Development and Achievement of Cervical Laminoplasty and Related Studies on Cervical Myelopathy.

Cervical laminoplasty (CL) is one of the surgical methods via the posterior approach for treating patients with multilevel affected cervical myelopathy (CM). The main purpose of CL is to decompress the cervical spinal cord by widening the narrowed spinal canal, combined with preserving the posterior anatomical structures to the degree possible and preserving the widened space stably. During the development and improvement of spine surgeries including CL, various studies on CM have progressed and useful achievements have been obtained: (1) posterior cervical spine fixation systems that can be used in combination with CL simultaneously have been developed; (2) various materials to stably maintain the enlarged spinal canal have been developed; (3) the main influential factors on the surgical results are the inner factors of the patients, such as the patient's age and the disease duration; (4) various surgical methods to preserve the function of the posterior cervical muscles have been tried to avoid postoperative kyphotic changes of the cervical spine; (5) postoperative complications, such as C5 palsy and axial pain, have been examined, and the countermeasures have been tried; (6) K-line on lateral X-ray films has been applied to evaluate the indication of CL in patients with CM due to ossification of the posterior longitudinal ligament (OPLL) preoperatively; and (7) the method and idea of CL have been adapted to surgeries at the thoracic and lumbar spine. However, some issues remain to be resolved, such as the deterioration of neurological findings, especially in patients with continuous or mixed-type OPLL, the postoperative kyphotic-directional alignment change of the cervical spine, C5 palsy, and axial pain.

Postoperative C5 Palsy: Conjectured Causes and Effective Countermeasures.

Postoperative C5 palsy (C5 palsy) is defined as de novo or aggravating muscle weakness mainly at the C5 region with slight or no sensory disturbance after cervical spine surgery. The features of C5 palsy are as follows: 1) one-half of patients are accompanied by sensory disturbance or intolerable pain at the C5 region; 2) 92% of patients have hemilateral palsy; 3) almost all palsy occurs within a week after surgery; 4) the incidence is almost the same between the anterior and posterior approaches to the cervical spine; 5) the prognosis is relatively good even in patients with severe muscle weakness. Even now, the precise causes of C5 palsy have not yet been revealed. From the viewpoint of the kinds of nerve tissue involved, the uncertain causes of C5 palsy are divided into two theories: 1) the segmental spinal cord disorder theory and 2) the nerve root injury theory. In the former, the segmental spinal cord, particularly the anterior horn cells, is thought to be chemically damaged because of preoperative ischemia and/or the aggression of reactive oxygen during postoperative reperfusion. By contrast, in the latter, the anterior rootlet and/or nerve root are believed to be mechanically damaged because of compression force and/or distraction force. In this theory, the features of C5 palsy can be well explained from anatomical viewpoints. Additionally, various countermeasures have been proposed, such as the intermittent relaxation of the tension of the hooks to the multifidus muscles during surgery; prophylactic foraminotomy to decompress C5 nerve root; prevention of excessive posterior shift of the spinal cord, which may cause the tethering effect of the nerve root; and prevention of excessive postoperative lordotic alignment of the cervical spine. These countermeasures have been proved effective, and may support the nerve root injury theory as the main conjectured theory on the causes of C5 palsy.

Recent Surgical Methods of Double-door Laminoplasty of the Cervical Spine (Kurokawa's Method).

INTRODUCTION: Double-door laminoplasty (DDL) of the cervical spine (Kurokawa's method) was developed as one of posterior decompression surgical methods in the late 1970s and after then has been modified by adding various procedures such as the posterior muscle handling and the use of artificial spacers. There are three principles of DDL: First, to decompress the cervical spinal cord by central splitting of the spinous processes and laminae, preserving those lengths as much as possible and widening the spinal canal space symmetrically. Second, to maintain the widened spinal canal space steadily by fixing spacers made of hydroxyapatite the contour is almost the same as the widened space. Third, to re-suture the semispinalis muscles to the C2 spinous process to restore the strength of the posterior cervical muscles. TECHNICAL NOTE: The important technical points in performing osteotomy are as follows: At each vertebra, osteotomy is performed from the caudal side and gradually proceeds to the cranial side because there is a space between the lamina and the dura mater at the caudal side and the osteotomy can be safely made. The surgeon must pay attention to the changes in color of the osteotomy site from red of cancellous bone, to white of the inner cortex, and finally to yellow of the yellow ligament and extradural fat tissue. Attention must be paid to the changes in sound and tactile sensation delivered from the air-drill when completing osteotomy of the inner cortex of lamina. By moving an air-drill slowly, tactile sensation can be more sensitive. During osteotomy, the process must be checked frequently by touching the inner cortex of the lamina with a probe. CONCLUSION: At present, DDL is a useful surgical method for cervical myelopathy at multiple level lesions.

