Loss Of Sagittal Alignment Research Articles

BIPLANAR IMAGING WITH TRIDIMENSIONAL CAPABILITIES: APPLICABILITY OF THIS NEW EXAMINATION TO SPINAL DEFORMITIES

ABSTRACT This study presents details about the applicability of the new image acquisition system, called the biplanar imaging system, with three-dimensional capabilities (EOS®) to the treatment of spinal deformities. This system allows radiographic acquisition of the entire body, with a great reduction in the dose of radiation absorbed by the patient and three-dimensional (3D) stereoradiographic image reconstruction of bone structures, including the spine. In the case of adolescent idiopathic scoliosis, the analysis of the spinal deformity with 3D reconstruction allows better understanding of the deformity and surgical planning. In the case of adult spinal deformity, full-body analysis allows an evaluation of the spinopelvic deformity, including loss of sagittal alignment, in addition to an evaluation of compensatory mechanisms recruited by the individual in an attempt to maintain the sagittal balance. Level of evidence III; Descriptive Review.

Reduction of intradiscal pressure by the use of polycarbonate-urethane rods as compared to titanium rods in posterior thoracolumbar spinal fixation

Loss of sagittal alignment and balance in adult spinal deformity can cause severe pain, disability and progressive neurological deficit. When conservative treatment has failed, spinal fusion using rigid instrumentation is currently the salvage treatment to stop further curve progression. However, fusion surgery is associated with high revision rates due to instrumentation failure and proximal junctional failure, especially if patients also suffer from osteoporosis. To address these drawbacks, a less rigid rod construct is proposed, which is hypothesized to provide a more gradual transition of force and load distribution over spinal segments in comparison to stiff titanium rods. In this study, the effect of variation in rod stiffness on the intradiscal pressure (IDP) of fixed spinal segments during flexion-compression loading was assessed. An ex vivo multisegment (porcine) flexion-compression spine test comparing rigid titanium rods with more flexible polycarbonate-urethane (PCU) rods was used. An increase in peak IDP was found for both the titanium and PCU instrumentation groups as compared to the uninstrumented controls. The peak IDP for the spines instrumented with the PCU rods was significantly lower in comparison to the titanium instrumentation group. These results demonstrated the differences in mechanical load transfer characteristics between PCU and titanium rod constructs when subjected to flexion-compression loading. The concept of stabilization with a less rigid rod may be an alternative to fusion with rigid instrumentation, with the aim of decreasing mechanical stress on the instrumented segments and the possible benefit of a decrease in the incidence of screw pullout.Graphical abstract

Effectiveness of pedicle screw inclusion at the fracture level in short-segment fixation constructs for the treatment of thoracolumbar burst fractures: a computational biomechanics analysis

When treating thoracolumbar burst fractures (BF), short-segment posterior fixation (SSPF) represents a less invasive alternative to the traditional long-segment posterior fixation (LSPF) approach. However, hardware failure and loss of sagittal alignment have been reported in patients treated with SSPF. Including pedicle screws at the fracture level in SSPF constructs has been proposed to improve stiffness and reliability of the construct. Accordingly, the biomechanical performance of the proposed construct was compared to LSPF via a computational analysis. Pedicle screws at fracture level improved the performance of the short-segment construct. However, LSPF still represent a biomechanically superior option for treating thoracolumbar BF.

Sagittal plane deformity: Evaluation and management

Sagittal alignment is a critical component of the evaluation and management of adult spinal deformities. Loss of sagittal alignment may be the result of iatrogenic-induced deformity, metabolic bone problems, progression of idiopathic or neuromuscular deformities, posttraumatic, or de novo. Goals of reconstruction involve restoration of global sagittal balance and lumbopelvic harmony. Treating the deformity often involves long construct fusion to the sacropelvis. Often times, multilevel osteotomies as well as circumferential approaches are needed to adequately address the deformity. Failure to address sagittal plane deformities has been linked to poor patient reported outcomes from surgical management. However, even with correction, postoperative complications are common. These included proximal and distal junctional failure, pseudoarthrosis, and the need for future surgery.

