Cervical foraminal stenosis as a risk factor for cervical kyphosis following cervical laminoplasty

Change of cervical flexion range of motion influences postoperative sagittal alignment of the cervical spine after laminoplasty

OBJECTIVE

The relationships between preoperative cervical spine range of motion (ROM) and postoperative cervical sagittal alignment (CSA), and clinical outcomes after laminoplasty (LMP) have been widely studied. However, the impact of ROM changes on postoperative CSA and clinical outcomes after LMP remains unclear. Herein, patients with cervical spondylotic myelopathy (CSM) were retrospectively analyzed to explore the association between postoperative cervical ROM changes and CSA and surgical outcomes.

METHODS

Patients who underwent cervical LMP at our hospital between January 2019 to June 2022 were retrospectively reviewed. CSA parameters were measured before the surgery and at the final follow-up. Loss of cervical lordosis (LCL) was defined as preoperative cervical lordosis (CL) - postoperative CL. An increase in the cervical sagittal vertical axis (I-cSVA) was defined as postoperative cervical sagittal vertical axis (cSVA) - preoperative cSVA. We defined the changes in cervical flexion range of motion (△Flex ROM, preoperative Flex ROM minus postoperative Flex ROM) > 10° as L- Flex ROM group, and △Flex ROM ≤ 10° as S- Flex ROM group. Japanese Orthopedic Association (JOA) score and visual analog score (VAS) were used to assess the surgical outcomes.

RESULTS

The study comprised 74 patients and the average follow-up period was 31.83 months. CL, total ROM, and Flex ROM decreased and cSVA increased after cervical LMP. LCL and I-cSVA were positively correlated with △Flex. Multiple linear regression analysis showed that a decrease in the Flex ROM was a risk factor for LCL and I-cSVA after LMP. LCL and I-cSVA were higher in the L-Flex ROM group than in the S-Flex ROM group. Postoperative JOA and the JOA recovery rate were worse in the L-Flex ROM group than in the S-Flex ROM group.

CONCLUSIONS

Cervical total and Flex ROM decreased after cervical LMP. The reduction of Flex ROM was associated with LCL and I-cSVA after surgery. The preservation of cervical Flex ROM helps maintain CSA after LMP. Therefore, more attention should be paid to maintaining cervical ROM to obtain good CSA and surgical effects after cervical LMP.

Favorable cervical extension capacity preventing loss of cervical lordosis after laminoplasty due to spontaneous restoration of initial lordosis

BACKGROUND CONTEXT

Cervical laminoplasty is a common approach for the treatment of multilevel cervical spondylotic myelopathy (CSM). Postoperative loss of cervical lordosis (LCL) was associated with lower extension motion of the cervical spine before laminoplasty.

PURPOSE

To analyze the possible causes of preoperative cervical extension capacity affecting LCL after laminoplasty by evaluating the changes in cervical lordosis (CL) at different stages.

STUDY DESIGN/SETTING

Retrospective study.

PATIENT SAMPLE

Seventy-two patients undergoing laminoplasty due to multilevel CSM.

OUTCOME MEASURES

Radiographic parameters included CL, extension CL (eCL), flexion CL (fCL), range of motion (ROM), extension ROM (eROM), flexion ROM (fROM) and LCL. Clinical outcomes were assessed using the Japanese Orthopedic Association (JOA) and neck disability index (NDI) score.

METHODS

The data were recorded before surgery and at 3- and 24-month follow-up. All patients completed a cervical extension test preoperatively. A receiver operating characteristic (ROC) curve of eROM was constructed to discriminate the patients with and without postoperative kyphotic deformity.

RESULTS

According to the optimal cut-off value of eROM, the patients were divided into two groups: extension group (eROM≥9.3°) and control group (eROM<9.3°). The radiographic outcomes demonstrated no significant differences in CL, eCL, fCL and ROM between the two groups. Both eROM and fROM were significantly different in the two groups. There was a significant change in CL in the extension group at 3-month follow-up and in the control group at 24-month follow-up. The extension group exhibited significantly lower LCL compared with the control group at follow-up. No significant difference between the two groups was noted in the JOA recovery rate, while the NDI score was significantly different at 24-month follow-up. The positivity ratio of the extension test was significantly greater in the extension group than that in the control group.

CONCLUSIONS

eROM in patients with favorable preoperative cervical extension capacity (eROM≥9.3°) consisted of the actual extension capacity and compensatory flexion. The cervical alignment would be spontaneously restored to its initial lordosis in the short term after laminoplasty. These patients had no substantial LCL at 24-month follow-up and would be good candidates for laminoplasty.

