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Hospital Healthcare Europe

Latest advances in bearing technology for hip arthroplasty

5 June, 2009  

The TriboFit® Hip System could solve the problem of too many hip replacement joints showing signs of wear and damage

Antonio Moroni

Rizzoli Orthopaedic Institute

Traditional artificial hip joints consisting of polyethylene, ceramics or metal all have significant drawbacks, and with
an estimated 21% of hip surgeries over the next few years being revisions, the need for improved bearing materials is ever more important.

A potentially revolutionary hip replacement system comes in the form of the TriboFit® Hip System, developed and marketed by Active Implants Corporation, Memphis, Tennessee, USA. In addition to the standard acetabular cup and femoral head, there is a 3 mm-thick TriboFit Acetabular Buffer made of polycarbonate–urethane, a hydrophilic, biocompatible,  endotoxinresistant material that mimics the fluid film layer naturally present in joints. This is a pliable substance whose modulus of elasticity is similar to that of normal human cartilage, thus providing optimum shock absorption. In addition, it induces lubrication, which is of the utmost importance as friction is almost eliminated, resulting in a subsequent decrease in the production of wear particles. Indeed, hip simulation wear tests have revealed negligible signs of wear and damage. The few particles that are produced are of a greater size than those produced by other bearing materials and are therefore much less reactive biologically.

The TriboFit Hip System has been approved all over Europe. From a surgical point of view, it offers the advantage of minimal bone reaming, performed with specific TriboFit Acetabular Reamers. Indeed, I believe that the TriboFit Hip System offers a less invasive acetabular component that is bone-conserving and allows the use of anatomical femoral head sizes to optimise joint stability and range of motion. Another advantage is the simplicity of a press–fit surgical technique whereby the buffer ledge is snapped into the circumferential groove made in the reamed acetabulum. To date, this system has been used in a large number of patients diagnosed with a variety of conditions, including osteoarthritis. In the latter patient population, the socket is deformed and is thus no longer spherical. In such cases, the Buffer alone cannot be used. However, Active Implants has manufactured a thin metal shell that can be press–fit into the socket and can be used in conjunction with the Buffer. Of particular interest are my cases involving young active patients diagnosed with avascular necrosis. In these patients who have a pristine socket, the Buffer can be inserted without socket reaming and is simply coupled with a hip resurfacing metal femoral head.

The TriboFit Hip System is a cutting-edge bearing technology. It has already shown promising results in the clinical setting, in both total hip arthroplasty and hip resurfacing. The inherent problems of other bearings in current use are circumvented. The osteolytic changes in bone due to ultrahigh-molecular-weight polyethylene and its debris products, cracking of ceramic bearings, and the release of metal ions associated with metal-on-metal articulations may all become concerns of the past. The innovative TriboFit Hip System is without doubt set to make a major breakthrough in the field of orthopaedic bearings.