Abstract

Introduction/Purpose: Modified Lapidus arthrodesis is performed in the treatment of different pathologies, including halluxvalgus and osteoarthritis of the 1C-MTT joint. Complications of this procedure include delayed union and non – union. To preventthem, several rigid fixation methods have been proposed. Biomechanically, plantar plate fixation may be the best solution.Therefore, we sought to investigate our clinical results and complications in patients operated on with a modified Lapidusarthrodesis using two different plantar plate fixation systems.Methods: After IRB approval, we reviewed our prospectively collected database for patients operated on with a modified Lapidusarthrodesis. Dedicated foot and ankle orthopaedic surgeons performed all procedures. Patients were included if they were olderthan 18 years, had a minimum FU of 1yr and agreed to participate in the study. Patients with neuropathy, previous surgery,concomitant midfoot/hindfoot procedures or those which fixation method was different from a plantar plate were excluded.Preoperative and postoperative IM angle was evaluated. Two independent musculoskeletal radiologists assessed consolidationunder CT scan at 12 weeks postop. Triaxial 2-mm reformatted CT slices were used to calculate joint fusion percentage. Eachpatient was assigned to a consolidation group considering joint fusion percentage: 0-24%, 25-50%, 51-74%, 75-100%.Intra/interobserver coefficients of variability were calculated. SF-36, SMFA, FAOS and FAAM were obtained preoperatively and atone year follow up. t-test was performed to address for functional outcomes differences in-between groups.Results: Twenty-three patients (35 feet) met inclusion criteria. Mean age was 47 years (13-65), 83% female and 17% male. Elevenpatients had bilateral surgery. Mean preoperative/postoperative IM angle were 16+3 and 9+2, respectively (p<0.001). Ten feetachieved <24% consolidation (33%) and 20 feet >25% (67%). With the numbers available, consolidation rate didn´t differ inpatients undergoing unilateral/bilateral surgery(p=1.0) or plating system(p=0.22). One patient had an anterior tibialis tendonrupture and 1 patient presented an infected non-union, prompting revision. Mean preoperative/postoperative values for SF-36physical and mental component were 49 and 76(p<0.001); and 43 and 68(p<0.001), respectively. FAOS-pain were 60 and81(p<0.001);FAOS-daily-life were 59 and 96(p<0.001);FAOS-sport were 43 and 74 (p<0.001);and FAAM-Daily-life score were 67and 87(p<0.001). No significant differences were found for SMFA.Conclusion: Despite a low consolidation rate at 12 weeks post op, patients with plantar plated Lapidus arthrodesis presented asignificant increase in functional outcomes and a low revision/complication rate at 1yr FU. Consideration should be given to delayevaluation under CT scan to 24 weeks post op.