To evaluate the efficacy of 3 different types of cervical disc prosthesis (Prodisc-C, Mobi-C and Prestige-LP) in the treatment of cervical spondylosis.

A cohort, retrospective analysis will be performed of 150 patients who were in implementation of artificial disc replacement in our department from 2008 to 2012 and accepted a regular postoperatively follow-up up to 5 years, the sample will be divided into 3 groups according to prosthesis and 50 people in each group. The outcome will be measured among 3 groups respectively on the operation (such as operation time, intraoperative bleeding.), postoperative complications (such as prosthesis sinking, displacement and prolapse, adjacent segments degeneration and heterotopic ossification), photographic indicators and functional efficacy analysis and then a comparison for self-contrast pre- and post-operatively.

Inclusion Criteria:

1. Patients was diagnosed as cervical spondylosis based on imaging and symptomology;
2. patients were purely underwent TDR within the three kinds of prosthesis;
3. the range of participants is from 20-65 years;
4. conservative treatment of 6 months is invalid;
5. never had cervical operations.

Exclusion Criteria:

1. Patients suffered from cervical trauma or congenital malformations;
2. non-artificial cervical disc replacement or hybrid surgery;
3. ones who refused to be followed up.

1. The range of participants is from 20-65 years;
2. conservative treatment of 6 months is invalid;
3. never had cervical operations;
4. operation on one to three segments.