Back muscle injury after posterior lumbar spine surgery. A histologic and enzymatic analysis

STUDY DESIGN

Back muscle injury after posterior lumbar surgery was studied by muscle histology and serum creatine phosphokinase MM isoenzyme activity.

OBJECTIVES

To investigate intraoperative factors influencing the magnitude of back muscle injury after posterior lumbar surgery.

SUMMARY OF BACKGROUND DATA

The authors previously have reported iatrogenic back muscle injury in an animal model and in humans. Serious injury of the back muscle has been shown by short-term and long-term follow-up evaluation.

METHODS

The retraction pressure was monitored, and the retraction pressure-time products were calculated in 24 patients. Early histologic changes of multifidus muscle, which were taken at completion of surgery, and serum creatine phosphokinase MM isoenzyme activity changes were examined.

RESULTS

The magnitude of back muscle injury was significant as the pressure-time product increased. Creatine phosphokinase MM isoenzyme activity increased after surgery and reached a plateau 1 day after surgery, followed by recovery to the normal value 1 week after surgery. Creatine phosphokinase MM isoenzyme activity tended to be high in cases with multilevel exposure and with high pressure-time product.

CONCLUSIONS

Back muscle injury occurs in all patients who underwent posterior lumbar surgery, and these injuries are related to the retraction pressure, time, and extent of exposure.

Back muscle injury after posterior lumbar spine surgery. Part 2: Histologic and histochemical analyses in humans

STUDY DESIGN

The histologic and histochemical changes in back muscle were studied in virgin surgery patients with lumbar spine disorders and in patients who underwent repeat posterior lumbar surgery.

OBJECTIVES

The results were correlated to provide the evidences of histologic changes of back muscle after posterior lumbar surgery.

SUMMARY OF BACKGROUND DATA

Back muscles were examined histologically and histochemically after posterior lumbar surgery. No previous study has assessed these changes.

METHODS

Back muscles were obtained before and after retraction from 18 virgin surgery cases with lumbar spine disorders. In four patients, the retraction pressure was monitored and the retraction pressure-time products ([P][T]) were calculated. In 21 repeat lumbar surgery cases, muscle samples were obtained before muscle retraction. Samples were evaluated by histologic and histochemical methods.

RESULTS

Abnormal findings were slight in virgin surgery cases. Early back muscle injury tended to depend on operation time and [P][T] products. Late back muscle injury in reoperated patients was marked. Various types of neurogenic changes were observed more than 10 months after the first operation.

CONCLUSIONS

Histologic damages of back muscle due to previous surgical intervention were long-lasting. To avoid permanent muscle injury, the retraction time and pressure should be shortened or the pressure on the back muscle should be monitored during posterior surgery.

Minimum 10-year followup after en bloc cervical laminoplasty

The long-term outcome (> 10 years) after cervical laminoplasty was assessed and the postoperative problems were clarified. One hundred thirty-three patients had laminoplasty between 1981 and 1989 for treatment of cervical myelopathy and 126 patients were available for the current study. The clinical results were evaluated using the Japanese Orthopaedic Association score. The radiologic findings were analyzed by postural anomalies and range of motion. The average preoperative score was 9.1 points, and the postoperative score improved to 13.7 points within a year. The Japanese Orthopaedic Association score and recovery rate were maintained at 13.4 points and 55.1% at the last followup. In 20 patients, the Japanese Orthopaedic Association score worsened during the followup. The causes of deterioration were axial spread of ossification of the posterior longitudinal ligament, other spinal lesions, cerebral infarction, and peripheral neuropathy. Postoperative cervical radiculopathy occurred in nine patients. Postoperative radiculopathy resolved in five patients, but remained in four patients. Kyphotic changes were observed in eight patients. The recovery rate in patients with kyphosis was poor. The postoperative range of motion decreased to 25.1% of preoperative range of motion. Sixty one percent of patients had a reduction of range of motion. Satisfactory results of cervical laminoplasty were maintained for more than 10 years after surgery; however, there were several postoperative problems, such as neurologic deterioration, postoperative radiculopathy, progression of kyphosis, and range of motion limitation.

Association between an aggrecan gene polymorphism and lumbar disc degeneration

STUDY DESIGN

A case-control study using magnetic resonance imaging findings and a polymerase chain reaction assay to investigate the association between aggrecan gene polymorphism and lumbar disc degeneration.

OBJECTIVE

To analyze whether the aggrecan gene polymorphism is related to lumbar disc disease in young women.

SUMMARY OF BACKGROUND DATA

It has been suggested that a genetic factor or familial predisposition contributes to the development of lumbar disc herniation. However, the precise genetic component related to disc disease remains unclear. Recently, a polymorphism has been identified in the region of the human aggrecan gene. The expressed variable numbers of tandem repeat polymorphism occur in the highly conserved repeat region.

METHODS

The participants were 64 young women with or without low back problems. Magnetic resonance imaging was used to evaluate the degeneration and herniation of the intervertebral disc. Genomic deoxyribonucleic acid was extracted from all participants. A polymerase chain reaction assay was carried out to detect the alleles of the aggrecan gene. The association of intervertebral disc degeneration and herniation with the distribution of the aggrecan gene alleles was analyzed.

