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

Motion Capture-based 3-Dimensional Measurement of Range of Motion in Patients Undergoing Cervical Laminoplasty

STUDY DESIGN

A prospective study.

OBJECTIVE

To measure 3-dimensional cervical range of motion (ROM) by noninvasive optical tracking-based motion-capture technology in patients undergoing laminoplasty, and to elucidate the postoperative effects of laminoplasty on cervical mobility.

SUMMARY OF BACKGROUND DATA

Cervical laminoplasty is a motion-sparing decompression surgery for degenerative cervical myelopathy. Unlike cervical laminectomy and fusion, the true postoperative impact of laminoplasty on neck motion has not been well studied.

METHODS

Participants comprised 25 patients undergoing double-door cervical laminoplasty for degenerative cervical myelopathy in a single center. Maximum flexion/extension, left/right rotation, and left/right side bending were recorded using the motion-capture device preoperatively and 3 months postoperatively. ROMs in 3 orthogonal axes were calculated. Preoperative differences in C2-7 Cobb angles on lateral flexion/extension x-rays were also measured as the radiologic ROM to assess reliability. Preoperative and 1-year postoperative Japanese Orthopaedic Association score, Neck Disability Index [NDI], and Euro-QOL were recorded, and correlations with ROMs were assessed.

RESULTS

Preoperative mean (±SD) ROMs for flexion/extension, rotation, and side bending were 90±17, 107±16, and 53±17 degrees, respectively. Although radiologic sagittal ROM measurement showed a smaller range than motion capture, averaging 36±13 degrees, a moderate to strong correlation between radiologic and motion capture values was observed (R=0.57, P =0.003). Preoperative NDI showed a negative correlation with coronal ROM (rho=-0.547, P =0.02). Postoperative ROM showed a significant reduction in rotation (95±16 degrees, P =0.002) but not in flexion/extension or side bending.

CONCLUSIONS

Three-dimensional motion-capture analysis allowed reliable measurement of cervical ROM. Rotational ROM was significantly reduced after laminoplasty, showing that cervical kinematics are still significantly altered.

Three-dimensional kinematic analysis of the cervical spine following posterior atlantoaxial fusion under physiological loading: An in vivo study

BACKGROUND

This study aimed to analyze the three-dimensional cervical motion characteristics in patients who underwent posterior atlantoaxial fusion surgeries using cone beam computed tomography and 3D3D registration technology.

METHODS

The study selected 20 patients who underwent posterior atlantoaxial fusion surgery and 20 healthy people as the control group. All subjects underwent cone beam computed tomography scans of the occipital and cervical spine in 7 different functional positions, then 3D3D registration of Occipital-C7 was performed at each functional position to calculate the motion characteristics of each segment. The ranges of motion of the entire cervical spine and each segment were obtained in each functional position.

FINDINGS

In the experimental group, ranges of motion of C1-C7 in flexion-extension and left-right twisting were significantly lower compared to controls (41.9° ± 13.8° vs. 56.6° ± 11.6°, 29.3° ± 9.6° vs. 91.2° ± 13.7°, respectively, P < 0.05). In the occipital-atlas segment, range of motion in flexion-extension was significantly smaller in the experimental group than controls (10.7° ± 3.2° vs. 19.4° ± 4.2°, P < 0.001), but it was larger in twisting (5.3° ± 4.2° vs. 2.1° ± 1.8°, P < 0.05). The twisting range of motion of C2-C3 was 4.7° ± 2.0° in the experimental group and 3.1° ± 1.6° in the control group (P < 0.05). Additionally, the alteration in ranges of motion during flexion-extension was primarily characterized by less extension.

INTERPRETATION

The posterior atlantoaxial fusion surgery induced biomechanical changes in the cervical spine. Following the procedure, the movement of C1-C7 during flexion-extension and twisting was significantly lower, with varying degrees of impact on adjacent and lower cervical segments. Moreover, the surgery had a greater effect on cervical extension than flexion.

