeon’s Perspective

The science of finite element analysis (FEA) is purely a mathematical way of solving complex problems in the universe. In medical field, this is an innovation in biomedical research and development, as it gives easier mathematical solution to biological problems. This article deals with the understanding of various basic material properties of bone like Young’s modulus, yield strength, Bulk modulus, shear modulus, Poisson’s ratio and density from a maxillofacial surgeon’s perspective. Basic concepts in FEA, its application, advantages, disadvantages, and limitations in the field of maxillofacial surgery have been discussed. The importance of surgical fraternity to be in coordination with evolving technologies has been emphasized for the future of evidence based practice of oral and maxillofacial surgery.     

Right Ventricular Involvement of an Aggressive Malignant Peripheral Nerve Sheath Tumor

We present a case of a 58-year-old woman who had a painful right thigh mass for a few months. A transthoracic echocardiogram revealed no evidence of an intracardiac mass. She had a whole-body positron emission tomography/computed tomography scan two months later that revealed masses in her right lower extremity and a mass in her right ventricle that had not been initially reported. She had been initially diagnosed with an undifferentiated pleomorphic sarcoma, but this diagnosis was changed to a malignant peripheral nerve sheath tumor with repeat pathology. She was subsequently hospitalized. An echocardiogram showed a mass covering 80% of her right ventricle (RV). Serial cardiac magnetic resonance imaging revealed a 9.4 × 5.6 cm RV mass with vascular and avascular portions and inflow and outflow tract obstruction. Computed tomography showed no other metastases. Due to a delay in diagnosis and a decline in left ventricular ejection fraction, the patient could not undergo palliative chemotherapy or radiotherapy     

A study on coronal incision for treating zygomatic complex fractures

Objective  To study the value of coronal incisions for treating zygomatic complex fractures and evaluate the advantages, indications and complications associated with it. Method  In this prospective study, 12 patients were randomly selected regardless of age, sex requiring open reduction and internal fixation of communited zygomatic complex fractures with or without other associated fractures of the midface. Patients were all treated by coronal approach for open reduction and internal fixation of fracture of the zygomatic complex. Other local incisions were used if required. Results  In all cases postoperative complications were relatively minor except in one case were the temporal branch of facial nerve weakness persisted at 3 months. Whereas 5 cases reported with slight weakness of the temporal branch of the facial nerve which resolved at the end of 3 months. The time taken for exposure of the fracture site via the coronal incision had a mean of 28.7 minutes. There were no cases of flap infection and just 1 case of stitch abscess reported. The same case later reported with a hypertrophic scar formation of greater than 0.5cm at 3months. In all other cases scar formation was negligible and well hidden within the hairline. There were no reported cases of paraesthesia at the operated site or hollowing of the temporal fossa. Conclusion  The coronal incision provides excellent access to the zygomatic arch and zygomatic complex, aiding in good anatomical reduction and also has the added advantage of the scar hidden in the hairline. It also has disadvantages like long operating time, risk of facial nerve injury, scarring in patients with male pattern baldness, paraesthesia of operated site etc. Therefore the incision should be judiciously used and not overused and indications strictly applied.     

Admission hyperglycemia as a prognostic indicator in trauma

OBJECTIVE: The purpose of this study was to assess the utility of two levels of hyperglycemia as predictors for mortality and infectious morbidity in traumatically injured patients. METHODS: All patients >or= 17 years old presenting to a Level I trauma center as a "trauma alert" or a "trauma code" from January 1, 2000, through December 31, 2000, were reviewed. Hypoglycemic patients (glucose concentration < 70 mg/dL) were excluded (n = 4). Patients were considered hyperglycemic with an admission glucose concentration > 200 mg/dL (moderate hyperglycemia) or an admission glucose concentration in the upper quartile for the group (mild hyperglycemia [glucose concentration > 135 mg/dL]). RESULTS: Seven hundred thirty-eight patients were included in the study. Hyperglycemia was associated with increased mortality among both patients with moderate hyperglycemia (34.1% vs. 3.7%, p < 0.01) and those with mild hyperglycemia (15.5% vs. 2%, p < 0.01) compared with corresponding normoglycemic groups. Hyperglycemia proved to be an independent predictor of mortality and of hospital and intensive care unit length of stay after multiple logistic regression while controlling for age, Injury Severity Score, Revised Trauma Score, and gender. Infectious complications, including pneumonia (9.4% vs. 2%, p = 0.001), urinary tract infections (6.6% vs. 1.4%, p = 0.001), wound infections (4.9% vs. 0.6%, p = 0.039), and bacteremia (5% vs. 1.1%, p = 0.004), were significantly increased in patients with elevated glucose concentrations. Hyperglycemia is an independent predictor of increased infectious morbidity controlling for age, gender, and Injury Severity Score in multiple logistic regression models. CONCLUSION: Hyperglycemia independently predicts increased intensive care unit and hospital length of stay and mortality in the trauma population. It is associated with increased infectious morbidity. These associations hold true for mild hyperglycemia (glucose concentration > 135 mg/dL) and moderate hyperglycemia (glucose concentration > 200 mg/dL).     

