Joäo D. M. B. Alvarenga Rossi

EXPERIMENTAL DETERMINATION OF BONE CORTEX HOLDING POWER OF ORTHOPEDIC SCREW

Cylindrical specimens of bone measuring 15 mm in diameter were obtained from the lateral cortical layer of 10 pairs of femurs and tibias. A central hole 3.2 mm in diameter was drilled in each specimen. The hole was tapped, and a 4.5 mm cortical bone screw was inserted from the outer surface. The montage was submitted to push-out testing up to a complete strip of the bone threads. The cortical thickness and rupture load were measured, and the shear stress was calculated. The results were grouped according to the bone segment from which the specimen was obtained. The results showed that bone cortex screw holding power is dependent on the bone site. Additionally, the diaphyseal cortical bone tissue is both quantitatively and qualitatively more resistant to screw extraction than the metaphyseal tissue.

Comparative Study of Ilizarov, Wagner, and Anderson Methods for Limb Lengthening (100 Lengthenings in 98 Patients)

Summary One hundred lower limb lengthenings were performed in 98 patients by the Anderson (25 tibias, group A), Wagner (45 femurs, group B), and Ilizarov (16 femurs and 14 tibias, group C) methods in the Department of Orthopaedic and Traumatologic Surgery of the University of Sao Paulo School of Medicine from 1971 to 1991. Results obtained with the three methods, problems and complications observed, and comparison of healing time between the methods of lengthening used are reported. In group A, lengthening ranged from 3 to 6 cm (average 4.2 cm); healing time ranged from 121 to 331 days (average 196.88 days), with an average lengthening index of 1.72 months/cm. In group B, femoral lengthening ranged from 1 to 12.5 cm (average 4.6 cm); average healing time for group Bl (percutaneous osteotomy) was 185.4 days, and lengthening index was 1.32 months/cm; healing time for group B2 (corticotomy) was 156.3 days, with lengthening index of 1.23 months/cm. In group C, femoral lengthening ranged from 1.0 to 7.5 cm (average 4.7 cm), and healing time ranged from 58 to 441 days (mean of 185.6 days); the lengthening index was 1.31 months/cm. For Ilizarov tibial lengthening, lengthening ranged from 1.0 to 7.5 cm (average 4.5 cm), healing time ranged from 94 to 386 days (mean of 184 days), lengthening index was 1.35 months/cm. With the Anderson method, the most common complication was delayed union; with the Wagner technique, the most common complications were related to bone healing (fracture, implant failure after the second stage, nonunion); and with the Ilizarov method, the most common complication was incomplete corticotomy. Overall results were good despite the complications, and we emphasize the necessity for the surgeon to understand the principles of leg lengthening to achieve good results.

Indication of myocardial perfusion scintigraphy for coronary artery disease detection based on clinical-epidemiological and treadmill test evidences.

OBJECTIVE To establish when the myocardial perfusion scintigraphy (MPS) should be performed based on well-defined information obtained from treadmill test results and clinical-epidemiological parameters for coronary artery disease (CAD). METHODS 2,100 patients who underwent MPS were classified according to the results of scintigraphy, the Duke score and a clinical-epidemiological score based on Framingham study. The patients with positive results on MPS were followed to define whether the results were true positives. Receiver operating characteristic (ROC) curves were used to establish the efficiency and the best Duke and clinical-epidemiological scores to define patients that should be submitted to scintigraphy. RESULTS It was observed that the MPS use restriction in patients with Duke score below 7.5 and/or clinical-epidemiological score above 4 could decrease the utilization of this method by 50% without exposing the patients to a significant misdiagnosis risk. CONCLUSION The utilization of the Duke score and a clinical-epidemiological score to classify the patients expressively decreased the number of unnecessarily requested scintigraphies.