STEINMANN’S AND DENHAM’S PINS

EQUIPMENT A sterile sharp pin. A blunt one promotes infection, so sharpen a pin each time, if necessary on a grindstone. A scalpel and local anaesthetic. Some surgeons sterilize the chuck, others use an unsterile chuck and a no–touch technique.

INSERTING THE PIN in most district hospitals this is best done in the theatre. if nursing and ward equipment are very good, you can do it in the ward under local anaesthesia.

Figure 70.14: TIBIAL TRACTION RIGHT AND WRONG. A, and B, at all sites the pin must be at 90 to the axis of the limb and in a horizonal plane. There must be the same length of pin each side of the limb. If the pin is very skew, one of the cords will slide along it and press into the skin (C, and D). E, if you don’t have a Thomas swivel, tie the cord to a cork, not to the pin directly (G). Don’t put the pin in too far anteriorly or put it in skew (H). Kindly contributed by John Stewart.

If you are going to hammer a pin in, do it through the cancellous bone near the end of a long bone, and not through the thick cortical bone of the shaft, because this may split. Take the patient to the theatre, find two assistants, and give him a general anaesthetic.

If you are using local anaesthesia, sedate him, and apply iodine to the skin where the pin will go in and come out. Inject local anaesthetic into the skin, subcutaneous tissue, and periosteum of both sides, making sure it goes under the periosteum.

Make a small nick in the skin with the point of a sharp scalpel. Put the pin in the chuck, and push it through the skin into the bone, twisting it slightly from side to side as you do so. Ask one assistant to hold the patient’s leg. Take great care to get the direction of the pin right. Ask your other assistant to check its direction by observing its alignment from the foot of the table. Putting it in is hard work!

As the pin comes out of the bone on the other side of the limb, its point will raise the skin, so nick this with a scalpel, and push the pin through it.

When the threads of a Denham pin reach the bone, screw them in about six turns, so that some of them enter its cortex. The threads should lie in the cortex, not in the medulla.

Finally, secure the pin in a Boehler’s stirrup or, preferably, with Thomas pin mounts. If the sharp point might injure the patient’s other leg, put a cork or a cap on it.

Figure 70.15: INSERTING A STEINMANN PIN THROUGH THE CALCANEUS. If you put the pin in too far posteriorly, you will dorsiflex his foot. If you leave it in for more than 15 days you will increase the risk of osteomyelitis. Kindly contributed by Peter Bewes.

PARTICULAR SITES FOR PIN FIXATION

THE UPPER FEMUR is occasionally used for the central dislocation of the head of a patient’s femur (77.4). insert the pin vertically through his greater trochanter.

THE LOWER FEMUR is one of the less satisfactory sites. Insert the pin at the level of the flare of the condyles, opposite the upper pole of the patella, slightly anterior to the midline of the leg.

THE UPPER TIBIA is much the most important site, and is used for most fractures of the femur, and many fractures around the knee. If you insert the pin from the lateral side, you are less likely to injure the patient’s common peroneal nerve. There are two alternative sites.

If you are using a chuck, put a 4 mm pin through firm cortical bone 3 cm distal to the patient’s tibial tuberosity. Go from the lateral to the medial side. Feel the neck of his fibula where his common peroneal nerve will be winding round it, and insert the pin anterior to that point.

If you have no chuck and you have to hammer a pin in, do so from the lateral to the medial side 1 cm distal to the tibial tuberosity through the junction of cortical and cancellous bone, that is, through the flare of the condyles. The pin will be less firmly held here but the bone is less likely to shatter.

CAUTION! in either site, don’t insert the pin too far anteriorly, because there will not be enough bone to hold it.

If his tibia is osteoporotic, apply a short leg cast around it and incorporate the pin in this.

LOWER TIBIA For some fractures of the upper tibia (80.5). Insert the pin from the lateral side 4 to 6 cm above the patient’s medial malleolus immediately in front of his fibula. This makes sure it is well clear of his ankle joint, and avoids injuring his superficial peroneal nerve. Align it carefully so that it is at right angles to the long axis of his limb and is in the coronal plane.

CALCANEUS For some fractures of the tibia (Fig. 81-10). Insert a 4 mm pin from the lateral side medially through the posterior part of the patient’s calcaneus, as in Figs. 70-13 and 70-16. Put the pin in, or just behind, a vertical line joining the tip of his lateral malleolus to the lower border of his heel. If you drive it in at right angles to the axis of his limb, it will emerge well clear of his posterior tibial vessels.

CAUTION! (1) If you put the pin in too far posteriorly, you will dorsiflex the patient’s foot. (2) If you leave it in more than 15 days you will increase the risk of osteomyelitis.

OLECRANON For some fractures of the radius and ulna. Use a thin 2 mm Steinmann pin, and insert it from the medial side laterally, avoiding the patient’s ulnar nerve. A Kirschner wire is better, if you have the equipment to apply it.

DRESSINGS Keep the pin track clean. Apply dressings to the entry and exit wounds of the pin and inspect them regularly.

CAUTION! if there are any signs of infection round a pin at any site, remove it immediately. if you cannot put it back through uninfected skin elsewhere in the bone, change to skin traction.

REMOVING A PIN Use an antiseptic such as iodine to clean the projecting point of the pin that will be drawn through the tissues. Pull it out with the chuck. Don’t remove it by hitting the point of the pin with a hammer. Unscrew a Denham pin, and don’t merely pull it.