Surgeons from the Cincinnati Children’s Hospital Medical Center in Ohio have taken the time to conduct a meta-analysis of supracondylar humeral fractures and offer us the results of their findings. In the medical world, a meta-analysis is a big deal. Because most surgeons don’t see 100s or 1000s of the same type of fracture, they depend on reports like this to guide their treatment. By combining the results from many patients, it’s possible to analyze what works best and what treatment to avoid because it causes significant problems.
For example, nerve injuries are the biggest complication with supracondylar humeral fractures. You may be wondering what’s a supracondylar humeral fracture? This is a break in the upper arm bone just above the elbow. It’s the most common type of elbow fracture in children but is relatively rare in adults. In fact, at least half and as many as 70 per cent of elbow fractures in children are supracondylar humeral fractures.
The fracture is caused most often by a fall on an outstretched hand. As the hand hits the ground, the elbow is hyperextended or hyperflexed resulting in fracture above the condyles. The condyles are the bumps you feel on either side of your elbow. Supracondylar means the break is just above those bumps (condyles).
Nerve injuries called neuropraxia associated with supracondylar humeral fractures occur for one of two reasons. The first is from damage done to the nerve by the jagged edges of the displaced (separated) broken bones. The second is from pins used to hold the bone together while it heals.
The authors’ intention with this meta-analysis was to find out: 1) how often do nerve injuries occur with displaced flexion versus extension supracondylar fractures, 2) how often do pins placed through the bone contribute to nerve damage, and 3) does it matter which side of the elbow the pins are placed through in relation to the neuropraxia?
A little bit of information about neuropraxia here might help explain what happens to the patients with this type of fracture-induced or pin-induced injury. Neuropraxia describes nerve damage without disruption of the nerve or its sheath (covering). There is enough damage done that the messages sent along the nerve are interrupted. This causes a temporary loss of sensation and motor function that can last hours to weeks to months. Recovery does occur but can take six to eight weeks or longer.
The meta-analysis provided 5154 cases of displaced supracondylar humeral fractures to study and compare. Children involved ranged in age from three months to 16 years old. About 11 per cent of the group had traumatic neuropraxia affecting one or more of the nerves (median, anterior interosseous, posterior interosseous, radial, ulnar).
Flexion-type supracondylar humeral fractures were slightly more common than extension type (16.6 per cent for flexion compared with 12.7 per cent for extension). The ulnar nerve was affected most often with flexion-type fractures. The anterior interosseous nerve was at risk most often with the extension injuries.
And damage to the nerves from pin fixation showed up in about four per cent of patients included in a subgroup analysis. Nerve damage from pins used to hold the bones together is referred to as iatrogenic neuropraxia (as opposed to traumatic neuropraxia from the injury itself). Iatrogenic means the problem developed as a result of the treatment. Placing the pin through the lateral side of the bone (side away from the body) was more likely to cause median nerve injury. Pin placement through the medial side (inside of the elbow) increased the risk of ulnar nerve damage.
Knowing the details of traumatic and iatrogenic neuropraxia associated with displaced supracondylar humeral fractures can help guide surgeons when treating children with these common elbow fractures. Anything surgeons can do to avoid or prevent neuropraxia makes for an easier recovery for these children. With the information gleaned from this meta-analysis, surgeons can watch carefully for nerve injuries based on type of fracture and placement of pins when fixation is required.