Minimally Invasive Anterior Cervical Discectomy Without Fusion to Treat Cervical Disc Herniations in Patients with Previous Cervical Fusions

A New Method to Evaluate Pressure Distribution Using a 3D-Printed C2-C3 Cervical Spine Model with an Embedded Sensor Array

Cervical degenerative disc diseases such as myelopathy and radiculopathy often require conventional treatments like artificial cervical disc replacement or anterior cervical discectomy and fusion (ACDF). When designing a medical device, like the stand-alone cage, there are many design inputs to consider. However, the precise biomechanics of the force between the vertebrae and implanted devices under certain conditions require further investigation. In this study, a new method was developed to evaluate the pressure between the vertebrae and implanted devices by embedding a sensor array into a 3D-printed C2-C3 cervical spine. The 3D-printed cervical spine model was subjected to a range of axial loads while under flexion, extension, bending and compression conditions. Cables were used for the application of a preload and a robotic arm was used to recreate the natural spine motions (flexion, extension, and bending). To verify and predict the total pressure between the vertebrae and the implanted devices, a 3D finite element (FE) numerical mathematical model was developed. A preload was represented by applying 22 N of force on each of the anterior tubercles for the C2 vertebra. The results of this study suggest that the sensor is useful in identifying static pressure. The pressure with the robot arm was verified from the FE results under all conditions. This study indicates that the sensor array has promising potential to reduce the trial and error with implants for various surgical procedures, including multi-level artificial cervical disk replacement and ACDF, which may help clinicians to reduce pain, suffering, and costly follow-up procedures.

[Comparison of the long-term outcomes of total arthroplasty and anterior spinal fusion in the treatment of cervical degenerative disc disease: a metaanalysis]

AIM

The study aim was to perform a meta-analysis based on the results of randomized clinical trials comparing long-term outcomes of total intervertebral disc arthroplasty (TA) and anterior cervical spinal fusion (ACSF) in the surgical treatment of cervical degenerative disc disease.

MATERIAL AND METHODS

We searched Pubmed, EMBASE, ELibrary, and Cochrane Library databases for randomized clinical trials reported between 2008 and August 2018. The relative risk and 95% confidence interval were calculated for dichotomous variables; for continuous variables, we used the standardized mean difference and their 95% CI with application of a random effects model.

RESULTS

The metaanalysis involved 9 randomized controlled clinical trials including the long-term outcomes of surgical treatment in 2,439 patients. A pooled analysis of the data showed that regression of neurological symptoms (p<0.00001), improvement in the quality of life of patients (Neck Disability Index), and lower pain severity (visual analogue scale for upper extremities) were significantly more often observed (p=0.02) in the group of TA patients. In addition, the TA technique was characterized by a statistically significantly lower rate of re-surgery (p<0.0005) and degeneration of the superjacent segment (p<0.0001), with the rate of adverse events being slightly increased (p=0.04).

CONCLUSION

Compared to anterior cervical spinal fusion, TA of cervical intervertebral discs is characterized by significantly better clinical efficacy in patients with cervical degenerative disc disease in the long-term postoperative follow-up.