Supracondylar elbow fractures in children are serious limb-threatening injuries. These injuries are limb threatening because the fractured bone ends can kink, stretch, or pinch the brachial artery and thus interfere with the blood supply to the forearm and the hand.
The supracondylar part of the humerus is the weak point, predisposed to break when strong enough forces are applied to the child's elbow.
In 95% of supracondylar humerus fractures, the mechanism of injury is forceful hyperextension of the elbow, usually after a fall from monkey bars. As the child's body impacts with the ground, the elbow starts out straight. As the force of the impact continues to overextend the arm, the anterior humeral cortex fails first, and a small gap is created in the front part of the humeral bone. At the same time the back part of the bone is compressed, crushed, and crumbles a little bit. As the injury progresses, the bone fragments separate, and it looks like the elbow bends backwards. In type 3 fractures, the injury continues until the broken fragments are fully separated and move independently of each other.
Supracondylar = "above the condyles." Condyles are the prominent lumps of bone just above the joint. The word supracondylar refers to the part of the humeral bone just above the elbow joint. This is an area where the round shaft of the humerus becomes wider side-to-side, and thinner front-to-back, as it joins the ulna and radius to form the elbow joint. Volkmann's ischemic contracture is the end result of the death of the forearm and hand muscles when blood supply is interrupted.
The problem with type 3 fractures fractures is that the artery that supplies blood to the forearm and hand is right in front of the broken humeral bone. This artery can be kinked, can be draped over the end of the broken bone, or can sometimes be caught between the broken bone fragments. The nerves that control the hand can likewise be stretched, kinked, pinched, compressed, etc. This is the reason why these fractures are limb threatening, for without blood supply the muscles of the forearm may die. Volkmann's ischemic contractures is a potentially devastating consequence of these injuries. In addition, disruption of the tissues causes quite a bit of bleeding and considerable swelling: this is another factor that contributes to poor circulation of blood in the injured limb.
Thankfully, prompt realignment of the fracture often restores normal blood flow.
Flexion injuries are a minority of supracondylar fractures. Flexion injuries make up 5% of the supracondylar fractures. In my experience, they occur when the child falls directly on the elbow.
Supracondylar humerus fractures are categorized as type 1, type 2, or type 3, based on the amount of fragment displacement.
Type 1 supracondylar fractures are not displaced. The front of the humeral bone has fractured, there is a crack in it, but the broken fragments are staying together. Type 1 supracondylar fractures are safely treated with splint or cast immobilization, without surgery.
In type 2 supracondylar fractures, the fragments are more displaced, but not fully. In type 2 fractures, the soft tissues behind the bone continue to provide some stability. When confronted with a type 2 fracture, it is important to realize that there is a good amount of interobserver variability in making the diagnosis. This is a nice way of saying that if you ask 2 different orthopedic surgeons "Which type of fracture is this?" they might give you 2 different answers. It turns out that it can be difficult for physicians to decide whether the fracture is a true type 2 fairly stable fracture, or more of a type 3 unstable pattern just by looking at static xrays. Therefore a consensus seems to have developed among the orthopedic profession that for type 2 supracondylar fractures, benefits of surgical treatment with pins outweigh the risks.
Type 3 supracondylar humerus fractures in children are limb threatening injuries. Treatment universally requires surgical stabilization with metallic pins.
A 2 year old boy, playing on a trampoline, fell, bent the arm backwards, and was brought in by his distressed parents. The xrays below show a type 3 extension injury.
Surgery was delayed a few hours, until the kid's stomach contents moved downstream. The fracture was reduced by feel and under x-ray guidance, and transcondylar pins were placed. Typically 2 lateral pins are enough, but as you can see one of the lateral pins did not have a good far cortex purchase. An additional medial pin was placed with a small incision, for a total of 3 pins. In this particular case, alignment of the bones is very good, with acceptable imperfection. Perfect alignment of the bone fragments would have required an incision, and was not necessary for a normal looking and functioning elbow.
After pins are placed, bones are examined with live fluoroscopy xray, to make sure that the fixation is stable.
Pins are removed between 3 and 4 weeks, in the office. The child's injured elbow is placed over the parent's shoulder, as if hugging the parent, the child's head turned in the opposite direction. Pins are removed simply by twisting and pulling them out. Usually a couple of drops of blood are seen and are not a cause for concern.
Cast is removed at the same time, while a sling is continued for 3-4 more weeks.
Occasionally, a family will prefer to have a second session of general anesthesia just to remove the pins. I highly recommend removal in the office without anesthesia.
Here are the xrays at 4 months. Fracture is healed by xray. Alignment of the bone is good. Elbow looks normal and moves without any limitation. No long term problems are expected.
The following are xrays of a 5 year old boy who fell down the stairs playing.
Fracture was reduced, pinned, and the pins were shortened and bent.
Xrays at 6 weeks show a well aligned fracture. Range of motion was fully restored by 3 months, including in extension.
Typical outcome. Note the small scar at the pin site on the side of the elbow.
For these injuries, I recommend that the child avoid contact sports for a minimum of 2 months after xrays show healing. This may be frustrating occasionally, but it is certainly the prudent thing to do.