A New Surgical Knife

Abstract

Original ArticlesA New Surgical Knife Kenneth G. ReidFRCS Kenneth G. Reid Consultant Cardiac Surgeon, Department of Surgery, King Faisal Specialist Hospital and Research Centre, P. O. Box 3354, Riyadh 11211, Saudi Arabia Search for more papers by this author Published Online:1 Jul 1987https://doi.org/10.5144/0256-4947.1987.239SectionsPDF ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail AboutABSTRACTABSTRACTA new surgical knife has been designed, developed through prototypes, and clinically tested over four years. It allows the surgeon intraoperatively to vary the position of the cutting blade relative to the long axis of the knife handle. The instrument has been designed primarily to extend the safety and accuracy of conservative mitral valve surgery during open heart operations and to promote new techniques of repair.IntroductionA well-designed product, be it a tractor or a pair of shoes, is something that works: it fulfills the wants, tastes, needs and priorities of those who use it. It is a successful fusion of market requirements, aesthetics and technology.—Louis Van Praag, in The Times, 15 October 1984RATIONALEThe mitral valve lies eight or nine inches from the surgeon’s hand, within the left atrium. The plane of the valve relative to the line of surgical access through a conventional left atriotomy varies with each patient from 45° to 90°. This restricted access imposes limitations on the use of a conventional straight knife when accurate and delicate surgery has to be performed at supravalve, valve and sub valve levels. It became necessary to develop an instrument that allows the angle of incidence of the cutting edge to the plane of the valve to be varied easily and intraoperatively by the surgeon.Four prototypes were tested clinically to achieve optimal length, weight, locking mechanism, materials, surface finish and cost effectiveness.DESCRIPTION OF INSTRUMENTThe knife consists of a cylindrical, machined and milled handle, as seen in Figure 1, with a screw thread at the distal end. An axle carrying a milled steel wheel (Figure 2) which is welded to a Swann-Morton blade holder rests within a short cylindrical head that screws onto the handle with a reversed thread so that pressure on the blade edge tightens it. A steel chisel also rests in the blade-carrying head. The position of the chisel is maintained by means of a pin slotting into a longitudinal groove in the side of the chisel. As the head is tightened on the handle, the chisel edge engages the milled grooves on the axle wheel, thus locking the blade in position. Unscrewing the head allows the chisel to fall back and disengage, and the surgeon can adjust the angle of the blade before relocking it. The blade can, therefore, be placed in any position through 180°, and by virtue of the cylindrical handle, in any plane. The blade has the same flexibility of position as a universal joint without the latter’s disadvantages (Figure 3).Figure 1. Distal screw thread and wheel axle.Download FigureFigure 2. The milled wheel and mounted blade carrier.Download FigureFigure 3. The blade may be placed in any angle through 180°.Download FigureThe knife handle is 8.5 inches long and made of surgical stainless steel which has been oxidized to give a black matt finish. It is fitted with standard surgical blades.CLINICAL APPLICATIONThe knife has been widely used for conservative mitral valve surgery and the design was endorsed at the 2nd International Mitral Valve Workshop in Santander, Spain, in September 1984. It has also been used for the excision of failed valve prostheses, for infundibular resection in obstructive cardiomyopathy and tetralogy of Fallot, and in resecting calcified aortic valves. Its particular merit is that it permits greater precision and safety when surgical access is limited.The knife is currently being tried in other surgical disciplines where the blade action has important advantages over conventional instruments.The instrument is unique and has established an important new principle which can be modified for use in many fields. Previous article Next article FiguresReferencesRelatedDetails Volume 7, Issue 3July 1987 Metrics History Accepted12 November 1986Published online1 July 1987 KeywordsSurgical instrumentsMitral valve - surgeryACKNOWLEDGEMENTThe author would like to thank Miss Lesley Skeates for preparing the illustrations. Manufacturer: Downs Surgical PLC, Mitcham, Surrey, EnglandInformationCopyright © 1987, Annals of Saudi Medicine