Kiyoshi Kaneda

Complications of Pedicle Screw Fixation in Reconstructive Surgery of the Cervical Spine

Study Design. Retrospective evaluation of complications in 180 consecutive patients with cervical disorders who had been treated by using pedicle screw fixation systems. Objectives. To determine the risks associated with pedicle screw fixation in the cervical spine and to emphasize the importance of preoperative planning and surgical techniques in reducing the risks of this procedure. Summary of Background Data. Generally, pedicle screw fixation in the cervical spine has been considered too risky for the neurovascular structures. There have been several reports describing the complications of lateral mass screw–plate fixation. However, no studies have examined in detail the complications associated with cervical pedicle screw fixation. Methods. One hundred eighty patients who underwent cervical reconstructive surgery using cervical pedicle screw fixation were reviewed to clarify the complications associated with the pedicle screw fixation procedure. Cervical disorders were spinal injuries in 70 patients and nontraumatic lesions in 110 patients. Seven hundred twelve screws were inserted into the cervical pedicles, and the locations of 669 screws were radiologically evaluated. Results. Injury of the vertebral artery occurred in one patient. The bleeding was stopped by bone wax, and no neurologic complication developed after surgery. On computed tomographic (CT) scan, 45 screws (6.7%) were found to penetrate the pedicle, and 2 of 45 screws caused radiculopathy. Besides these three neurovascular complications directly attributed to screw insertion, radiculopathy caused by iatrogenic foraminal stenosis from excessive reduction of the translational deformity was observed in one patient. Conclusions. The incidence of the clinically significant complications caused by pedicle screw insertion was low. Complications associated with cervical pedicle screw fixation can be minimized by sufficient preoperative imaging studies of the pedicles and strict control of screw insertion. Pedicle screw fixation is a useful procedure for reconstruction of the cervical spine in various kinds of disorders and can be performed safely.

Graft Site Morbidity with Autogenous Semitendinosus and Gracilis Tendons

To distinguish between morbidity caused by harvesting semitendinosus and gracilis tendons and morbidity as sociated with anterior cruciate ligament reconstruction surgery, we performed a prospective randomized study using 65 patients who underwent anterior cruciate liga ment reconstruction using these tendons. The patients underwent either contralateral (N = 34) or ipsilateral (N = 31) graft harvest. For the nonoperated knees in the ipsilateral harvest group, isometric and isokinetic strength of the quadriceps and hamstring muscles in creased to approximately 120% of the preoperative value at 12 months after surgery. Compared with these knees, the tendon harvest did not affect quadriceps muscle strength at all. However, harvest did decrease hamstring muscles strength for 9 months after surgery. The graft harvest in the knees with anterior cruciate liga ment reconstruction also did not significantly affect quadriceps muscle strength, but it did significantly de crease hamstring muscles strength only at 1 month. Activity-related soreness at the donor site was rarely restricting and resolved by 3 months. This study dem onstrated that the semitendinosus and gracilis tendon graft is a reasonable choice to minimize the donor site morbidity in ligament reconstruction using autografts.

Anterior decompression and stabilization with the Kaneda device for thoracolumbar burst fractures associated with neurological deficits

One hundred and fifty consecutive patients who had a burst fracture of the thoracolumbar spine and associated neurological deficits were managed with a single-stage anterior spinal decompression, strut-grafting, and Kaneda spinal instrumentation. At a mean of eight years (range, five years to twelve years and eleven months) after the operation, radiographs showed successful fusion of the injured spinal segment in 140 patients (93 per cent). Ten patients had a pseudarthrosis, and all were managed successfully with posterior spinal instrumentation and a posterolateral arthrodesis. The percentage of the canal that was obstructed, as measured on computed tomography, improved from a preoperative mean of 47 per cent (range, 24 to 92 per cent) to a postoperative mean of 2 per cent (range, 0 to 8 per cent). Despite breakage of the Kaneda device in nine patients, removal of the implant was not necessary in any patient. None of the patients had iatrogenic neurological deficits. After the anterior decompression, the neurological function of 142 (95 per cent) of the 150 patients improved by at least one grade, as measured with a modification of the grading scale of Frankel et al. Fifty-six (72 per cent) of the seventy-eight patients who had preoperative paralysis or dysfunction of the bladder recovered completely. One hundred and twenty-five (96 per cent) of the 130 patients who were employed before the injury returned to work after the operation, and 112 (86 per cent) of them returned to their previous job without restrictions. We concluded that anterior decompression, strut- grafting, and fixation with the Kaneda device in patients who had a burst fracture of the thoracolumbar spine and associated neurological deficits yielded good radiographic and functional results.

transpedicular Screw Fixation for Traumatic Lesions of the Middle and Lower Cervical Spine : description of the Techniques and Preliminary Report

Thirteen patients with fractures and/or dislocations of the middle and lower cervical spine were treated by transpedicular screw fixation using the Steffee variable screw placement system. Postoperative immobilization was either not used or simplified to short-term use of a soft neck collar. Recovery of nerve function and correction of kyphotic and/or translational deformities were satisfactory. All patients had solid fusion without loss of correction at the latest follow-up. There were no neurovascular complications. It was concluded that transpedicular screw fixation is as strong a fixation procedure for the cervical spine as it is for the thoracic and lumbar spine. This surgical procedure is associated with some risks of major neurovascular injuries; however, safety is adequate if the procedure is performed by experienced surgeons using meticulous surgical techniques.