Normal coronary artery dimensions in Indians

Background There is no available data on normal coronary artery size in the Indian population. We attempted to establish a database for normal dimensions of the coronary artery segments during life by using quantitative coronary angiography and compared these with Western estimates of coronary artery size. Material and Methods Between december 2003 and June 2004, 94 patients who underwent quantitative coronary angiography for evaluation of symptoms of ischemic heart disease and were found to have no coronary artery disease form the sample size. Results The dimensions of branches in the left coronary system in our patients were less and those of the distal circumflex, and the proximal and distal left anterior descending coronary arteries were significantly greater than those of Indian Asians living in the United Kingdom and the native Caucasians but the dimensions of the right coronary artery were significantly greater in our patients. Conclusions Coronary artery dimensions for at least some branches of the left coronary system are similar to that reported in the West and the dimensions of the right coronary are greater. These findings contradict the general perception that Indians have smaller coronary arteries.     

Reconstruction of Orbital Floor Fractures with Porous Polyethylene Implants: A Prospective Study

Purpose

The main aim of our study was to assess and evaluate the efficacy, long standing outcome and infection of porous polyethylene implants in treatment of orbital floor fractures.

Patient and methods

Twelve patients with fractures of orbital floor were included in the study. The cause of fracture was road traffic accident, self fall and cow hit respectively. They also complained of enophthalmos (n = 9), diplopia (n = 3), restricted eye movement (n = 2), impairment of infraorbital nerve (n = 3) and dystopia (n = 6). All the fractures were reconstructed with thin porous polyethylene sheets.

Results

No implants were extruded and there were no signs of inflammatory reactions against porous polyethylene implant. In all nine patients with pre-op enophthalmos it was corrected post-operatively with p value = 0.000 and was statistically significant; diplopia in one patient was corrected; persistence of double vision was noted in two patients. Restricted eye movement was corrected in all patients, dystopia was corrected in four patients and in two patients have persisting dystopia. Paresthesia persisted in all three patients.

Conclusion

Our experience was that reconstruction of orbital floor fracture using porous polyethylene implant is reliable, safe and effective and may be used for reconstruction of the orbital floor fracture with no donor site morbidity.

     

Association of Technetium99m MAG-3 renal scintigraphy with change in creatinine clearance following chemoradiation to the abdomen in patients with gastrointestinal malignancies

Background

Information on differential renal function following abdominal chemoradiation is limited. This study evaluated the association between renal function as measured by biochemical endpoints and scintigraphy and dose volume parameters in patients with gastrointestinal malignancies.

Materials and methods

Patients who received abdominal chemoradiation between 2002 and 2009 were identified for this study. Technetium^99m MAG-3 scintigraphy and laboratory data were obtained prior to and after chemoradiation in 6 month intervals. Factors assessed included age, gender, hypertension, diabetes, and dose volume parameters. Renal function was assessed by biochemical endpoints and renal scintigraphy.

Results

Significant reductions in relative renal function of the primarily irradiated kidney and creatinine clearance were seen. Split renal function decreased from 49.75% pre-radiation to 47.74% and 41.28% at 6-12 months and >12 months post-radiation (P=0.0184). Creatinine clearance declined from 90.67ml/min pre-radiation to 82.23ml/min and 74.54ml/min at 6-12 months and >12 months post-radiation (P<0.0001). Univariate analysis of patients who had at least one post-radiation renogram showed the percent volumes of the primarily irradiated kidney receiving ≥ 25 Gy (V₂₅) and 40 Gy (V₄₀) were significantly associated with ≥5% decrease in relative renal function (P=0.0387 and P=0.0438 respectively).

Conclusion

Decline in split renal function using Technetium^99m MAG-3 scintigraphy correlates with decrease in creatinine clearance and radiation dose-volume parameters following abdominal chemoradiation. Change in split perfusion can be detected as early as 6 months post-radiation. Scintigraphy may provide early determination and quantification of subclinical renal injury prior to clinical evidence of nephropathy.