Described are the basic concepts of diagnosing and surgically treating cervical and lumbar spondylosis. Stenotic lesions of the central canal in the cervical spine result in myelopathy and in the lumbar intermittent claudication occurs. That of the nerve root canal results in radiculopathy. Pathological impingement on the nerve tissue is classified into orthostatic and dynamic compressions. Orthostatic factor is due to degenerated disc, osteophyte, hypertrophic facet joints and yellow ligament. Dynamic change of the spinal canal concomitant with physiological posture change contributes to these impingement. Pathological instability of the spine enhances the above dynamic compression. CT with myelography is the most reliable diagnostic method to diagnose cervical and lumbar spondylosis, since this provides precise information about both the anatomical and pathological status of a bony and/or a soft tissue involvements. MRI provides three-dimensional images of neural tissue entrapment and information on intervertebral disc degeneration. Our basic surgical procedures for spondylosis are removal of static compressing components and fusion for instability. We treated cervical spondylosis with osteophytectomy and interbody fusion. Long postoperative follow-up results evaluated by the Neurosurgical Cervical Spine Scale (NCSS) up to 7-20 years have shown 74% recovery from myelopathy and 84% of patients returned to the previous social activities. For lumbar spondylosis a laminectomy was done for a central spinal stenosis, a medial facetectomy for a lateral recess stenosis and a facetectomy for a foraminal stenosis. In view of possible post-operative instability, we do a bilateral partial laminectomy for central spinal stenosis, which is a limited interlaminar decompressive procedure. We usually avoids discectomy unless disc extrusion presented. Posterolateral fusion is performed for some cases given a facetectomy. Our follow-up results show 94% recovery of intermittent claudication.

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Surgical management of cervical injuries has been drastically changing for the last decade with the advent of refined instruments which are compatible with magnetic resonance (MR) imaging. The usage of spinal instrumentation can be extended to cervical spondylosis and ossification of the posterior longitudinal ligament (OPLL) with or without instability, rheumatoid arthritis and spinal tumors. However its surgical indication is often controversial and operative techniques are demanding high skills. Anterior plating system such as "Synthes" and "Orion" are relatively easy to use and very effective in flextion or burst injury which requires anterior decompression and fixation. This can be also used in cervical spondylolisthesis and in some cases of anterior approach for cervical OPLL. Posterior lateral mass plate system such as "Universal" and "Axis" is quite useful in cases with lamina fractures and unstable cervical stenosis due to spondylosis or OPLL which require multilevel laminoplasty and fixation. Transarticular screw fixation along with midline C1-C2 fixation with cable and graft provides solid internal fixation in atlantoaxial dislocation due to odontoid fracture, rheumatoid arthritis and congenial anomalies. But great care has to be taken to avoid injury to the vertebral arteries and the neural structures. In conclusion spinal instrumentation is a very effective method in internal fixation for unstable cervical spine, facilitating early ambulation and rehabilitation, if one can select good indications and master surgical skills.

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Compression of the spinal cord was marked at the level of the intervertebral disk, and the spinal cord was strikingly flattened anteroposteriorly. Intensive damage was seen in the gray matter as compared to the white matter. The white matter showed demyelination and axon loss with status spongiosus, which was more marked in the posterolateral than in the anterior column. The cross-sectional shape of the spinal cord at the most severely affected segment was classified into two categories : boomerang and triangular. A triangular-shaped spinal cord with a taransverse area less than 60% of normal in more than one segment appeared to be associated with severe and irreversible pathological changes in case of OPLL. The most seriously damaged parts of the spinal cord showed tissue necrosis and cavity formation that extended from the central parts of the gray matter to the ventral parts of the posterior column. Venous congestion and subsequent necrosis seemed to play a significant role in the pathogenesis of spinal cord cysts secondary to chronic compression. The spinal nerve roots that showed marked demyelination and axon loss were damaged by ossification where the anterior nerve roots emerge from the spinal cord and where the roots penetrate the dura. As cause of compression myelopathy, hypertrophy of the PLL and ossification of the dura mater were also important. Aberrant peripheral nerve bundles and peripheral type remyelination were observed in severely damaged parts of the spinal cord.

