Getting Bitten by the Dog Bone — AC Joint Buttons and Tunnel Widening

Top hats are for parties and dog bones are for the pooch; these button constructs are not behaving as well as we'd hoped

What’s the Claim?

In a report of two sequential case series, patients who had Rockwood Type III to V AC joint injuries underwent stabilization either with extracortical button fixation (AC Dog Bone, Arthrex; the first group, from April 2015 to July 2018) or a low-profile (LP) AC implant (Arthrex; from August 2018 to October 2020). Loss to follow-up in this series was profound, at 45% and 32%, respectively, and mean follow-up was only about 6 months in both groups. The Dog Bone group did not consistently get additional AC cerclage; all patients in the LP group received additional AC cerclage fixation. The groups also differed in terms of gender composition (more women in the LP group) and Rockwood classifications (more Rockwood V’s in the LP group). We’ll explain why we’re still covering this article despite all these serious issues in just a moment.

The key takeaway was that clavicular tunnel widening was seen in most patients in both groups and didn’t differ by much between the groups (6.5 mm versus 6 mm). Widening was conical in shape (worse at the inferior clavicular cortex than superiorly). The amount and consistency of the widening got our attention; use of augmentative cerclage fixation did not seem to prevent it.

How’s It Stack Up?