Mitchell's osteotomy augmented with bio-absorbable pins for the treatment of hallux valgus: A comparative finite element study.

BACKGROUND

There is an inadequacy of conventional means to assess the surgical outcomes of a bunion surgery. We used the Finite Element Analysis for evaluating the typical Mitchell's procedure outcomes with or without bio-absorbable pins.

METHODS

We developed a 3D FE model based on the CT images of a female volunteer with hallux valgus. A typical procedure was simulated on the foot model and two pins were virtually inserted for enhancing the fixation. We validated our model by comparing the predicted pressure results with the plantar pressure measured by a specific platform.

RESULTS

The comparison of the plantar pressure distribution revealed similar patterns. A greater displacement was observed on the medial side of the osteotomy, but it was decreased after using pins. The maximum average pressure under the 1 metatarsal head was decreased after the osteotomy. The respective pressure under the 3 and 5 metatarsal head was decreased more after using pins, while, under the 2 and 4 metatarsal head, an increase was developed.

CONCLUSION

The use of pins had no significant influence on the healing process but gave additional stability inside the osteotomy and could be used in cases where enhancement is needed. The surgeon should be familiar with the expected stress rising to the other metatarsal, considering the concomitant pathology or the additional interventions that should be performed.