Medical Engineering & Physics
Volume 28, Issue 7 , Pages 682-693, September 2006

Evaluation and improvement of the efficiency of the Seidel humeral nail by numerical–experimental analysis of the bone-implant contact

  • Fabio Giudice

      Affiliations

    • DIIM, Department of Industrial and Mechanical Engineering, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
    • Corresponding Author InformationCorresponding author. Tel.: +39 095 7382418; fax: +39 095 330258.
    • ,
  • Guido La Rosa

      Affiliations

    • DIIM, Department of Industrial and Mechanical Engineering, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
    • ,
  • Tullio Russo

      Affiliations

    • Department of Orthopaedics and Trauma, P.O. Vittorio Emanuele, Via Plebiscito 628, 95124 Catania, Italy
    • ,
  • Roberto Varsalona

      Affiliations

    • Department of Orthopaedics and Trauma, P.O. Vittorio Emanuele, Via Plebiscito 628, 95124 Catania, Italy

Received 22 September 2004; received in revised form 25 October 2005; accepted 31 October 2005. published online 05 December 2005.

Abstract 

Seidel intramedullary humeral nail is locked distally by a spreading device and proximally by transverse cross locking screws. The main problems found in its use are: the loosening of the distal anchorage, even after X-ray verification of the correct expansion of the device; the formation of distal fractures, occurring even 1 month after the operation; the system's low stability.

The problems noted can be ascribed to the behaviour of the spreading device for distal fixing. The present study, therefore, was directed at analysing the contact between the spreading mechanism and the medullary canal in relation to the geometric parameters of the mechanism itself. The main objective was to define the correct regulation of the expansion in the operating theatre, and to delimit the more appropriate conditions of use, allowing the surgeon to evaluate the suitability of this particular device for the type of fracture under treatment.

Numerical and experimental techniques were used to perform an analysis of the implant behaviour. This investigation, referred to immediate post-operative condition, allowed to evaluate the stability to traction of the system, to define the typology and properties of the bone-implant contact zone and to quantify the stresses produced, all as a function of the parameter on which the surgeon intervenes in the operating theatre: the number of turns used to tighten the spreading screw.

The results obtained confirm and explain the disadvantages associated with the distal expansion system: the bone-implant contact turns out to be inefficient, as revealed by the distribution of the pressure on the inner wall of the medullary canal.

On the basis of the results, it is possible to define the optimal conditions of use of the nail, and to formulate a simple solution for the improvement of its performance.

Keywords: Humeral fractures, Intramedullary nailing, Seidel, Biomechanical system, Numerical–experimental analysis

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PII: S1350-4533(05)00228-6

doi:10.1016/j.medengphy.2005.10.012

Medical Engineering & Physics
Volume 28, Issue 7 , Pages 682-693, September 2006

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