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Jungle Orthopaedics
ORTHOPAEDIC PROBLEMS IN A PRIMITIVE SETTING
Diplomate American Board of Orthopaedic Surgery
Date of production in this revised format: February 15, 2001
Monograph #3, February, 1995
In this monograph I would like to discuss intramedullary fixation and external fixation. These are two relatively simple but extremely effective ways of dealing with many fractures, and are well suited to a primitive setting.
Intramdedullary Fixation
One should avoid the use of plates and screws in open fractures. The same used to be felt truein regard to intramedullary fixation, but now it is not uncommmon to use intramedullary fixation in open fractures. If infection does occur, the intramedullary fixation can remain and fulfill its function of holding fragments in alignment. Later, after the fracture has healed, removal of the intramedullary fixation is relatively simple. ON the other hand, infection involving plates and screws most otfen results in loosening of the screws and loss of fixation.
For example: Let's consider an open fracture of the forearrm with displacement of the fragments. If one treats the wound and leaves the fracture alone, until the wound is healed, going back in to insert plates and screws is a large undertaking. On the other hand, careful debridement, followed by intramedullary fixation, and then leaving the wound open for secondary closure will result in maintenance of alignment while the wound is healing. Also, in a busy schedule, this will reduce the load on the operating room.
Rush Rods
Rush rods are very useful in many types of fractures, both open and closed. A similar type rod can be made in your own workshop out of the type 316 stainless steel rods I mentioned before. For femurs and tibias you need 1/4" or 3/16" rods. Forearms usually need 1/8" or 3/32".
First of all you have to fashion a hook on one end, awhich will prevent the rod from migrating deeper into the bone and will remain superficial to allow later removal. The hook can be fashioned with a vice, vise-grip pliers, channel-lock pliers, etc. and looks like this:
Making the hook on 3/16" and 1/4" stock is more challenging. It is usually necessary to heat the tip with a blowtorch to a glowing red, before attempting to bend it. Then, the hook must be inserted into cold water while it is still hot, to resotre the temper.
Then a sled-type point is constructed at the other end with the point of the sled on the same side as the hook:
It is very helptful to have a sterile vice, hacksaw, extra blades and files that can be set up in the operating room to enable you to cut long pins down to make shorter ones. Be sure to get a hacksaw with an all-metal handle, so it won't melt in the autoclave. The file will rust and wilh ave to be replaced from time to time. After cutting pins or rods, be sure to wash them thoroughly in sterile water, to remove fillings and dust.
After the hook and the point have been constructed, polish the rod with steel wool before sterilizing.
Technique of insertion: The rods should be bent somewhat, like this:
This results in "three-point fixation" within the medullary canal of the bone. Be sure to bend it so that the flat part of the sled-end skids along the interior of the medullary canal. Otherwise the point will dig in and you are in trouble:
About the only tool you really need besides a mallet is a Rush pin driver. The concave end of this driver allows you to control rotation as the rod is introduced. The hole in the tip is useful for bending the rod. This driver can also be used to extract the rod, by hooking the tip under the hook and driving the rod out in reverse:
However, removal is much facilitated by an extractor, such as the McNutt Driver-bender-extractor:
It is also helpful to have an awl, to make the original hole. The Rush awl reamer has a channel along one side of the pointed end. After you have made the hole, insert the point of the rod into the channel and slide it down into the hole:
Benders will allow you to shape the rods more easily:
An Atlas of Rush Pin Techniques, by Berivon is available free of charge and is highly recommended-phone 1-800-251-7874.
External fixation
External fixation may be better than internal in some situations, especially in severely comminuted or very dirty fractures. We have tried the various types of external fixation apparatus, and found them hard to use. Moreover, we didn't dare send someone home with one of those erector sets in place, as we knew we would never see it again. We devised a method of our own, based on a technique I first saw in Japanese literature.
We fashion external fixation pins out of threaded 316 stainless steel stock. First, we sharpen the tip and then cut a channel along one side of the tip, to make it a self-tapping tip:
If you are working with exposed bone, all that is necessary is to drill a starter hole in the bone and then insert the external fixation pins, two proximal to the fracture and two distal to the fracture. Be sure that the fixation pin penetrates both cortices of the bone:
If you do not have exposed bone, you can use a drill-sleeve apparatus, to protect the soft tissues, while you drill the hole and drive the external fixation pins:
After the pins have been inserted, you then connect them with a rod (we usually used I/4" galvanized steel, available from a hardware store), tying the junctions with small wire, such as stove-wire, to temporarily hold things in place. Then we used non-sterile dental methylmethacrylate "bone cement". At this point in the procedure, it is necessary for the wound to be partially dressed and protected from the unsterile bone cement, and the operator has to break sterility in order to apply the cement. You can also use sterile bone cement, but it is much more expensive. Sometimes you can get outdated sterile cement from orthopaedic supply places, or from hospitals, and this can be admirably well used in external fixation techniques. A ball of bone cement is placed at each junction:
Be sure to leave enough room between the pins, with bare wire showing, to allow you to later cut the wire between the pins for removal of the pins. You can then strike the cement with a hammer and shatter it, thereby saving the external pins to be used again, and again. The total cost of this method of fixation is very reasonable, if you use the pins over and over. It usually is far less than the cost of plaster.
The fracture is held in approximate alignment while the cement sets (about five minutes). Then, x-rays can be taken. The wire between the two sets of pins can be bent with wire benders to adjust the angulation of the fracture, if necessary. At first we also had a “sliding block” between the two sets of pins, to allow us to let the fracture fragments compress. While theoretically advantageous, we seldom saw the need for this, and eventually virtually abandoned it.
In the case of a large bone, such as the femur or tibia, it may be necessary to place two connecting rods between the fixation pins, for additional strength:
If bone cement is not available you can still use this technique, using plaster of paris at the junctions of the pins with the external wire splint. Use 1” wide plaster bandage and wrap the junction tightly.
The biggest advantage of using external fixation like this is that you still have excellent access to the soft tissue wound. You can immerse the extremity in a whirlpool (providing bone cement has been used at the junctions), or use wet packs, without getting a plaster cast all soggy. You can secondarily close a wound with a skin graft, without removing the ext. fix. apparatus.
Placement of the pins requires knowledge of the anatomy, so as to not injure important structures. It is best to apply the external fixation apparatus on the tension side of the fracture, just as in the case of plates.
This apparatus allows construction of triangle frames for control of complicated fractures, or fractures on both sides of a joint, etc. -– it is extremely versatile.
We have found this technique useful in pelvic fractures, inserting two pins between the tables of the ilium on each side, connecting the pins with a short rod, and then connecting these two short rods with one or more long curved rods crossing from one side of the pelvis to the other. This gives good fixation of “open book” types of pelvic fractures.
Disadvantages and hazards of external fixation:
- Pin tracts must be carefully cleansed with hydrogen peroxide daily, to prevent pin-track infection.
- Pins inserted through muscles impale the muscle, and motion is very painful.
- Prolonged use of the external fixator may “unload” the fracture and result in delayed or non-union.
- The external fixation pin inserted through a closed compartment may cause a compartment syndrome.
- There is very little peripheral callus formation, and the fracture site is still weak at the time of removal of external fixation. It must be protected by a cast, brace, crutches, etc. for a few weeks.
- Care must be exercised that the deep tip of the external fixation pin does not protrude very far beyond the distal cortex, or harm to important structures may result.