RESULTS

Findings showed an overrepresentation of alleles with small numbers of repeats in subjects with multilevel disc degeneration, thus indicating a significant distribution difference. There also was a significant difference between the distribution of alleles and the severity of disc degeneration. No significant association was found between any of the alleles either in number or type of disc herniation.

CONCLUSIONS

The current study showed that multilevel and severe disc degeneration was present in the participants with shorter variable numbers of tandem repeat length of the aggrecan gene. This suggests that subjects with shorter variable numbers of tandem repeat length of the aggrecan gene have a risk of having multilevel disc degeneration develop at an early age.

Back muscle injury after posterior lumbar spine surgery. Topographic evaluation of intramuscular pressure and blood flow in the porcine back muscle during surgery

STUDY DESIGN

Intramuscular pressure and blood flow of the back muscles were evaluated topographically during posterior lumbar spine surgery. The topographic damage of the back muscle after surgery was studied.

OBJECTIVE

To investigate the relationship between intramuscular pressure or blood flow during posterior lumbar surgery and the back muscle injury after surgery.

SUMMARY OF BACKGROUND DATA

Latrogenic back muscle injury in an animal and human model has been reported previously. Changes of intramuscular pressure and blood flow during surgery might be related to the muscle injury. No previous study on this issue has been published.

METHODS

The contact pressure between the retractor blade and muscle tissue was monitored in 10 pigs during posterior surgery of the lumbar spine. On one side, intramuscular pressure at 5, 10, and 20 mm lateral to the retractor and on the other side blood flow of the back muscle at 5 and 20 mm during surgery were measured. Histologic changes of the back muscle at 5, 10, and 20 mm to the midline were evaluated 3 hours after surgery.

RESULTS

The contact pressure decreased exponentially with time. Intramuscular pressure 5 mm lateral to the retractor was 114 +/- 31 mm Hg and was significantly higher than at 10 mm and 20 mm. Blood flow markedly decreased during surgery and recovered incompletely after releasing the retractor at 5 mm and 20 mm lateral to the retractor. Blood flow at 5 mm was significantly lower than at 20 mm throughout surgery. The muscle damage 3 hours after surgery was more severe near the retractor blade.

CONCLUSIONS

The back muscles were exposed to pathophysiologic condition by a retractor during posterior lumbar spine surgery. External compression by a retractor increases intramuscular pressure to levels that impede local muscle blood flow. The muscle degeneration after surgery could be explained by direct mechanical damage and by the increased intramuscular pressure of muscle tissue by the retractor.

The association of lumbar disc disease with vitamin-D receptor gene polymorphism

BACKGROUND

Although the etiology of lumbar disc disease is unknown, it has been suggested that a genetic factor contributes to its development. Recently, some genetic polymorphisms have been found to be related to clinical disorders. We investigated the association between vitamin-D receptor gene and estrogen receptor gene polymorphisms and lumbar disc disease in young adults.

METHODS

The participants included 205 young adults (166 women and thirty-nine men) with or without low-back problems. A magnetic resonance imaging scan of the lumbar spine was performed for all subjects, and the grade of disc degeneration was determined, according to the four-grade classification system of Schneiderman et al. The presence or absence of disc herniation was also evaluated. Genomic DNA was extracted from peripheral blood samples. The polymorphisms of the vitamin-D receptor and estrogen receptor genes were detected with use of a polymerase-chain-reaction assay. The restriction fragment length polymorphisms (RFLPs) for the vitamin-D receptor gene were analyzed by TaqI and ApaI restriction enzymes. XbaI and PvuII restriction enzymes were used for the estrogen receptor gene analysis. The distribution of polymorphism in subjects with disc degeneration and/or disc herniation was compared with that in the normal subjects.

RESULTS

The allelic frequencies of both vitamin-D receptor gene and estrogen receptor gene polymorphisms were similar to those in previous analyses of Japanese subjects. The allelic variation in the vitamin-D receptor gene was associated with multilevel and severe disc degeneration and disc herniation. The Tt allele was found to be more frequently associated with multilevel disc disease, severe disc degeneration, and disc herniation than was the TT allele. No additional associations were found.

CONCLUSIONS

This study revealed that the Tt allele of the vitamin-D receptor gene was more frequently associated with multilevel and severe disc degeneration and disc herniation than was the TT allele, pointing to an increased risk of disc disease at an early age in subjects with the Tt allele in the vitamin-D receptor gene.

Axial symptoms after en bloc cervical laminoplasty

Eighty-two patients were evaluated after cervical laminoplasty to explore measures that could minimize future postoperative axial complaints. Patients were divided into two groups: Group A--severe postoperative axial symptoms, and Group B--mild axial complaints. Japanese Orthopaedic Association outcomes scores were similar for the two groups. Radiologic studies demonstrated greater restriction of range of motion in Group A patients who had undergone longer and more extensive surgical procedures.