Effect of preoperative dynamic cervical sagittal alignment on the loss of cervical lordosis after laminoplasty

PURPOSE

Cervical laminoplasty (CLP) is a developed surgical procedure for the treatment of cervical spondylotic myelopathy (CSM), but only a few of those studies focus on preoperative dynamic cervical sagittal alignment and the study of different degrees of loss of cervical lordosis (LCL) is lacking. This study aimed to analyze patients who underwent CLP to investigate the effect of cervical extension and flexion function on different degrees of LCL.

METHODS

In this retrospective case-control study, we analyzed 79 patients who underwent CLP for CSM between January 2019 and December 2020. We measured the cervical sagittal alignment parameters on lateral radiographs (neutral, flexion, and extension positions) and used Japanese Orthopedic Association (JOA) score to assess clinical outcomes. We defined the extension ratio (EXR) as 100 × Ext ROM (cervical range of extension)/ROM (cervical range of motion). We observed the relationships between collected variables (demographic and radiological variables) and LCL. Patients were classified into the following three groups according to the LCL: stability group: (LCL ≤ 5°); mild loss group (5° < LCL ≤ 10°); and severe loss group (LCL > 10°). We compared the differences of collected variables (demographic, surgical and radiological variables) among the three groups.

RESULTS

Seventy-nine patients were enrolled (mean age 62.92 years; 51 men, 28 women) in the study. Among the three groups, cervical Ext ROM was the best in the stability group (p < 0.01). Compared with the stability group, range of flexion (Flex ROM) was significantly higher (p < 0.05) and EXR was significantly lower (p < 0.01) in the severe loss group. Compared with the severe loss group, JOA recovery rates were better (p < 0.01) in the stability group. Receiver-operating characteristic curve (ROC) analysis to predict LCL > 10° (area under the curve = 0.808, p < 0.001). The cutoff value for EXR was 16.80%, with sensitivity and specificity of 72.5% and 82.4%, respectively.

CONCLUSION

CLP should be carefully considered for patients with a preoperative low Ext ROM and high Flex ROM, as a significant kyphotic change is likely to develop after surgery. EXR is a useful and simple index to predict significant kyphotic changes.

Posterior Preventive Foraminotomy before Laminectomy Combined with Pedicle Screw Fixation May Decrease the Incidence of C5 Palsy in Complex Cervical Spine Surgery in Patients with Severe Myeloradiculopathy

C5 palsy is a frequent sequela of cervical decompression surgeries for cervical myeloradiculopathy. Although many researchers have suggested various risk factors, such as cord shifting and the correction of lordotic angles, the tethering of the C5 root beneath the narrow foramen is an independent risk factor for C5 palsy. In this study, we tried to investigate different techniques for foramen decompression with posterior cervical fusion and assess the incidence of C5 palsy with each technique depending on the order of foraminal decompression. A combined 540° approach with LMS and uncovertebrectomy was used in group 1. Group 2 combined a 540° approach with pedicle screws and posterior foraminotomy, while posterior approach only with pedicle screws and foraminotomy was used in group 3. For groups 2 and 3, prophylactic posterior foraminotomy was performed before laminectomy. Motor manual testing to assess C5 palsy, the Neck Disability Index (NDI) and the Japanese Orthopedic Association (JOA) scores were determined before and after surgery. Simple radiographs, MRI and CT scans, were obtained to assess radiologic parameters preoperatively and postoperatively. A total of 362 patients were enrolled in this study: 208 in group 1, 72 in group 2, and 82 in group 3. The mean age was 63.2, 65.5, and 66.6 years in groups 1, 2, and 3, respectively. The median for fused levels was 4 for the three groups. There was no significant difference between groups regarding the number of fused levels. Weight, height, comorbidities, and diagnosis were not significantly different between groups. Preoperative JOA scores were similar between groups (p = 0.256), whereas the preoperative NDI score was significantly higher in group 3 than in group 2 (p = 0.040). Mean JOA score at 12-month follow-up was 15.5 ± 1.89, 16.1 ± 1.48, and 16.1 ± 1.48 for groups 1, 2, and 3, respectively; it was higher in group 3 compared with group 1 (p = 0.008) and in group 2 compared with group 1 (p = 0.024). NDI score at 12 months was 13, 12, and 13 in groups 1, 2, and 3, respectively; it was significantly better in group 3 than in group 1 (p = 0.040), but there were no other significant differences between groups. The incidence of C5 palsy was significantly lower in posterior foraminotomy groups with pedicle screws (groups 2 and 3) than in LMS with uncovertebrectomy (group 1) (p < 0.001). Thus, preventive expansive foraminotomy before decompressive laminectomy is able to significantly decrease the root tethering by stenotic lesion, and subsequently, decrease the incidence of C5 palsy associated with posterior only or combined posterior and anterior cervical fusion surgeries. Additionally, such expansive foraminotomy might be appropriate with pedicle screw insertion based on biomechanical considerations.