The efficacy of an intramedullary nitinol implant in the correction of claw toe or hammertoe deformities

  • Jesús Payo-OlleroEmail author
  • Ahinoa Casajús-Ortega
  • Rafael Llombart-Blanco
  • Carlos Villas
  • Matías Alfonso
Orthopaedic Surgery



A multitude of procedures has been described in the literature for the treatment of lesser toe deformities and there is currently no general consensus on the optimal method of fixation. The aim of this study is to assess the clinical and radiological outcomes of an intramedullary nitinol implant for the correction of lesser toe deformities, and to determine if the distal interphalangeal (DIP) joint and metatarsophalangeal (MTP) joint are modified during patient follow-up after correction of the PIP joint.

Materials and methods

A prospective analysis of 36 patients with claw toe or hammertoe who were treated with an intramedullary nitinol implant. Clinical manifestations and angulation of the metatarsophalangeal, proximal and distal interphalangeal (MTP, PIP, DIP) joints were evaluated in radiographic studies preoperatively, at first medical revision post-surgery, and after a minimum of 1 year of follow-up. Complications such as non-union rate, implant rupture, and implant infection were also evaluated during follow-up.


All patients were women with an average age of 65.5 (range 47–82) years. The average follow-up time was 2.4 (range 1–5.7) years. Fifty intramedullary nitinol implants were used. The MTP joint extension and PIP joint flexion decreased by 15.9° (95% CI – 19.11 to – 12.63) and 49.4° (95% CI – 55.29 to – 43.52), respectively, at the end of follow-up. Moreover, the DIP joint flexion increased progressively during follow-up (13.7° pre-surgery versus 35.6 in last medical check-up, 95% CI 13.24–30.57). There were four (8%) asymptomatic implant ruptures. The rate of fusion was 98%.


The reduction of the PIP joint using an intramedullary nitinol implant is a good option in lesser toe deformities, with few complications and a high rate of arthrodesis. Moreover, the PIP joint reduction affects both the MTP and DIP joints.


Hammertoe Claw toe Arthrodesis Smart-Toe® Intramedullary implant Forefoot disorders 



We express our gratitude to Ruth Breeze for the language editing of the manuscript.

Compliance with ethical standards

Conflict of interest

Each author certifies that he or she has no commercial associations that might pose a conflict of interest in connection with the submitted article.

Ethical review committee statement

This manuscript is accepted by the Regional Ethical Review Board.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Orthopaedic Surgery and Traumatology DepartmentClínica Universidad de NavarraPamplonaSpain
  2. 2.Faculty of MedicineUniversidad de NavarraPamplonaSpain

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