THE EFFECT OF TOURNIQUET CONTROL ON INTRAMEDULLARY REAMING

Participants: E.P. Frankenburg, M. Karunakar, D.S. Scott, K.A. Mueller, S. Matuszak, P. Pazmino, R. Taylor, K.A. Sweet, B.T. Nolan, D. Kayner, C. Roehm, S.A. Goldstein

Keywords: thermal necrosis, tourniquet control, animal model

Introduction

Reamed intramedullary nailing is commonly used for the treatment of acute fractures, diaphyseal delayed unions, non-unions and mal-unions. Tourniquets are often inflated to minimize blood loss during the surgical approach and deflated prior to intramedullary reaming. The purpose of this study is to quantify the effect of tourniquet control on intramedullary temperatures that occur during reamed tibial nailing. The null hypothesis is that there is no significant difference in the elevation of cortical temperatures during the reaming process whether a tourniquet is used or not. An improved understanding of the physiology of reaming may result in the development of new techniques for intramedullary fixation that promote fracture healing. Additionally, improvements in reamer design may reduce potentially deleterious local and systemic effects

Materials and Methods

Five adult male mongrels with bilateral anatomically correct tibiae will be used to determine the effects of tourniquet control during tibial reaming. The use of a tourniquet will be randomized to either the right or left tibia prior to reaming. Similar techniques of sequential reaming will take place in both the right and left tibias. Prior to reaming, however, four small drill holes will be made in the cortex of the tibia, at the level of the isthmus. One thermocouple probe will be placed into each hole, at varying depths ranging from the cortical surface to the intramedullary canal. The thermocouples will be held in place by means of a specially designed jig that is screwed into the cortical tissue.

The thermocouples will be connected to an A/D converter, and the temperature readings will be recorded and correlated with events that occurred during the surgical procedure. The computer based acquisition system will sample all four thermocouples simultaneously and write the data to disk. The data will then be available to analyze as a function of time. Additional information recorded will include reamer sequence, cortical chatter and size of reamer. All data will be analyzed to look for maximum temperature and temperature/time function.

Immediately after surgery, the animals will be euthanized. The central third of the tibias will be sectioned and placed in neutral buffered formalin and decalcified before embedding in paraffin. Sections six to seven micrometers thick will be prepared and stained with hematoxylin and eosin. The specimens will then be examined under light microscopy.

Progress

Two dogs have undergone surgery to date, and their respective data analyzed. The tibias have been harvested, and are starting the histologic protocols.