Anterior cervical multilevel decompression and fusion using fibular strut as revision surgery for failed cervical laminoplasty

Hao1 Is Not a Pathogenic Factor for Ectopic Ossifications but Functions to Regulate the TCA Cycle In Vivo

Ossification of the posterior longitudinal ligament (OPLL), a disease characterized by the ectopic ossification of a spinal ligament, promotes neurological disorders associated with spinal canal stenosis. While blocking ectopic ossification is mandatory to prevent OPLL development and progression, the mechanisms underlying the condition remain unknown. Here we show that expression of hydroxyacid oxidase 1 (Hao1), a gene identified in a previous genome-wide association study (GWAS) as an OPLL-associated candidate gene, specifically and significantly decreased in fibroblasts during osteoblast differentiation. We then newly established Hao1-deficient mice by generating Hao1-flox mice and crossing them with CAG-Cre mice to yield global Hao1-knockout (CAG-Cre/Hao1flox/flox; Hao1 KO) animals. Hao1 KO mice were born normally and exhibited no obvious phenotypes, including growth retardation. Moreover, Hao1 KO mice did not exhibit ectopic ossification or calcification. However, urinary levels of some metabolites of the tricarboxylic acid (TCA) cycle were significantly lower in Hao1 KO compared to control mice based on comprehensive metabolomic analysis. Our data indicate that Hao1 loss does not promote ectopic ossification, but rather that Hao1 functions to regulate the TCA cycle in vivo.

Ectopic gas in the fibular graft after anterior cervical corpectomy and fusion

Background

Ectopic gas in the graft is occasionally encountered upon follow-up computed tomography (CT) after anterior cervical corpectomy and fusion (ACCF). However, most cases lack inflammatory responses and manifestations of infection. Although the clinical significance of ectopic gas in the graft has not yet been established, to the best of our knowledge, no previous studies have described ectopic gas in the graft after ACCF. This study evaluated ectopic gas in the fibular graft upon follow-up CT after ACCF.

Methods

We reviewed 112 patients who underwent ACCF and follow-up CT, with a minimum follow-up period of 3 years. CT images were retrospectively reviewed to confirm the presence of ectopic gas in the graft and bone fusion. Bone fusion was defined as follows: mobility less than 2 mm between spinous processes on the flection-extension radiograph or a bone bridge on CT images.

Results

Of the 112 patients, 30 (27%) patients had ectopic gas in the fibular grafts. Among them, ectopic gas was initially observed 3 months after surgery (early onset) in 23 (77%) patients and 6 months after surgery (late-onset) in the remaining seven (23%) patients. Upon the latest follow-up CT, ectopic gas more frequently remained in late-onset (4/7, 57%) rather than in early-onset (3/23, 13%) cases (p = 0.033). Bone fusion was not observed when CT images exhibited ectopic gas in the graft, whereas ectopic gas was not observed when CT images exhibited bone fusion.

Conclusion

Ectopic gas in the fibular graft was observed at both early and late-onset after ACCF; late-onset gas remained significantly. The remaining gas was strongly associated with pseudoarthrosis; therefore, pseudoarthrosis should be considered when ectopic gas in the graft is observed on CT images.

Novel Technique as a Revision Surgery for Failed Anterior Cervical Corpectomy and Fusion in the Treatment of Cervical Myelopathy Due to Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

This article aimed to introduce a novel technique, the "seesaw technique," for failed anterior cervical corpectomy and fusion (ACCF) in the treatment of cervical ossification of the posterior longitudinal ligament.

METHODS

A patient who underwent ACCF 12 years ago and suffered gradually deteriorating neurologic function was referred to our institution. Preoperative imaging showed residual ossified mass at C5/6 level, causing compression to his spinal cord. He patient was treated by the seesaw technique. The main surgical procedures include removal of the plate and screws, removal of the osteophytes and diskectomy of C4/5, resection of the anterior part of C5 vertebral body, establishment of a transverse hinge at C7 vertebral body, installation of cervical plate and hoisting tool, and antedisplacement of C5 vertebral body and titanium mesh. Images were investigated before and after the procedure. The Japanese Orthopaedic Association score was used to evaluate his neurologic function, and surgery-related complications were also analyzed.

RESULTS

The patient acquired significant improvement of his neurologic function 2 days after the surgery, and he could walk by himself without assistance. Postoperative images showed his spinal canal was enlarged sufficiently and the compression at C5/6 level was also released. At 13 months follow-up, his Japanese Orthopaedic Association score increased from 9 before surgery to 14, with an improvement rate of 62.5%. No surgery-related complications were observed during the whole follow-up.