Progression of ossification of the posterior longitudinal ligament following en bloc cervical laminoplasty

BACKGROUND

Ossification of the posterior longitudinal ligament often causes compressive myelopathy. Ossification is a progressive disease, and it has been reported that the area of ossification increases after decompressive surgery. However, it is uncertain how the progression of ossification affects the long-term outcome after cervical laminoplasty. This study was performed to clarify the relationship between the progression of ossification of the posterior longitudinal ligament and the clinical results following en bloc cervical laminoplasty.

METHODS

Forty-five patients who were followed for more than ten years after laminoplasty participated in this study. Radiographs and tomograms of the cervical spine of each patient were made before and after the operation and at the time of the latest follow-up. The extent of ossification in the longitudinal and sagittal axes was evaluated. Neurological function was graded with use of the Japanese Orthopaedic Association scoring system. The relationship between the progression of ossification and the score-based rate of recovery was analyzed.

RESULTS

Thirty-three (73%) of the patients had progression of ossification of the posterior longitudinal ligament after laminoplasty. Progression was frequent in patients with the mixed type of ossification and in those with the continuous type, whereas it was rare in patients with the segmental type. The patients with progression of the ossification were significantly younger than those without progression (p = 0.018). The Japanese Orthopaedic Association score improved rapidly within one year and continued to improve up to five years after surgery. The score tended to decrease thereafter. For thirteen patients, the score had worsened at the time of the latest follow-up. Three patients had neurological deterioration following an increase in the thickness of the ossification.

CONCLUSIONS

Progression of ossification of the posterior longitudinal ligament was often observed during the long-term follow-up period after laminoplasty. Young patients with mixed and continuous types of ossification had the greatest risk for progression. Preventive measures, such as the use of a wider laminar opening during the laminoplasty, should be considered for patients who are at risk for progression of ossification.

Back muscle injury after posterior lumbar spine surgery. Part 1: Histologic and histochemical analyses in rats

STUDY DESIGN

Back muscle injury caused by retractor application during posterior spine surgery in rats was examined histologically and histochemically according to the postoperative time with reference to the retraction time-pressure relationship.

OBJECTIVES

The results were correlated to provide the risk factors for back muscle injury during posterior spine surgery.

SUMMARY OF BACKGROUND DATA

Back muscles were examined histologically and histochemically after application of quantitative pressure and retraction time. No previous study has assessed this relationship.

METHODS

Five groups were studied: Group 1, 1-hour low-pressure load group; Group 2, 1-hour high-pressure load group; Group 3, 3-hour low-pressure load group; Group 4, 3-hour high-pressure load group; and sham group. In each group, the multifidus muscle was evaluated 3 hours, 48 hours, 1 week, 3 weeks, and 6 weeks after surgery.

RESULTS

In all groups except the sham group, degeneration of the muscle and neuromuscular junction was found at a very early postoperative time, but regeneration began at 1 week, and recovery was attained by 6 weeks. The extent of muscle fiber necrosis and the severity of degeneration of the neuromuscular junctions showed a parallelism with the magnitude of the pressure load and retraction time. As the duration and pressure load increased, the time required for regeneration also increased. The fiber type grouping in group 3 and 4 was consistent with the severity of degeneration of neuromuscular junctions.

CONCLUSIONS

The muscular degeneration and the regeneration was largely dependent on the retraction pressure-time product. These results suggest that denervation muscle injuries are likely secondary responses to muscle retraction injury in any case of posterior spine surgery.

Changes in serum creatine phosphokinase MM isoenzyme after lumbar spine surgery

STUDY DESIGN

Serum concentrations of creatine phosphokinase and its isoenzyme were measured serially in 47 patients who underwent lumbar surgery.

OBJECTIVE

To analyze the significance of postoperative creatine phosphokinase MM levels as indicators of muscle trauma after lumbar surgery.

SUMMARY OF BACKGROUND DATA

The authors of the present study previously have reported on iatrogenic back muscle injury in an animal model and in man. However, the relationship between the change of the creatine phosphokinase MM isoenzyme level and muscle injury after surgery has not been clarified.

METHODS

Peripheral venous blood samples were collected serially before surgery, just after surgery, and at 1, 3, 7, 14, and 21 days after surgery. The serum concentration of total creatine phosphokinase and its isoenzymes was measured by agarose gel electrophoresis. The serial postoperative change of the creatine phosphokinase MM isoenzyme concentration was evaluated with respect to age, gender, body weight, types and levels of surgery, and surgery time.

RESULTS

Creatine phosphokinase MM activity increased after surgery and reached a maximum value 1 day after surgery, followed by recovery to the normal value 1 week after surgery. The maximum concentration of creatine phosphokinase MM isoenzyme in posterior lumbar surgery was significantly higher than that in anterior surgery (P = 0.04). It was significantly higher in men than in women (P = 0.02). Serum concentration of creatine phosphokinase MM isoenzyme showed no significant correlation to the extent of muscle exposure and surgery time.

CONCLUSION

The time course of postoperative serum creatine phosphokinase MM isoenzyme activity is correlated with the histologic changes of the back muscles after surgery. The concentration of creatine phosphokinase MM isoenzyme in posterior lumbar surgery was significantly higher than that in anterior surgery. It was also significantly higher in men than in women.

