Fig. 1 Anteroposterior radiograph of a distal radius injury (A) fixed with a volar locking plate (B). The distal ulna was not surgically stabilized.
Courtesy of Arvind D. Nana, MD.

AAOS Now

Published 11/1/2009
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Peter Pollack

Ulnar styloid base union and nonunion are comparable

Outcomes after distal radius fracture are not linked to ulnar styloid base nonunion

Nonunions of ulnar styloid base fractures are consistent with an excellent recovery after distal radius fractures, according to data presented by Geert A. Buijze, MD, at the annual meeting of the American Society for Surgery of the Hand.

“One of the complications of distal radius fractures is instability of the radial ulnar joint,” explained David C. Ring, MD, PhD, who co-authored the study “Nonunion of an ulnar styloid base fracture after volar plate fixation of a fracture of the distal radius.”

“Distal radius fractures are often associated with a fracture of the ulnar styloid at its base, which raises the issue of instability of the distal radioulnar joint. Even after 6 months, these fractures often fail to heal,” said Dr. Ring. “Because patients may have residual pain or symptoms, physicians could easily assign the symptoms to the unhealed bone.”

Dr. Ring pointed out that ulnar-sided wrist pain is often the last symptom to disappear after a fracture of the distal radius—an outcome that is counterintuitive for both patients and surgeons, given that the main injury was on the radial side. When a surgeon sees that the ulnar styloid base has not healed, it automatically becomes a target for treatment (Fig. 1)

Whether a fracture at the ulnar base is functionally different than torn ligaments, however, is unclear. Accumulating data suggest that patients with either torn ligaments or ulnar styloid fractures function equally well—if radiographs show nonunion, according to this study.

Healing by scar
The research team hypothesized that no difference in outcomes would be found between patients with union and those with nonunion of an ulnar styloid base fracture. They reviewed a convenience sample of patients with ulnar styloid base fractures taken from two clinical trials designed to evaluate aspects of volar plate fixation of the distal radius. They examined the records of 36 consecutive patients who had fractures of both the distal radius and ulnar styloid base. All patients were assessed for wrist function, arm-specific disability, and fracture healing at 6 months follow-up.

At 6-month follow-up, 16 ulnar styloid fractures had united and 20 had not. The researchers found no differences between the two groups in the areas of motion; strength; Gartland and Wereley score; Mayo wrist score; or Disabilities of the Arm, Shoulder and Hand score.

“The ulnar styloid base almost certainly heals by scarring; it’s a fibrous union. The only way to prove that, however, would be to perform another surgery or do histopathology studies. But the distal radioulnar joint appears to stabilize, so it would seem that the fracture is scarred in,” explained Dr. Ring.

Further studies are needed to build on these findings, said Dr. Ring. “We studied outcomes, but we did not directly evaluate the stability of the distal radioulnar joint.”

He suggested that a prospective study with a 2-year follow-up would be the logical next step. He also stressed the importance of developing an agreed-upon, objective, quantitative, reproducible measure of distal radioulnar joint instability that can be applied in a prospective trial. “My concern is that we do not adequately differentiate pain and instability,” he said.

“Some people have called for a prospective randomized trial, in which half the patients would have their ulnar styloid base fracture surgically repaired,” he said, “but I think that it might not be ethical to treat all those patients operatively, given that a fair amount of data suggests that most patients do well without surgery.

“I would recommend doing a prospective cohort study, with an objective definition and measurement of instability, which we don’t have yet. If no difference is found between the two groups, we could probably stop right there. If the study suggests that there might be a difference, then it would make sense to follow up with the randomized surgical trial,” Dr. Ring said.

It pays to be patient
“The point of this, for both the patient and the surgeon, is that the unhealed bone on the radiograph is consistent with an excellent recovery,” said Dr. Ring. “It can heal by scar and a fracture would still be apparent on the radiograph, but the wrist is recovered and healthy and does not require further treatment.

“Remember that ulnar-sided wrist pain is the last to dissipate and can continue for a year or more. As long as everything else checks out, the pain is likely to go away. The persistent fracture line on the ulnar styloid should not be a source of concern. The patient and surgeon will usually be rewarded for waiting on ulnar-sided pain.”

Dr. Buijze reports no conflicts of interest; Dr. Ring reports the following disclosures: Journal of Hand Surgery – American; Journal of Orthopaedics and Traumatology; Journal of Shoulder and Elbow Surgery; Shoulder and Elbow; Journal of Surgical Orthopaedic Advances; DePuy; Wright Medical Technology, Inc.; Acumed, LLC; Synthes; Biomet; Stryker; Tornier; Joint Active Systems; Mimedex; Illuminoss.

Peter Pollack is a staff writer for AAOS Now. He can be reached at ppollack@aaos.org