Cervical disc dimensions of the Thai population

Abstract

Problem : The incidence of complications in cervical disc arthroplasty was 6.2% per treat level. Perioperative kyphosis, heterotopic ossification and migration may occur be due to undersized prosthesis. Measurement of the dimensions of cervical discs of the Thai population was aimed to be a pilot study to know the estimation of the dimensions of cervical discs that could be referred to the size of disc prosthesis devices.

Objective : To provide data regarding the diamension of cervical discs dimensions that can be used in Thailand for preoperative planning and design of cervical disc prosthesis in Thailand.

Study design : Descriptive study.

Setting : Department of Orthopedics, King Chulalongkorn Memorial Hospital.

Method and Material : From January 2008 to December 2008, 60 consecutive C-spine magnetic resonance imaging studies were performed on Thai subjects. MRI was performed using a 1.5 Tesla whole body MR imaging system with an extremity coil. Pulse sequences were T2-weighted images. The direction of the axial slice imaging placed the slice perpendicular to the spinal mechanical axis in the coronal plane and perpendicular to the long axis of the spine in the sagittal plane. All 60 images were reconstructed at 3-mm intervals.

Result : Total mean maximum disc height in Thai population are as follows: C3-4 6.44 mm, C4 - 5 5.90 mm, C5 - 6 5.79 mm, C6 - 7 6.28 mm and C7 - T1 6.21 mm. The differences in the maximum disc heights between males and females were significant. The maximum and minimum distances from all samples are 6.63 mm and 5.47 mm, respectively. The total mean sagittal diameter in the Thai population are: C3i 14.77 mm, C4s 14.77 mm, C4i 15.23 mm, C5s 15.13 mm, C5i 15.74 mm, C6s 15.62 mm, C6i 15.72 mm, C7s 15.69 mm, C7i 15.79 mm and T1s 16.00 mm. The maximum and minimum distances from all samples are 16.47 mm and 13.33 mm respectively. The differences in maximum disc height between males and females were significant. The total mean transverse diameters in the Thai population are C3i 21.77 mm, C4s 22.15 mm, C4i 22.15 mm, C5s 22.95 mm, C5i 23.44 mm, C6s 24.23 mm, C6i 25.36 mm, C7s 26.28 mm, C7i 26.92 mm and T1s 26.95 mm. The maximum and minimum distances from all samples are 27.73 mm and 20.80 mm respectively. The differences in the maximum disc height between males and females were significant.

Conclusion : Measurement of disc dimensions can refer to the ranges of size to manufacturers for the devices to cover the use in Thai patients. The data fulfill the goal described for cervical disc dimension for the Thai population. The results of the project could provide design and data for the manufacturers and next step of experiment for cervical disc prosthesis suitable for the Thai population.