Anterior Strut Grafting Research Articles

Early reconstruction failures after multilevel cervical corpectomy.

A retrospective analysis of graft and plate complications after multilevel anterior cervical corpectomy and fusion (ACF) attributed to spondylosis, stenosis, and ossification of posterior longitudinal ligament was conducted. To identify factors contributing to graft and plate complications in this population. Biomechanical factors contributing to the increased morbidity associated with plated multilevel ACF were evaluated. Graft- and/or plate-related complications were retrospectively reviewed in 33 patients undergoing two-level ACF reconstructions and in seven patients having three-level ACF reconstructions performed with iliac crest grafting and instrumentation with a fixed-plated design (cervical spine locking plate). Neurologic status was assessed before surgery and after surgery using both the Nurick Grading Scale and modified JOA (Japanese Orthopaedic Association) Score. The patients were observed an average of 31.4 months after surgery. The follow-up included lateral flexion and extension radiographs and a neurologic examination. Two of the 33 patients undergoing two-level fusions available for long-term follow-up after surgery developed reconstruction failures. All of the remaining fusions were successful, demonstrated by lateral flexion and extension radiographs. Seven patients had plated three-level corpectomy reconstructions. Five of the seven who had anterior-only reconstruction failed. A two-level ACF reconstruction is reliable with an anterior strut graft and fixed screw plate construct. A three-level ACF reconstruction is not reliably achieved with an anterior-only construct. The construct failures may be attributed in part to the fixed-plated design being used, as well as the long lever arm of the construct. There is a 6% failure rate after fixed-plated (cervical spine locking plate) two-level ACF reconstruction but a 71% failure rate after three-level fixed-plated ACF reconstruction. Future consideration should be given to simultaneous posterior fusion.

Spinal deformity in chondrodysplasia punctata.

Our purpose was to describe the deformities, natural history, and course of treatment in chondrodysplasia punctata, a skeletal dysplasia characterized by stippled epiphysis in infancy, short stature, and progressive kyphoscoliosis. We identified 20 patients (15 female, 5 male) with chondrodysplasia punctata and spinal abnormalities. The spinal deformity was rarely present in the neonatal radiographs but typically appeared during the first year. We identified three patterns of spinal deformity. The first was a C2 dentocentral synchondrosis separation, which was successfully fused. Scoliosis had two patterns: one slowly progressive without dysplastic vertebrae or significant kyphosis (two patients) and the other rapidly progressive with dysplastic vertebral bodies often appearing similar to a congenital kyphoscoliosis (17 patients). Follow-up averaged 7.9 years (range 2-20 years). The slowly progressive type was fused successfully with standard posterior techniques. The dysplastic type, however, required on average 2.5 procedures, including anteroposterior fusions, repeat fusions for pseudarthrosis repair, extension of the fusions for progression beyond the curves, and osteotomies for progression through the fusion mass. Unlike congenital deformities, they did not respond well to hemiepiphysiodesis. Three types of spinal deformities were identified in children with chondrodysplasia punctata, including cervical bony disruption, a slowly progressive, nondysplastic scoliosis responding well to standard fusion techniques and a dysplastic kyphoscoliosis, which is rapidly progressive and resistant to fusion. The best results in dysplastic curves are obtained with an anterior strut graft and a posterior fusion. The patients must be observed long-term for further vertebral dysplasia and progressive kyphoscoliosis.

Long structural allografts in the treatment of anterior spinal column defects.

A retrospective study of 41 patients who had anterior spinal column reconstruction using long-segment allografts between 1983 and 1998 is reported. A long-segment allograft was defined as an allograft strut that replaces a vertebral body or approximates the height of the adjacent vertebral body for the thoracolumbar or lumbar spine, or more than two vertebral bodies for the cervical or cervicothoracic spine. Forty of the 41 patients had successful anterior strut grafting with radiographic evidence of allograft incorporation at the last followup with the majority of patients having radiographic evidence of incorporation by 6 months. There where three early complications related to the allograft (two end plate fractures and one repeated cervical spine allograft dislodgment) and one late complication associated with the posterior adjunct instrumentation unrelated to the allograft (degenerative lumbar stenosis). The only procedural complication was a deep venous thrombosis and a resultant nonfatal pulmonary embolus. No allografts fractured or collapsed. These data suggest that long-segment anterior allografts work exceptionally well in maintaining vertebral height and structural integrity in numerous pathologic deformities including traumatic and infectious etiologies.