CONCLUSION

The seesaw technique provides satisfactory outcomes with wide enough decompression window and serves as a safe, effective surgical alternative for patients with failed ACCF.

Motion Preservation at All Costs? Multilevel Hinge Nonunion, Plate Breakage, and Intradural Plate Migration After Cervical Laminoplasty: A Case Report and Literature Review

BACKGROUND

Cervical laminoplasty is a motion-preserving procedure that addresses spinal cord compression and avoids postlaminectomy kyphosis associated with cervical laminectomy. The most common complications include C5 nerve palsy, axial neck pain, hinge nonunion, and premature closure. Plating is a relatively newer method of laminoplasty fixation that may provide greater stabilization postoperatively and reduce the risk of laminoplasty closure compared with less rigid (e.g., suture) fixation techniques. Although prior studies have reported low rates of laminar/lateral mass screw back out, plate breakage and migration have not been previously described in the literature. The purpose of this paper is to present a case of multilevel hinge nonunion, plate breakage, and plate fragment migration. Although rare, plate failure may result in a dural tear and spinal cord injury/compression.

CASE DESCRIPTION

In this case, a 61-year-old man with a history of cervical spondylotic myelopathy treated with C3-7 laminoplasty 7 years prior presented to our hospital with severe headaches and electrical-type pain through the left upper and lower extremities. Imaging studies revealed several broken laminoplasty plates and intradural migration of a fragment of the C7 plate.

CONCLUSIONS

We provide recommendations for preventing hinge nonunion because resultant micromotion likely contributed to the plate breakages observed in this patient.

Posterior Revision Surgery for Cervical Open-Door Laminoplasty Because of Poor Expansion of the Spinal Canal

OBJECTIVE

Few studies have addressed the causes of poor expansion of the spinal canal after open-door laminoplasty (ODL) that require revision surgery. The aim of this study is to identify the reasons of poor expansion of the spinal canal after ODL and to discuss the surgical methods and clinical outcomes of the posterior revision surgery.

METHODS

All patients who underwent posterior revision surgery because of poor expansion of the spinal canal after ODL were retrospectively reviewed at our spine center. Clinical data, radiologic findings, method of surgical revision, interval between surgeries, Japanese Orthopaedic Association (JOA) score, and complications were analyzed.

RESULTS

We identified 16 patients that underwent posterior revision surgery because of poor expansion of the spinal canal after ODL. The main causes of poor expansion of the spinal canal included inadequate expansion degree of the spinal canal (75%, 12/16) and improper expansion range of the spinal canal (25%, 4/16). Revision surgery was performed with posterior ODL, laminectomy and fusion (LCF), or laminectomy of responsible lamina. The interval between the initial procedure and revision surgery was 72.2 months (range, 0.5-168 months). The mean JOA score was restored from 10.6 (range, 8-13) to 14.3 (range, 13-17) after the revision surgery.

CONCLUSIONS

The main causes of poor expansion of the spinal canal after ODL were inadequate expansion degree of the spinal canal and improper expanded range of the spinal canal. Posterior revision surgeries, such as ODL, LCF, and laminectomy of responsible lamina, could guarantee fine clinical results.

Factors predicting adjacent segment disease after anterior cervical discectomy and fusion treating cervical spondylotic myelopathy: A retrospective study with 5-year follow-up

The purpose of this study is to explore perioperative factors predicting symptomatic adjacent segment disease (ASD) after anterior cervical discectomy and fusion (ACDF) for patients with cervical spondylotic myelopathy (CSM) at 5-year follow-up.This study included 356 patients who underwent ACDF for CSM from Jan.2011 to Jan.2013. Up to Jan. 2018, 39 patients suffered from ASD and 317 did not. Assessments include: age, sex, body mass index (BMI), diabetes, smoking, alcohol, duration of symptoms, preoperative Cobb angle of C2 to 7, T1 slope, C2 to 7 range of motion (C2-7 range of motion [ROM]), C2 to 7 sagittal vertical axis (C2-7 SVA), fusion level involved, superior fusion segment, high signal intensity on T2-WI of magnetic resonance imaging (MRI), preoperative visual analogue scale (VAS)-neck, VAS-Arm, Neck Disability Index (NDI) and Japanese Orthopaedic Association (JOA). Factors were processed by univariate analysis and multivariate linear regression.Data analyzed by univariate and multivariate analysis shows that age (68.9 years old), duration of symptoms (18.8 months), superior fusion segment, more fusion level involved (2.7), high signal intensity on T2-WI (17 of 39 patients), Cobb angle of C2 to C7 (18.7°), C2 to C7 SVA (31.0 mm), T1 slope (28.4°), preoperative VAS-neck (5.2), VAS-Arm (5.6) and NDI (36.7) in ASD group are significantly higher than those in non-ASD group, however, preoperative JOA (8.2 vs 11.2, P < .001) has an opposite trend in 2 groups.The rate of ASD after ACDF is 10.9% in 5-year follow up. Patients with cervical sagittal imbalance, advanced age and sever state of CSM, which have a positive relation with ASD before surgery should be paid attention for surgeons.

