Product Overview
The Versafitcup Double Mobility is based on the original Dual Mobility design, with more than 30 years of successful clinical history. In fact, this concept was first proposed by Prof. Bousquet and the Medical School of St. Etienne, France, back in 1976. The introduction of the Highcross (cross-linked polyethylene by Medacta) Double Mobility liner drastically reduces the wear rate, reproducing performances comparable to Ceramic-on-Ceramic and Metal-on-Metal bearing combinations.
• DUAL MOBILITY - Articulation Liner/Shell
• DUAL MOBILITY - Articulation Head Liner
• THIRD ARTICULATION - Articulation Neck/Liner
WHY CHOOSE A DOUBLE MOBILITY CUP?
Better than standard fixed liner cups:
• Extremely low wear rate thanks to the Dual Mobility and Third Articulation.
• Low dislocation rate thanks to increased head diameter.
• High Range of Motion (ROM) thanks to increased head/neck ratio.
The question of a potential UHMWPE wear increase due to the double articulation has been raised, and clinical follow up from more than 30 years on similar systems has been reassuring. Additionally the dynamic mechanism of action is becoming better understood.
The Dual Mobility and Third Articulation concepts are responsible for the low wear rate of the Versafitcup Double Mobility:
• Head/Liner Articulation (A1)
• A1 is always smaller than A2. Under physiological loading conditions, Al is the first to be mobilized up to contact of stem neck with UHMWPE liner rim. During 80% of one gate cycle the only movement is A1.
Liner/Shell Articulation (A2)
A2 starts only when the stem neck enters into contact with the rim of the liner. The rim of the liner is chamfered to articulate with polished neck (Third Articulation concept). The movement A2 happens with activities requiring high Range Of Motion (ROM) such as climbing stairs.
Thanks to this concept, the wear rate of the Versafitcup is lower compared with standard fixed UHMWPE liner coupled with metal head.
By using a Ceramic head instead of a Cobalt Chrome head, the wear rate can be significantly reduced.
It is important to always couple the Versafitcup Double Mobility with Medacta femoral stems which have a highly polished neck and a short taper design.
Test on Versafitcup Double Mobility size 64 mm, coupled with standard and Highcross liners, CoCr 28 mm head, 5 Million Cycles with 3400 N according to ISO 14242-1. Other data are an extrapolation from literature and the above mentioned test.
VERSAFITCUP HIGHCROSS DOUBLE MOBILITY LINER
The Versafitcup Double Mobility design provides a low wear rate. The usage of Highcross, cross-linked polyethylene by Medacta, guarantees a further drastic reduction of wear production. In fact, Highcross Double Mobility liners show a 94% reduction in volumetric wear rate versus the same liners fabricated of ETO sterilized, conventional UHMWPE, thanks to the enhanced properties of cross-linked polyethylene.
HIGHCROSS by Medacta is characterised by:
• gamma irradiation at 100 kGy,
• stabilisation temperature of 150°C,
controlled cooling rate in order to optimise the cristallinity of the material,
final sterilisation with ethylene oxide.
Such innovative production characteristics yield a high quality material with enhanced properties.
It has been demonstrated that for Metal-on-Metal bearing, the prosthesis components positioning is very critical and a poor positioning can lead to early failures due to excessive metal debris.
Also in the case of Ceramic-on-Ceramic bearing, the implants positioning is really critical, in fact a poor positioning can augment the risk of liner fracture or squeaking.
The Versafitcup Double Mobility eliminates all these issues, adding additional protection against dislocation, which is the most common cause of Total Hip Arthroplasty revision, according to a recent market survey.
(http://www.medacta.us.com/US/home-med-pro-us)