Postoperative delirium in spine surgery

BACKGROUND CONTEXT

Postoperative delirium is a great concern in the treatment of hip fracture. However, there have been no reports regarding the postoperative delirium in spine surgery.

PURPOSE

To determine the incidence and risk factors for postoperative delirium in the patients who have had spine surgery.

STUDY DESIGN/SETTING

The incidence and intraoperative risk factors of postoperative delirium were retrospectively examined in patients who had spine surgery during a 3-year period.

PATIENT SAMPLE

Three hundred forty-one patients who underwent spine surgery from 2000 to 2002 were included.

METHODS

The presence of delirium was determened by the Confusion Assessment Method. Laboratory data were checked preoperatively, at 1 day and 1 week postoperatively. The prognosis of postoperative delirium was evaluated.

RESULTS

Postoperative delirium was found in 13 patients; all of them were in their 70's or 80's. The incidence of delirium was 12.5% in the patients over 70 years old. Hemoglobin and hematocrit levels at 1 day after surgery in the delirium group were significantly lower than those in the control group. One patient had persistent cognitive dysfunction after surgery. Two patients who developed postoperative delirium died during the follow-up period.

CONCLUSION

Low concentrations of hemoglobin and hematocrit 1 day after surgery were risk factors for postoperative delirium. As delirium is thought to represent not only brain dysfunction, but also impaired general physical condition, careful observation is necessary for the management of patients with postoperative delirium.

Surgical outcome of cervical expansive laminoplasty in patients with diabetes mellitus

STUDY DESIGN

The results from cervical laminoplasty in 18 patients with diabetes mellitus were compared with results from the same procedure in 34 nondiabetic patients matched for age, gender, and disease.

OBJECTIVE

To analyze the effects of diabetes mellitus on the surgical outcome after cervical laminoplasty.

SUMMARY OF BACKGROUND DATA

There have been no reports on the results of cervical laminoplasty patients with diabetes.

METHODS

A retrospective analysis of 18 patients with diabetes mellitus who underwent cervical laminoplasty and 34 nondiabetic patients who underwent the same surgical procedure was undertaken. The postoperative score, intra- and postoperative findings, complications, and radiologic factors were compared between the two groups. In the group with diabetes, the correlation between the recovery rate of the Japanese Orthopedic Association score and the factors indicating the severity of diabetes was assessed.

RESULTS

There was no statistical difference between the total Japanese Orthopedic Association scores of the two groups. However, the group with diabetes mellitus showed a poor recovery of sensory function of the lower extremities. Three patients in the group with diabetes had superficial wound complication after surgery. In contrast, none of the patients in the control group had a wound problem. Furthermore, a negative correlation was observed between the recovery rate and the preoperative HbA1 level in the group with diabetes.

CONCLUSIONS

Although patients with diabetes mellitus who had cervical myelopathy experienced benefits from cervical laminoplasty similar to those of nondiabetic patients, the patients with diabetes were more likely to have wound complication. Furthermore, the negative correlation between the recovery rate and the preoperative HbA1 value might suggest that long-term diabetes control of more than 2 to 3 months before surgery at least is recommended for a favorable surgical outcome.

Ossification of the posterior longitudinal ligament in not only the cervical spine, but also other spinal regions: analysis using multidetector computed tomography of the whole spine

STUDY DESIGN

A prospective cohort study.

OBJECTIVE

To evaluate ossification of the posterior longitudinal ligament (OPLL) of the whole spine in patients with cervical OPLL and to analyze which types of cervical OPLL were associated with the other lesions in the thoracic and/or lumbar spine.

SUMMARY OF BACKGROUND DATA

OPLL is most frequently seen in the cervical spine. The coexisting ossified lesions are sometimes observed in other spinal regions. However, coexisting OPLL in other spinal regions have not yet been precisely evaluated in patients with cervical OPLL.

METHODS

One hundred seventy-eight patients with a diagnosis of cervical OPLL whose plain radiographs were obtained were included. Computed tomographic images of the whole spine were obtained. The ossification index (OS index) was newly determined according to the sum of the levels of vertebral bodies and intervertebral discs with OPLL. The patients were divided into 2 groups, the group that had OPLL only in the cervical spine (C group) and the group that had OPLL in multilevel spinal regions other than the cervical spine (M group).

RESULTS

Ninety-five (53.4%) had OPLL not only in the cervical spine, but also in other spinal regions. The M group had more females than the C group. The incidence of bridge formation in the cervical spine was higher in M group than in C group. More females had a high OS index. A positive correlation was found between the OS index of the cervical spine and the OS index of the thoracic and lumbar spine; however, the r value was small.

CONCLUSION

This study demonstrated that more than half of the patients with cervical OPLL had coexisting OPLL in the thoracic and/or lumbar spine. We strongly recommend computed tomographic analysis of the whole spine for patients with radiographical evidence of OPLL in the cervical spine for the early detection of additional sites of ossification.