Postoperative Changes in Spinal Rod Contour in Adolescent Idiopathic Scoliosis

Prospective case series. To evaluate the change in spinal rod contour from before implantation to after surgical correction of thoracic curves in patients with adolescent idiopathic scoliosis. With segmental pedicle screw spinal instrumentation and vertebral derotation, many authors have reported a loss of thoracic kyphosis postoperatively. Although surgeons anticipate some flattening of the preimplantation rod contour in the sagittal plane, the magnitude of this change in shape has not been documented. The concave and convex rod shapes of 5.5-mm ultrahigh-strength steel spinal rods (200 KSI) from patients with thoracic adolescent idiopathic scoliosis (n = 27), which were contoured with benders by the surgeon, were traced prior to insertion. Postoperative (average, 5 weeks) sagittal rod shape was determined from lateral 2-dimensional radiographs. Maximal rod deflection and angle of the tangents to rod end points (Cobb) were measured. Repeated measures analysis of variance assessed differences between pre- and postoperation. The scoliosis of 55° ±14° was corrected 72% to 15° ± 5°. The preinsertion rod shapes were more kyphotic for the concave (45.6°) than for the convex (31.4°) rods. Following correction, the concave rods flattened, with decrease in deflection of 13 mm and reduction in angle of 21° (both P < 0.001). The convex rods increased 1.5 mm in deflection and 2° in angle (P < 0.01, P = 0.18). The sagittal profile was maintained postoperatively as measured from T5-T12: 19° ±14° versus 22° ± 6° (pre vs. post, P > 0.1). We found a significant difference between pre- and postoperative rod contour, particularly for concave rods. Rod overcontouring (by ~20° for concave rod) resulted in high degrees of correction without loss of sagittal alignment. The resulting deformations are likely associated with substantial in vivo deforming forces.

Anterior corpectomy and reconstruction with titanium mesh cage and dynamic cervical plate for cervical spondylotic myelopathy in elderly osteoporosis patients

This retrospective study was to evaluate the relationship between osteoporosis and dynamic cervical plates in screw-plate or screw-bone interface of elderly cervical spondylotic myelopathy (CSM) patients. Retrospective study was conducted on elderly CSM patients, treated by anterior corpectomy and reconstruction with titanium mesh cages (TMC) and dynamic cervical plate between July 2004 and June 2007. All patients underwent bone mineral density (BMD) assessment in preoperation, and according to the osteoporosis degree they have been divided into two groups: moderate osteoporosis degree group and severe osteoporosis degree group. The clinical outcome [Japanese Orthopaedic Association score (JOA) and Visual Analogue Scale (VAS)], bone fusion assessment (CT mielogram), the change of titanium mesh cages and plate of cephalic screw-plate-angle (SPA) and cephalic endplate-plate-angle (EPA) of plain X-ray films were measured. The mean JOA score and recovery rate were not different between the two groups (P > 0.05). There was no loss of sagittal alignment after surgery in any patient, and no significant difference between both groups on lordosis measurements (P > 0.05). Although there was a significant difference of the cage subsidence rate between the two groups (P < 0.001), all patients had favorable bone union and none required additional treatment. The average changes of SPA were greater in A group patients than in B group patients, while the variation of EPA was higher in B group patients than in A group patients (P < 0.001). Despite the fact that there is a significant difference of the cage subsidence rate between the two groups no clinical outcome, nor sagittal alignment or fusion rate differences among groups was observed in elderly CSM patients.

Single-Stage Treatment of Pyogenic Spinal Infection With Titanium Mesh Cages

Single institution retrospective review. To report a series of pyogenic spinal infections treated with single-stage debridement and reconstruction with titanium mesh cages. Various studies have reported surgical results of pyogenic spinal osteomyelitis with anterior debridement, strut grafting and fusion, including delayed posterior spinal instrumentation. Additionally, various authors have recommended against the use of instrumentation because of the concern about glycocalyx formation on the metal and chronic infection. At our institution, we routinely treat chronic vertebral osteomyelitis with single-stage debridement, reconstruction with a titanium mesh cage filled with allograft chips and demineralized bone matrix, and posterior pedicle screw instrumentation. To our knowledge, this is the largest single series reporting single-stage debridement and instrumentation of pyogenic spinal infection with titanium mesh cages and posterior instrumentation. We retrospectively reviewed the patient records and radiographs of 21 consecutive patients (average age 49.3 years, range 23 to 80 years) with pyogenic vertebral osteomyelitis, all treated with titanium mesh cages. Average follow-up was 44 months (range, 25 to 70 months). Spinal levels included 6 thoracic, 4 thoracolumbar, 9 lumbar, and 2 lumbosacral (L5-S1) lesions. All patients had preoperative serum evaluation, which usually included blood cultures, complete blood count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), in addition to plain radiographs and magnetic resonance imaging. A positive needle biopsy was available in only 2/7 patients (29%), and overall, preoperative pathogen identification was available in only 7/21 patients (33%). All patients were treated postoperatively with a minimum of 6 weeks of intravenous antibiotics, with a specific antibiotic regimen directed toward the postoperative pathogen when identified (17/21 cases). Extensive radiographic evaluation was also performed. ESR and CRP were routinely elevated (18/20 and 11/17 cases respectively), whereas the white blood count was elevated in only 8 out of 21 cases (38%). The average duration of symptoms to diagnosis was approximately 13.6 weeks (range 3 weeks to 10 months). The indications for surgery included neurologic compromise, significant vertebral body destruction with loss of sagittal alignment, failure of medical treatment, and/or epidural abscess. All patients had resolution of infection, as noted by normalization of the ESR and CRP. Further, 16 out of 21 patients also had a significant reduction of pain. There were no deaths or new postoperative neurologic compromise. The most common pathogen was Staphylococcus aureus. Two patients required a second surgery (posterior irrigation and debridement) during the same admission for persistent wound drainage. Radiographically, the average segmental kyphosis (or loss of lordosis) was 11.5 degrees (range, 0 to 24 degrees) preoperatively, and +0.8 degrees (range, -3 to +5 degrees) at latest postoperative follow-up. There was an average of 2.2 mm cage settling (range, 0 to 5 mm) on latest follow-up. There were no instrumentation failures, signs of chronic infection, or rejection. Titanium mesh cages present a viable option for single-stage anterior surgical debridement and reconstruction of vertebral osteomyelitis, without evidence of chronic infection or rejection. When used in conjunction with pedicle screw instrumentation, there is minimal cage settling without loss of sagittal alignment.

