Correction Of Pelvic Obliquity Research Articles

Biomechanical Comparison of Spinopelvic Fixation Constructs: Iliac Screw Versus S2-Alar-Iliac Screw

Study DesignBiomechanical cadaveric study. ObjectiveTo compare the biomechanical properties of the iliac and S2-Alar-Iliac (S2AI) screw in a similar spinopelvic fixation construct. Summary of Background DataSpinopelvic fixation is used in the correction of pelvic obliquity, high-grade spondylolisthesis, and long spinal fusions. With the development of pedicle screw fixation, the iliac screw has been used as an anchor point to the pelvis. The associated morbidity with this fixation has led to the development of the S2AI screw. Many studies have examined the biomechanical properties of iliac and S2AI screws; however, a direct comparison has not been performed. MethodsEight cadaveric spines were instrumented with pedicle screws bilaterally at L5 and S1. Four specimens were further instrumented with iliac screws placed with a starting point at the posterior superior iliac spine, and four specimens were instrumented with S2AI screws placed with a starting point 1 mm inferolateral to the S1 foramen. Screws were connected with 6.35 mm rods. Subfailure testing was performed by loading at 1°/second to a torque of 10 Nm in four directions: left bending, right bending, extension, and flexion. Specimens then underwent a monotonic load to failure under flexion at a rate of 1°/second. ResultsThere were no significant differences for torsional stiffness in extension, flexion, left bending, or right bending between S2AI and iliac screw constructs. There were no significant differences in S2AI versus iliac screws for failure torque (30.9 ± 12.00 Nm vs. 22.61 ± 6.25 Nm) and yield torque (11.86 ± 0.41 Nm vs. 12.01 ± 1.70 Nm). ConclusionIliac screws have been associated with increased dissection, wound complications, an additional construct failure point, and hardware prominence. The S2AI screw was developed as an alternative and has been associated with less morbidity. The iliac and S2AI screw demonstrate no statistical difference in stiffness and load-to-failure in a spinopelvic fixation model. Level of EvidenceLevel V.

Does Pelvic Fixation Increase Morbidity and Mortality in Patients undergoing Posterior Lumbar Fusion?

Pelvic fixation is utilized for various indications including lumbosacral fixation for long fusions to the sacrum, correction of pelvic obliquity and high-grade spondylolisthesis. Due to the complex nature of such a procedure there is the potential for considerable morbidity.

Morbidity Associated with Pelvic Fixation in Patients Undergoing Fusion for Spinal Deformity: A Matched Propensity Adjusted Analysis

Pelvic fixation is utilized for various indications including lumbosacral fixation for long fusions to the sacrum, correction of pelvic obliquity and high-grade spondylolisthesis. Due to the complex nature of such a procedure there is the potential for considerable morbidity.

Early pelvic fixation failure in neuromuscular scoliosis.

To report on early failures of pelvic fixation in posterior spinal fusions for neuromuscular scoliosis. A retrospective review of posterior-only spinal instrumentation and fusion to the pelvis with iliac screws was performed. Forty-one patients with a mean age of 14 years and mean 16 levels fused met the inclusion criteria. Diagnoses include cerebral palsy (22), Duchenne muscular dystrophy (7), other neuromuscular (10), and spina bifida (2). Cox proportional hazards regression modeling was used to compare rates of failure. The mean preoperative primary Cobb angle was 82 degrees (range, 21 to 144 degrees). The pelvic obliquity correction was 76%. The fixation in the pelvis failed in 12/41 patients (29%). Failures include: screw head disengaged from screw shaft (5), iliac screw disengaged from rod (2), iliac connector disengaged from rod (2), iliac connector disengaged from iliac screw (4), and iliac screw loosened from bone (3). No failures occurred if there were at least 6 screws in L5, S1, and pelvis (0/7 patients). The failure rate with <6 screws in L5, S1, and pelvis was higher at 35% (12/34 patients) (P=0.16). When using traditional iliac screws with connectors to rods, all constructs had <6 screws in L5, S1, and pelvis. Only 1 failure occurred when S2-iliac screws were used, but was without clinical consequence. The mean time from surgery to failure was 18 months (range, 1 to 49 mo). Not placing bilateral pedicle screws at L5 and S1, in addition to 2 iliac screws, was associated with a 35% early failure rate of pelvic fixation. Level IV.

