Performance of UHMWPE in the Spine

Range of Motion in Degrees for Intact and Implanted L5-SI Segments with a PRODISC  

Compressive load State of PSU Flexion- extension Lateral bending Axial torsion 

A cadaveric study comparing the range of motion in the L5-S1 motion segment in five human spines, before and after implantation with the PRODISC, has indicated that implantation of fhis device did not significantly affect the ROM (Lipman et al. 2003). Specimens were tested in an apparatus that applied pure bending moments. The specimens were cycled in torque to a maximum of 10 Nm in flexion-extension, lateral bending, and torsion with 600 N and 1200 N compressive loads. The ROM at 8 Nm after the fifth cycle of loading was documented and used for comparison between intact and implanted specimens. Summary data is shown in Table 10.3. 

Artificial discs had been implanted in patients in Europe long before they were implanted in patients in the United States under the IDE studies. There are a number of reports in the literature on the short-term (Griffith et al. 1994, Lemaire 2003, Lemaire et al. 1997, Zeegers et al. 1999) ( 5 years) and long-term (Lemaire 2003, Van Ooij, Oner, and Verbout 2003) ( 10 years) clinical experience of the SB Charite in Europe. Only recently have we seen reports of the initial clinical experience in the United States (Hochschuler et al. 2002, McAfee et al. 2003). 

Because the follow-up of the SB Charite implantations in the United States are still imder the auspices of the IDE, currently there are only preliminary reports available in the literature from two different centers that are participating in the study, with follow-up from 1 to 3 years (Hochschuler et al. 2002, McAfee et al. 1999). The fimctional outcome measures used in both studies showed significant improvement following implantation of the SB Charite (Hochschuler et al. 2002, McAfee et al. 2003). Neither of the two series report any device failures or dislocations. 

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