A Novel Anterior Revision Surgery for the Treatment of Cervical Ossification of Posterior Longitudinal Ligament: Case Report and Review of the Literature

PURPOSE

A 62-year-old blind man with severe ossification of the posterior longitudinal ligament was presented. The patient underwent posterior laminectomy and fixation. After surgery, the patient was not satisfied with the recovery of his upper limbs although his Japanese Orthopedic Association (JOA) score had increased from 9 to 12 points. Because the tactile sensation of his hands was especially important to his daily life, the patient asked for further treatment after 6 months. This report describes the novel revision surgery we invented and the outcome in the patient after the surgery.

METHODS

We performed the revision surgery using an anterior approach from C3 to C7 with a novel technique, anterior controllable antedisplacement and fusion (ACAF). The patient was followed up for 6 months. The clinical data, including JOA score and radiologic images, were collected and analyzed.

RESULTS

After the revision surgery, the patient had improved sensation in both hands, and his JOA score increased to 14 points. Satisfactory decompression was assessed by magnetic resonance imaging after operation. Bone fusion was confirmed by computed tomography 3 months after operation. No specific complications related to this surgery were observed.

CONCLUSIONS

The application of such an operative procedure in revision surgery for OPLL has not been reported earlier and might be an alternative choice for patients with an unsatisfactory outcome from previous posterior surgery.

Incidence and Risk Factors for Late Neurologic Deterioration after C3-C6 Laminoplasty for Cervical Spondylotic Myelopathy

Study Design Retrospective study. Objective We previously reported that the long-term neurologic outcomes of C3-C6 laminoplasty for cervical spondylotic myelopathy (CSM) are satisfactory, with reduced frequencies of postoperative axial neck pain and kyphotic deformity. However, only 20 patients were included, which is a limitation in that study. The present study investigated the incidence of late neurologic deterioration (LND) of myelopathic symptoms after C3-C6 laminoplasty for CSM and attempted to identify significant risk factors for LND in a larger patient population. Methods Subjects comprised 137 consecutive patients with CSM who underwent C3-C6 laminoplasty (bilateral open-door laminoplasty, n = 85; unilateral open-door laminoplasty, n = 52) and were followed for >24 months (mean follow-up, 70 months; range, 25 to 124 months). The patients' medical records were examined for evidence of LND due to cervical myelopathy. The age at time of surgery, sex, surgical procedures, anteroposterior spinal canal diameter at the C7 level, type of C6 spinous process, pre- and postoperative C2-C7 angle, C3-C6 range of motion (ROM), and disk height at the C6-C7 level were analyzed to identify risk factors for LND. Results Three patients (2.2%) developed LND of myelopathic symptoms due to caudal segment pathology adjacent to the C3-C6 laminoplasty (LND group). In these three patients, mean Japanese Orthopaedic Association (JOA) score improved from 10.2 before surgery to 12.2 at the time of maximum recovery, and declined to 9.7 just before additional surgery. On the other hand, in 134 patients without LND (non-LND group), the mean JOA score significantly improved from 10.2 before surgery to 13.4 at the time of maximum recovery and was maintained by the final follow-up (13.2). Compared with the non-LND group, the LND group showed significantly smaller anteroposterior spinal canal diameter at C7, more restricted postoperative C3-C6 ROM, and greater postoperative decrease in disk height at C6-C7, although a logistic regression analysis showed no significant differences. Conclusions In patients with CSM with more severe developmental spinal canal stenosis at C7, accelerated degeneration at the caudal segment resulting from restricted C3-C6 ROM after C3-C6 laminoplasty might lead to LND.

Revision surgery after cervical laminoplasty: report of five cases and literature review

BACKGROUND CONTEXT

Revision surgery after laminoplasty is rarely performed, and there are few reports of this procedure in the English literature.

PURPOSE

To evaluate the reasons why patients underwent revision surgery after laminoplasty and to discuss methods of preventing the need for revision surgery. A literature review with a comparative analysis between previous reports and present cases was also performed.

STUDY DESIGN

Case report and literature review.

PATIENT SAMPLE

Five patients who underwent revision surgery after laminoplasty.

OUTCOME MEASURES

Diagnosis was based on the preoperative computed tomography and magnetic resonance imaging findings. Neurologic findings were evaluated using the Japanese Orthopedic Association score.

