Assessing Range of Cervical Rotation After Laminoplasty Using Axial CT

Cervical rotation before and after hinge-door cervical laminoplasty for cervical spondylotic myelopathy

Background:

Hinge-Door Cervical laminoplasty is commonly performed procedure in patients with cervical spondylotic myelopathy. Most available studies have established restriction of flexion and extension motion post laminoplasty but the literature on post-laminoplasty axial rotation is sparse.

Objective:

To study the axial neck rotation on either side following hinge door cervical laminoplasty.

Materials and Methods:

Twenty consecutive patients of cervical spondylotic myelopathy planned for cervical laminoplasty were included in the study. Preoperative and postoperative radiological data was recorded for each patient and analysed by an experienced neuroradiologist. The clinical and radiological follow-up was recorded at 6 months post surgery. All patients underwent standard hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra.

Results:

There were 13 men and 7 women with a mean age of 60.5 years, age range 58-70 years. The mean preop C1 C2 rotation was 46.5 degrees and mean post-operative C1-C2 rotation was 44.3 degrees. The average subaxial cervical spine rotation was 11.66 degrees preoperatively and 12.47 degrees postoperatively. The global cervical spine rotation was 80.95 degrees preoperatively and 76.82 degrees postoperatively. There is no significant change in segmental, subaxial and global cervical spine rotation following hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra.

Conclusion:

Cervical laminoplasty preserves cervical ROM and is a motion-preserving surgery as far as axial rotation is concerned.

Cervical laminoplasty developments and trends, 2003-2013: a systematic review

OBJECT

Despite extensive clinical experience with laminoplasty, the efficacy of the procedure and its advantages over laminectomy remain unclear. Specific clinical elements, such as incidence or progression of kyphosis, incidence of axial neck pain, postoperative cervical range of motion, and incidence of postoperative C-5 palsies, are of concern. The authors sought to comprehensively review the laminoplasty literature over the past 10 years while focusing on these clinical elements.

METHODS

The authors conducted a literature search of articles in the Medline database published between 2003 and 2013, in which the terms "laminoplasty," "laminectomy," and "posterior cervical spine procedures" were used as key words. Included was every single case series in which patient outcomes after a laminoplasty procedure were reported. Excluded were studies that did not report on at least one of the above-mentioned items.

RESULTS

A total of 103 studies, the results of which contained at least 1 of the prespecified outcome variables, were identified. These studies reported 130 patient groups comprising 8949 patients. There were 3 prospective randomized studies, 1 prospective nonrandomized alternating study, 15 prospective nonrandomized data collections, and 84 retrospective reviews. The review revealed a trend for the use of miniplates or hydroxyapatite spacers on the open side in Hirabayashi-type laminoplasty or on the open side in a Kurokawa-type laminoplasty. Japanese Orthopaedic Association (JOA) scoring was reported most commonly; in the 4949 patients for whom a JOA score was reported, there was improvement from a mean (± SD) score of 9.91 (± 1.65) to a score of 13.68 (± 1.05) after a mean follow-up of 44.18 months (± 35.1 months). The mean preoperative and postoperative C2-7 angles (available for 2470 patients) remained stable from 14.17° (± 0.19°) to 13.98° (± 0.19°) of lordosis (average follow-up 39 months). The authors found significantly decreased kyphosis when muscle/posterior element-sparing techniques were used (p = 0.02). The use of hardware in the form of hydroxyapatite spacers or miniplates did not influence the progression of deformity (p = 0.889). An overall mean (calculated from 2390 patients) of 47.3% loss of range of motion was reported. For the studies that used a visual analog scale score (totaling 986 patients), the mean (cohort size-adjusted) postoperative pain level at a mean follow-up of 29 months was 2.78. For the studies that used percentages of patients who complained of postoperative axial neck pain (totaling 1249 patients), the mean patient number-adjusted percentage was 30% at a mean follow-up of 51 months. The authors found that 16% of the studies that were published in the last 10 years reported a C-5 palsy rate of more than 10% (534 patients), 41% of the studies reported a rate of 5%-10% (n = 1006), 23% of the studies reported a rate of 1%-5% (n = 857), and 12.5% reported a rate of 0% (n = 168).

CONCLUSIONS

Laminoplasty remains a valid option for decompression of the spinal cord. An understanding of the importance of the muscle-ligament complex, plus the introduction of hardware, has led to progress in this type of surgery. Reporting of outcome metrics remains variable, which makes comparisons among the techniques difficult.