Preventive measures for axial symptoms following cervical laminoplasty

We have modified the operative procedure of laminoplasty and changed the postoperative therapy since 1997. In the modified group, several modifications were incorporated. The open door type of cervical en bloc laminoplasty was performed. 1) Bone grafts in the open gap were placed at three levels only. 2) Bone grafting in the hinged side was not performed. 3) The neck collar was worn for only 1 month. 4) The doctors explained the importance of the neck muscle and advised patients to perform early exercise of the posterior neck muscle. The patients who had the original operation and postoperative therapy served as the control (control group). The original operation and postoperative therapy were as follows: Bone grafts from dissected spinous processes were put in the opened laminae and fixed with braided wires or nylon threads. Bone grafts in the open gap were placed to extend from three to five levels. Bone chips were also placed in the hinged side. The orthosis was applied for up to 1 months after surgery, and a neck collar was recommended for 1 additional month. Postoperative neurologic recovery and axial symptoms after cervical laminoplasty were compared between the two groups. There was no statistical difference in postoperative neurologic recovery. However, the incidence of axial symptoms was much lower in the modified group compared with the control group. Radiologic examination showed that postoperative range of motion of the cervical spine in the modified group was significantly well preserved and the number of postoperative fused laminae in the modified group was less than that in the control group. Based on these results, we concluded that the modified method is beneficial for the postoperative status of cervical laminoplasty patients.

Radiologic findings of the lumbar spine in patients with rheumatoid arthritis, and a review of pathologic mechanisms

We have analyzed the radiologic findings on the lumbar spine and the clinical symptoms in patients with rheumatoid arthritis (RA). A total of 106 patients who fulfilled the revised criteria of the American Rheumatism Association were subjected. All of the patients were asked to fill out a questionnaire about the existence of low back pain, leg pain, and leg numbness. Radiologic features of the lumbar spine, including scoliosis, spondylolisthesis, disc space narrowing, endplate erosion, osteophyte, and osteoporosis, were checked. Radiographs of the cervical spine were also taken. The clinical background of RA, such as mutilating disease or not, was assessed. Forty-two patients (40%) had the symptoms of low back pain. Abnormal radiologic findings in lumbar spine were detected in 57%. The prevalence of clinical symptoms tended to be higher in the patients with endplate erosion. Forty-two percent of the patients had both lumbar and cervical lesions. The prevalence of lumbar lesion was not high in the mutilating type of RA, except for facet erosion and severe osteoporosis. The patients with pulse steroid therapy revealed a higher prevalence of vertebral fracture. From these results, we concluded that lumbar lesions were frequently observed in patients with RA. The possibility of lumbar lesions as well as the lesions in the cervical spine and peripheral joints should be examined in patients with RA.

Preventive measures of back muscle injury after posterior lumbar spine surgery in rats

STUDY DESIGN

Postoperative back muscle injury was studied in rats. Postoperative findings were compared among three groups: 2-hour continuous back muscle retraction, 5-minute retraction release after 1 hour of retraction, and 5-minute release at every 40 minutes of retraction.

OBJECTIVE

To determine whether intermittent release of the retractor during surgery is effective to prevent severe muscle injury.

SUMMARY OF BACKGROUND DATA

In surgery performed on the extremities using a tourniquet, intermittent reperfusion intervals can permit extended tourniquet application when the operation is prolonged. However, there have been no specific studies on the effects of intermittent retraction release for postoperative back muscle injury.

METHODS

The back muscle of rats was retracted using a self-retaining retractor for 2 hours. The 36 rats were divided equally into the following three groups: Group 1, 2 hours of continuous retraction; Group 2, two 1-hour retractions interposed with a 5-minute retraction release; and Group 3, three 40-minute retractions interposed with a 5-minute retraction release. In each group, the multifidus muscle was histologically analyzed at 48 hours, 1 week, and 6 weeks after surgery. The muscles were stained by a variety of histochemical methods. The level of serum CPK-MM isoenzyme was measured 48 hours after surgery.

RESULTS

Postoperative back muscle degeneration was the most severe in Group 1. The concentration of CPK-MM in Group 1 was significantly higher than that in Groups 2 and 3. One week after surgery, the lesser diameter of regenerated fibers in Group 1 was smaller than that in Groups 2 and 3. The incidence of neurogenic muscle damage was the highest in Group 1.

CONCLUSIONS

During posterior lumbar spine surgery, 5-minute retraction release after 1 hour or after 40 minutes of retraction was effective in preventing severe back muscle injury after surgery.

Development of a new technique for pedicle screw and Magerl screw insertion using a 3-dimensional image guide

STUDY DESIGN

We developed a new technique for cervical pedicle screw and Magerl screw insertion using a 3-dimensional image guide.

OBJECTIVE

In posterior cervical spinal fusion surgery, instrumentation with screws is virtually routine. However, malpositioning of screws is not rare. To avoid complications during cervical pedicle screw and Magerl screw insertion, the authors developed a new technique which is a mold shaped to fit the lamina.

SUMMARY OF BACKGROUND DATA

Cervical pedicle screw fixation and Magerl screw fixation provide good correction of cervical alignment, rigid fixation, and a high fusion rate. However, malpositioning of screws is not a rare occurrence, and thus the insertion of screws has a potential risk of neurovascular injury. It is necessary to determine a safe insertion procedure for these screws.