The Use of Intraoperative Traction in Pediatric Scoliosis Surgery: A Systematic Review

Study DesignSystematic review. ObjectiveTo study the morbidity and the potential benefits of using intraoperative skeletal traction as an adjunct method for correcting scoliosis. Summary of Background DataCotrel et al., used intraoperative skeletal traction in all patients in their original series of segmental spinal instrumentation for scoliosis correction (Cotrel et al., Clin Orthop Relat Res 1988;227:10–23). However, the use of intraoperative traction may introduce other forms of surgical morbidity, which has not been systematically studied. MethodsTwo independent reviewers searched MEDLINE (1948–current) and EMBASE (1980–current) using the keywords scoliosis, intraoperative, and traction in all fields, combined with AND. Studies were subject to full-text assessment against specific inclusion and exclusion criteria; discrepancies between the reviewers were resolved by a third independent reviewer. Data were extracted into standardized extraction tables and papers were critically appraised papers with regards to their relative strengths and weaknesses, with particular attention to the study objective. ResultsNine papers were included: case report (n = 1), retrospective case series (n = 2), retrospective case–control (n = 6), and studies included both adolescent idiopathic scoliosis (AIS) and neuromuscular scoliosis. Seven studies reported positive effects of intraoperative skeletal traction on diverse outcome measures, such as correction of pelvic obliquity, Cobb angle, and axial plane deformity, as well as precluding the need for an anterior release preceding posterior instrumentation for large curves. Overall, there was only one reported postoperative traction-related complication (anterosuperior iliac spine pressure sore). One paper reported that intraoperative traction may evoke neuromonitoring signal changes in a large proportion of patients undergoing AIS surgery. These changes were responded to intraoperatively by decreasing or removing weight and none of the patients had postoperative neurologic deficits. ConclusionIsolated intraoperative skeletal traction may be a low-morbidity adjunct to facilitate scoliosis surgery. Further studies are needed to compare outcomes of scoliosis surgery with or without intraoperative skeletal traction.

Correction of severe pelvic obliquity using maximum-width segmental sacropelvic screw fixation: an analysis of 20 neuromuscular scoliosis patients.

The present study was a retrospective analysis. The purpose of the study was to evaluate the safety and efficacy of the maximum-width (M-W) segmental sacropelvic fixation technique, comprising iliac screws and/or iliosacral pedicle screws, to correct severe pelvic obliquity. Classic spinal fixation using the Luque-Galveston procedure for the correction of neuromuscular scoliosis may be inadequate to manage severe pelvic obliquities. A series of 20 consecutive patients with severe neuromuscular spinopelvic deformities was reviewed by an independent observer. Coronal and sagittal Cobb angle, frontal pelvic obliquity, and trunk shift were measured preoperatively, immediately postoperatively and at final follow-up. All 20 patients underwent spinal fusion with instrumentation extending to the pelvis. Fourteen cases had primary operations, and six patients had undergone previous spinal fusion above the pelvis, requiring extension to the pelvis. The mean age of the patients at surgery was 13 years, and the mean duration of the follow-up period was 36 months. The mean preoperative Cobb angle was 84° (range 56°-135°), which was corrected to a mean of 41° (range 8°-75°) postoperatively. At the final follow-up, the mean spinal curve remained at 42° (range 10°-75°). The mean preoperative pelvic obliquity was 42° (range 15°-105°), which was corrected by 78 % to 9° (range 0°-49°) postoperatively, with a pelvic obliquity of 10° (range 2°-49°) at final follow-up. Comparing the results of the present study with results in the literature describing the Luque-Galveston or unit rod techniques, despite patients in the present study having a greater mean pelvic obliquity (42° compared with 21° in the literature), a 78 % correction was still achieved, which is similar and, in certain instances, superior to the results of other published case series (78 % compared with 53 %). Maximum-width (M-W) segmental sacropelvic fixation, comprising iliosacral screws and/or iliac screws, enables a superior correction of severe pelvic obliquity in patients with neuromuscular scoliosis.