Burst fractures with neurologic deficits of the thoracolumbar-lumbar spine. Results of anterior decompression and stabilization with anterior instrumentation.

Twenty-seven burst fractures with neurologic deficits of the thoracolumbar-lumbar spine were treated with an one-stage anterior operation consisting of anterior decompression through vertebrectomy, realignment and stabilization with Zlelke instrumentation (12 patients), and our new anterior instrumentation (15 patients). Only two disc spaces directly related to the injury were fused. No patient showed neurologic deterioration after surgery. All 26 patients with incomplete lesions improved postoperatively, with 19 of them entering the next Frankel subgroup. The newly designed anterior instrumentation afforded enough stability to enable early ambulation with alignment and solid fusion.

Posterior occipitocervical reconstruction using cervical pedicle screws and plate-rod systems.

STUDY DESIGN This retrospective study was conducted to analyze the clinical results in 26 patients with lesions at the craniocervical junction that had been treated by occipitocervical reconstruction using pedicle screws in the cervical spine and occipitocervical rod systems. OBJECTIVES To evaluate the effectiveness of pedicle screw fixation in occipitocervical reconstructive surgery and to introduce surgical techniques. SUMMARY OF BACKGROUND DATA Many methods of occipitocervical reconstruction have been reported, but there have been no reports of occipitocervical reconstruction using pedicle screws and occipitocervical rod systems for reduction and fixation. METHODS Twenty-six patients with lesions at the craniocervical junction underwent reconstructive surgery using pedicle screws in the cervical spine and occipitocervical rod systems. The occipitocervical lesions were atlantoaxial subluxation associated with basilar invagination, which was caused by rheumatoid arthritis in 19 patients and other disorders in 7. The lowest cervical vertebra of fusion in 16 patients was C2, and the remaining 10 patients underwent fusion downward from C3 to C7. Flexion deformity of the occipitoatlantoaxial complex was corrected by application of extensional force, and upward migration of the odontoid process was reduced by application of combined force of extension and distraction between the occiput and the cervical pedicle screws. RESULTS Solid fusion was achieved in all patients except two with metastatic vertebral tumors who did not receive bone graft for fusion. Correction of malalignment at the craniocervical junction was adequate, and postoperative magnetic resonance imaging showed improvement of anterior compression of the medulla oblongata. There were no neurovascular complications of cervical pedicle screws. CONCLUSIONS Occipitocervical reconstruction by the combination of cervical pedicle screws and occipitocervical rod systems provided the high fusion rate and sufficient correction of malalignment in the occipitoatlantoaxial region. Results of this study showed the effectiveness of cervical pedicle screw as a fixation anchor for occipitocervical reconstruction.

Stability of posterior spinal instrumentation and its effects on adjacent motion segments in the lumbosacral spine.

Study Design. An in vitro biomechanical analysis of three anterior instability patterns was performed using calf lumbosacral spines. Stiffness of the constructs was compared, and segmental motion analyses were performed. Objectives. To clarify the factors that alter the stability of the spinal instrumentation and to evaluate the influence of instrumentation on the residual intact motion segments. Summary of Background Data. Recently, many adverse effects have been reported in fusion augmented with rigid instrumentation. Only few reports are available regarding biomechanical effects of stability provided by spinal instrumentation and its effects on residual adjacent motion segments in the lumbar‐lumbosacral spine. Methods. Eighteen calf lumbosacral spine specimens were divided into three groups according to instability patterns‐one‐level, two‐level, and three‐level disc dissections. Six constructs were cyclically tested in rotation, flexion‐extension, and lateral bending of intact spines, of destabilized spine, and of spines with four segmental posterior instrumentation systems used to extend the levels of instability (Cotrel‐Dubousset compression hook and three transpedicular screw fixation systems). During each test, stiffness values and segmental displacements were measured. Results. The rigidity of the instrumented construct increased as the fixation range became more extensive. Although application of the instrumentation effectively reduced the segmental motion of the destabilized vertebral level, the motion at the destabilized level tended to increase as the number of unstable vertebral levels increased, and the fixation range of the instrumentation became more extensive. Instrumented constructs produced higher segmental displacement values at the upper residual intact motion segment when compared with those of the intact spine. In contrast, the instrumented constructs decreased their segmental displacement values at the lower residual intact motion segment with higher magnitude of the translational (shear) motion taking place compared with the intact spine in flexion‐extension and lateral bending. These changes in the motion pattern became more distinct as the fixation range became more extensive. Conclusions. As segmental spinal instrumentation progresses from one level to three levels, the overall torsional and flexural rigidity of the system increases. However, segmental displacement at the site of simulated instability becomes more obvious. Application of segmental instrumentation changes the motion pattern of the residual intact motion segments, and the changes in the motion pattern become more distinct as the fixation range becomes more extensive and as the rigidity of the construct increases.

