Evaluating the Necessity of Distal Tibia-Fibular Syndysmosis Screw Fixation in the Gradual Correction of Angular Lower-Limb Deformities.

Background:  Gradual correction of lower-limb angular deformities using external fixators such as the Taylor Spatial Frame (TSF) is a well-established technique for addressing complex, multiplanar deformities. A common yet understudied adjunct to this method is the use of a distal tibio-fibular syndesmotic screw to stabilize the ankle mortise during correction. Despite being frequently practiced, the necessity and efficacy of this intervention remain unclear.

Objective:  To evaluate the clinical and radiographic outcomes of patients who underwent gradual correction of lower limb deformities using TSF without the placement of a distal tibio-fibular syndesmotic screw.

Methods:  A retrospective review was conducted on a sample of 20 limb-deformity-correction procedures performed between September 2017 and January 2020 at a single tertiary care center. Radiographic parameters, including medial clear space (MCS), tibio-fibular clear space (TFCS), and talocrural angle (TCA), were measured pre- and post-operatively. Functional outcomes were assessed using the Foot and Ankle Disability Index (FADI). Statistical analysis was conducted using paired t-tests, Wilcoxon signed-rank tests, Mann-Whitney U tests, and Chi-square tests.

Results:  No statistically significant differences were observed in MCS or TFCS following surgery. TCA improved significantly (p=0.009), indicating successful correction of angular deformity. However, there was no significant difference in FADI scores between patients who had syndesmotic screw placement and those who did not (p=0.523). Furthermore, FADI scores for post-operative patients were lower than those of the normative population (p<0.001).

Conclusion:  The use of a distal tibio-fibular syndesmotic screw during TSF-assisted gradual correction of lower-limb angular deformities does not significantly influence radiographic or functional outcomes. Given the additional operative time and resources involved, its routine use should be reconsidered. Larger, prospective studies are warranted to establish definitive clinical guidelines.