Contribution of Lateral Column Lengthening to Correction of Forefoot Abduction in Stage IIb Adult Acquired Flatfoot Deformity Reconstruction.

BACKGROUND: Correction of forefoot abduction in stage IIb adult acquired flatfoot likely depends on the amount of lateral column lengthening (LCL) performed, although this represents only one aspect of a successful reconstruction. The purpose of this study was to evaluate the correlation between common reconstructive variables and the observed change in forefoot abduction.

METHODS: Forty-one patients who underwent flatfoot reconstruction involving an Evans-type LCL were assessed retrospectively. Preoperative and postoperative anteroposterior (AP) radiographs of the foot at a minimum of 40 weeks (mean, 2 years) after surgery were reviewed to determine correction in forefoot abduction as measured by talonavicular coverage (TNC) angle, talonavicular uncoverage percent, talus-first metatarsal (T-1MT) angle, and lateral incongruency angle. Fourteen demographic and intraoperative variables were evaluated for association with change in forefoot abduction including age, gender, height, weight, body mass index, as well as the amount of LCL and medializing calcaneal osteotomy performed, LCL graft type, Cotton osteotomy, first tarsometatarsal fusion, flexor digitorum longus transfer, spring ligament repair, gastrocnemius recession and any one of the modified McBride/Akin/Silver procedures.

RESULTS: Two variables significantly affected the change in lateral incongruency angle. These were weight (P = .04) and the amount of LCL performed (P < .001). No variables were associated with the change in TNC angle, talonavicular uncoverage percent, or T-1MT angle. Multivariate regression analysis revealed that LCL was the only significant predictor of the change in lateral incongruency angle. The final regression model for LCL showed a good fit (R2 = 0.70, P < .001). Each millimeter of LCL corresponded to a 6.8-degree change in lateral incongruency angle.

CONCLUSION: Correction of forefoot abduction in flatfoot reconstruction was primarily determined by the LCL procedure and could be modeled linearly. We believe that the lateral incongruency angle can serve as a valuable preoperative measurement to help surgeons titrate the proper amount of correction performed intraoperatively.