Metaphyseal callus formation in pilon fractures is associated with loss of alignment: Is stiffer better?

OBJECTIVE: To assess the relationship between metaphyseal callus formation and preservation of distal tibial alignment in pilon fractures treated with internal plate fixation.

DESIGN: Retrospective Review SETTING: Academic Level I Trauma Center PATIENTS: Forty-two patients with AO/OTA type C2 or C3 pilon fractures treated with plate fixation.

INTERVENTION: Internal fixation with anterolateral plating, medial plating, or both. Modified Radiographic Union Score in Tibial fracture (mRUST) scores were determined from six-month radiographs.

MAIN OUTCOME MEASUREMENTS: Change in lateral and anterior distal tibial angles (LDTA and ADTA) at six months post-operatively.

RESULTS: High callus formation (mRUST ≥ 11 at six months) was associated with a greater loss of coronal reduction as measured by LDTA compared to low callus formation (mRUST < 11): 3.8 vs 2.1° (p = .019), with no difference in ADTA change between groups. In a multivariable logistic regression controlling for age, smoking, obesity, and open fracture, higher mRUST scores were a predictor of coronal reduction loss of five or more degrees (OR 1.71, p=.039). Dual column plating did not independently predict maintenance of alignment.

CONCLUSIONS: Recent literature has popularized dual column fixation for pilon fractures, but it remains unknown whether increased metaphyseal stiffness enhances or impairs healing. In this series, decreased metaphyseal callus formation was associated with maintained coronal alignment, suggesting that a stiffer mechanical environment may be preferable to prevent short term reduction loss in these complex injuries.

LEVEL OF EVIDENCE: III.