Total Disc Replacement Designs Using UHMWPE

Total Disc Replacement Designs Using UHMWPE 

The PRODISC was acquired by Synthes USA (Paoli, PA), with tire final completion of the negotiation contingent upon successful completion of the clinical trials. The SB Charity III was acquired by Depuy Acromed (Johnson Johnson), with a similar condition on further contingent payments due upon achievement of regulatory and other milestones. 

In tire early 1980s, Schellnack and Biittner-Janz initiated the development of the artificial disc that later became the SB Charite. The naming of the implant is after the initials of the inventors and the hospital where it was designed and first implanted (S, Kurt Schellnack, B, Karin Biittner-Janz, and CharitC site of development and first implantation) (Biittner-Janz, Hochschuler, and McAfee 2003, Link 2002). The first implantation took place on September of 1984 in the Charite Hospital in Berlin. To date, three generations of designs have evolved and the current design SB Charite 111 was first produced by Waldemar LINK in 1987 (Biittner-Janz, Schellnack, and Zippel 1987, Link 2002). 

The main concept in this design was based on the already existing low-friction principle in the TJR field, using a metal alloy articulating with UHMWPE. The SB Charite artificial disc is made of three components, two of which are metal endplates that attach to the upper and lower vertebral body endplates by means of anchor teeth, and an UHMWPE sliding core that moves in between these two metal endplates. The endplates of the first two models of the SB Charite (1 and 11) were manufactured from 1-mm thick stainless steel. Specifically, the ones in model Type 1 were round and later evolved to an oval shape in model Type 11 (Buttner-Janz, Hochschuler, and McAfee 2003). 

The properties for the UHMWPE are listed in Table 10.1. It is identified under the trade name Chirulen , which (as described in Chapter 2) denotes a 

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Total Disc Replacement Designs Using UHMWPE... 

As summarized in Table 12.3, there are currently four lumbar total disc replacement designs incorporating UHMWPE in clinical use today CHARITE, ProDisc-L, Mobidisc, and Activ-L. In the previous section, we reviewed the clinical history and bioengineering studies related to the CHARITE. The three newer designs differ from the CHARITE in several respects, such as the amount of constraint in the bearing and the incorporation of keels into the endplates (Table 12.3). 

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