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Ossification of the posterior longitudinal ligament (OPLL) in the cervical region is now regarded as a curable disease. However, the selection of surgical procedure, whether it should be by anterior approach or posterior approach, is still controversial. The purpose of this paper is twofold : (I) to describe our selection of treatment for cervical OPLL in our institute ; and (II) to evaluate results of two major surgical procedures ; i.e., anterior decompression with inter-body fusion and posterior decompression. The series consisted of 169 patients who were surgically treated. Their age ranged from 24 to 76 years with a mean of 55.4 years. Anterior approach was performed in 132 patients, and posterior decompression was carried out in 37 patients. We mainly use the anterior approach because it can extirpate the ossified lesion itself. The indication for choosing posterior decompression is as follows : (1) extensive OPLL longer than 4 vertebral bodies, (2) non-localized spinal cord compression, (3) narrow spinal canal. Postoperative results were satisfactory in both groups. It is essential to decide the most suitable method of treatment, whether anterior or posterior decompression, for cervical OPLL patients.

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Cervical ossification of the posterior longitudinal ligament (OPLL) is one of the well-known causes of myelopathy and radiculomyelopathy. The choice of surgical procedures including laminectomy, laminoplasty, anterior fusion, and anterior decompression with fusion, remains controversial. We choose anterior vertebrectomy and fusion for multilevel OPLL, because we believe that cervical cord and root compression caused by the lesions located in the anterior spinal canal must be completely relieved and this can be achieved better via the anterior approach. Postoperative neurological complication, especially fifth cervicalradiculopathy has been reported after multilevel vertebrectomy for cervical OPLL. One explanation for this complication includes the factor of traction and its influence following on the cervical roots caused by anterior shifting of the spinal cord following wide decompression. However, we ourselves do not think that the spinal cord could shift so pathologically as to result in traction on the cervical roots after removal of anterior pathology such as OPLL. This conviction has led us to change the width of vertebractomy. Before December, 1992, 46 patients underwent multilevel vertebrectomy for cervical OPLL, and the width of the anterior decompression was 12 to 14 mm. Since January, 1993, 18 patients have had multilevel vertebrectomy for cervial OPLL, and the width of the anterior decompression was 14 to 20 mm (average 16.4 mm). In our former series, 4 patients (8.7%) suffered C5 radiculopathy and 37 patients (80%) got good results. In our later series, the incidence of postoperative radiculopathy was 0 and 18 patients (100%) got good results. In conclusion, from our small experience of vertebrecotmy in these two series, the greater width of the anterior decompression most likely reduces the incidence of neural tissue complication and results in better outcome.

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Although there has been a long debate whether ossification of the posterior longitudinal ligament (OPLL) of the cervical spine should be treated anteriorly or posteriorly, direct removal of the ossified mass for relieving cord compression by the anterior approach is widely considered as the most suitable surgical treatment. The authors present their surgical experience of anterior decompression of OPLL. Among 119 cases (121 operations) of cervical OPLL treated with anterior medial corpectomy and direct removal of OPLL, 60 cases were treated with iliac graft, one with fibula graft and 58 recent cases of mostly segmental OPLL were treated with autogenous vertebral bone graft to avoid the use of halo brace and discomfort in the iliac donor site. As for the operative results, 60(51%) were excellent, 44(38%) good and 13(11%) fair. There was a significant correlation between the operative results and the preoperative severity of myelopathy. However, no such correlation was found between the operative results and the number of the affected level. Regarding complications, dural defect with cerebrospinal fluid leakage occurred in 22 cases (18%), in which lumbar drainage was required only in 8 cases. Other complications including dislocation of the grafted bone in 7 cases, root injury in 3, but no cord injury was noted. Anterior approach is a reasonably safe and effective method with few major complications. Autogenous vertebral graft avoids halo brace and pain in the donor site, and it helps patients achieve early rehabilitation when the anterior approach is chosen in segmental OPLL of the cervical spine with discs and spurs.

