Metasul® Metal-on-Metal Technology

Design

Design Key Factor: Where Technology and Experience Meet

For two decades the majority of total hips have utilized a modular insert. Modularity offers more intraoperative choices during primary and revision surgery, including a variety of bearing materials, articulation diameters and insert options.

Modular Metasul inserts are available either with a sandwich design, where the metal inlay is fixed into a polyethylene liner, or a monoblock design that will accommodate the use of large diameter heads.

Design Key Factor: Maximizing Range of Motion and Stability

Reducing the Risk of Dislocation

Prosthetic impingement and insufficient stability are known to be risk factors for dislocation. Soft tissue or bone interference, orientation of the prosthesis, and implant design can all contribute to impingement and dislocation1.   Therefore, the aim must be to enhance the stability and maximize ROM by optimizing implant design and improving component positioning intraoperatively. The head-to-neck diameter ratio and design of femoral head, stem, and acetabular components will all contribute to component ROM performance2.

Improving ROM for Modular Inserts

To reduce potential impingement between femoral and acetabular components when using Metasul Technology, the traditional inlay design has been slightly modified. Moderately reducing the entrance plane helps ensure sufficient coverage of the femoral head by the metallic inlay and promote stability in vivo.

The newly designed Metasul Alpha 28 and 32mm inserts provide up to 15° more technical ROM than original Metasul Alpha inserts.

Reducing the Cup Profile Increases ROM

A slightly reduce cup profile for monoblock acetabular devices improves ROM. The Durom Acetabular Component is less than hemispherical and subtends an angle of 165°, similar to the natural acetabulum. This design offers both enhanced ROM and preservation of bone.

The Durom Acetabular Component is available with Metasul LDH® large diameter heads. These heads are offered in outside diameters from 38mm to 60mm and promote hip stability through a technical ROM of 144° to 168°, depending on the head size and femoral stem being used.

References

  1. Siebenrock KA, Ganz R: The impingement problem in total hip arthroplasty, in: World Tribology Forum in Arthroplasty, Rieker C (ed). Berne, Hans Huber, 2001, 47–52
  2. Oehy J, et al: Design parameter to improve range of motion (ROM) in total hip arthroplasty, in: Lazennec JY and Dietrich M (eds). Bioceramics in Joint Arthroplasty, 9th Biolox Symp Proc, Steinkopff Verlag, Darmstadt, 2004, 149–155