FUSION EVALUATION AFTER ANTERIOR CERVICAL DISCECTOMY AND FUSION WITH STAND ALONE LOCKING CAGE WITH BLADE HRCC®

Introduction:

Cervical degenerative disease is an almost universal concomitant of human aging. Over half of the middle aged population has radiological or pathological evidence of cervical spondylosis. This condition is often asymptomatic, but in 10% to 15% of the cases, it is associated with, or progresses to, neural compression. Cervical spondylotic radiculopathy is a condition due to a root nerve compression while cervical spondylotic myelopathy is a condition due to a medullar cord compression. Root nerve or medullar cord can be compressed either by a soft disc extrusion or by osteophyte due to a degenerative disc. Anterior cervical discectomy and fusion is the gold standard treatment of those conditions when non-surgical treatment failed. The aim of this surgery is to provide a neurologic decompression associated to an intervertebral segmental stabilization. Decompression is achieved by discectomy and stabilization by cervical interbody bone fusion. This bone fusion is supported by implantation of material in the interbody space like bone or Poly-Ether-Ether-Keton cage with bone substitute. This cage provides a bone fusion matrix and an intervertebral height and stability support at the same time. To enforce the stabilization, a plate can be screwed on the anterior cervical vertebral wall. The HRCC® cage is a stand-alone cage with no need to implant plate. One risk of this technic is the secondary migration of the cage. That's why this cage is maintained with two rotary blades which penetrate into vertebral plates. It allows easier surgical procedure, with a lower duration of surgery. But one of the reasons of treatment failure is pseudarthrosis. It is defined as the absence of bone bridging the fusion area without any lucencies. It mays occur as an increase of axial pain or radicular pain. The aim of this study is to demonstrate similar results on bone fusion in the surgical treatment of cervical radiculopathy or myelopathy with HRCC cage used in anterior cervical discectomy and fusion compared with other technics based on a prospective cohort study and a literature review.

Materiel and Method In the context of standard practices, patients are included in the study when they consult the neurosurgical team of the REIMS University Hospital Center with diagnosis of one level cervical discopathy causing cervical radiculopathy or myelopathy with non-surgical treatment failure needing a one level anterior cervical discectomy and fusion. Patients are proposed to be included during this pre-operative consultation and they are informed about the protocol and the data collected. If they accept it and sign the non-opposition form, they are included in the study.

The collected data at the pre-operative consult are classic demographic data with age and sex, clinic data with weight, height and BMI, pseudarthrosis risk factors with diabete, tobacco addiction, chronic use of corticosteroid and osteoporosis with confirmed diagnosis, pre-operative symptomatology with presence of cervical radiculopathy with or without deficit, cervical myelopathy with or without pyramidal syndrome at the inferior limb and measurement of neck and radicular arm pain using a numeric scale, quality of life data with the Neck Disability Index (NDI) and the 12-Item Short Form Survey (SF-12), pre-operative imagery data with cervical IRM and the discopathy level, with cervical X-Ray in the profile incidence and measurement of cervical lordosis, measurement of regional lordosis, height. Per-operative collected data are duration of surgery, bleeding, used bone graft either allograft or autograft and final arthrodesis level. Immediate post-operative data are collected the last day of hospitalization with measurement of neck and arm pain using a numeric scale, complications with dysphagia, dysphonia, cervical compressive hematoma with urgent surgical revision, motor neurological deficit with rating if present, surgical revision, duration of the hospitalization in days, post-operative imagery data with cervical lordosis, regional lordosis, height as previously describe, and cage migration. There is a 12 months follow-up with consultations at 6 weeks, 6 months and 12 months. Collected data are for all measurement of neck and radicular arm pain using a numeric scale for the neck and for the arm, persistence of complications with dysphagia, dysphonia, and motor neurological deficit with rating if present, imagery data with cervical lordosis, regional lordosis, height as previously describe, and cage migration. At 6 months and 12 months we add quality of life data with the NDI and the SF-12, dynamic cervical X-Ray data with the measurement of the spinous process shift and CT-scan data. The diagnosis of pseudarthrosis is established on this multimodal imagery. As secondary outcomes, we will search to correlate pseudarthrosis and quality of life impact, to identify complications and to describe the sagittal balance evolution of the cervical spine.

Then, when all the data will be collected, statistical analyses will be performed with description of the cohort and descriptive statistics of all the demographic, radiographic and clinical parameters detailed above for the whole cohort: Mean (±SD) for the continuous variables and Median (±IQR) for the categorical variables. A comparison between pseudarthrosis group and fused group will be performed with univariate analysis (Student test, Wilcoxon test, Chi2 or Exact Fisher test) then a multivariate analysis will be performed with a logistic regression.