To investigate the short-to medium-term therapeutic effects of a new internal fixation device, intraosseous internal fixation (IO-FIX), in the foot-ankle arthrodesis.

From August 2016 to December 2018, 32 patients (40 feet) underwent foot-ankle arthrodesis with IO-FIX at De-partment of Orthopaedic Surgery, The Ninth People’s Hospital of Shanghai.They were 6 males and 26 fe-males, aged from 23 to 83 years (61.7±15.1 years).There were 28 cases (36 feet) of hallux valgus, 2 cases (2 feet) of ankle arthritis, one case (1 foot) of ankle rheumatoid arthritis and one case (1 foot) of naviculocuneiform arthrosis.The therapeutic effects were assessed in terms of imaging evaluation, American Orthopaedic Foot and Ankle Society (AOFAS) score, fusion rate and full weight-bearing time.

The follow-up ranged from 3.0 to 31.3 months (mean, 12.6 months).The total fusion rate was 95.0%(38/40); the total AOFAS score increased significantly from preoperative 41.9±9.5 to postoperative 86.9±4.7 (P< 0.05).The 28 patients (36 feet) with hallux valgus achieved a successful fusion rate of 97.2%(35/36) and full weight-bearing at 8 weeks after operation.Their fusion time ranged from 45 to 64 days (57.1 days).Their metatarsophalangeal angle was decreased significantly from 52.1°±13.5° preoperatively to 13.4°±4.9° postoperatively and their 1-2 intermetatarsal angle significantly from 14.5°±2.4° to 8.9°±2.4° (P<0.05). Their AOFAS ankle-hindfoot score was improved significantly from 41.8±9.9 to 87.0±4.8 (P<0.05). All the 3 cases of ankle arthrodesis achieved good bone union and full weight-bearing within 12 weeks and their AOFAS ankle-hindfoot score was improved significantly from preoperative 43.4±3.5 to 86.3±3.5 at the final follow-up.

In foot-ankle joint arthrodesis, due to advantages of stable fixation, zero profile, limited soft tissue irritation, reinforced bone bridge and easy reproducibility, IO-FIX can lead to satisfactory short-to mid-term therapeutic effects.

Foot; Arthrodesis; Internal fixators