Fusion or no Fusion After Decompression of the Spinal Cord in Patients With Degenerative Cervical Myelopathy (MyRanC)

Fusion or no Fusion After Decompression of the Spinal Cord in Patients With Degenerative Cervical Myelopathy

Comparison of Posterior Muscle-preserving Selective Laminectomy and Laminectomy With Fusion for Treating Degenerative Cervical Myelopathy: Myelopathy Randomized Controlled Trial (MyRanC)

Background: Degenerative cervical myelopathy (DCM) is characterized by neck pain, neck stiffness, weakness, paresthesia, sphincter disturbance and balance disorder. The mean age for symptoms is 64 years and more men than women, 2.7:1, are affected. The most common level is C5-C6. DCM is the predominant cause of spinal cord dysfunction in the elderly worldwide. Surgical options include stand-alone laminectomy, laminectomy and fusion and laminoplasty. The preferable surgical approach is though, a matter of controversy. The objective of this study is to compare stand-alone laminectomy to laminectomy and fusion. Methods/Design: This is a multicenter randomized, controlled, parallel group non-inferiority trial. A total of 300 adult participants are allocated in a ratio of 1:1. The primary endpoint is reoperation for any reason within 5 years of follow-up. Sample size and power calculations were performed by estimating the reoperation rate after laminectomy to 3.4% and after laminectomy with fusion to 7.9% based on data from the Swedish spine registry (Swespine) on patients with DCM. Secondary outcomes are the patient derived modified Japanese orthopaedic association (P-mJOA) score, Neck disability index (NDI), European quality of life five dimensions (EQ-5D), Numeric rating scale (NRS) for neck and arm pain, Hospital anxiety and depression scale (HADS), development of kyphosis measured as the cervical sagittal vertical axis (cSVA) and, death. Clinical and radiological follow-up is performed at 3, 12, 24 and 60 months after surgery. The main inclusion criteria is 1-4 levels of DCM in the subaxial spine, C3-C7, with or without deformity. The REDcap will be used for safe data management. Data will be analyzed in the per protocol (PP) population, defined as randomized patients who are still alive without having emigrated or left the study after five years. Discussion: This will be the first randomized controlled trial comparing two of the most common surgical treatments for DCM; the posterior muscle-preserving selective laminectomy and posterior laminectomy with instrumented fusion. The results of the MyRanC study will provide surgical treatment recommendations for DCM. This may result in improvements in surgical treatment and clinical practice regarding DCM.