Surgical Treatment for Ossification of the Posterior Longitudinal Ligament (OPLL) at the Thoracic Spine: Usefulness of the Posterior Approach.

Various methods via anterior or posterior approach with or without spinal stabilization have been performed in accordance with the level and configuration of ossification of the posterior longitudinal ligament (OPLL) as the decompression surgery for thoracic myelopathy due to OPLL. Among them, anterior decompression at the middle thoracic level (T4/T5-T7/T8) is especially difficult to perform because of the special anatomical structures, where the spinal alignment is kyphotic and the thoracic cage containing circulatory-respiratory organs exist nearby. Of the anterior decompression procedures at this level, the posterior approach has various advantages compared to the anterior one. In the anterior approach, the procedure is complicated and the effect of decompression of the spinal cord can be obtained only by direct resection or anterior floating of the OPLL. However, complications such as spinal cord injury and dural tear are most likely to occur at that time. On the contrary, in the posterior approach, the procedure is simple, and various options to obtain decompression can be selected from, these are, laminectomy, laminoplasty, dekyphosis surgery, staged decompression surgery (Tsuzuki's method), circumferential decompression via posterior approach alone (Ohtsuka's method), and circumferential decompression via combined posterior and anterior approaches (Tomita's method). Among them, in laminectomy, laminoplasty, and dekyphosis surgery, anterior decompression can be obtained to some extent without performing direct procedure on the OPLL. In Ohtsuka's method, complete decompression can be obtained via posterior approach alone, although it is somewhat technically demanding. It is preferable to drop the shaved down and separated OPLL anteriorly instead of trying to remove it completely to avoid complications, especially in patients with severe adhesion between the dura mater and OPLL.

Ossification of the ligamentum flavum.

Ossification of the ligamentum flavum (OLF or OYL: ossification of the yellow ligament) usually occurs at the lower thoracic level and causes various types of neurological symptoms in accordance with the compression level of the spinal cord, the nerve roots, the conus medullaris, and the cauda equina. Although the greatest compression level to the nerve tissues is thought to be the most pathognomonic one, it is difficult to diagnose it in some cases. The effectiveness of conservative treatment such as applying a corset is small. Early surgical treatment is strongly recommended for the patients with spastic gait, severe decrease of muscle power in the lower extremities, bladder-bowel disturbance, combined ossification of the posterior longitudinal ligament at the same level, and severe compression to the spinal cord due to thickly hypertrophied ossification. However, numbness of the lower extremities and spastic gait tend to remain even after surgery.

SEM analysis of microstructure of adhesive interface between resin cement and dentin treated with self-etching primer.

The purpose of this study was to examine the microstructure of the adhesive interface between resin cement and dentin treated with a self-etching primer by SEM in order to clarify the adhesive efficiencies of four self-etch type resin cement systems, Bistite II (BII), Linkmax (LM), Panavia F2.0 (PF), and ResiCem (RC) to dentin. The fluidity and inorganic filler content of these cements were also determined to examine their influences on the adhesion. A hybrid layer with 0.5-1.5 µm thickness and many resin tags could be confirmed clearly at the interface between BII cement and dentin, but was not observed distinctly for the other resin cements. It was suggested that the hybrid layer and resin tags might contribute to the high adhesive efficiency for BII. As the fluidity of cement had been adjusted to be suitable for luting in all cements, it did not significantly influence the adhesive efficiency of cement.

Two types of laminoplasty for cervical spondylotic myelopathy at multiple levels.