METHODS

A total of 237 patients who underwent cervical laminoplasty for cervical spondylotic myelopathy from 1990 to 2010 were reviewed. Patients with ossification of the posterior longitudinal ligament, renal dialysis, infection, tumor, or rheumatoid arthritis were excluded. Five patients who underwent revision surgery for symptoms of recurrent myelopathy or radiculopathy were identified, and the clinical courses and radiological findings of these patients were retrospectively reviewed.

RESULTS

The average interval from the initial surgery to revision surgery was 15.0 (range 9-19) years. The patients were four men and one woman with an average age at the time of the initial operation of 49.8 (range 34-65) years. Four patients developed symptoms of recurrent myelopathy after their initial surgery, for the following reasons: adjacent segment canal stenosis, restenosis after inadequate opening of the lamina with degenerative changes, and trauma after inadequate opening of the lamina. One patient developed new radiculopathy symptoms because of foraminal stenosis secondary to osteoarthritis at the Luschka and zygapophyseal joints. All patients experienced resolution of their symptoms after revision surgery.

CONCLUSIONS

Revision surgery after laminoplasty is rare. Inadequate opening of the lamina is one of the important reasons for needing revision surgery. Degenerative changes after laminoplasty may also result in a need for revision surgery. Surgeons should be aware of the degenerative changes that can cause neurologic deterioration after laminoplasty.

Benefit of degenerative posterior longitudinal ligament removal during anterior decompression in cervical spondylotic myelopathy

It remains controversial whether degenerative posterior longitudinal ligaments should be removed during anterior decompression procedures for cervical spondylotic myelopathy. Few data are available from studies that have compared removing and retaining the degenerative posterior longitudinal ligament. The goal of this retrospective study was to evaluate the benefit of degenerative posterior longitudinal ligament removal during such operations. Clinical data on 130 patients with confirmed degenerative posterior longitudinal ligament who underwent anterior cervical decompression surgery were retrospectively reviewed. All procedures were performed by the same senior orthopedic surgeon at the authors' spinal surgery center. The degenerative posterior longitudinal ligament was removed in 62 patients (group A) and retained in 68 patients (group B). The 130 patients were followed for 36 months. The Japanese Orthopedic Association score improved from 9.0±2.7 to 14.7±1.5 in group A and from 9.4±2.6 to 14.1±1.7 in group B (P=.028). The recovery rate for spinal cord neurologic function was 66.7% in group A and 61.3% in group B (P=.031). Operating time was longer (P=.002) and the sagittal median diameter of the vertebral canal was enhanced in group A (P<.001). Narrowing of previously enlarged canals occurred at a significantly higher rate in group B (P=.044). No significant difference was found in the rates of common complications between groups. Removal of the degenerative posterior longitudinal ligament in anterior decompression procedures for cervical spondylotic myelopathy appeared to be beneficial and provided more complete decompression and better postoperative outcomes than surgery without removal of the ligament. Although this procedure was generally safe, it required longer operating times, was more technically challenging, and required more experienced surgeons than surgery without removal of the ligament.

Morphological character of cervical spine for anterior transpedicular screw fixation

BACKGROUND

Anterior cervical interbody grafts/cages combined with a plate were frequently used in multilevel discectomies/corpectomies. In order to avoid additional posterior stabilization in patients who undergo anterior reconstructive surgery, an anterior cervical transpedicular screw fixation, which offers higher stability is desirable. We investigated in this study the anatomical (morphologic) characters for cervical anterior transpedicular screw fixation.

MATERIALS AND METHODS

Left pedicle parameters were measured on computed tomography (CT) images based on 36 cervical spine CT scans from healthy subjects. The parameters included outer pedicle width (Distance from lateral to medial pedicle surface in the coronal plane), outer pedicle height (OPH) (Distance from upper to lower pedicle surface in the sagittal plane), maximal pedicle axis length (MPAL), distance transverse insertion point (DIP), distance of the insertion point to the upper end plate (DIUP), pedicle sagittal transverse angle (PSTA) and pedicle transverse angle (PTA) at C3 to C7.

RESULTS

The values of outer pedicle width and MPAL in males were larger than in females from C3 to C7. The OPH in males was larger than in females at C3 to C6, but there was no difference at C7. The DIP and PTA were significantly greater in males than in females at C3, but there was no difference in the angle at C4-7. The PSTA was not statistically different between genders at C3, 4, 7, but this value in males was larger than females at C5, 6. The DIUP was significantly greater in males at C3, 4, 6, 7 but was non significant at C5.

CONCLUSIONS

The placement of cervical anterior transpedicular screws should be individualized for each patient and based on a detailed preoperative planning.