Surgical Treatment of Scoliosis in Non-Ambulatory Spastic Quadriplegic Cerebral Palsy Patients: A Matched Cohort Comparison of Unit Rod Technique and All-Pedicle Screw Constructs

Study DesignMatched cohort. ObjectiveTo compare the unit rod instrumentation (UR) technique with all–pedicle screw (PS) constructs in the surgical care of scoliosis in Gross Motor Function Classification System IV/V non-ambulatory spastic quadriplegic cerebral palsy patients. Summary of Background DataOver the past 20 years, there has been a transition from the UR technique to the use of pedicle screws and iliac screws in neuromuscular scoliosis. To date, no head-to-head comparative analysis has been reported between the UR technique and PS constructs for posterior segmental spinal instrumentation and fusion in cerebral palsy patients. MethodsA matched cohort study was performed between 2 tertiary-care pediatric centers: 1 using UR technique and the other PS constructs. Minimum follow-up was 2 years postoperatively (PS 2.5 years, UR 4.6 years, not significant). Fourteen patients were matched from each center based on age (mean age: PS 15.4 years, UR 15.5 years), preoperative pelvic obliquity (mean: PS 33.8°, UR 29.1°) and major coronal Cobb angle (mean: PS 100.9°, UR 100.1°). ResultsThere was posterior-only surgery in 14 of 14 PS and 11 of 14 UR surgeries. The final follow-up Cobb angle was lower in the PS group (13.5° vs. 34.3°, p < .05), with 86.5% correction in the PS group and 65.7% in the UR group. Final follow-up pelvic obliquity was similar (PS 8.5° vs. UR 3.3°; not significant). There were no major complications in the PS group. In the UR group, there was 1 deep infection and 1 reoperation for removal of a prominent sublaminar wire. ConclusionsThis is the first study to directly compare UR with PS constructs using matched patient cohorts in this patient population. All–pedicle screw constructs had better correction of coronal Cobb angle, lower blood loss, and shorter hospital stays. There was no difference in the correction of pelvic obliquity, complications, or reoperations.

Correction of pelvic obliquity in neuromuscular spinal deformities using the “T construct”: results and complications in a prospective series of 60 patients

We present the results of a prospective series of 60 patients treated for neuromuscular spinal deformities with an original spinopelvic construct using two sacral screws and two iliac screws. Clinical and radiological results obtained with this new surgical technique were studied and discussed according to the epidemiological data and relevant literature. From January 2008 to June 2010, the clinical data of every patient who underwent spinopelvic fixation for treatment of a neuromuscular spinal deformity were recorded prospectively. Sixty patients were operated on during the study period. Spinal correction and fusion was performed by posterior approach. In six patients with a residual spinopelvic imbalance more than 15° on lateral preoperative bending films, an anterior release of the thoracolumbar junction was performed on the same day, before posterior correction. Preoperative pelvic obliquity (PO) ranged from 4° to 44° (mean 21.6°). Postoperative pelvic obliquity ranged from 0° to 14 (mean 4.6°). No significant loss of correction was noted at the last follow-up. One patient died 3months after the initial procedure due to respiratory compromise. 11 patients had early postoperative infections of the posterior approach. Despite a high rate of infectious complications, optimal correction of pelvic obliquity requires extension of spinal instrumentation to the pelvis. Spinopelvic fixation remains a difficult challenge in neurological patients with hypotrophy. We think that pelvic fixation with the "T construct" did provide effective and improved spinal stabilization in these patients, while reducing the need for a postoperative cast or brace. As a result, patients had a favourable postoperative course with early mobilization and return to a comfortable sitting position.

Surgical Technique for Balancing Posterior Spinal Fusions to the Pelvis Using the T Square of Tolo

Correcting pelvic obliquity and improving sitting balance in neuromuscular scoliosis often requires fixation to the pelvis. We describe the use of a T square instrument to assist intraoperatively in evaluating the alignment of these curves and achieving balance in the coronal plane. The T square instrument was constructed with a vertical limb perpendicular to 2 horizontal limbs in a T formation. At the conclusion of the instrumentation and preliminary reduction maneuvers, the T square was positioned with the horizontal limbs parallel to the pelvis and the vertical limb in line with the central sacral line. If the spine and pelvis were well balanced, fluoroscopic images demonstrated that the superior aspect of the vertical limb of the T square was crossing the vertebral body of T1. If this was not shown, then some combination of compression, distraction, or a change in the contouring of the rods was performed until this balance was achieved. In this series, we describe case examples in which the T square has been successfully used to aid in achieving balance in the coronal plane. This technique helps to overcome the challenges with positioning and imaging often encountered in managing these long, rigid curves. The T square is a useful adjunct in balancing posterior spinal fusions and evaluating the correction of pelvic obliquity in cases of neuromuscular scoliosis. This novel, yet simple, T square technique can be used for any method of posterior spinal fusion with lumbopelvic fixation to assist in the intraoperative evaluation and achievement of balance in the coronal plane and has become routine at our institution. IV.