Based on the results from pathological analysis and computer simulations by means of finite element analysis that were reported before, the pathological changes of cervical spondylotic myelopathy (CSM) seem to begin at the posterolateral parts of the spinal cord, because the mechanical stress is mainly concentrated in these parts. With progression of the compression, the pathological changes become distributed to a wider area of the spinal cord. In patients with spinal canal stenosis, these changes spread to multiple levels of the cervical spine. Therefore, posterior decompression surgery at multiple levels such as cervical laminoplasty is thought to be reasonable.

Comparison of enlargement of the spinal canal after cervical laminoplasty: open-door type and double-door type.

The purpose of this study was to compare the degree of enlargement of the spinal canal between two methods of cervical laminoplasty (open-door laminoplasty and double-door laminoplasty) and to determine their appropriate surgical indications based on the results. Tension-band laminoplasty (TBL, one method of open-door type) was performed in 33 patients and double-door laminoplasty (DDL) in 20 patients. The operation level ranged from C2 to C7 in all patients. The width of the spinal canal and the inclination angle of the lamina at the C5 and C6 levels were measured using a computer software program (Image J) and pre- and postoperative CT films. Concerning the degree of enlargement of the spinal canal, the mean expansion ratio at the C5 level was 148.9% in TBL and 148.2% in DDL, and there was no significant difference between them. However, at the C6 level, it was 159.0% in TBL and 140.3% in DDL, which was significantly larger in TBL than DDL (p < 0.05). The increase of inclination angle of the lamina was 11.0° in TBL and 19.0° in DDL at the C5 level, and 9.2° in TBL and 19.3° in DDL at the C6 level. At both the C5 and C6 levels, it was significantly larger in DDL than TBL (p < 0.0001). In conclusion, the appropriate surgical indications of TBL were considered to be (1) cervical spondylotic myelopathy (CSM) combined with hemilateral radiculopathy, (2) severe prominence of ossification of the posterior longitudinal ligament (OPLL), and (3) patients with tiny spinous processes who cannot undergo DDL. Those of DDL were considered to be (1) usual CSM, (2) small and slight prominence of OPLL, (3) CSM combined with bilateral radiculopathy, and (4) cervical canal stenosis combined with instability necessitating posterior spinal instrumentation surgery.

Occipitocervical fusion using a hook and rod system between cervical levels C2 and C3.

We aimed to evaluate the clinical utility and safety of the hook and rod method for occipitocervical fusion. Eleven consecutive patients (3 males, 8 females; 50-78 years old, average 63.8 years; 16-77 months follow-up, average 33.7 months) with unstable lesions at the craniocervical junction who underwent occipitocervical fusion using a hook and rod system were examined. A Compact Cotrel-Dubousset cervical system (Sofamor-Danek, Memphis TN, USA) was used in all patients. The claw mechanism was applied bilaterally between the hook on the C2 lamina and the hook on the C3 inferior articular process. No complications occurred during surgery. Solid bony fusion was obtained in all patients and no patient became clinically worse postoperatively. Occipitocervical fusion using a hook and rod system is a useful procedure that allows decompression of the spinal cord and secure spinal fusion at multiple levels simultaneously.

[Using tension-band laminoplasty as a management for cervical ossification of posterior longitudinal ligament].

OBJECTIVE: To evaluate the effectiveness of Tension-band Laminoplasty (TBL) as a management for cervical ossification of posterior longitudinal ligament (OPLL). METHODS: Forty-six patients with cervical OPLL and undergone TBL in our department were chosen for the present study, including 33 male and 13 female. The mean age was 59 years (36 - 77 years). These OPLLs were confirmed as following types: 4 cases of single spinal level, 20 cases of continuous and 22 cases of mixed type. C(3) or/and C(2) levels were involved in 16 cases. All the patients underwent C(2 - 7) TBL, to which C(1) laminectomy was added for the cases with C(3) and/or C(2) involved. The neurological effect was evaluated by using Japanese Orthopedic Association (JOA) scoring criteria for cervical myelopathy. The anatomical effect was analyzed by comparing the pre- and post-operatively roentgenograms and MRIs. Wilcoxon's rank test was used for the statistics study. RESULTS: For 42 (91.3%) patients, the JOA scores were improved for approximately 2 points after the operation, posterior shift of the spinal cord was obtained, while the diameters of dural sleeves and spinal cords were enlarged, yet the spinal alignments were not significantly interrupted. CONCLUSIONS: TBL was proved an effective treatment for cervical OPLL and it could be expanded to include C(1) laminectomy if the spinal levels upper than C(4) were involved.

