A Method for Prediction of Femoral Component of Hip Prosthesis Durability due to Aseptic Loosening by Using Coffin/Manson Fatigue Model.

The purpose of this work is to develop a new model estimate of the fatigue life of a hip prosthesis due to aseptic loosening as a multifactorial phenomenon. The formula developed here is a three-parameter model based on Basquin's law for fatigue, eccentric compression formula for the compressive stress and torsion in the prosthesis due to the horizontal components of the contact force. With our model, we can accurately predict the durability of a hip prosthesis due to the following four parameters: body weight, femoral offset, duration, and intensity of daily physical activities of a patient. The agreement of the prediction with the real life of the prosthesis, observed on 15 patients, is found to be adequate. Based on the formula derived for a particular implant, there was a high degree of concurrence between the model-predicted and actual values of aseptic loosening (durability) proved by the Mann-Whitney U test. By virtue of the validated model, it is possible to predict, quantitatively, the influence of various factors on the hip life. For example, we can conclude that a 10% decrease of a patient's body mass, with all other conditions being the same, causes 5% increase of the hip fatigue life.

Harmonic Scalpel hemorrhoidectomy: a painless procedure?

Since the surgical treatment of hemorrhoidal disease has been characterized by intense postoperative pain, recent studies have tried to modify the standard Milligan-Morgans technique. The up-to-date literature, in the experience of authors, has confirmed that the new method of Harmonic Scalpel hemorrhoidectomy reduces postoperative pain. The aim of our study was to statistically evaluate, based on our experience, the efficacy of this surgical approach in terms of reducing postoperative pain and establishing a stable hemostasis. Seventy-seven (77) patients suffering from hemorrhoidal disease, stage III and IV, underwent surgery in our clinic during the last five years. The postoperative pain was determined using the visual analog scale on the 1st, 2nd and 7th postoperative days. Patients were divided into two groups in regard to the surgical procedure applied. The data were statistically processed using the Statistica 7.0 software. We concluded that Harmonic Scalpel hemorrhoidectomy, due to less thermal damage, statistically significantly reduced postoperative pain with better hemostasis, compared with Milligan-Morgan's method of treating hemorrhoidal disease.