Surgeons face some interesting challenges when dealing with broken bones in children. One of the most common bone fractures in children between the ages of four and 14 is the forearm. There are two bones in there: the radius and the ulna.
In a simple (undisplaced) fracture of both bones, the forearm can be put in a cast and the bones will knit together. But when the fracture separates and no longer lines up properly, surgery is often needed to reduce the fracture (i.e., bring the edges back together and line them up). When it comes to a fracture of both bones in the forearm, reduction can get tricky.
These two bones make it possible for the forearm to rotate. Forearm rotation allows the hand to turn palm up (a movement called supination) or palm down (pronation. Surgery must be done in such a way that the bones are stabilized (held in place) while preserving forearm rotation.
Placing a metal rod down the middle of each broken bone has been a popular fixation method for many years. Maintaining good bone alignment is necessary to save forearm rotation. Then back in 1996, the first orthopedic surgeon tried using a metal rod just down one of the two broken forearm bones (the ulna). This type of fixation is called single intramedullary fixation.
Since that time, other surgeons have tried the new technique and reported on their results. There have been good and not-so-good results. Sometimes single intramedullary fixation yielded excellent outcomes. In other cases, there were problems with failure of the fractured bone to heal, loss of reduction, and increased bend in the bone. The last complication (angulation of the healing bone) can lead to loss of forearm rotation, which is a major concern.
To help answer the question of whether or not single bone fixation is safe and effective, hand surgeons from Children’s Hospital in Boston tried the single bone intramedullary fixation. They used it in 48 cases of fractures of the ulna and radius in children. They hoped to identify possible risk factors for failed cases. In this way, it might be possible to screen children ahead of time and only perform the double rod fixation when absolutely needed or when the patient is at risk for malunion or nonunion.
In all 48 patients, only the ulna was stabilized with the rod. Surgeons with special training in pediatric medicine did the surgeries. Special imaging X-rays called fluoroscopy was done in the operating room to make sure the bones were stable and in place before putting a cast on the arm.
After collecting all the data on each case and analyzing the post-operative results, they found two potential risk factors for complications after single rod fixation for double bone fracture. The first was an open fracture. Open fracture refers to the fact that the two ends of the broken bone have not only moved apart but separated sideways so that they no longer line up. When this happens, the soft tissue structures around the broken ends are also affected, making it more difficult to maintain reduction.
Another potential risk factor is the cast that is applied after surgical reduction and fixation. If the cast is molded around the forearm too tightly, a condition called compartment syndrome can develop. Swelling and pressure on the soft tissue structures from a too-tight cast can cause more problems including death of tissue. Applying a cast that is too loose increases the risk of forearm movement inside the cast. During the early days of healing, movement can cause the fractured bones to distract even more. Either complication leads to a second surgery.
After looking over the results of their own study as well as the results of other studies examining single-rod fixation, the authors also saw that younger patients seem to be the best candidates for this approach. Surgeons can use these newly identified risk factors to carefully select who can be treated with the less invasive single-rod fixation for a double-bone forearm fracture.
The results of this study support the idea that single-rod fixation can be used with double bone fractures in the forearm. Fluoroscopy can be used during the surgery to confirm that the fractures are lined up and stable. Careful patient selection for this surgical technique is advised. Loss of bone reduction can result in a bone angle that limits forearm rotation. Some of this angulation can be prevented with intramedullary fixation and proper cast molding.
More studies are needed to determine long-term results of a single rod to support double forearm fractures. It would be good to have some studies that directly compare patients who are treated with a single rod vs. those who have a rod placed down through both bones. For now, it looks like certain patients can benefit from single-rod intramedullary fixation for fractures of both the radius and ulna.