Osteotomy to Correct Elbow Deformity After Supracondylar Elbow Fractures
Straighten your arm and let the forearm drop down to your sides. Now turn your hands so the palms are facing forward. Look at your elbow and notice the angle formed from the shoulder to the wrist with the center at the elbow. This is called the carrying angle of the elbow.
You don't think much about your elbow angle until something happens to disrupt it. In the case of elbow fractures (especially supracondylar fractures), posttraumatic deformities can cause changes in the carrying angle of the elbow. The most common late complication of a supracondylar fracture is called a cubitus varus deformity.
A supracondylar fracture occurs in the lower portion of the humerus (upper arm bone) just above the elbow. In the normal arm, the bottom end of the humerus flares out on each side forming a part of the bone called the condyles. A fracture just above the condyle is a supracondylar fracture.
A cubitus varus deformity gives the elbow an unnatural outward curved angle -- like a bowed leg only affecting the elbow instead. Cubitus refers to the inner soft side of the elbow. Varus is the outwardly bowed angle. When the person with cubitus varus looks down at the carrying angle of the elbow, it's curved in the opposite direction from normal.
Why does this varus deformity occur in the first place? The elbow is a very complex joint when viewed in three-dimensional (3-D) space. Getting the broken bone lined back up in all three dimensions isn't always easy. Viewed from the side on X-ray, the fracture might look fine. But viewed from the front, back, or from above, the malalignment remains and is much easier to see.
Deformities affecting the carrying angle are equally difficult to correct. Surgery is required and in particular, a supracondylar osteotomy procedure is usually the preferred treatment.
What is a supracondylar osteotomy? Supracondylar tells you where the osteotomy is performed (above the condyle). An osteotomy refers to a wedge-shaped piece of bone that is removed from one side of the bone. The two remaining edges of bone (now separated by a space that looks like a piece of pie taken out of the bone) is then allowed to collapse. The result is a correction of the deformity.
In some cases, a triangular-shaped piece of bone (instead of a pie-shaped piece) is removed. This is done in order to get maximum correction of the varus deformity. The result is a correction of the bone and carrying angle of the elbow. An alternate technique to correct the carrying angle is the step-cut osteotomy.
But that's only two of the three dimensions. Now the surgeon considers what the elbow looks like from above. That view gives an idea of what kind of rotational forces have affected the elbow. To correct a situation of too much internal (inward) rotation, the surgeon might use a procedure called the rotational dome osteotomy.
In the rotational dome osteotomy, a cut is made in the shaft of the humerus just above the condyles. The upper portion of the humerus is then shifted (rotated and/or tipped forward) to create a more natural elbow carrying angle. Using this type of osteotomy, the surgeon can correct for deformities in all three planes. The result is to correct the carrying angle, reduce the excess elbow extension, and realign the internal rotation malunion.
In this study from Japan, orthopedic surgeons investigated the various osteotomies used to correct elbow varus deformities. The goal was to find which one worked best for supracondylar fractures with this varus deformity. They had a total of 86 patients ranging in ages from three to 31 years old who had this type of problem after a traumatic elbow fracture.
One group had the three-dimensional type of osteotomy. A second group had the standard simple osteotomy with correction only when viewed from the side. The question was: is a three-dimensional correction even necessary? Does the simple correction work just as well?
The answer was determined by looking at the carrying angle and passive elbow motion from before to after surgery. They also calculated the loss of correction as a means of deciding which surgical technique yields the best results.
They found no difference between the groups in terms of carrying angle or elbow motion from before to after surgery. The only significant finding was that the three-dimensional group lost more of their correction than the one-dimensional group. Complications such as infection, nerve palsies, refracture, or elbow instability were nearly equal between the two groups.
The loss of correction in the three-dimensional group was explained as the result of an unstable osteotomy from the way the bones were cut and arranged. Pins were used to hold everything together until complete bone union took place. But the decrease in contact area between the bones made it difficult to stabilize the osteotomy site.
For patients who were experiencing palsy of the ulnar nerve, the nerve was moved away from the bone where it was getting pinched. This procedure called a nerve transposition can be done at the time of the osteotomy surgery. Older children (10 years old and older) are more likely to develop hyperextension of the elbow as a result of the varus deformity. This occurs because there is less bone remodeling at this age to self-correct the problem.
The authors concluded that the most important deformity to correct in cubital varus elbows following traumatic supracondylar fractures is the carrying angle. If the joint is off its normal alignment because the bone has rotated, the shoulder can compensate and function is not lost. A three-dimensional correction is not needed for children under the age of 10. And a one-dimensional osteotomy may not be enough for older children.
Takehiko Takagi, MD, et al. Supracondylar Osteotomy of the Humerus to Correct Cubitus Varus: Do Both Internal Rotation and Extension Deformities Need to be Corrected? In The Journal of Bone and Joint Surgery. July 2010. Vol. 92-A. No. 7. Pp. 1619-1626.
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