Treatment of Neuromuscular Scoliosis with Posterior Spinal Fusion Using the Galveston Procedure: Retrospective of Eight Years of Experience with Unit Rod Instrumentation

Posterior spinal fusion with instrumentation to the pelvis (the Galveston Procedure) is widely accepted as an effective treatment for neuromuscular scoliosis. Unit rod instrumentation is commonly used in these cases, but it is not universally accepted as superior to separate Luque rods. This study is a retrospective review of 115 consecutive cases in which the unit rod was used. The following statistics were collected from the records of these patients: operative time, estimated blood loss, PICU stay, hospital stay, transfusion rate, complication rate, scoliosis correction, and correction of pelvic obliquity . Results at 2-year follow-up were compared to those reported in the literature and to results previously reported from the same facility in which separate Luque rods were used. The unit rod provides excellent control of pelvic obliquity and superior scoliosis correction compared with separate Luque rods. Improvements were also found in reduced operative times, lower blood loss, a lower complication rate, and shorter hospital stay.

Cotrel–Dubousset instrumentation in neuromuscular scoliosis

The study design is retrospective. The aim is to describe our experience about the treatment of patients with neuromuscular scoliosis (NMS) using Cotrel-Dubousset instrumentation. Neuromuscular scoliosis are difficult deformities to treat. A careful assessment and an understanding of the primary disease and its prognosis are essential for planning treatment which is aimed at maximizing function. These patients may have pelvic obliquity, dislocation of the hip, limited balance or ability to sit, back pain, and, in some cases, a serious decrease in pulmonary function. Spinal deformity is difficult to control with a brace, and it may progress even after skeletal maturity has been reached. Surgery is the main stay of treatment for selected patients. The goals of surgery are to correct the deformity producing a balanced spine with a level pelvis and a solid spinal fusion to prevent or delay secondary respiratory complications. The instrumented spinal fusion (ISF) with second-generation instrumentation (e.g., Luque-Galveston and unit rod constructs), are until 1990s considered the gold standard surgical technique for neuromuscular scoliosis (NMS). Still in 2008 Tsirikos et al. said that "the Unit rod instrumentation is a common standard technique and the primary instrumentation system for the treatment of pediatric patients with cerebral palsy and neuromuscular scoliosis because it is simple to use, it is considerably less expensive than most other systems, and can achieve good deformity correction with a low loss of correction, as well as a low prevalence of associated complications and a low reoperation rate." In spite of the Cotrel-Dubousset (CD) surgical technique, used since the beginning of the mid 1980s, being already considered the highest level achieved in correction of scoliosis by a posterior approach, Teli et al., in 2006, said that reports are lacking on the results of third-generation instrumentation for the treatment of NMS. Patients with neuromuscular disease and spinal deformity treated between 1984 and 2008 consecutively by the senior author (G.D.G.) with Cotrel-Dubousset instrumentation and minimum 36 months follow-up were reviewed, evaluating correction of coronal deformity, sagittal balance and pelvic obliquity, and rate of complications. 24 patients (Friedreich's ataxia, 1; cerebral palsy, 14; muscular dystrophy, 2; polio, 2; syringomyelia, 3; spinal atrophy, 2) were included. According the evidence that the study period is too long (1984-2008) and that in more than 20 years many things changed in surgical strategy and techniques, all patients were divided in two groups: only hooks (8 patients) or hybrid construct (16 patients). Mean age was 18.1 years at surgery (range 11 years 7 months-max 31 years; in 17 cases the age at surgery time was between 10 and 20 years old; in 6 cases it was between 20 and 30 and only in 1 case was over 30 years old). Mean follow-up was 142 months (range 36-279). The most frequent patterns of scoliosis were thoracic (10 cases) and thoracolumbar (9 cases). In 8 cases we had hypokyphosis, in 6 normal kyphosis and in 9 hyperkyphosis. In 8 cases we had a normal lordosis, in 11 a hypolordosis and in 4 a hyperlordosis. In 1 case we had global T4-L4 kyphosis. In 8 cases there were also a thoracolumbar kyphosis (mean value 24°, min 20°-max 35°). The mean fusion area included 13 vertebrae (range 6-19); in 17 cases the upper end vertebra was over T4 and in 11 cases the lower end vertebra was over L4 or L5. In 7 cases the lower end vertebra was S1 to correct the pelvic obliquity. In 5 cases the severity of the deformity (mean Cobb's angle 84.2°) imposed a preoperative halo traction treatment. There were 5 anteroposterior and 19 posterior-only procedures. In 10 cases, with low bone quality, the arthrodesis was performed using iliac grafting technique while in the other (14 cases) using autologous bone graft obtained in situ from vertebral arches and spinous processes (in all 7 cases with fusion extended until S1, it was augmented with calcium phosphate). The mean correction of coronal deformity and pelvic obliquity averaged, respectively, 57.2% (min 31.8%; max 84.8%) and 58.9% (mean value preoperative, 18.43°; mean value postoperative, 7.57°; mean value at last follow-up, 7.57°). The sagittal balance was always restored, reducing hypo or hyperkyphosis and hypo or hyperlordosis. Also in presence of a global kyphosis, we observed a very good restoration (preoperatory, 65°; postoperatory, 18° kyphosis and 30° lordosis, unmodified at last f.u.). The thoracolumbar kyphosis, when present (33.3% of our group) was always corrected to physiological values (mean 2°, min 0°-max 5°). The mean intraoperative blood lost were 2,100 cc (min 1,400, max 5,350). Major complications affected 8.3% of patients, and included 1 postoperative death and 1 deep infection. Minor complications affected none of patients. CD technique provides lasting correction of spinal deformity in patients with neuromuscular scoliosis, with a lower complications rate compared to reports on second-generation instrumented spinal fusion.