In vivo 3D kinematic changes in the cervical spine after laminoplasty for cervical spondylotic myelopathy

Object

Cervical laminoplasty is an effective procedure for decompressing the spinal cord at multiple levels, but restriction of neck motion is one of the well-known complications of the procedure. Although many authors have reported on cervical range of motion (ROM) after laminoplasty, they have focused mainly on 2D flexion and extension on lateral radiographs, not on 3D motion (including coupled motion) nor on precise intervertebral motion. The purpose of this study was to clarify the 3D kinematic changes in the cervical spine after laminoplasty performed to treat cervical spondylotic myelopathy.

Methods

Eleven consecutive patients (6 men and 5 women, mean age 68.1 years, age range 57–79 years) with cervical spondylotic myelopathy who had undergone laminoplasty were included in the study. All patients underwent 3D CT of the cervical spine in 5 positions (neutral, 45° head rotation left and right, maximum head flexion, and maximum head extension) using supporting devices. The scans were performed preoperatively and at 6 months after laminoplasty. Segmental ROM from Oc–C1 to C7–T1 was calculated both in flexion-extension and in rotation, using a voxel-based registration method.

Results

Mean C2–7 flexion-extension ROM, equivalent to cervical ROM in all previous studies, was 45.5° ± 7.1° preoperatively and 35.5° ± 8.2° postoperatively, which was a statistically significant 33% decrease. However, mean Oc–T1 flexion-extension ROM, which represented total cervical ROM, was 71.5° ± 8.3° preoperatively and 66.5° ± 8.3° postoperatively, an insignificant 7.0% decrease. In focusing on each motion segment, the authors observed a statistically significant 22.6% decrease in mean segmental ROM at the operated levels during flexion-extension and a statistically insignificant 10.2% decrease during rotation. The most significant decrease was observed at C2–3. Segmental ROM at C2–3 decreased 24.2% during flexion-extension and 21.8% during rotation. However, a statistically insignificant 37.2% increase was observed at the upper cervical spine (Oc–C2) during flexion-extension. The coupling pattern during rotation did not change significantly after laminoplasty.

Conclusions

In this first accurate documentation of 3D segmental kinematic changes after laminoplasty, Oc–T1 ROM, which represented total cervical ROM, did not change significantly during either flexion-extension or rotation by 6 months after laminoplasty despite a significant decrease in C2–7 flexion-extension ROM. This is thought to be partially because of a compensatory increase in segmental ROM at the upper cervical spine (Oc–C2).

Open-door laminoplasty with plate fixation at alternating levels for treatment of multilevel degenerative cervical disease

STUDY DESIGN

A retrospective study.

OBJECTIVE

To evaluate the feasibility, efficacy, and safety of laminoplasty with plate fixation at alternating levels through radiologic analysis of the enlarged spinal canal and clinical follow-up.

SUMMARY OF BACKGROUND DATA

Laminoplasty is commonly used to manage cervical myelopathy. Because of the absence of rigid fixation, traditional laminoplasty commonly results in complications, including secondary narrowing of the spinal canal and neurological deterioration. At present, miniplate fixation is promising to prevent reclosure of the opened lamina efficiently by applying plates at each level. However, plates are also used at alternating levels (ie, C3, C5, C7) in clinical settings to reduce the cost of patients. To date, no thorough studies on plates used at alternating levels have been published.

METHODS

Forty-two consecutive patients who underwent cervical laminoplasty for the treatment of cervical spondylotic myelopathy with plate fixation at alternating levels between January 2008 and April 2011 were reviewed for this study. Clinical and radiologic outcomes were assessed.

RESULTS

Lateral cervical spine x-rays showed improvements in anteroposterior diameter (APD) of the spinal canal in all levels. No difference of APD was found between alternating fixed levels and unfixed levels preoperatively. Postoperative increased APD in alternating fixed levels was larger than unfixed levels. The mean increased APD in C6 level was smaller than C3, C5, and C7 level (P<0.05). However, there was no difference of the mean increased APD between C4 and C6 levels. Similar results were seen for the mean open angle from computed tomography scan. The mean Japanese Orthopaedic Association (JOA) improvement rate was 58.9%±17.8% on follow-up. However, the available JOA data from all 4 patients with insufficient open angle in unfixed levels exhibited limited improvement of neurological deficit.

CONCLUSIONS

Laminoplasty with plate fixation at alternating levels is a safe, relatively fast, and cost-effective surgical method for most patients with cervical myelopathy. However, unfixed levels (C4 and C6) still have the risk of closure of open angle, which could be associated with remaining spinal cord compression. C6 is a much higher risk level compared with C4.

