Radiographic and Clinical Comparison of Proximal Interphalangeal Joint Arthrodesis Between a Static and Dynamic Implant

Hammertoe deformation is a frequent motive for consultation in forefoot surgery, and proximal interphalangeal joint arthrodesis is a classic treatment for fixed deformation, which tends to be achieved more and more thanks to specific implants. This work evaluated and compared clinical improvement, radiologic fusion, and complication rates between dynamic (Difuse®) and static (TinyFix®) implants from Biotech Ortho. A total of 95 patients (110 feet and 166 toes; 97 static and 69 dynamic implants) were included. Mean age was 63.6 (±12.6) years in the dynamic group and 62.3 (±14.01) years in the static group. Epidemiologic and intraoperative radiologic data were collected. Pain, toes deformity, complications, and radiologic findings (bone fusion and osteolysis) were recorded at 4 months postoperatively and at the last follow-up. Mean follow-up was 11.5 (range 4 to 28) months, and the position of the implants was more often satisfying in the dynamic group (p = .01). Fusion rates at 4 months were 67% and 80% in the dynamic and static groups, respectively (p = .05). Radiologic osteolysis occurred more frequently in the dynamic group (p = .05 at 4 months), and pain was still present in 3% in the dynamic group at the last follow-up compared with 7% in the static group. Complication rate was 7% in the dynamic group (implant fractures) and 4% in the static group. Revision was considered more often in the dynamic group (p = .01). The static titanium implant seems superior to the dynamic memory shape implant in Nitinol alloy with regard to fusion (p = .04), complications (p = .03), and revision rates (p = .01). The literature review seems to support the good results of static implants compared with the rest of the available arthrodesis implant solutions.