Thursday, November 3, 2011
I'll never forget the first orthopedic surgery I observed while at medical school training for my medical illustration degree. I was shocked at the crude brutality of the procedure with all the hammering, sawing, drilling and reaming. It seemed more like carpentry than what I had envisioned as modern medicine. If nothing else, orthopedic surgery is certainly dramatic and perhaps this inherent drama is what makes it such a popular subject for demonstrative evidence. Because of that popularity, I have selected one orthopedic issue as our topic for the month. Let's learn a bit about intramedullary fixation.
We'll begin with the basics. When a bone is broken, the body has a remarkable ability to repair itself by producing new bone to knit the fracture back into a solid structure. This can only occur successfully if the fractured edges of bone are in contact with one another and if the fracture site is immobilized during the healing process. That is the primary goal of the orthopedist when dealing with a fracture: to align and stabilize the fracture site. In many instances, this alignment and stabilization can be done without surgery. Non-displaced fractures can be stabilized in a splint or cast. Some displaced fractures can be realigned externally before stabilization. More complex or severe fractures must be aligned surgically and held in position with fixation hardware to provide the stabilization required for healing.A variety of fixation techniques and types of fixation hardware have been developed over centuries. Orthopedic surgeons may use wires, staples, plates, screws or rods to hold fractures in position as they heal. One of the most popular techniques for fixation of large long bone (extremities) fractures is the insertion of an intramedullary rod inside the length of the bone. Long bones in the arms, legs, feet and hands consist of a hard compact outer layer that forms a tube surrounding a hollow chamber called the medullary cavity containing the bone marrow. This hollow chamber is ideal for the placement of a fixation rod allowing for the stabilization of the entire length of the bone.
The surgical technique for intramedullary fixation includes the access of the end of the broken bone through a small open incision. A hole is created through the hard outer compact bone to expose the medullary canal. A guidewire is inserted down the length of the bone to insure alignment and to identify the medullary canal. A drill-like reamer is advanced over the guidewire to clear the marrow and open a pathway for the fixation rod. Finally, the rod itself is hammered into position. Locking screws may be placed at either end of the rod to hold the rod in position. This fixation rod may be left in position permanently or may be removed at a later date following the full healing of the fracture.
Beyond the great stability offered by intramedullary fixation, there are other advantages to utilizing this technique. Intramedullary fixation can be accomplished with a much smaller incision than the large open incision required for the placement of fixation plates across the external aspect of the fracture. This reduces post-operative pain and recovery time and also involves lower risk of damage to vessels and nerves that may lie in the region of the fracture. Also, because the open incision is not at the actual site of the fracture, there is no additional disruption and risk of infection that would prevent bone healing.
Larger bones are more commonly treated with intramedullary fixation. This includes the femur (thigh), the tibia (shin) and the humerus (upper arm). Smaller bones such as the fibula (smaller lower leg bone), metacarpals (hand), metatarsals (foot), phalanges (fingers and toes) and even the clavicle (collar bone) can be fixated with smaller intramedullary rods or pins, but this is less common than the use of small plates and screws. Another term you may run across is "retrograde". Retrograde fixation means that the rod is placed through the distal end of the bone extending upward rather than into the proximal end and extending downward.
If you handle any personal injury cases in your practice, you'll eventually run across a case involving an intramedullary fixation. Hopefully this overview has helped you to better understand these dramatic orthopedic procedures.