Clinical and radiographic characteristics of increased signal intensity of the spinal cord at the vertebral body level in patients with cervical myelopathy

BACKGROUND

Increased signal intensity (ISI) is usually recognized at the disc level of the responsible lesion in the patients with cervical myelopathy. However, it is occasionally seen at the vertebral body level, below the level of compression. We aimed to investigate the clinical significance and the radiographic characteristics of ISI at the vertebral body level.

METHODS

This retrospective study included 135 patients with cervical spondylotic myelopathy who underwent surgery and with local ISI. We measured the local and C2-7 angle at flexion, neutral, and extension. We also evaluated the local range of motion (ROM) and C2-7 ROM. The patients were classified into group D (ISI at disc level) and group B (ISI at vertebral body level).

RESULTS

The prevalence was 80.7% (109/135) and 19.3% (26/135) for groups D and B, respectively. Local angle at flexion and neutral were more kyphotic in group B than in group D. The local ROM was larger in group B than in group D. Moreover, C2-7 angle at flexion, neutral and extension were more kyphotic in group B than in group D. Two years later, local angle at flexion, neutral, and extension were also kyphotic in group B than group D; however, local and C2-7 ROM was not significantly different between the two groups. There was no significant difference of clinical outcomes 2 years postoperatively between both groups.

CONCLUSIONS

Group B was associated with the kyphotic alignment and local greater ROM, compared to group D. As the spinal cord is withdrawn in flexion, the ISI lesion at vertebral body might be displaced towards the disc level, which impacted by the anterior components of the vertebrae. ISI at the vertebral body level might be related to cord compression or stretching at flexion position. This should be different from the conventionally held pincer-mechanism concept.

The Anatomical and Biomechanical Superiority of Novel Posterior En Bloc Elevation Cervical Laminoplasty

Objectives. In this study, we performed a novel type of posterior en bloc elevation cervical laminoplasty (PEEL) to keep the integrity of the posterior structure, aiming to reduce axial symptoms complicated by a conventional cervical laminoplasty procedure. Methods. Twelve human cervical cadaveric spines (C2-T1) were sequentially tested in the following order: intact condition, open-door laminoplasty (ODL) through bilateral intermuscular approach (mini-invasive ODL), PEEL, and laminectomy (LN). After bilateral transecting at the junction of lamina and lateral mass through the tubular retraction system, the PEEL procedure symmetrically elevated all the posterior structure which was further stabilized with bone grafts and titanium plates. Computed tomography (CT) scan and biomechanical testing were performed after each condition. Results. Both mini-invasive ODL and PEEL procedures were accomplished with 2 small incisions on each side. Two types of laminoplasties could enlarge the spinal canal significantly both in cross-sectional area and anteroposterior diameter comparing with intact condition. The PEEL procedure demonstrated a significantly higher enlargement rate on a canal area and a symmetrical expansion pattern. Compared with intact condition, mini-invasive ODL performed from C3-C7 demonstrated significantly decreased motion in all testing directions except the flexion range of motion (ROM); the PEEL procedure showed mild and insignificant decrease on ROM in all directions. Laminectomy resulted in a statistically significant increase in all directions except the lateral bending ROM. Conclusions. Posterior en bloc elevation cervical laminoplasty can enlarge the canal more effectively and preserve better ROM after operation than the ODL procedure. Although technically challenging, the PEEL procedure probably would decrease the common complications associated with ODL laminoplasty.

Measurement of three-dimensional cervical segmental kinematics: Reliability of whole vertebrae and facet-based approaches

BACKGROUND

Previous studies have used orientation and translation of whole-vertebrae to describe three-dimensional cervical segmental kinematics. Describing kinematics using facet joint movement may be more relevant to pathology and effects of interventions but has not been investigated in the cervical spine. This study compared the reliability of two different methods (whole-vertebrae vs facet joint) to evaluate cervical kinematics.

METHODS

Two healthy adults each had six cervical (C1 to T1) magnetic resonance imaging scans, two each in neutral and left and right rotation. A semi-automated method of segmentation and alignment determined the relative orientation and translation of each whole-vertebrae and translation of each facet joint. Intra-rater and inter-rater reliability was determined using limits of agreement (LOA) with 95% confidence intervals and intraclass correlation coefficients (ICC_3,1 for intra- and ICC_2,1 for inter-rater).

