Vertebral body replacement using patient-specific three-dimensional-printed polymer implants in cervical spondylotic myelopathy: an encouraging preliminary report.

BACKGROUND CONTEXT: Resulting from recent studies that suggest a benefit of implant design on the achievement of fusion and stability in cervical spinal disease management, manufacturing development has increased over the past years. This article attempts to describe how the development of patient-specific implants, which are used during the procedures of anterior cervical corpectomy and vertebral body replacement (VBR), impacts the outcomes of cervical spondylotic myelopathy (CSM) management.

MATERIALS AND

METHODS

This prospective clinical study included six patients who were implanted with patient-specific VBR for single-level or multilevel CSM. The following clinical scores were collected: visual analog scale (VAS), modified Japanese Orthopaedic Association (mJOA), Neck Dysfunction Index (NDI), and European myelopathy score (EMS), along with radiological measurements.

RESULTS

Six patients reached a mean follow-up date of 21months (12-24). Angle measurements remained constant during follow-up, including the C2-C7 Cobb angle and the corpectomy Cobb angle. Furthermore, no deformations, such as hyperlordosis or kyphosis, were detected. The anterior height (Ha) and the posterior height (Hp) of the corpectomy segment remained constant (ratio close to 1) with no severe subsidence (>3 mm) at the last follow-up. No height differences were detected between the preoperative and the last follow-up dates, neither for the upper Hp and Ha (0.97±0.09 and 1.00±0.06, respectively) nor for the lower adjacent vertebrate Hp and Ha (0.96±0.04 and 1.02±0.12). The mean mJOA and EMS recovery rates were 60.4% (standard deviation [SD] 20.4) and 77.0% (SD 29.7), respectively, at last the follow-up. An EMS of at least 16 of 18 was observed in 83% (5 of 6) of the patients. We recorded a preoperative NDI score at 47.1% (SD 18.6) that improved to 11.2% (SD 4.1) at the last follow-up (p<.01). The preoperative VAS neck (6.3, range 4-7) and the VAS arm (6.1, range 3- 9) scores improved to 1.3 (range 0-3) and 2.8 (range 0-5), respectively, at the last follow-up.

CONCLUSIONS

This preliminary report suggests a possible benefit of the use of patient-specific implants in CSM treatment. The favorable clinical and radiological outcomes were associated with a correct achievement rate; these are promising elements toward the development of the concept of personalized therapy. Nonetheless, these encouraging results have to be confirmed now with a longer follow-up and a larger cohort.