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The authors describe the results of surgical treatment for ossification of the posterior longitudinal ligament of the cervical spine. This series consisted of 50 patients who underwent anterior decompression with anterior cervical fusion using bone grafts obtained from cervical vertebral bodies, and 5 patients who underwent expansive laminoplasty or laminectomy as a method of posterior decompression. Twelve out of 50 patients were operated for anterior cervical fusion at one level, 29 at two levels and 9 at three levels. The patients were out of bed within one day postoperatively with a soft collar for two months. In all patients, the symptoms improved postoperatively. Postoperative X-ray films showed solid bone fusion in all patients with anterior cervical fusion at a mean follow up time of 2 years and nine months (range 6 months to 6 years and one month). Anterior angulation was found in one out of nine patients (11%) with three-level fusions. Concerning the method of operation, the authors think that anterior decompression and fusion should be applied to cases of ossification of up to three consecutive vertebrae with either one level fusion or two level fusions. Posterior decompression is applied in cases in which anterior decompression is not indicative. If necessary, a two-stage combined decompression is recommended.

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In order to discuss the surgical approaches used in surgery for ossification of the cervical longitudinal ligament (OPLL), we undertook retrospective study of 240 cases with OPLL operated on in the past 17 years. The patients were grouped into 3 categories depending upon the approaches adopted in the operation. Those were anterior decompression group (A), posterior decompression group (P) and combined group (C). In group A, anterior fusion was carried out, after removal of OPLL via the anterior approach. In group P, laminectomy or laminoplasy was performed. In group C, both anterior and posterior decompression were performed in a two stage operation. There were 181 men and 59 women with a mean age of 56.3 years old. Group P had a significantly higher mean age than group A and C. Preoperative neurology indicated that myelopathy had became more severe in group P than in group A and more severe in group C than in group P. Preoperative neuroradiological studies indicated that the OPLL extended longer rostro-caudally in group C than in group A and longer in group P than in group C. CT-myelography (CTM) showed the thickest part of the OPLL in group A was less than 50% of the A-P distance of the spinal canal, while the stenotic ratio was over 50% in group P and C. Extent of anterior fusion was within 2 intervertebral spaces in 78.3% of group A and 60% of group C. Anterior fusion of more than 3 intervertebral space was carried out in 40% of group C. Cervical canal stenosis was complicated in 8.7, 24.6 and 34% in group A, P and C, respectively. Thus it was evident that patients in group A had smaller OPLL and were neurologically less affected compared to group P and C. The operation proved effective in more than 89% of the patients in this group. Neurologically, patients in group C had the severest myelopathy and had larger OPLL than patients of group A. The rostro-caudal extent of OPLL was the largest in group P though myelopathy was less severe than that in group C. Incidence of sequel was 7.6, 4.0 and 18% in group A, P and C, respectively. In group C, all the sequelae were provoked in the anterior approach. Alternative techniques to improve the results among group C patients were discussed. The results suggested that posterior decompression was the safest approach in the surgical management of OPLL.

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The growth of OPLL after the posterior decompression of the cervical spine was reported by some authors. In this study 66 patients with cervical OPLL were operated with the spinous processes reconstructive laminoplasty (Yamagata University method). Regarding to the classification of OPLL, 35, 24 and 7 patients were of segmental, mixed and continuous type respectively. The average age at surgery was 61.6 years. The mean follow-up period was 4 years and 10 months ranging from 3 years to 10 years. The twenty-four out of 66 patients (36.4%) revealed growth of OPLL. The growth of OPLL was observed in 9 out of 35 patients (25.7%) classified as segmental type, 9 out of 24 of mixed type and 6 out of 7 of continuous type. The growth of OPLL did never cause neurological deterioration. The average preoperative JOA score was 9.2, which increased to 13.4 point 2 years after surgery (Hirabayashi's recovery rate was 62%). Preoperative range of motion of the cervical spine was 25.6 degree which decreased to 12.5 degree (48.8%) 2 years after surgery. Though 4 patients (6.1%) developed temporary paralysis of C5 after surgery, any other patients did not show operative complications. In conclusion, spinous processes reconstructive laminoplasty is recommended as one of the methods of posterior decompression in the cervical OPLL.