RESULTS

The LOA for intra-rater evaluation of facet movement was superior to whole vertebra translation. Both methods showed excellent intra-rater ICC_3,1 (0.80-0.99) and inter-rater ICC_2,1 (0.79-0.85) for all variables except for Euler angle for flexion/extension which was good (0.65). Intra-and inter-rater ICCs were better for facet movement than all measures of whole of vertebrae movement except Euler angles of axial rotation where no difference was detected.

CONCLUSIONS

Measurement of three-dimensional segmental kinematics using either the facet joint or the whole-vertebrae method demonstrated excellent and comparable reliability. These findings support the use of the facet joint method as an option for describing and investigating cervical segmental kinematics.

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.

Surgical outcomes after laminoplasty for cervical spondylotic myelopathy: A focus on the dynamic factors and signal intensity changes in the intramedullary spinal cord on MRI

OBJECTIVE

We aimed to analyze the relationship between the dynamic factors and signal intensity changes in the intramedullary spinal cord on MRI, and surgical outcomes, following double-door laminoplasty for cervical spondylotic myelopathy (CSM).

PATIENTS AND METHODS

This retrospective study included 100 consecutive patients who underwent double-door laminoplasty for CSM. The following factors were analyzed: JOA score recovery rate, age, duration from onset to surgery, intraoperative bleeding, signal intensity changes in the intramedullary spinal cord on MRI, pre and postoperative C2-7 lordotic angle (LA), changes in C2-7 LA, pre and postoperative C2-7 range of motion (ROM), and pre and postoperative segmental ROM. The Charlson Comorbidity Index (CCI) was also used for the assessment of complications.

RESULTS

Age, CCI, preoperative segmental ROM, and pre and postoperative MRI grade significantly correlated with JOA score recovery rate (P<0.01), whereas number of expanded laminae, duration from onset to surgery, surgery time, intraoperative bleeding, preoperative and postoperative C2-7 LA, change in C2-7 LA, and preoperative C2-7 ROM did not. Multivariate analysis showed that the preoperative segmental ROM (OR=-0.988, P=0.017) and preoperative MRI grade (OR=-7.170, P=0.042) were significantly associated with JOA score recovery rate.

CONCLUSION

Considering the dynamic factors, there was no correlation with C2-7 ROM and surgical outcome, but preoperative segmental ROM and a change in signal intensity of the intramedullary spinal cord on MRI were negatively correlated with surgical outcome. From these results, we suggest that preoperative segmental ROM is possibly associated with spinal cord damage due to repeated minor trauma and affects surgical outcome of laminoplasty.

Restrictions of cervical flexion after laminoplasty increase in the mechanical stress at the occipitocervical junction in non-rheumatoid arthritis patients

Increased range of motion (ROM) at O-C2 after cervical laminoplasty is thought to be a compensatory change due to loss of cervical ROM after surgery. Retro-odontoid pseudotumor in non-RA patients is also caused by loss of ROM at C2-C7 causing mechanical stress on upper cervical spine. The aim of this study was to measure the occipitocervical alignment before and after cervical laminoplasty, and examine the factors associated with postoperative retro-odontoid soft tissue (ROST) enlargement. The study comprised 72 non-RA patients (51 males and 21 females, mean age 65.2years) who underwent cervical laminoplasty. The cervical angles (O-C1, O-C2, C1-C2, and C2-C7) were measured and ROST thickness was evaluated on mid-sagittal T1-weighted MRI before surgery and 2years after surgery. Correlations between radiographic changes and postoperative ROST enlargement were examined. The results shows that postoperative ROM and kyphotic angle in flexion position at O-C2 significantly increased, and postoperative ROM and kyphotic angle in flexion position at C2-C7 significantly decreased compared with preoperative values. On stepwise multiple regression analysis, age (beta=0.273, p<0.01) and restriction of cervical flexion postoperatively (beta=0.235, p<0.01) were independently associated with ROST enlargement. In conclusion, occipitocervical ROM increased and C2-C7 ROM, especially C2-C7 kyphotic angle in flexion, reduced after cervical laminoplasty. The ROST enlargement was associated with reduction in cervical flexion. These results indicate that preservation of cervical ROM, especially kyphotic angle in flexion, after cervical laminoplasty contribute to reduction of mechanical stress at the occipitocervical junction.