Lateral mass screw fixation for cervical spine trauma: associated complications and efficacy in maintaining alignment

Background context Many studies have documented the efficacy of lateral mass screws, but there are no studies examining the alignment maintenance capability and few large studies examining the complications associated with the use of these devices in cervical spine trauma. Purpose To evaluate complications and alignment maintenance capability associated with lateral mass screw placement for cervical spine trauma by one surgeon at one institution. Study design A retrospective chart and radiograph review of adult patients who underwent lateral mass screw fixation after traumatic injuries to the cervical spine. Patient sample Of 34 consecutive patients with cervical spine injuries who were treated surgically at a level-I regional trauma center, 29 met the inclusion criteria and formed the study group. Outcome measures Sagittal alignment, screw placement, and fusion were assessed on postoperative radiographs. Methods Inclusion criteria included an unstable cervical vertebral fracture or a fracture-dislocation treated with posterior spine fusion and lateral mass instrumentation and a minimum follow-up of 24 months. A review of hospital charts, operative reports, clinic notes, and plain radiographs for the 29 patients was performed, with an emphasis on operative and postoperative complications and alignment maintenance. Results For 28 of the 29 patients, the mean change in sagittal alignment from the immediate postoperative to the most recent follow-up radiographic examination was 2° (range, 0° to 6°). Radiographically, there was one case of instrumentation/fixation failure and loss of sagittal alignment 3 months postoperatively. Other complications included one case of C5 nerve root injury and four wound infections. Conclusions The use of lateral mass screws for traumatic injuries of the cervical spine is associated with excellent maintenance of alignment and minimal complications.

最近の脊椎カリエスに対する手術例の検討

Nine patients with thoracic and lumbar tuberculosis were treated by anterior debridement and fusion. Subjects included 4 males and 5 females, 58 to 75 years old (average age 67.2 years old). We added posterior fusion with instrumentation to 6 patients by pedicle screw or hook system. None showed persistent or recurrent spine tuberculosis despite posterior instrumentation. The 6 patients with posterior instrumentation were able to get out of bed about 37 days earIier than the 3 without posterior instrumentation. Loss of sagittal alignment was not greater than 10 degrees in 8 patients but reached 27 degrees in one patient who developed postoperative vertebral compression fracture above the posteriorly-stabilized vertebra. All patients achieved stable bone union with satisfactory results.

Unconventional pedicle spinal instrumentation. The Bombay experience.

A retrospective study of all patients who underwent spinal fusion between 1986 to 1989 with inexpensive, locally made unconventional pedicle spinal instrumentation systems was undertaken. Implants were made with passivated 316L stainless steel, and a single level of instrumentation cost +f430. To demonstrate that simple, cheap pedicle instrumentation systems are as effective as the conventionally available expensive systems, provided proper anterior column support is maintained. Ninety out of 102 patients were available for review. Average follow-up was 41 months (range, 22 to 60 months). Implant failures, screw placement, fusion rates, infection, neurologic deficit due to the implant, patient satisfaction, and the benefit of anterior column grafting with the unconventional pedicle spinal instrumentation systems in the long term were evaluated. Forty-four out of 467 screws failed (9%) in 16 patients, seven of whom were symptomatic. There were no plate failures. On comparing burst fractures with (n = 12) and without (n = 10) anterior column grafting, the latter group had a significant increase in implant failures, loss of sagittal alignment, and the time required to fusion. Overall, fusion occurred within 6.5 months. Anterior column reconstruction in anterior column deficient spines will re-create the normal biomechanics and significantly reduce the incidence of implant failures and loss of sagittal alignment with these systems. Pedicle screw failure in itself is not necessarily associated with a bad result. These inexpensive, locally made unconventional systems, with the proper understanding of biomechanics and creation of appropriate load-sharing constructs, are as good as the conventional systems available today.