Achieving elbow stability key to performing radial head arthroplasty

SAN FRANCISCO — The key to managing unreconstructable radial head fractures using a radial head prosthesis is achieving a stable elbow, which involves ensuring that lateral ligaments are intact or repaired, according to a surgeon speaking here.

"The [radial] head functions as a secondary stabilizer to the medial collateral ligament. It is important to understand that the radial head acts in concert with the coronoid to form an anterior wall or an anterior buttress to the elbow, resisting posterior joint subluxation," said Mark S. Cohen, MD, in a presentation at the American Society for Surgery of the Hand and American Association for Hand Surgery joint Subspecialty Day held during the American Academy of Orthopaedic Surgeons 75th Annual Meeting.

"Only when [the elbow] is stable can you begin an early, protected rehabilitation program," he said.

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According to Cohen, the indications for radial head arthroplasty are slowly evolving. But one "absolute" indication is in the setting of trauma, such as fracture dislocations with concomitant injury to the medial collateral ligament.

"If the ligaments are injured ... that's an absolute indication for arthroplasty," Cohen said. "Only when you replace the radial head and repair the ligaments have you allowed for a stable elbow."

In cases where the elbow is stable, the radial head can be resected without inducing instability, "as long as we have an intact medial collateral ligament," he noted.

"I will say that the pendulum is swinging toward replacement in irreparable radial head fractures without ligament trauma. That is because people are starting to understand the radial head's importance in the anatomy and in balance of the elbow," he said. "Without a radial head, all of the forces shift to the ulno-humeral joint."

Cohen noted that this trend is supported by the "explosion" of radial head implants that have become available. However, "There is no science to date as to which radial head [prosthesis] is better than another," he said.

"We do know one thing: The old silicone implants are out. They simply do not have the stability to support the lateral elbow; they are too flexible. So, some type of metallic implant is indicated when you are putting in a radial head," Cohen said.

For more information:

• Cohen MS. Radial head implants: When to use and which implants are indicated. Presented at the American Society for Surgery of the Hand and American Association for Hand Surgery joint Subspecialty Day meeting. March 8, 2008. San Francisco.