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A long term follow-up of patients after antero-lateral partial vertebrectomies (ALPV) was performed using patient charts and questionnaires. During the past 15 years, ALPV has been performed on 159 patients with cervical spinal disorders. Among them, 136 patients whose survey was performed more than 1 year ago were selected. 92 were male and 44 were female. Their ages ranged from 41 to 82, and the average age was 63.1. The follow-up period was from 1 to 14 years (the average being 3.8 years). Pathology included spondylosis 119, OPLL 31, canal stenosis 8 and combined lesion 22 cases. Surgical resuts were evaluated using a 5 grade scale (excellent ; E, good ; G, fair ; F, poor ; P and dead ; D). At discharge, group E was 40.2%, G was 51.5%, F was 7.2%, P was 0%, D was 0.7%. At the end of the follow-up period E was 36.9%, G was 35.7%, F was 20.2%, P was 7.1% and dead was 9.8%. None of the deaths were related to the surgery. However, the score obtained from the Neurosurgical Cervical Spinal Scale were essentially consistent. Results of the questionnaire showed that 61.4% of the patients were satisfied, 30.1% were fairly satisfied and only 8.4% were dissatisfied. Dissatisfied cases included 2 cases of surgical failure but most of them were related to the progressive worsening of other lesions such as thoracic, lumbar spinal lesions or peripheral neuropathy. In 2 cases reoperation was performed, one anterior fusion with fibular strut graft for kyphoscoliosis and the other anterior fusion with a mini-plate for a fracture of the lamina and slippage of the vertebral body. In some cases, weakness of the C5 root area was encountered but most of these were resolved in a few months. Radiologically, the bony defects of the vertebral body were observed to become smaller, namely they were replaced by new growth of bone slowly in all cases. Thus, ALPV seems to be a useful surgical procedure for multilevel cervical spinal disorders.

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A total of 54 patients with cervical disc disease who underwent vertebral column autograft with the intervertebral disc were studied before and after surgery by flexion/extension cervical X-ray film and MRl. 46 patients were operated on at one level and 8 patients were operated on at two levels. Postoperative X-ray film showed some movement in the operated disc level in all patients (average postoperative follow up period was 27 months, ranging over a period of 1 year to 4 years 1 month). A significant decrease in motion in the extension position was observed postoperatively (P<0.0001), but there was no significant difference between the preoperative motion and postoperative motion in the flexion position. Our postoperative MRl examination showed no degenerative changes because a high intensity of implanted intervertebral disc tissue was preserved. However, because the observation periods were short, further follow up research is required to confirm the extent of the preservation of implanted tissues.

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This paper describes the technique of expanding laminoplasty employed for cervical OPLL (ossification of the posterior longitudinal ligament) patients and its results with 3 years or more follow-up. Several techniques are available in performing expanding laminoplasty for cervical myelopathy patients due to OPLL. Technical complexity and limitation of the postoperative neck movement remain as issues where improvement is desirable. Our technique is simpler than the other previous techniques and provides better post-operative neck movement in the long-term follow-up period. Twenty cervical OPLL patients were treated by expanding laminoplasty using spinous process roofing technique with follow-up period of 3 years or more. They were investigated for the expansion of the cervical canal, bone fusion on CT, neck movement on X-ray and neurological evaluation. Forty-two percent increase of cervical canal diameter was shown to have been achieved in average on lateral X-ray. On CT bone fusion rate was 96%. Post-operative neck movement was confirmed at 83% of the preoperative level. An average preoperative JOA score was 7.9, increasing to 14.1 at 3 years after operation. Based on these results, the technique we described here is safe and simple along with a high bone fusion rate as well as better postoperative neck movement than is found after other laminoplasties.

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A follow up study of 20 patients who were managed with en-bloc laminoplasty for ossification of the posterior londitudinal ligament (OPLL) in the cervical spine was conducted. The duration of follow up ranged from 8 to 120 months (mean, 47 months). Satisfactory results were obtained without any major complication. The maximum recovery rate of JOA score was 68.1% on the average. The average enlargement in the anteroposterior diameter of the canal was 8.9mm, and it was shown to be well maintained at the final follow-up.

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