Surgical results and related factors for ossification of posterior longitudinal ligament of the thoracic spine: a multi-institutional retrospective study.

STUDY DESIGN: Retrospective multi-institutional study OBJECTIVE: To describe the surgical outcomes in patients with ossification of the posterior longitudinal ligament in the thoracic spine (T-OPLL) and to clarify factors related to the surgical outcomes. SUMMARY OF BACKGROUND DATA: Detailed analyses of surgical outcomes of T-OPLL have been difficult because of the rarity of this disease. METHODS: The subjects were 154 patients with T-OPLL who were surgically treated at 34 institutions between 1998 and 2002. The surgical procedures were laminectomy in 36, laminoplasty in 51, anterior decompression via anterior approach in 25 and via posterior approach in 29, combined anterior and posterior fusion in 8, and sternum splitting approach in 5 patients. Instrumentation was conducted in 52 patients. Assessments were made on (1) The Japanese Orthopedic Association (JOA) scores (full score, 11 points), its recovery rates, (2) factors related to surgical results, and (3) complications and their consequences. RESULTS: (1) The mean JOA score before surgery was 4.6 +/- 2.0 and, 7.1 +/- 2.5 after surgery. The mean recovery rate was 36.8% +/- 47.4%. (2) The recovery rate was 50% or higher in 72 patients (46.8%). Factors significantly related to this were location of the maximum ossification (T1-T4) (odds ratio, 2.43-4.17) and the use of instrumentation (odds ratio, 3.37). (3) The frequent complications were deterioration of myelopathy immediately after surgery in 18 (11.7%) and dural injury in 34 (22.1%) patients. CONCLUSION: The factors significantly associated with favorable surgical results were maximum ossification located at the upper thoracic spine and use of instrumentation. T-OPLL at the nonkyphotic upper thoracic spine can be treated by laminoplasty that is relatively a safe surgical procedure for neural elements. The use of instrumentation allows correction of kyphosis or prevention of progression of kyphosis, thereby, enhancing and maintaining decompression effect, and its use should be considered with posterior decompression.

Posterior atlantoaxial subluxation due to os odontoideum combined with cervical spondylotic myelopathy: a case report.

In patients with os odontoideum and posterior atlantoaxial subluxation are extremely rare. No reports have described posterior atlantoaxial subluxation associated with os odontoideum combined with cervical spondylotic canal stenosis, both of which require surgical treatment. We report one case of a 75-year-old female who underwent arthrodesis between the occiput and C3 using a hook-and-rod system and also a double-door laminoplasty from levels C3 to C7. The claw mechanism was applied between the C2 lamina and the C3 inferior articular process. The posterior atlantoaxial subluxation was completely reduced by the method that the rod gradually pushed the posterior arch of C1 anteriorly during connection to the occiput. Twelve months after surgery, the patient showed improvement in preoperative clumsiness and gait disturbance, and the latest plain radiographs showed solid osseous fusion, with no loss of correction or instrumentation failure.

Traumatic anterior lumbosacral dislocation caused by hyperextension mechanism in preexisting L5 spondylolysis: a case report and a review of literature.

Of many reports referring to injury mechanism in anterior lumbosacral dislocation, there were none concerning hyperextension mechanism. We report a case of a 46-year-old man with preexisting L5 spondylolysis sustaining traumatic complete anterior lumbosacral dislocation. The operative findings, together with the radiologic findings, strongly suggested that the dislocation occurred by hyperextension mechanism. Open reduction was done by applying force of distraction with flexion using a rod and screw system, followed by the internal fixation from the L3 to S1 vertebrae and the postero-superior iliac spine. The lumbosacral dislocation was reduced to 77%. At the follow-up at 5 years after surgery, bony union was obtained and the patient could move with a wheelchair although the neurologic deficit in lower extremities observed preoperatively did not recover. Preexisting L5 spondylolysis was considered to increase the potential for anterior lumbosacral dislocation by additional force of compression with hyperextension. Posterior instrumentation using a rod and screw system was considered a useful method for reduction, decompression, stabilization, and fusion.