Background: Degenerative cervical myelopathy (DCM) is characterized by neck pain and stiffness, weakness and paresthesia of the extremities, sphincter disturbance and bowel and balance disorder. DCM is the most common cause of spinal cord dysfunction in the elderly worldwide (1) and the incidence is 41 per million within North America (2). The mean age for symptoms is 64 years of age, more men than women, 2.7:1, are affected and the most common level is C5-C6 (3). Mechanism: DCM is typically the consequence of degenerative disc herniation, osteophyte formation and hypertrophy of the ligamentum flavum that compress the spinal cord. Ossification of the posterior longitudinal ligament (OPLL), which is more prevalent in the Asian population, may also cause compression of the spinal cord. With non-operative treatments, i.e. medication and physiotherapy, 20-60% of the patients deteriorate neurologically and surgical treatment is indicated (4). Existing knowledge: The surgical treatment for DCM is decompression of the spinal cord. Decompression may be achieved with an anterior or posterior approach. Several algorithms have been proposed on whether to choose anterior diskectomy and fusion, anterior corpectomy and fusion, posterior laminectomy with fusion, posterior laminoplasty or, posterior laminectomy alone (5,6). Anterior discectomy/corpectomy with fusion is recommended in patients with a straight or kyphotic spine with compression of less than three levels (6). A posterior approach is recommended in patients with cervical lordosis and compression of more than three levels (7). The WFNS Spine Committee modified these recommendations in 2019 towards a wider use of posterior approaches, e.g. in patients with posterior compression at 1 or 2 levels and patients with a flexible kyphosis (8). It was recommended to address anterior compression with an anterior approach and posterior compression by a posterior approach. Hence, when propensity score matching is performed on the basis of MRI classification and description of the degenerative changes in each patient, anterior and/or posterior compression of the spinal cord, there is no difference between anterior or posterior decompression and fusion approaches (9). Fusion is recommended in patients with DCM and concurrent signs of instability but there is no definition of instability in the degenerated cervical spine (10). In the traumatic cervical spine, however, instability is defined as >3.5 mm translation or 11° rotation on lateral flexion-extension radiographs (11) but there are no indications that degenerative changes with intact ligaments and unfractured joints would be unstable in the same way. Kyphosis of cSVA > 40 mm (13) has been correlated to worse postoperative outcome (normal cSVA = 17-11 mm) (14). Consequently the recommendation is to correct kyphosis by an anterior approach (8) but a correction does not seem to affect the outcomes (15). It remains a matter of debate among spinal surgeons whether posterior fusion after laminectomy for DCM, should be mandatory or not. After reports of post-laminectomy kyphosis in the 1970s and 1980s (16) prophylactic fusion has commonly been combined with the laminectomy procedure (9). In a report from 1999, 34% of the patients developed kyphosis or swan neck deformity after laminectomy compared with 7% of patients surgically treated with laminoplasty, using a muscle-preserving technique (17). However, a muscle-preserving technique that retains the facet integrity as well as the extensor musculature may be used when performing posterior laminectomy as well and is observed to maintain sagittal balance after surgery without progression of kyphosis (18). Distal junction kyphosis (DJK) is a kyphotic angulation of at least 10° at the distal segment adjacent to a fused level and occurs in 24% of patients within a year after fusion surgery (19). Adjacent segment pathology (ASP) is progression of degeneration at the levels adjacent to a fused level and may also necessitate reoperation with decompression and extended fusion surgery (20). Considering the existence of muscle-preserving laminectomy techniques that can maintain cervical lordosis (26), there is reason to explore the additional value of instrumented fusion in the cervical spine. Although both methods are widely used, they are yet to be compared in a randomized controlled study. Need for a trial: There exists a controversy among spinal surgeons regarding the need for posterior fusion when laminectomy for DCM is performed. We hypothesize that laminectomy without fusion results in shorter hospital stay and quicker return to an active life, without reduced patient satisfaction, functional scores, or delayed kyphosis. It is important to achieve good outcome with a single surgery, to spare this frail group of patients from reoperations. Therefore, reoperation for any reason within five years after the primary surgery will be the primary endpoint of the current study. Long-term follow-up radiographs and magnetic resonance imaging (MRI) is needed to assess differences in the subsequent degenerative changes including spondylolisthesis, kyphosis, and adjacent segment pathology (ASP) to compare the two strategies. Additionally, data from this study can be used to identify risk factors for poor outcome to guide surgical decision making. Objectives: To determine the surgical treatment associated with the lowest frequency of reoperations