A case for 77-bromine labelled radiopharmaceuticals.
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Animals↗
Biomedical subjects
S H Stern
Publications and source records attributed to S H Stern.
A fatigue life analysis of small fragment screws.
OBJECTIVES: To conduct a comparative fatigue analysis of several commonly used small fragment screws. DESIGN: Biomechanical laboratory study. SETTING: Research laboratory. MAIN OUTCOME MEASUREMENTS: A fatigue life analysis of seven different types of small fragment screws was conducted using a Wohler fatigue-testing machine. Four different types of 3.5-millimeter cortical screws were subjected to fatigue analysis. These included solid stainless steel screws from Synthes Ltd. (core diameter 2.4 millimeters), Zimmer Inc. (core diameter 2.4 millimeter), and Smith and Nephew Richards Inc. (core diameter 2.4 millimeters) and cannulated stainless steel screws from Synthes Ltd. (core diameter 2.5 millimeters). In addition, three types of 4.0-millimeter cancellous screws were tested. These included stainless steel screws from Synthes Ltd. (core diameter 1.9 millimeters), titanium screws from Synthes Ltd. (core diameter 2.0 millimeters), and titanium alloy screws from DePuy-Ace (core diameter 2.8 millimeters). Fatigue lives, as reflected by mean cycles to failure, were compared. RESULTS: The four types of cortical screws had longer fatigue lives than the Synthes cancellous screws did ( p < 0.001) but shorter fatigue lives than the DePuy-Ace cancellous screws did ( p < 0.0001). Among the cortical screws, the cannulated and solid Synthes screws and the solid Zimmer screws did not differ statistically. The Smith and Nephew Richards cortical screws failed at statistically fewer cycles than the Synthes solid and cannulated cortical screws did ( p < 0.003) but did not statistically differ from the Zimmer screws. The DePuy-Ace titanium alloy cancellous screw had the longest fatigue life of the tested implants by a large margin ( p < 0.0001). The Synthes pure titanium and stainless steel cancellous screws did not significantly differ. CONCLUSIONS: This analysis supports core diameter as the principal factor determining fatigue life as the results paralleled implant geometry. This design modification to improve bending and fatigue strength may come at a price to pullout strength, however, because of a decreased major-to-minor diameter and increased pitch. Cortical screws differed in fatigue performance despite identical dimensions, presumably highlighting the importance of implant processing and machining. Cannulated cortical screws performed well relative to solid screws, thereby supporting their clinical use. Pure titanium and stainless steel cancellous screws performed similarly in fatigue despite differing material properties, presumably because of geometric design differences. This report highlights some of the differences in the in vitro fatigue performance among several commonly used small fragment screws.
Bone Screws↗
Patellar taping in the treatment of patellofemoral pain. A prospective randomized study.
The purpose of this prospective study was to evaluate the efficacy of a patellar taping program in the conservative management of patellofemoral pain. Twenty-five patients with patellofemoral pain were randomized into two groups. One group underwent a standard physical therapy program for patellofemoral pain. The other group underwent the same physical therapy program, but use of a patellar taping technique was added to this program. Results of a subjective visual analog scale and changes in isokinetic strength and electromyographic activity of the quadriceps muscle were analyzed. Both the tape and no-tape groups experienced a statistically significant decrease in symptoms (P < 0.05), but no difference in improvement of patellofemoral pain was noted between the groups. Likewise, both groups demonstrated significant improvement in quadriceps muscle isokinetic strength (P < 0.05) and activity (P < 0.001), but no difference in improvement was noted between groups. The results of this study suggest no beneficial effect of adding a patellar taping program to a standard physical therapy program in the conservative treatment of patellofemoral pain. Larger prospective studies are warranted to support this opinion.
Adolescent↗