A large-scale genetic association study of ossification of the posterior longitudinal ligament of the spine.

Research to date has identified several genes that are implicated in the etiology of ossification of the posterior longitudinal ligament of the spine (OPLL); however, their pathogenetic relevance remains obscure. The aim of this study is to identify susceptibility genes for OPLL through a large-scale case-control association study and to re-examine previously reported associations. A total of 109 single nucleotide polymorphisms (SNPs) in 35 candidate genes were genotyped for 711 sporadic OPLL patients and 896 controls. The differences in allelic and genotypic distribution between patients and controls were assessed using the chi (2) test with Bonferroni's correction. We also analyzed the association by separating patients into subgroups according to sex, age and the number of ossified vertebrae. The nominal P values fell below 0.05 for five SNPs in three genes. An intronic SNP in the TGF3 gene (P=0.00040) showed the most significant association. Previously reported associations of COL11A2, NPPS and TGFB1 with OPLL could not be reproduced. Further, no significant associations were detected in stratified analyses based on sex, age or the number of ossified vertebrae. TGFB3 warrants further investigation because it is located within a genomic region that has been positively linked with OPLL.

Effectiveness of multiple-level decompression in laminoplasty and simultaneous C1 laminectomy for patients with cervical myelopathy.

A retrospective study to investigate the relationship between the surgical levels and decompression effects was performed in patients with cervical myelopathy who had undergone Tension-band laminoplasty (TBL) with/without simultaneous C1 laminectomy. One hundred and sixty-eight patients (115 males, 53 females; age: 31-80 years, average 58.9 years; follow-up period: 12-120 months, average 20 months) were divided into three groups according to the range of the surgical levels: seventy-two patients in group A underwent TBL at the C2-C7 levels with C1 laminectomy; 60 patients in group B underwent TBL at the C2-C7 levels; 36 patients in group C underwent TBL at the C3-C7 levels. Neurological evaluation was performed by using the Japanese Orthopedic Association (JOA) scoring system. The alignment changes of the spinal column and the spinal cord were analyzed using pre- and post-operative roentgenograms and MRIs. The differences in the pre- and post-operative anterior subarachnoid spaces (D-ASAS), the spinal cord diameters (D-CORD), and the dural sleeve diameters (D-DURA) at the C1-C7 levels were also analyzed by using MRIs. The JOA scores improved in all groups. As for the spinal alignment, neither significant changes between pre- and post-operation in any group nor significant differences among the three groups were found. The lordosis of the cervical spinal cord was decreased in all groups. D-ASAS of group A was larger than that of group B at the C1-C5 levels (P<0.05), as were those of D-CORD and D-DURA at the C1-C2 and C4-C5 levels (P<0.05). D-ASAS of group A was larger than that of group C at the C1-C4 levels (P<0.05), as were those of D-CORD and D-DURA at the C1-C5 levels (P<0.05). In conclusion, laminoplasty including the C2-C7 levels with simultaneous C1 laminectomy was proven to allow the most posterior shift of the spinal cord within the widened dural sleeve at C5 or higher levels without significantly changing the spinal alignment.

Occipitocervicothoracic fixation using a hook and rod system for patients with rheumatoid cervical spine.