Tuberculosis of the thoracic spine

In spinal tuberculosis MRI can clearly demonstrate combinations of anterior and posterior lesions as well as pedicular involvement. We propose a classification system, using information provided by MRI, to help to plan the appropriate surgical treatment for patients with thoracic spinal tuberculosis. We describe a series of 47 patients, divided into four groups, based on the surgical protocol used in the management. Group A consisted of patients with anterior lesions which were stable with no kyphotic deformity, and were treated with anterior debridement and strut grafting. Group B comprised patients with global lesions, kyphosis and instability who were treated with posterior instrumentation using a closed-loop rectangle with sublaminar wires, and by anterior strut grafting. Group C were patients with anterior or global lesions as in the previous groups, but who were at a high risk for transthoracic surgery because of medical and possible anaesthetic complications. These patients had a global decompression of the cord posteriorly, the anterior portion of the cord being approached through a transpedicular route. Posterior instrumentation was with a closed-loop rectangle held by sublaminar wires. Group D comprised patients with isolated posterior lesions which required posterior decompression only. An understanding of the extent of vertebral destruction can be obtained from MRI studies. This information can be used to plan appropriate surgery.

Tuberculosis of the thoracic spine. A classification based on the selection of surgical strategies.

In spinal tuberculosis MRI can clearly demonstrate combinations of anterior and posterior lesions as well as pedicular involvement. We propose a classification system, using information provided by MRI, to help to plan the appropriate surgical treatment for patients with thoracic spinal tuberculosis. We describe a series of 47 patients, divided into four groups, based on the surgical protocol used in the management. Group A consisted of patients with anterior lesions which were stable with no kyphotic deformity, and were treated with anterior debridement and strut grafting. Group B comprised patients with global lesions, kyphosis and instability who were treated with posterior instrumentation using a closed-loop rectangle with sublaminar wires, and by anterior strut grafting. Group C were patients with anterior or global lesions as in the previous groups, but who were at a high risk for transthoracic surgery because of medical and possible anaesthetic complications. These patients had a global decompression of the cord posteriorly, the anterior portion of the cord being approached through a transpedicular route. Posterior instrumentation was with a closed-loop rectangle held by sublaminar wires. Group D comprised patients with isolated posterior lesions which required posterior decompression only. An understanding of the extent of vertebral destruction can be obtained from MRI studies. This information can be used to plan appropriate surgery.

Anterior instrumentation for the treatment of spinal tuberculosis.

Kyphosis and neurological impairment are the major residual problems of spinal tuberculosis after the microorganism has been eradicated with use of appropriate medications. Spinal instrumentation is needed to support anterior strut grafts in patients who have kyphosis that affects more than two levels. Most surgeons use posterior instrumentation. Anterior instrumentation, despite its advantages, has not been widely accepted, partly because of concerns about introducing foreign material into infected tissue. The purpose of the current study was to address those concerns. Twenty-two patients who had tuberculosis of the spine with moderate-to-severe localized kyphosis and sixteen patients who had more than two involved levels had stabilization with anterior instrumentation. Antituberculous medication was used postoperatively according to a standardized regimen. The patients were followed to determine if there was any recurrence of the disease and if the correction had been maintained. The twenty-two patients who had involvement of one or two levels had an average correction of the deformity of 64 percent (range, 58 to 90 percent), and the sixteen patients who had more than two levels of involvement had an average correction of 81 percent (range, 75 to 97 percent). The correction was maintained in twenty-one patients, the maximum loss was 3 degrees in sixteen, and one patient died on the second postoperative day. There was no recurrence of the disease. We believe that anterior instrumentation is more effective than posterior instrumentation for reducing the deformity and stabilizing the vertebral column in patients who have kyphosis related to tuberculosis of the spine.

The Spinal Nail

The biomechanics of a new spinal implant were evaluated and its dependence on an anterior strut graft was determined. Six fresh-frozen adult porcine spines were used. An L3 corpectomy was created. The spinal nail was inserted intraosseously into the middle column of the L2-L4 vertebral bodies in a trough. Implant drill holes were made for proximal and distal locking bolts in L2 and L4. A locking plate bridged the L2 and L4 trough and anchored the exposed ends of the locking bolts. Testing was performed in axial compression, torsion, and flexion. The axial and torsional stability of the spine instrumented with the spinal nail are similar to results with other devices when used with anterior strut grafting. The axial and flexural stiffnesses of the instrumented spine are independent of strut grafting. This study suggests that this device may be useful for reconstruction of the anterior spine because of instability.