when treating participants with CSM by performing a non-inferiority study comparing laminectomy alone with laminectomy and fusion. To evaluate potential differences in outcome including participant satisfaction, functional scores, late degenerative changes including spondylolisthesis, kyphosis, DJK, ASP and, death. Study setting: Uppsala University Hospital Karolinska University Hospital, Stockholm Ryhov Hospital, Jönköping Sahlgrenska University Hospital, Gothenburg Sample size: Based on data from the national Swedish spine registry on patients with CSM, reoperation was estimated to 3.4% after standalone laminectomy and 7.9% after laminectomy and fusion. Five year mortality was estimated to 16.3% in the same population. We further determined that excluding a 5% excess rate of reoperation in the laminectomy group vs laminectomy and fusion was a clinically relevant target for the study, and therefore set the non-inferiority margin at 5 percentage points (pp). With a sample size of 300 participants and with regards to mortality and an additional 5% loss due to dropout and emigration, we end up with 236 analyzable patients. This results in a power of 87% based on simulation using rerandomization. Recruitment: All participants diagnosed with DCM referred for surgical consultation to the orthopedic or neurosurgery departments at the participating centers will be eligible for the study. Oral and written information about the study will be given at the routine physiotherapist appointment before the scheduled doctor's appointment and repeated by the treating surgeon at the following consultation. Participants may be enrolled if they meet the inclusion criteria and sign informed consent. Allocation: Participants will be allocated to either standalone laminectomy or laminectomy and fusion through randomization with a 1:1 ratio using the REDcap software (Research Electronic Data Capture), after informed consent and agreement to be included in the study. After inserting the patient´s personal number into REDcap the program reports the random allocation of the patient according to the pre-constructed randomization list. The randomization is stratified for center and participant sex, i.e. using separate lists for each center and sex. The allocation sequence utilizes balanced blocks of three different sizes occurring in random sequence. The principal investigator and study collaborators are blinded to the sequence, the block sizes and block sequence. Blinding: Trial participants will not be blinded after assignment to interventions as they have online access to their medical records by a centrally managed system. The outcome assessors and data analysts will be blinded by using a coding system for the treatment groups. Dropouts: Dropouts may be one out of two entities; 1) the participant actively leaves the study or, 2) the participant has died or do not show up on follow-ups for unclear reasons. In case 1, the participant will not be part of the study anymore and data will not be retrieved from other information sources. In case 2, information about living participants will be retrieved from the medical records, radiographs, and the Swedish patient registry. Statistical methods: To test for non-inferiority, a two-sided 95% confidence interval (CI) for the difference in failure rates between the two groups will be computed. To account for sparsity of events, the CI will be computed using rerandomization techniques,10 blocked on sex, since the randomization was stratified on sex. Non-inferiority will be claimed if the upper limit of the CI is less than 5 pp. If non-inferiority is demonstrated, superiority will also be tested using the same CI, although the study is likely underpowered to detect this. All endpoints will be analyzed in the per protocol (PP) population, defined as randomized patients who are still alive without having emigrated or left the study after five years. The secondary outcomes listed above will be analyzed using ordinal regression models, adjusted for sex. In addition, each secondary endpoint will be dichotomized and analyzed using logistic regression. The dichotomization will be done by comparing baseline and follow-up data, either based on MCID when applicable, or else by defining success as an improvement from baseline. All secondary endpoints will be analyzed at 1, 2 and 5 years of follow-up, but not until the study is closed and the primary results is published. The study statistician is Lars Lindhagen at Uppsala Clinical Research Center. Data collection: Questionnaires including baseline questionnaires and postal follow-up questionnaires as well as validated PROMs will be distributed the participants preoperatively. Postoperatively the participants are routinely followed via the Swespine (swespine.se) and follow-up questionnaires and PROMS will be retrieved from Swespine.41,49,50 Closing statement: Degenerative cervical myelopathy is the most common cause of spinal cord dysfunction in the elderly worldwide and the incidence is 41 per million within North America. Until now there is no consensus whether to fuse or not when laminectomy is performed and the choice of surgical method is mainly up to the surgeon's preference. This will be the first randomized controlled trial comparing two of the most common surgical treatments for DCM; the posterior muscle-preserving selective laminectomy and posterior laminectomy with instrumented fusion.

