Beware This Meta-analysis Favoring ORIF of Posterior Malleolar Fragments in Ankle ORIF

Small benefits + overstated benefits = a study not to change practice over

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Editor’s Note: Sometimes at CORRelations, we’ll cover an article we think is likely to cross your desk, but is one whose message we have reservations about. Here’s one. — SSL

What’s the Claim?

A meta-analysis concluded in favor of ORIF of posterior malleolar fragments during surgical treatment of bi- or trimalleolar ankle fractures rather than closed reduction using AP screws or no treatment. We’re covering it because meta-analyses are more likely than other article types to generate practice changes, but we have reservations about this one, and we recommend not changing your current practice based on this study’s findings.

How’s It Stack Up?

Systematic reviews necessarily comport with their source data, so rather than go through those, we’ll offer a summary of the concerns that cause us to be leery of this systematic review’s main findings:

  • Meta-analyses of treatments should not pool data drawn from retrospective studies because of the “garbage in, garbage out” problem; in fact, this meta-analysis would not have been considered for publication in leading orthopaedic journals (JBJS, CORR) for this reason.
  • Specifically, retrospective studies — such as those that the authors included here — will tend to inflate the apparent benefits of the intervention being studied (ORIF of the posterior fragment, in this case) because of problems like selection bias, follow-up that is insufficiently long or complete, and assessment bias.
  • Those benefits here were quite small, less than 10 points out of 100 on the AOFAS score, for example (which itself is not a validated tool). It doesn’t seem likely that most patients would be interested in an extra open procedure for such an incremental apparent benefit. For comparison, the minimum clinically important difference for most 100-point orthopaedic outcomes tools is more commonly in the range of 15 to 20 points, not < 10 points.
  • The key factor most of us use in making the decision of whether or not to treat these fragments — the size of the fragment and its displacement — was not handled in this study in a way that was easy to interpret.

What’s Our Take?

We believe the combination of design flaws in this study and shortcomings in the source studies it used should cause us to discount the authors’ conclusion favoring ORIF of posterior malleolar fragments. Those problems will inflate the apparent benefits of ORIF of these fragments, benefits that were somewhere between small and imperceptible in size.

Fragment size and displacement, along with your clinical judgment, remain the key factors to consider when faced with a posterior malleolar fragment during an ankle ORIF.

Source

Miksch RC, Herterich V, Barg A, Böcker W, Polzer H, Baumbach SF. Open Reduction and Internal Fixation of the Posterior Malleolus Fragment in Ankle Fractures Improves the Patient-Rated Outcome: A Systematic Review. Foot Ankle Int. 2023;44:727-737.