Lower Limb Malrotation following Minimally Invasive Plating in Distal Tibia Fractures.

Introduction: Minimally invasive percutaneousosteosynthesis (MIPO) plating techniques havedemonstrated good outcomes in the treatment of distal tibia fractures. Early arthritis and functional impairment mayoccur if length and rotation are not restored. This study aims to determine the incidence and severity of tibia malrotation following MIPO plating of isolated unilateral distal tibia fractures, defined as torsional difference of greater than 10° as compared to the contralateral limb and whether the degree of malrotation affects functional outcomes scores.

Materials and methods: This was a level 2 prospective cohort study. All patients with fractures of the distal tibia who underwent surgical fixation with the exclusion ofpatients with polytrauma, neurovascular injuries or pre-existing disabilities were recruited. Patients underwent MIPO plating followed by a post-operative ComputedTomography (CT) scan of bilateral lower limbs. AOFAS ankle-hindfoot score was recorded at six months and one year follow-up.

Results: A total of 24 patients (28 to 83 years old) were recruited. Nineteen patients obtained CT scans. Nine of the 19 patients (47.3%) had tibia malrotation. The mean tibia malrotation angle was 10.3° (0° - 45°). The average AOFAS scores was 82.4 and 84.3 at 6 months and 1 year follow-up. Degree of CT malrotation was not significantly associated with AOFAS scores at 6 month (spearman rho -0.386) and 1 year (spearman rho -0.343).

Conclusions: Tibia malrotation following MIPO plating of distal tibia fractures is common, with an incidence of 47.3% and an average malrotation angle of 10.3°. The degree of malrotation does not appear to have significant mid-term functional impact on the patient.