METHODS

Preoperative computed tomographic (CT) scans of 1-mm slice thickness were obtained of the whole surgical area. The CT data were imported into a computer navigation system. We developed a 3-dimensional full-scale model of the patient's spine using a rapid prototyping technique from the CT data. Molds of the left and right sides at each vertebra were also constructed. One hole (2.0 mm in diameter and 2.0 cm in length) was made in each mold for the insertion of a screw guide. We performed a simulated surgery using the bone model and the mold before operation in all patients. The mold was firmly attached to the surface of the lamina and the guide wire was inserted using the intraoperative image of lateral vertebra. The proper insertion point, direction, and length of the guide were also confirmed both with the model bone and the image intensifier in the operative field. Then, drilling using a cannulated drill and tapping using a cannulated tapping device were carried out. Eleven consecutive patients who underwent posterior spinal fusion surgery using this technique since 2009 are included. The screw positions in the sagittal and axial planes were evaluated by postoperative CT scan to check for malpositioning.

RESULTS

The screw insertion was done in the same manner as the simulated surgery. With the aid of this guide the pedicle screws and Magerl screws could be easily inserted even at the level where the pedicle seemed to be very thin and sclerotic on the CT scan. Postoperative CT scan showed that there were no critical breaches of the screws.

CONCLUSION

This method employing the device using a 3-dimensional image guide seems to be easy and safe to use. The technique may improve the safety of pedicle screw and Magerl screw insertion even in difficult cases with narrow sclerotic pedicles.

Serum biomarkers in patients with ossification of the posterior longitudinal ligament (OPLL): Inflammation in OPLL

BACKGROUD

Ossification of the posterior longitudinal ligament (OPLL) is characterized by replacement of ligamentous tissue by ectopic new bone formation. OPLL causes narrowing of the spinal canal, resulting in neurological impairment. However, the pathogenesis of OPLL has not been fully elucidated. We investigated whether inflammation occurs in OPLL or not using high-sensitivity CRP (hs-CRP) in a case-control study.

METHODS AND FINDINGS

This study included 103 patients with OPLL in the patient group and 95 age- and sex-matched volunteers with degenerative spinal disease in the control group. Of the 103 OPLL patients, 88 patients who were available for more than 2 years follow-up were checked for OPLL progression. A blood sample was obtained and Hs-CRP, and other routine data, including total protein (TP), albumin (ALB), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), glucose (Glu), calcium (Ca), inorganic phosphate (Pi), white blood cell count (WBC), hemoglobin (Hb) and platelet (PLT), were analyzed. The data were compared between the patients with OPLL and the controls. The severity of the ossified lesions in the whole spine were evaluated by the ossification index (OS index) in patients with OPLL. The data were also compared between the patients with OPLL progression (the progression group) and the patients without OPLL progression (the non-progression group). In the results, the mean hs-CRP in the OPLL group was higher than that in the controls. The Pi in the OPLL group was lower than that in the control group. A negative correlation was found between the Pi and the OS index. The mean hs-CRP in the progression group was higher than that in the non-progression group. There was a positive correlation between the average length of the OPLL progression per year and the hs-CRP.

CONCLUSIONS

The results may suggest the occurrence of local inflammation in OPLL and the inflammation might cause OPLL progression. These facts are important for understanding the pathology of OPLL.

Pathomechanism of myelopathy and surgical results of laminoplasty in elderly patients with cervical spondylosis

STUDY DESIGN

Clinical and radiologic analyses in elderly patients with cervical myelopathy.

OBJECTIVE

To investigate the pathomechanism of cervical myelopathy and the surgical results of laminoplasty in elderly patients older than 70 years old.

SUMMARY OF BACKGROUND DATA

To date, there have been no reports on the pathomechanism of cervical myelopathy in elderly patients. Further, the surgical results and postoperative complications of laminoplasty have not been fully evaluated in elderly patients.

METHODS

Eighty-nine patients who underwent cervical laminoplasty were reviewed. The patients were divided into 2 groups according to the age at the time of operation (the elderly patient group: 20 patients who were older than 70 years old, and the control group: 69 patients who were younger than 69 years old). Pre- and postoperative neurologic status (the Japanese Orthopedic Association score) and postoperative complications were compared between the two groups. Radiologic features were also examined.

RESULTS

There was no statistical difference in the recovery rate of Japanese Orthopedic Association score between the elderly patient group and the control group. Activities of daily living improved in the elderly patients. Several complications, such as delirium and worsening hypertension, were found in the elderly patient group. In the preoperative radiographs, the incidence of either retrolisthesis or anterolisthesis in the elderly patient group was significantly higher than that in the control group.

CONCLUSIONS

Retrolisthesis and anterolisthesis are often the cause of myelopathy in elderly patients. Surgical decompression for cervical myelopathy was beneficial even in elderly patients older than 70 years old. Laminoplasty achieves stability of the cervical spine, and this procedure is reasonable for the treatment.