Muscle-preserving selective laminectomy with a posterior midline incision and dissection through the nuchal fascia. The spinous processes are split in the midline using a high-speed burr/ultrasound knife and without disturbing the deep extensor muscles on either side. Angulating away from the midline, the spinous processes are divided at their bases. Laminectomy is performed with a width no more than 2-3 mm wider than the dural borders. The facet joints are not exposed. Finally, the split spionous processes are sutured together. No collar or restrictions will be used in either group.

Laminectomy with instrumented fusion with a midline incision over the appropriate levels defined as the same levels as the extension of laminectomy plus one level above and below but not extending beyond C3-C7. Soft tissue dissection and retraction is performed to identify osseous landmarks. Special care is taken to spare muscle attachments on C2 and C7. Spinal instrumentation is performed with lateral mass or pedicle screws (C3-C7) combined with rod fixation. Laminectomy is performed with a width not extending more than 2 mm outside the dural borders. Facet joint injury should be avoided. Special care is taken to spare the C7 spinous process and distal half of C7 lamina. The sagittal alignment is corrected before spinal fixation. No collar or restrictions will be used in either group.

Muscle-preserving selective laminectomy differ from traditional laminectomy by the spinous process split that preserves the deep extensor muscles. The bilateral facet joints are not exposed. After the laminectomy is finished the split fragments of the spinous process are sutured together so that the deep extensor muscles are restored.

A traditional laminectomy is complemented with lateral mass and/or pedicle screws connected with rods.

The primary endpoint will be reoperation for any reason to reflect whether laminectomy alone or laminectomy with instrumented fusion results in fewer reoperations without increasing the frequency of complications.

Reoperation will be considered in case of: Postoperative hematoma or reperfusion injury with neurologic deterioration within hours/days after the primary surgery. Change in sagittal alignment (kyphosis, DJK of more than 40 mm cSVA and/or C2-C7 Cobb < -10°) with corresponding symptoms of camptocormia/increased pain/neurological deterioration. ASP defined as degenerative changes on an adjacent level diagnosed with MRI and concomitant symptoms of myelopathy and/or radiculopathy. Implant failure (clear radiolucency around >1 screw or rod breakage with increased neck pain and/or neurologic deterioration). Postoperative infection that requires revision surgery.

Change from baseline in myelopathy score on the patient derived modified Japanese Orthopedic Association scale (P-mJOA) at 2 years.

P-mJOA is a self-administered questionnaire with four domains, measuring motor (upper and lower extremities), sensor (upper extremities) and sphincter dysfunction in patients with cervical degenerative myelopathy. The first domain is scored from zero to five, second domain from zero to seven, third and four domains from zero to three. The maximum score is 18 points, indicating no deficits and the minimum score is zero, total tetraplegia. The minimum clinically important difference (MCID) in mJOA has been reported to be 2 overall with a threshold of 1 in mild myelopathy (mJOA >14), 2 in moderate myelopathy (mJOA 12-14) and 3 in severe myelopathy (mJOA <12). Consistency between P-mJOA and mJOA is demonstrated with identical mean scores and a SD of 1.5 together with a strong agreement of 0.83 with the use of intraclass correlation coefficient and the Spearman correlation.

Change of at least 17% in the NDI (100 points) compared with baseline (adjustable according to results from own minimal clinically important change results for Neck Disability Index). The NDI range from 0-100% with higher scores indicating severe disability. The MCID is 15%-17% for NDI.

Change in pain, as defined by ≥2.5 points on a 10 graded Numeric rating scale (NRS) for arm/shoulder pain. NRS for neck and arm pain range from 0-10, with higher scores indicating more severe pain. The MCID is 2.59 for NRS of the neck and arm.

Change at baseline in number of participants with psychological impairment on the Hospital anxiety and depression scale (HADS) in both groups.

HADS range from 0-42 with higher scores indicating more anxiety/depression. The cutoff for depression defined as >10 p.

Change in number of satisfied participants on the patient global assessment in both groups at 2 years.

The Global Assessment is a "satisfaction index" for evaluating the participants´ experienced overall result after surgery. The participant is asked "How is your attitude regarding the treatment result". The alternative answers are "satisfied", "uncertain", "dissatisfied".

The 10-s grip and release test is performed with the forearm in pronation and the wrist in mild extension. The participant is asked to grip and release with their fingers as rapidly as possible and the number of completed cycles of movement within 10 seconds is counted.

