The biomechanical capacity of the periosteum in intact long bones.

INTRODUCTION: The biological function of the periosteum is profusely described but its contribution to the biomechanical properties of the bone has been considered negligible. The purpose of this study was to examine the biomechanical properties of periosteum-preserved long bones. MATERIALS AND METHODS: The biomechanical properties of both femora and tibiae of 30 male, 4-month-old Wistar rats were evaluated using a destructive three-point-bending testing protocol. In both bones from one side the periosteum was preserved, while in the contralateral bones the periosteum was stripped off. Ultimate strength, stiffness, energy absorption and deflection were derived automatically from the load-deformation curve recorded for each bone. RESULTS: As regards the femur, the periosteum-covered bones displayed statistically significant higher values for all parameters measured compared to the periosteum-stripped bones. Ultimate strength, stiffness, absorbed energy and deflection of stripped and periosteum-covered femora were, respectively, 146.76 +/- 44.71 and 196.01 +/- 41.47 N, 44.25 +/- 17.35 and 61.62 +/- 15.07 N/mm, 0.00054 +/- 0.00274 and 0.00011 +/- 0.00354 Nmm, 0.67 +/- 0.25 and 1.07 +/- 0.28 mm. In the tibia, only energy absorption (0.00353 +/- 0.00199 and 0.0010 +/- 0.00339 Nmm) and deflection (1.71 +/- 0.56 and 0.86 +/- 0.36 mm) were significantly higher in the periosteum-covered bones. The pattern of bone failure was also different in the two groups. In periosteum-covered bones the two bone parts remained in close apposition stabilized by the periosteal membrane, while in a few cases the periosteum was stretched or torn opposite the loading site. CONCLUSION: The periosteum not only has significant biological function but also provides mechanical support to the bone and amplifies the biomechanical capacity of intact rat long bones in bending, probably taking advantage of its fibrous and elastic properties.

Distal intramedullary nail interlocking: the flag and grid technique.

Distal interlocking in intramedullary nailing of long bone fractures accounts for a significant proportion of the total fluoroscopy and operative time. We describe a modification of the "perfect circles" freehand technique employing a metallic grid temporarily attached to the skin of the lateral surface of the femur or to the medial surface of the tibia that acts as a fixed "navigational" aid. The position of the distal nail holes in relation to the grid is fluoroscopically ascertained. Subsequently, under fluoroscopic control, a modified Steinmann pin with a metallic handle attached to its blunt end ("flag") is used to accomplish targeting and to create the screw holes, affording improved visualization. This technique was compared with the traditional freehand technique in 2 groups of patients. Use of the modified technique led to reduction of radiation exposure and total distal interlocking time, and there were no significant complications related to the technique.

Innoxious removal of suction drains.

Suction drains are commonly used in orthopedic elective and trauma surgery; however, drain tube removal causes pain, discomfort, and anxiety. A method of drain tube removal is described in patients who underwent total hip replacement and in adolescents who underwent lower extremity surgery. Ten milliliters of lidocaine was injected through the skin wound around the drain tube. The efficiency of this practice was evaluated using a visual analog scale score in two patient groups. Pain during tube removal and pain on post-removal were significantly decreased in the study group compared to the placebo group. Using this technique drain tube removal was painless, comfortable, and safe.