Characteristics of ossification of the spinal ligament; incidence of ossification of the ligamentum flavum in patients with cervical ossification of the posterior longitudinal ligament - Analysis of the whole spine using multidetector CT

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) and ossification of the ligamentum flavum (OLF) are characterized by replacement of ligamentous tissue by ectopic new bone formation. Although the background of both diseases might be similar, there are some differences between two diseases. Some patients have both OPLL and OLF. However, the incidence of both OPLL and OLF is still unclear and the precise lesions have not been investigated, yet. This study was conducted to evaluate OLF of the whole spine in patients with cervical OPLL and to analyze the relationship of the ossified lesions between OLF and OPLL.

METHODS

One hundred seventy eight patients who were diagnosed as cervical OPLL by plain radiographs were included. CT images of the whole spine were taken. Ossified lesions were checked at each level of vertebral body and intervertebral disc. The ossification index of OPLL (OPLL OS index) was determined by the sum of the levels of vertebral bodies and intervertebral discs where OPLL existed. The same index was applied for detecting the level of OLF (OLF OS index). Age, gender and OPLL characteristics were compared between the OLF(+) group, OLF was seen at any levels of the spinal canal, and the OLF(-) group, OLF was not seen.

RESULTS

The most frequent level of OPLL was at C5 vertebral level and OLF was predominant at upper and lower thoracic levels. Seventeen patients (9.6%) had OPLL and OLF at the same spinal level. The averaged OPLL OS index of the total spine in these patients was 8.7 ± 6.1, ranged from 1 to 36. The averaged OLF OS index of the total spine was 3.1 ± 2.2 (ranged from 1 to 13) in the patients who had OLF at any levels of the whole spine. One hundred fifteen patients (64.6%) with cervical OPLL had OLF at any levels of the whole spine. No relationship was found between the OPLL OS index and the OLF OS index. There was no significant difference among the data between the OLF(+) group and the OLF(-) group.

CONCLUSIONS

This study demonstrated 64.6% of the patients with cervical OPLL had OLF, mainly in the thoracic spine. However, there was no relationship regarding the severity of the ossified lesions between OPLL and OLF. CT analysis of the whole spine should be carried out for the early detection of OPLL and OLF in patients with cervical OPLL.

Variables affecting postsurgical prognosis of thoracic myelopathy caused by ossification of the ligamentum flavum

BACKGROUND CONTEXT

Ossification of the ligamentum flavum (OLF) may result in thoracic myelopathy (TM) because of narrowing of the spinal canal. Because symptoms vary and are subjective, diagnosis of TM caused by OLF is sometimes difficult when based on symptoms and physical examination. Posterior decompression is indicated in patients with TM caused by OLF because it is believed that surgery is the most effective treatment. However, surgical outcomes vary. We are unaware of reports of objective presurgical diagnostic parameters, such as neurologic and radiologic findings, relating to the postsurgical prognosis in patients with TM caused by OLF.

PURPOSE

To determine which presurgical and surgical variables were most closely related to postsurgical prognosis of TM caused by OLF.

STUDY DESIGN

Retrospective review of the records of the cohort of patients who had undergone surgery from 1988 through 2008 at the University of Toyama Hospital for TM caused by OLF.

PATIENT SAMPLE

Forty-one patients who had surgery for TM caused by OLF that was progressive, severe, or both and for which the diagnosis was based on clinical, radiologic, and pathologic evaluations.

OUTCOME MEASURES

Relationship between the highest follow-up Japanese Orthopaedic Association (JOA) score for neurologic evaluation and of Hirabayashi's formula to indicate the extent of normalization after surgery with respect to the following 10 variables: age at surgery; sex; duration of presurgical symptoms; complications of diabetes mellitus; complications of hypertension; presence of presurgical hyperreflexia in either or both of the patellar tendon reflex and the Achilles tendon reflex; presurgical impairment of joint position sense in the big toes; number of levels affected by OLF; concurrent spinal lesions including ossification of the posterior longitudinal ligament; and intramedullary change of the spinal cord seen on magnetic resonance imaging (MRI).

METHODS

Multiple linear analyses were used to evaluate the variables related to postsurgical recovery.

RESULTS

Presurgical impairment of joint position sense in the big toe was the most important predictor of the highest postsurgical JOA score and of the highest percentage recovery rate. The number of affected OLF levels also predicted the postsurgical highest JOA score, but not statistically significantly so. Age at surgery, sex, and duration of symptoms presurgically did not affect postsurgical recovery. Complications of diabetes mellitus or of hypertension did not affect percentage recovery rate. The difference between recovery rate in patients with or without concurrent spinal lesions was not significant. Presurgical hyperreflexia was not correlated with recovery. Postsurgical JOA scores and percentage recovery rates of scores in patients whose presurgical MRIs had shown intramedullary signal change were not statistically significantly different from those whose MRIs had not shown signal change.

CONCLUSIONS

An excellent postoperative prognosis is not always possible in patients with TM caused by OLF. It may be important to check for impairment of joint position sense in the big toe, the number of levels affected by OLF, and presurgical intramedullary signal change on MRI before continuing to surgery.