Surgical treatment of severe L5-S1 spondylolisthesis in children and adolescents. Results of intraoperative reduction, posterior interbody fusion, and segmental pedicle fixation.

A retrospective study was done in 12 teenagers with severe L5-S1 spondylolisthesis surgically treated with a single-stage posterior procedure for reduction, posterior interbody fusion, and segmental instrumentation. To evaluate the effectiveness and reliability of intraoperative reduction and posterior interbody fusion in severe lumbosacral spondylolisthesis in children. Twelve young patients (age, 13-18 years; mean = 16 +/- 1.5) with severe L5-S1 spondylolisthesis (slip, 59%-85%; mean = 70.4 +/- 8.8%) were available for follow-up evaluation (6-24 months after surgery). All presented with serious preoperative clinical signs (tight hamstrings, waddling gait, lumbosacral pain, radiated leg pain). The patients underwent surgery using a single posterior surgical procedure. After removal of the loosened arch and complete discectomy, a temporary device placed bilaterally between L1 and the sacral wings was used to achieve reduction by distraction. This was followed by a posterior interbody strut graft and pedicle segmental fixation. No postoperative casting was used. Clinical examination was done, and radiographic measurements were taken after surgery and at follow-up evaluation. Patients were evaluated for fusion rate, stability of reduction, clinical outcome, and possible complications. All patients underwent solid fusion without loss of reduction. No intraoperative or postoperative complications were observed. Mean correction of the initial slipping was 79.5 +/- 7% of the initial deformity. No clinical signs were present at follow-up evaluation. Intraoperative distraction appears to be truly effective in reducing severe lumbosacral olyshtesis in children. Posterior interbody fusion (and eventual sacral dome osteotomy) successfully combines the goals of solid fusion with the requirements of root decompression. No neurologic problems were seen as a consequence of distraction. The solidity of the posterior segmental pedicle instrumentation combined with the anterior strut graft eliminate the need for postoperative casting.

Short-segment pedicle instrumentation. Biomechanical analysis of supplemental hook fixation.

This biomechanical study of fractures in cadaver vertebrae used specially designed pedicle screws to determine screw strains during loading of two different fixation constructs. The authors determined the relative benefit of adding offset sublaminar hooks to standard pedicle screw constructs to reduce screw bending moments and prevent fixation failure and sagittal collapse. Clinical studies have demonstrated a high incidence of early screw failure in short-segment pedicle instrumentation constructs used to treat unstable burst fractures. Strategies to prevent early construct failure include longer constructs, anterior strut graft reconstruction, and use of offset sublaminar hooks at the ends of standard short-segment pedicle instrumentation constructs. Human cadaver spines with an L1 burst fracture were instrumented with a standard short-segment pedicle instrumentation construct using specially instrumented pedicle screws. Mechanical testing was carried out in flexion, extension, side bending, and torsion, and stiffness and screw bending moments were recorded. Offset hooks were applied initially, then removed and testing repeated. Stiffness data were compared to intact and postfracture results, and between augmented and standard constructs. Addition of offset laminar hooks, supralaminar at T11 and infralaminar at L2, to standard short-segment pedicle instrumentation constructs increased stiffness in flexion by 268%, in extension by 223%, in side bending by 161%, and in torsion by 155% (all were significant except torsion). Sublaminar hooks also reduced pedicle screw bending moments to roughly 50% of standard in both flexion and extension (P < 0.05). Supplemental offset hooks significantly increase construct stiffness without sacrificing principles of short-segment pedicle instrumentation, and absorb some part of the construct strain, thereby reducing pedicle screw bending moments and the likelihood of postyield deformation and clinical failure.