Increased Segmental Range of Motion Is Correlated With Spondylolisthesis in the Cervical Spine After Laminoplasty

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to determine the incidence of increased segmental range of motion (ROM) after laminoplasty and to clarify whether increased ROM is associated with spondylolisthesis. Finally, we explored the effect of increased segmental ROM on clinical results.

SUMMARY OF BACKGROUND DATA

Cervical laminoplasty for cervical spondylotic myelopathy causes reduced ROM, possibly due to the unintended contracture of the facet joint or a bony union. Although it is rarely studied, ROM may also increase following laminoplasty. Thus far, there are no reports describing the correlation between increased segmental ROM and segmental spondylolisthesis after laminoplasty.

METHODS

We evaluated 187 segments from 39 cervical spondylotic myelopathy patients who underwent bilateral open door laminoplasty from C2 to C7. The segmental ROM and spondylolisthesis were measured using dynamic radiographs that were obtained preoperatively and 2 years postoperatively. The Japanese Orthopedic Association (JOA) score was used for clinical evaluation. To compare the clinical results, we compared the cases with increased ROM in at least one segment with the remaining cases.

RESULTS

Increased segmental ROM (i.e., ≥5° increase) was observed in 25 of 187 segments (13.4%) from 14 cases. There was a strong correlation between increased ROM and spondylolisthesis. A high preoperative disc height was associated with increased segmental ROM 2 years postoperation. Regardless of the correlation with spondylolisthesis, there was no statistically significant correlation between increased segmental ROM and JOA score.

CONCLUSION

The decrease in segmental ROM after laminoplasty was not uniform. Approximately 13.4% of all segments showed increased ROM. The preoperative disc height might influence the risk for increased segmental ROM. Furthermore, increased ROM was correlated with spondylolisthesis in the segment, though it was not correlated with clinical results.

LEVEL OF EVIDENCE

4.

Clinical Outcome of Cervical Laminoplasty and Postoperative Radiological Change for Cervical Myelopathy With Degenerative Spondylolisthesis

STUDY DESIGN

A retrospective cohort study with prospectively collected data.

OBJECTIVE

The aim of this study was to investigate the clinical and radiological outcome of cervical laminoplasty for cervical myelopathy with degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

The presence of spondylolisthesis is thought to represent segmental instability in spine. Cervical laminoplasty is a common decompression surgery for cervical myelopathy, but its clinical result for cervical spondylolisthesis has not been well studied.

METHODS

One hundred seventeen patients who underwent cervical laminoplasty for degenerative cervical myelopathy were included. Japanese Orthopaedic Association score (JOA score) and visual analog scale of neck pain, upper arm pain and numbness were evaluated before surgery, and at scheduled time points after surgery. Spondylolisthesis was defined as more than 2 mm slip on plain radiograph, and the clinical results were compared between the patients with spondylolisthesis (group S) and without spondylolisthesis (group C). In the patients with spondylolisthesis, the slip distance and translational motion between flexion and extension was examined on plain lateral radiograph before surgery and 2 years after surgery.

RESULTS

Degenerative cervical spondylolisthesis was found in 49 levels of 33 patients (28.2%), and the average age of group S was significantly higher than group C. JOA score and each VAS score was significantly improved after surgery in both groups. Average JOA score of group S was significantly lower than group C at every time points, but the recovery rate was similar between the two groups. In the level of spondylolisthesis, average slip distance did not changed, but average translational motion was significantly decreased in 2years after surgery.

CONCLUSION

Cervical spondylolisthesis was common in elderly patients. The clinical outcome in group S was comparable with group C, and the level with spondylolisthesis has been stabilized after surgery. Thus, laminoplasty can be a treatment option even for cervical myelopathy with degenerative spondylolisthesis.

LEVEL OF EVIDENCE

3.