Association between polymorphism of the transforming growth factor-beta1 gene with the radiologic characteristic and ossification of the posterior longitudinal ligament

STUDY DESIGN

A study was conducted to examine the relation between the transforming growth factor-beta1 (TGF-beta1) polymorphism (T-->C transition in the signal sequence) and ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVE

To investigate the association between the polymorphism of TGF-beta1 and the radiologic characteristics of OPLL.

SUMMARY OF BACKGROUND DATA

Ossification of the posterior longitudinal ligament has a strong genetic background. Several genes contribute to the expression of OPLL. Transforming growth factor-beta1 is present in the ossified matrix and chondrocytes of cartilage adjacent to areas of OPLL.

METHODS

The difference in the TGF-Tbeta1 allele distribution ("TT," "TC," and "CC") between 369 patients with OPLL and 258 control subjects was assessed. The relations between the allele frequency and radiologic features of OPLL involving the cervical, thoracic, and lumbar spine and the width of the ossification area were evaluated.

RESULTS

There was no statistical difference with respect to the type of OPLL and the width of the ossification area for the TGF-Tbeta1 allele between the OPLL and the control groups. However, in the patients with "TC" or "CC" alleles, OPLL frequently was found in the cervical, thoracic, and/or lumbar spine.

CONCLUSIONS

Transforming growth factor-beta1 polymorphism is not a factor associated with the occurrence of OPLL, but rather a factor related to the area of the ossified lesion. The "C" allele might be a risk factor for patients with OPLL in other areas in addition to the cervical lesion.

Clinical symptoms and surgical outcome in lumbar spinal stenosis patients with neuropathic bladder

We evaluated the clinical and radiologic features of patients with lumbar spinal stenosis with neuropathic bladder. Based on cystometrogram analysis, the patients were divided into two groups--the neuropathic bladder (NB) group: the NB+ group (23 patients), and the nonneuropathic bladder group: the NB- group (14 patients). The symptom of incontinence was characteristic in patients in the NB+ group. Patients in the NB+ group had a more severe neurologic disturbance, compared with those in the NB- group. The more severe neurologic disturbance was caused by the more striking finding of degenerative spinal stenosis associated with developmental narrowing of the spinal canal. Decompressive surgery had a beneficial effect on the recovery of the neurologic symptoms in both groups. Residual urine volume was reduced after surgery. Postoperative cystometrogram was carried out in nine patients in the NB+ group. It showed a normal pattern in six patients; however, three patients remained in an underactive pattern. Furthermore, four patients still required clear intermittent self-catheterization after surgery.

More Than 20 Years Follow-up After En Bloc Cervical Laminoplasty

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of the study was to evaluate clinical outcomes and to clarify the potential risks of cervical laminoplasty by a long-term follow-up of more than 20 years.

SUMMARY OF BACKGROUND DATA

There is no follow-up report exceeding 20 years after cervical laminoplasty.

METHODS

Two hundred sixteen patients underwent en bloc cervical laminoplasty for the treatment of cervical compressive myelopathy due to cervical spondylosis or ossification of the posterior longitudinal ligament between 1981 and 1994. Of these, 148 patients with a follow-up of more than 20 years were retrospectively studied (68 survived patients and 80 dead patients). The neurological evaluation was graded using Japanese Orthopaedic Association (JOA) score and the recovery rate. Neurological recovery was defined by the increase in JOA score. Radiological examinations were carried out using pre- and postoperative radiographs. As for the dead patients, the cause and age of death were reviewed.

RESULTS

The JOA score and recovery rate increased to 14.2 ± 2.7% and 64.9 ± 28.6%, respectively, at 5 years. The JOA score and recovery rate were maintained at 13.9 ± 3.2% and 61.6 ± 34.6% at 10 years. The JOA score decreased to 11.4 ± 5.1 at the last follow-up. In 32 out of 65 patients (49.2%), the JOA scores worsened mainly due to other spinal lesions. Cervical alignment became kyphotic when comparing preoperatively and at the last follow-up (ossification of the posterior longitudinal ligament: 15.7 ± 12.2° and 6.9 ± 17.8°, cervical spondylosis: 11.0 ± 8.9° and 3.3 ± 9.4°). Range of motion (ROM) decreased and one of the causes of ROM reduction was interlaminar fusion. The mean age at death was 78.2 years. The most frequent cause of death was malignant tumor.

CONCLUSION

Spine surgeons must be aware that patients have a long postoperative lifetime when cervical laminoplasty is performed. A long postoperative follow-up should be carried out after laminoplasty.

LEVEL OF EVIDENCE

4.

Quantitative analysis of the effect of lumbar orthosis on trunk muscle strength and muscle activity in normal subjects

We studied the effect of lumbar orthosis on trunk muscle strength and muscle activity during flexion-extension bending of the trunk in 31 male volunteers. Trunk muscle strength was measured with a kinetic measurement system. Peak torque was calculated by using the mean torque of five repetitions. Trunk muscle activity was measured with commercially available equipment that has portable EMG data-collection units. The maximum level of the EMG signal was evaluated by employing the analyzing part of the computer's measuring program. With the application of the lumbar orthosis, the strength of the abdominal muscle and the back muscle increased; conversely, the activities of both muscles were decreased significantly. This might imply that lumbar orthosis reduces the load of the trunk muscles during performance.