How do pilon fractures heal? An analysis of dual plating and bridging callus formation.

OBJECTIVES

1) To determine the effect of single versus dual plate metaphyseal fixation for pilon fractures on callus formation and reoperation rates, 2) to determine the effect of biomechanically matched versus unmatched fixation, and 3) to determine whether patient or surgical factors were independent predictors of bridging callus formation or need for reoperation.

DESIGN

Retrospective comparative study.

SETTING

Single level one trauma center.

PATIENTS: Fifty patients with AO/OTA type C2 or C3 pilon fractures treated with plate fixation.

INTERVENTION: Internal fixation with a plate and screw construct, with comparisons made between patients with single versus dual plate fixation, and patients treated with biomechanically matched or unmatched fixation.

MAIN OUTCOME MEASUREMENTS: Modified RUST (mRUST) scores at three and six months and reoperation rate.

RESULTS

At six months, mean mRUST scores were significantly lower in patients treated with dual metaphyseal plates compared to a single plate (8.7 vs 10.4, p=0.046) There were 15 open fractures; eight were treated with supplemental fixation, while seven were treated with single-column fixation. Open fracture (OR 51.05, p=0.008) was a risk factor for reoperation. Screw density between 0.4 and 0.5 was a protective factor against reoperation (OR 0.03, p=0.026). Biomechanically unmatched fixation did not affect mRUST scores or reoperation rates.

CONCLUSIONS

Pilon fractures treated with a single plate had more callus formation six months after surgery compared to those treated with dual plate fixation, and there was no difference in reoperation rates. Screw density between 0.4-0.5 was protective against reoperation. These data may serve as the basis of future work to determine the ideal fixation construct for the frequently comminuted metaphysis in pilon fractures. Further work is necessary to determine whether callus formation in these injuries is desirable.

LEVEL OF EVIDENCE: Three.