Relationship between postoperative axial symptoms and the rotational angle of the cervical spine after laminoplasty

INTRODUCTION

An axial symptom is one of the postoperative problems after cervical laminoplasty. The range of motion (ROM) of the cervical spine decreases after laminoplasty. It is speculated that the reduction in neck ROM is one of the causes of axial symptoms. However, most reports have focused on ROM of the cervical spine in flexion and extension, and few papers describe the rotational motion after surgery. It is impossible to assess the rotational motion in plain X-rays. This study was undertaken for the following two purposes: (1) to compare segmental rotational angles of the cervical spine between control subjects and patients with cervical laminoplasty ; (2) to analyze the relationship between postoperative axial symptoms and the range of cervical rotational angle after laminoplasty.

METHODS

Eleven young volunteers (control 1 group) and 10 elderly subjects (control 2 group) who did not have any neck problems and 23 patients who had en bloc cervical laminoplasty due to cervical spondylotic myelopathy were included. Dynamic CT scan was conducted in neutral, right, and left maximum rotational positions from C1 to T1. We measured the rotational angle in each vertebral segment. The axial symptoms, such as limited neck motion and neck stiffness, were assessed by a questionnaire. The rotational angle of the cervical spine was compared between the patients with axial symptoms and the subjects without.

RESULTS

The rotational angle in control 1 group was greater than that in control 2 group. The rotational angle was markedly decreased in the patients with cervical laminoplasty compared to that in control 2 group. The reduction was observed at the upper vertebral segment. Twelve patients were judged to have axial symptom after cervical laminoplasty (symptom + group), and 11 patients did not have symptoms (symptom - group). The rotational angle in the symptom + group was significantly smaller than that in symptom - group. The reduction in the rotational angle was found below C2 level, whereas the C1-2 angle was not significantly different in the two symptom groups.

CONCLUSION

Reduction of the rotational angle in the cervical spine was clearly observed in patients with cervical laminoplasty, compared to that in the controls. The marked reduction might be related to the axial symptoms after laminoplasty.

"Spring-back" closure associated with open-door cervical laminoplasty

BACKGROUND CONTEXT

Spring-back complication after open-door laminoplasty as described by Hirabayashi is a well-known risk, but its definition, incidence, and associated neurologic outcome remain unclear.

OBJECTIVE

To investigate the incidence and the neurologic consequence of spring-back closure after open-door laminoplasty.

STUDY DESIGN

A retrospective radiographic and clinical review.

OUTCOME MEASURES

Lateral cervical spine X-rays were evaluated. Anteroposterior diameters (APD) of the vertebral canal of C3-C7 were measured. Spring-back was defined as loss of APD on follow-up in comparison to immediate postoperative canal expansion. The loss of the end-on lamina silhouette with consequent reappearance of the lateral profile of the spinous processes was also assessed to verify the presence of spring-back. Spring-back closure was classified based on whether the collapse was total or partial, and whether all the operated levels or only a subset had collapsed (ie, complete vs. partial closure, segmental closure vs. total-construct closure). Neurologic status was documented using the Japanese Orthopaedic Association (JOA) score.

METHODS

Thirty consecutive patients who underwent open-door laminoplasty from 1995 to 2005 at a single institution with a minimum follow-up of 2 years were assessed. They were all operated on using the classic Hirabayashi technique. Radiographic outcomes were assessed independently by two individuals.

RESULTS

Sixteen men and 14 women with an average follow-up of 5 years (range, 2-12 years) were included. Of these patients, 24 had cervical spondylotic myelopathy and six had ossification of the posterior longitudinal ligament. Spring-back closure was found in three patients (10%) and 7 of 117 laminae (6%) within 6 months of the operation, which was further confirmed by computed tomography and magnetic resonance imaging. All spring-back closures were partial segmental closures. Gender and age were not significant factors related to spring back (p>.05). The mean JOA score on follow-up was 12.5, with a recovery rate of 40%. All patients with spring back and available JOA data exhibited postoperative neurologic deterioration. Of the three patients with spring back, two patients underwent revision surgery, whereas one declined.

CONCLUSIONS

Spring-back closure occurred in 10% of our patients at or before 6 months after surgery. The incidence of spring-back by level (ie, 117 laminae) was 6%, mainly occurring at the lower cervical spine. All spring-back closures were partial segmental closures, most commonly involving C5 and C6. Postoperative neurologic deficit was associated with spring-back closure; therefore, surgeons should adopt preemptive surgical measures to prevent the occurrence of such a complication.