ペディクルスクリュー（ＰＳ）を用いた下位腰椎破裂骨折に対する手術成績の検討

We reviewed clinical and radiological results of five patients with lower lumbar burst fractures treated by pedicle screws. All patients achieved successful union of the fracture with good alignment and improved their neurological deficits as well as reducing their low back pain. Posterior decompression with reduction of the prolapsed fracture fragment in the spinal canal was useful for treating patients who underwent surgery within four weeks from the time of injury. It may be possible to preserve the lower disc segment in Dennis type B fractures by using posterolateral fusion of the upper disc segment only. To achieve earlier mobility, and reduce the period of bed-rest required, anterior strut grafting may be needed in patients with a burst fracture whose spinal bodies and upper and lower discs are severely destroyed including those with Dennis type D fractures.

Effects of anterior vertebral grafting on the traumatized lumbar spine after pedicle screw-plate fixation.

This study was conducted to determine the effects of corpectomy and anterior strut grafting on the biomechanics of traumatized lumbar spine after pedicle screw-plate fixation. Eight lumbar spines were loaded until fracture (initial cycle) and then reloaded to the same deformation (injury cycle). After transpedicular fixation, spines were again loaded (fixation cycle). Partial corpectomy of the fractured body and anterior strut grafting were accomplished; the spine reloaded (strut cycle). Spine angles were measured and biomechanical strength and kinematic parameters analyzed. Load-deformation relationships were similar for fixation and strut cycles until maximum load; at failure, loads were higher for the former (P < 0.05), however. Alignment was improved by stabilization or stabilization plus anterior grafting (P < 0.05). Vertebral height was best maintained by grafting as an adjunct to pedicle fixation (P < 0.05). Kinematics were largely unaffected by grafting, except for reduced motion at the posterior vertebral targets between the fixated levels (P < 0.05). The strength of the fixated spine is relatively unchanged by corpectomy and anterior grafting; alignment may be improved in the latter group.

血管柄付遊離ひ骨を用いたａｎｔｅｒｉｏｒ ｓｔｒｕｔ ｇｒａｆｔの経験

For the treatment of kyphoscoliosis of the spine associated with tuberculosis or neurofibromatosis, it must be required to get much stronger strut graft concomitantly with posterior instrumentation of the spine. Five cases (2 tuberculosis, 2 neurofibromatosis and 1 thoracolumbar OPLL) were treated by free vascularized fibular grafts as anterior strut grafts. An average length of the grafted fibula was 9.9cm (maximal length, 12.5cm). The nutrient arteries of the fibula were anastomosed with the thoracodorsal artery in one case and the lumbar arteries in 4 cases. Four out of 5 cases obtained good bony union and 3 cases showed increase in diameter of the grafted fibulae at an average follow-up period of 15.2 months. In conclusions, this free vascularized fibular grafting is a good procedure to get stability of the spine in combination with posterior instrumentation for the unstable spine associated with tuberculosis, neurofibromatosis, etc.

Decompression and circumferential stabilization of unstable spinal fractures.

A technique of anterior decompression of the spinal canal with anterior strut grafts, followed by posterior instrumentation and local fusion, is described in a group of 18 patients with unstable thoracolumbar fractures. All patients were found to have greater than 50% encroachment of the spinal canal and a preoperative kyphosis of 21.8 degrees. At follow-up 81% of patients with incomplete neurological lesions improved at least one Frankel Grade. Residual encroachment on the spinal canal was 4.6% and at follow-up the kyphotic angle was 17.1 degrees. Complications included one anterior graft loosening (not requiring revision), three loosened rods, only one of which required revision, and one fractured Harrington rod which did not require revision. The authors conclude that this technique is an effective and safe method for treating unstable thoracolumbar injuries and is recommended if anterior instrumentation is unavailable.

Treatment of kyphosis and lumbar stenosis in achondroplasia.

In summary, neurological symptoms in the achondroplast are related to the anatomical spinal canal with degenerative changes and aging altering the delicate biomechanical and microvascular balance. An accurate and detailed history is necessary for diagnosis. Decompression is via a posterior approach with a multi-level wide laminectomy with undercutting of the facets and usually multi-level foraminotomies. Kyphosis when present at the time of decompression, or if angular or progressive, requires treatment. A combined two-stage approach with an anterior disc excision and fusion combined with a posterior and posterolateral fusion is the treatment of choice. In angular deformities anterior strut grafting is indicated. The use of instrumentation posteriorly is contraindicated with the possible exception of transpedicular fixation. The instrumentation stabilizes the spine and does to correct the deformity. Using this approach the kyphosis in the achondroplast and the symptomatic spinal stenosis are adequately treated.