The 10-s foot-tapping speed test is performed with the participant sitting on a chair adjusted so that the hip and knee are flexed at 90° and the bilateral soles have contact with the floor. The participant is asked to move their toes up and down, tapping the floor as quickly as possible for 10 sec with their heels firmly planted on the floor. The number of completed cycles of movement within 10 seconds is counted.

Difference in number of participants with treatment-related adverse events in both groups at 5 years.

All adverse events in both groups will be presented. The adverse events will be graded according to severity: grade 1, any non-life-threatening complication treated without invasive procedures; grade 2, complications requiring invasive management such as surgical, endoscopic, and endovascular procedures; grade 3, life-threatening adverse events requiring treatment in an intensive care unit (ICU); and grade 4, deaths as a result of complications.

Standing radiographs of the cervical spine in neutral, flexion and extension will be performed. When radiographs of the neutral position are executed the patient will be in a comfortable standing position with the head facing forward for horizontal gaze. The radiographs will be used to investigate the sagittal alignment by measuring the C2-C7 Cobb angle, C2-C7 sagittal vertical axis (cSVA), C7 slope and T1 slope.

Number of participants with change in adjacent segment pathology (ASP) on MRIs from baseline to 5 years of follow-up.

Magnetic resonance imaging (MRI) of the cervical spine with T1- and T2-weighted images in sagittal and T2-weighted in axial planes will be performed. Hereby the degenerative development over time may be assessed.

Number of participants with change in compression of the spinal cord on the index level on MRIs from baseline to 5 years of follow-up.

Magnetic resonance imaging (MRI) of the cervical spine with T1- and T2-weighted images in sagittal and T2-weighted in axial planes will be performed preoperatively, after three months and at five years of follow-up. Hereby the compression of the spinal cord may be assessed as well as the performed decompression and the degenerative development over time.

Direct costs includes hospital stay related to the surgical procedure, implant related costs, and pain medication usage.

Indirect costs includes pain medication usage, societal costs for absence from work and workers compensation.

Inclusion Criteria: Age >18 years 1-4 levels of cervical degenerative myelopathy in the subaxial spine, C3-C7, without or with deformity not exceeding exclusion criteria, see below. Eligible for both treatments Ability to understand and read Swedish language Symptomatic myelopathy with at least one clinical sign of myelopathy No previous spine surgery Psychosocially, mentally, and physically able to fully comply with this protocol, including adhering to scheduled visits, treatment plan, completing forms, and other study procedures Personally, signed and dated informed consent document prior to any study-related procedures, indicating that the patient has been informed of all pertinent aspects of the trial Definition of kyphosis - cSVA > 40 mm and/or C2-C7 Cobb > 10° kyphosis. Definition of spondylolisthesis - anterior slippage of > 2 mm on cervical radiographs taken in the neutral position. Exclusion Criteria: Local kyphosis; a modified K-line minimum interval distance (INT) of <4 mm Spondylolisthesis >4 mm and simultaneous translation >2 mm on lateral flexion/extension radiographs Soft disc herniations only (no signs of osteophyte formation and hypertrophy of the ligamentum flavum) Active infection Neoplasm Trauma Inflammatory disease (i.e., rheumatoid arthritis or ankylosing spondylitis or DISH) Systemic disease including HIV Lumbar or thoracic spinal disease to the extent that surgical consideration is probable or anticipated within 6 months after the cervical surgical treatment (significant lumbar stenosis as defined by Schizas C or worse). OPLL Parkinson´s disease Drug abuse, dementia, or other reason to suspect poor adherence to follow-up Previous cervical spine surgery

The REDcap* with a two-stage verification login will be used for safe data management. Participants will be coded, and collaborators and statisticians will only have access to encrypted data. Access to decrypted data and safekeeping of the decryption key will be limited to the principal investigator and the study nurse. Participating spine surgeons have only access to his/hers own site and cannot see the other recruiting centers. * (project-redcap.org) (redcap.vanderbilt.edu)

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