Macrophage migration inhibitory factor up-regulates expression of matrix metalloproteinases in synovial fibroblasts of rheumatoid arthritis.

Neutral matrix metalloproteinases (MMPs) are responsible for the pathological features of rheumatoid arthritis (RA) such as degradation of cartilage. We herein show the up-regulation of MMP-1 (interstitial collagenase) and MMP-3 (stromelysin) mRNAs of cultured synovial fibroblasts retrieved from rheumatoid arthritis (RA) patients in response to macrophage migration inhibitory factor (MIF). The elevation of MMP-1 and MMP-3 mRNA was dose-dependent and started at 6 h post-stimulation by MIF, reached the maximum level at 24 h, and was sustained at least up to 36 h. Interleukin (IL)-1β mRNA was also up-regulated by MIF. These events were preceded by up-regulation of c-jun and c-fos mRNA. Tissue inhibitor of metalloproteinase (TIMP)-1, a common inhibitor of these proteases, was slightly up-regulated by MIF. Similarly, mRNA up-regulation of MMP-1 and MMP-3 was observed in the synovial fibroblasts of patients with osteoarthritis. However, their expression levels were much lower than those of RA synovial fibroblasts. The mRNA up-regulation by MIF was inhibited by the tyrosine kinase inhibitors genestein and herbimycin A, as well as the protein kinase C inhibitors staurosporine and H-7. On the other hand, the inhibition was not seen after the addition of the cyclic AMP-dependent kinase inhibitor, H-8. The mRNA up-regulation of MMPs was also inhibited by curcumin, an inhibitor of transcription factor AP-1, whereas interleukin-1 receptor antagonist, an IL-1 receptor antagonist, failed to inhibit the mRNA up-regulation. Considering these results, it is suggested that 1) MIF plays an important role in the tissue destruction of rheumatoid joints via induction of the proteinases, and 2) MIF up-regulates MMP-1 and MMP-3 via tyrosine kinase-, protein kinase C-, and AP-1- dependent pathways, bypassing IL-1β signal transduction.

Pedicle screw fixation for nontraumatic lesions of the cervical spine.

Study Design. This retrospective study was conducted to analyze the clinical results in 45 patients with nontraumatic lesions of the cervical spine treated by pedicle screw fixation. Objectives. To evaluate the effectiveness of pedicle screw fixation in reconstructive surgery for nontraumatic cervical spinal disorders. Summary of Background Data. Pedicle screw fixation for hangmans fracture of the axis and traumatic lesions of the middle and lower cervical spine has been reported; however, there have been no reports on pedicle screw fixation for nontraumatic lesions of the cervical spine. Methods. Forty‐five patients with nontraumatic lesions of the cervical spine underwent reconstructive surgery including pedicle screw fixation and fusion. Five patients underwent occipitocervical fixation for the lesion of the upper cervical spine, and one patient underwent separate occipitocervical fixation and cervicothoracic fixation. Cervical or cervicothoracic fixation was performed in 39 patients. Twenty‐six of these patients underwent simultaneous laminectomy or laminoplasty. Supplemental anterior surgery was conducted for 15 patients. Results. Solid fusion was obtained in all patients except eight with metastatic vertebral tumors who did not receive bone graft. Correction of kyphosis was adequate. There were no neurovascular complications, except one case of transient radiculopathy caused by screw threads. Conclusions. Pedicle screw fixation is a useful procedure for posterior reconstruction of the cervical spine. This procedure does not require the lamina for stabilization, and should be especially valuable for simultaneous posterior decompression and fusion. The risk to neurovascular structures, however, cannot be completely eliminated.

Local kyphosis reduces surgical outcomes of expansive open-door laminoplasty for cervical spondylotic myelopathy.

Study Design. This retrospective study analyzed the effects of cervical alignment on surgical results of expansive laminoplasty (ELAP) for cervical spondylotic myelopathy (CSM). Objective. To determine the limitation of posterior decompression by ELAP for CSM in the presence of local kyphosis. Summary of Background Data. Several studies have reported that cervical malalignment affected surgical outcomes of ELAP. However, there has been no report to demonstrate crucial determinants of surgical outcomes of ELAP for CSM in relation to cervical sagittal alignment. Methods. The study group comprised 114 patients who underwent ELAP for CSM. All were followed up for more than 2 years. The Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy (full score, 17 points) was used to evaluate surgical outcomes for each patient 2 years after surgery. Statistical analysis with multivariate logistic regression models was used to ascertain the risk factors affecting postoperative surgical outcomes. Results. The average JOA scores were 9.9 points before surgery and 14 points 2 years after surgery. The recovery rate was 60.2%. Statistical analysis showed that signal intensity change on MRI and local kyphosis were the most crucial risk factors for poor surgical outcomes. Calculated with the logistic regression model, the highest risk of poor recovery was local kyphosis exceeding 13°. Conclusions. The influence of cervical malalignment on neurologic recovery after ELAP for CSM was shown. When patients have local kyphosis exceeding 13°, anterior decompression or posterior correction of kyphosis as well as ELAP should be considered. Expansive laminoplasty for CSM is best indicated for patients with local kyphosis less than 13°.