外傷性脊椎損傷に対するｔｒａｎｓｐｅｄｉｃｕｌａｒ Ｚｉｅｌｋｅ ｆｉｘａｔｉｏｎの試み

We have been using spinal instrumentation across the unfused vertebrae in the treatment of thoracolumbar fractures. But it was hoped that only injured level was internally immobilized and fused. Three cases of thoracolumbar spinal injuries were treated by anterior decompression and fusion combined with posterior transpedicular. Zielke fixation between injured levels: the first lumbar bursting fracture, the second lumbar bursting fracture, and fracture-dislocation of the twelfth thoracic spine on the first lumbar spine. Transpedicular instrumentation with anterior strut graft gave sufficient stabilization to the unstable spinal segment.

Reconstruction of the cervical spine following anterior vertebral body resection: a mechanical analysis of a canine experimental model.

In some quadriplegic patients whose acute spinal injury consists of a vertebral body fracture with bony retropulsion anteriorly and ligamentous damage posteriorly, it is appropriate to perform a decompression of the injured spinal cord by excision of the fractured body. Reconstruction of such a spine to achieve immediate and ultimate stability can be quite difficult. This is a report of mechanical testing using a canine in vitro experimental model to simulate different general types of reconstruction systems applicable to the spine destabilized as above. The results explain some of the previously noted failures of the traditional anterior strut grafting procedures. In addition, one of the reconstruction systems tested (anterior and posterior tension bands compressing an anterior strut graft into place) appeared to have sufficient immediate stability to eliminate the need for a halo-vest in the postoperative period. If such a reconstruction system were to prove clinically applicable, it would be quite beneficial to the quadriplegic patient in his rehabilitation.

TWO-STAGE RESECTION AND SPINAL STABILIZATION FOR ANEURYSMAL BONE CYST. A REPORT OF TWO CASES

Two cases of aneurysmal bone cyst of the dorsal lumbar spine are presented with four- and seven-year follow-up periods. The lesion in each case involved the vertebral bodies and posterior elements and extended to contiguous bony structures. Both anterior and posterior staged procedures were required for maximal excision, rendering the spine extremely unstable at the involved levels. Anterior strut grafting with autogenous iliac bone was done during the first stage after the vertebral bodies had been curetted. Three weeks later the remaining dorsal elements and associated tumor were removed through a posterior approach, and the spine was stabilized with the Harrington compression-distraction system and posterior autogenous iliac crest grafts. Both patients were neurologically normal after operation, and the spines in both were stable and solidly fused. Both have remained symptom-free and have had no evidence of recurrence.

Two-stage Resection and Spinal Stabilization for Aneurysmal Bone Cyst

Two cases of aneurysmal bone cyst of the dorsal lumbar spine are presented with four- and seven-year follow-up periods. The lesion in each case involved the vertebral bodies and posterior elements and extended to contiguous bony structures. Both anterior and posterior staged procedures were required for maximal excision, rendering the spine extremely unstable at the involved levels. Anterior strut grafting with autogenous iliac bone was done during the first stage after the vertebral bodies had been curetted. Three weeks later the remaining dorsal elements and associated tumor were removed through a posterior approach, and the spine was stabilized with the Harrington compression-distraction system and posterior autogenous iliac crest grafts. Both patients were neurologically normal after operation, and the spines in both were stable and solidly fused. Both have remained symptom-free and have had no evidence of recurrence.

Anterior strut-grafting for treatment of kyphosis.

Anterior strut-grafting for treatment of kyphosis.

Anterior strut-grafting for the treatment of kyphosis. Review of experience with forty-eight patients.

Anterior strut-grafting was used in forty-eight patients to treat structural kyphosis of the thoracic and lumbar spine. Forty patients had a combined anterior and posterior arthrodesis. Kyphosis was corrected from an average of 93 degrees preoperatively to an average of 59 degrees at follow-up. Eight patients underwent anterior cord decompression, five of whom showed improvement of neural function at follow-up. Ten patients had a loss of correction averaging 19 degrees. In four patients a pseudarthrosis developed at the strut graft-vertebral body junction. The strut graft fractured in five of nine patients in whom the graft was four centimeters or more from the apical vertebra. Complications were frequent, but for the most part they were thought to have been preventable. Anterior strut-grafting appears to be a valid and logical technique for managing structural kyphosis.