Discrepancy between cervical disc prostheses and anatomical cervical dimensions.

OBJECTIVE

The aim of this study was to assess appropriateness of the sizes of available cervical disc prostheses based on tomographic measurement of human cervical vertebrae.

METHODS

The anatomic dimensions of the C3-C7 segments were measured on 50 patients (age range 26-47 years) with computerized tomography scan and compared with the sizes of the popular cervical total disc prostheses (CTDP) at the market [Bryan (Medtronic), Prodisc-C (Synthes), Prestige LP (Medtronic), Discover (DePuy)]. The mediolateral and anteriorposterior diameters of the upper and lower endplates were measured with a digital measuring system.

RESULTS

Overall, 43.7% of the largest implant footprints were smaller in the anterior-posterior diameter and 42.6% in the mediolateral diameter were smaller than cervical endplate measurements. Discrepancy of the level C5/C6 and C6/C7 was calculated as 56.2% at the anteroposterior diameter and 43.8% at the center of mediolateral diameter.

CONCLUSION

Large disparity has been found between the sizes of devices and cervical anatomic data. Companies that produce CTDP should take care of the anatomical dimensions and generate different sizes of CTDP. Spine surgeon should be familiar with the size mismatch in CTDP that may affect the clinical and radiological outcome of the surgery.