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280 Injury, 15, 280-281 Printed in Great Britain An improved traction system for fragile bones David Smith Department of Orthopaedics, University Hospital, Nottingham Summary The problems of transcutaneous tibia1 pins for skeletal trac- tion in elderly patients are considered, and the reasons be- hind loosening of the pin are discussed. A novel method of skeletal traction using two pins is proposed. INTRODUCTION SKELETAL traction has been part of the armamen- tarium of the orthopaedic surgeon since Steinmann introduced his transcutaneous tibia1 pin in 19 16. Since then, various workers have reported that prolonged periods of traction predispose to loosening of the pin in the bone (Charnley, 1972; Rockwood and Green, 1975; Wilson, 1976; Scull, 1979). The features which promote loosening are thought to be: 1. Rotational and axial forces acting on the pin. 2. Excessive traction. 3. Osteoporosis. Movement resulting from loosening of the pin pro- duces pain and predisposes to infection (Charnley, 1972; Wilson, 1976), although significant infection has been said to occur infrequently (Wilson, 1976). How- ever, the fact that excessive loosening of the pin does cause trouble is borne out by the variety of methods and devices introduced to prevent loosening. These include the use of threaded pins, insertion into the bone distal to the tibia1 tubercle (Rockwood and Green, 1975) and traction stirrups designed to prevent rotation (Fidler, 1974; Scull, 1979). If inserted cor- rectly, transcutaneous tibia1 pins should remain in situ for several months without trouble (Charnley, 1972). This is certainly true for young patients: how- ever, elderly, osteoporotic patients almost invariably develop some loosening of the pin before their period of traction is completed. Even if this is not severe enough to warrant removal of the pin, it often causes discomfort. Many elderly patients become confused on admission to hospital; the restlessness sometimes associated with this, coupled with their osteoporosis, give rise to a high incidence of pin loosening. Often this occurs within a few days of admission, so that some patients may need their pins replacing several times. METHOD AND MATERIALS If loosening of transcutaneous tibia1 pins is due to an imbalance between the forces applied through the pin and the strength of the bone, it is logical to suppose that by using two pins clamped rigidly together to apply traction, the force exerted by each on the bone could be halved. In addition, rotational forces would be eliminated and the use of the Denham type threaded pins would resist axial movement (Charnley 1972). The apparatus is shown in Fig 1. It consists of two Denham pins inserted in parallel through the tibia, at a right angle to the longitudinal axis of the bone, and connected rigidly together at each end with a clamp from the Hoffman external fixation set, the pins passing through the grooves in the clamps. Insertion of the pins involves first marking the entry and exit sites of the pins on the skin ofthe leg, referring to the Hoffman clamps. The skin is then prepared and draped in the usual way before insertion of the pins. A generous cut is made with a scalpel at each entry site. The pins are then inserted without pre-drilling, care being taken to keep the pins parallel. As each pin emerges from the tibia1 cortex and tents the overlying skin, a further generous cut is made to facilitate the exit of the pin and reduce skin tension around the pin. Our practice is then to place a simple dressing of Melolin gauze over each skin puncture site, the Melo- lin being cut to fit over the pin and sit snugly against the skin. These are held in position with micropore tape; no occlusive dressing is used. The Hoffman clamps are then mounted on the pins and traction may be applied via cords attached to each clamp, or via a Nissen loop located on the distal pin. Care of the pin entry and exit sites simply involves changing the Melolin gauze dressing daily for the first week and weekly thereafter. Encrustations are removed with a swab soaked in saline. Polymixin and Bacitracin ointment (Polyfax) is applied to any pin entry site if the surrounding skin is reddened or there are other early signs of infection. RESULTS This traction system has been used successfully in Nottingham for the past 18 months. Eleven patients (see 7’uble I) have been treated; in one case this system was the primary traction unit, and in the other ten cases insertion of the two pin unit was undertaken as a secondary procedure following the failure of single pin traction. All eleven cases retained their two pin traction units for the full duration of traction-in the case of one 64-year-old lady for five months-without the need to