Abstract We retrospectively examined the outcomes of occipitocervicothoracic fixation using a hook and rod system for rheumatoid patients with cervical myelopathy in which decompression of the spinal cord and spinal fusion were performed simultaneously at multiple levels. There were 10 female patients with rheumatoid arthritis (ages 51-77 years, average 62.8 years; follow-up period 6 months to 3 years and 9 months, average 2 years and 8 months). Atlantoaxial subluxation was found in 5 patients, vertical subluxation in 4 patients, and subaxial subluxation in 8 patients. The progression of the disorder was assessed as class 4 stage 4 in 3 patients and class 3 stage 4 in 7 patients. The average time taken for surgery was 4 h 41 min, and the average volume of blood loss was 729 ml. There were no complications during surgery. One patient died of malignant lymphoma 1 month after surgery, and one patient died of heart failure 2 years and 3 months after surgery. The average Japanese Orthopaedic Association (JOA) score improved from 7.0 preoperatively to 9.5 postoperatively. Preoperative nuchal pain in 3 patients and difficulty in breathing on flexion of the cervical spine in 2 patients were improved after surgery. Good bony union was obtained in 9 patients. The exception being one patient who died of a disease unrelated to the surgery 1 month postoperatively. Occipitocervicothoracic fixation using a hook and rod system is an easy and safe procedure, and can facilitate not only good bony union, but also adequate decompression of the spinal cord with simultaneous laminoplasty because of the secure long fixation extending to the upper thoracic level and bilateral grafting of a considerable volume of bone.

Surgical anatomy of the nerves and muscles in the posterior cervical spine: a guide for avoiding inadvertent nerve injuries during the posterior approach.

STUDY DESIGN: An anatomic study investigated the cervical dorsal rami and major cervical paravertebral muscles. OBJECTIVE: To provide a detailed description of the cervical dorsal rami and important paravertebral muscles as a way of avoiding inadvertent injuries during the posterior approach. SUMMARY OF BACKGROUND DATA: No detailed anatomic studies of the nerves and the muscles in the posterior neck useful for the posterior approach have been reported previously. METHODS: Running courses of the cervical dorsal rami of spinal nerves and the morphology of cervical major paravertebral muscles were studied using 14 cadavers. In four posterior approaches of cervical laminoplasty, subcutaneous facial exits of cutaneous nerves and the running course of the right C3 medial branches around facet joint were exposed for observation of living anatomy. RESULTS: Every medial branch from the dorsal rami of the C3-C8 spinal nerves passed through an anatomic tunnel dorsolateral to the facet joint. The base of the tunnel was a bony gutter between neighboring facet joint capsules, and the roof was the tendon of the semispinalis capitis. In this tunnel, the medial branch had a little laxity in moving, and was assumed to be the most susceptible to iatrogenic injury during the operation. The semispinalis cervicis was composed with long muscle bundles. Each of these had only one or two innervating nerves from the dorsal rami of cervical spinal nerves. Cutaneous branches from the dorsal rami were found adjacent to every spinous process below the C2 spinous process in cadaveric studies. However, only two or three larger cutaneous nerves were discernible below the C5 or C6 spinous process in surgical approaches. CONCLUSIONS: With the posterior approach to the cervical spine, a precise knowledge of the cervical dorsal rami anatomy and the innervating patterns of the paravertebral muscles is necessary for avoidance of inadvertent injuries to the nerves.

Anatomically correct reduction and fixation of a Tile C-1 type unilateral sacroiliac disruption using a rod and pedicle screw system between the S1 vertebra and the ilium: experimental and clinical case report.

We have developed a new surgical technique for the treatment of Tile C-1 type sacroiliac disruption. We tried this procedure first in a cadaveric specimen and then applied it to a clinical case. We used the Texas Scottish Rite Hospital (TSRH) rod and pedicle screw system to insert one screw into the S1 vertebra without using an image intensifier and the other screw into the bone marrow of the ilium from the posterosuperior iliac spine. A straight rod was connected between the two screws by using a manipulator to attempt to reduce and fix the sacroiliac disruption. The combined pubic symphysis diastasis could be simultaneously reduced and fixed by using a plate through another incision, resulting in anatomically correct reconstruction of the pelvic ring. In this procedure, the alignment of the sacroiliac joint can be reversibly and directly changed during reduction and fixation. The sacroiliac joint can be strongly fixed because the screws can be freely inserted into the intact portion of the pelvis and the adjacent lumbar spine, if necessary. Good reduction is obtained because direct compression force is applied to the fracture site. The posterior and anterior procedures can be simultaneously performed under the same lateral position.