The “T-construct” for spinopelvic fixation in neuromuscular spinal deformities. Preliminary results of a prospective series of 15 patients

We present the results of a prospective series of 15 patients treated for neuromuscular spinal deformities with an original spinopelvic construct using two sacral screws and two iliac screws. Results were compared to a prospective cohort of 62 patients treated for neuromuscular spinal deformities by spinopelvic fixation using iliosacral screws. From November 2005 to June 2007, the clinical data of every patient who underwent spinopelvic fixation for treatment of a neuromuscular spinal deformity were recorded prospectively. Fifteen patients weighting less than 35 kg were operated on with a special segmental construct using two sacral screws and two iliac screws for pelvic anchorage. Sixty-two patients had spinopelvic fixation using iliosacral screws. Severity of the curve (Cobb angle) and reducibility were statistically equal in both groups. Operative time and blood loss were statistically identical in both groups. Curve correction was similar in both groups and postoperative pelvic obliquity ranged between 2° and 4°. No significant loss of correction was noted at the last follow-up. Fifteen patients had early postoperative infection of the posterior wound requiring re-operation. Despite a high rate of infectious complications, optimal correction of pelvic obliquity requires extension of spinal instrumentation to the pelvis. Pelvic fixation with the "T-construct" did provide effective and improved spinal stabilization in these patients, while reducing the need for a postoperative cast or brace. As a result, patients had a favorable postoperative course with early mobilization and return to a comfortable sitting position.

A new pelvic rod system for the surgical correction and fixation of pelvic obliquity in pediatric neuromuscular scoliosis

To describe surgical outcomes using the new device in pediatric neuromuscular scoliosis. All patients with neuromuscular disorders requiring surgery with pelvic fixation for the correction of scoliosis in the period 2002-2009 were operated by the new pelvic rod fixation device. Coronal and sagittal alignment before and after surgery until the latest follow-up were evaluated by standard X-rays. Intraoperative and postoperative complications were recorded. All 18 study patients (mean age at surgery 15years, range 10-27) achieved solid fusion at a mean follow-up of 41months. The coronal Cobb angle improved from 82°±31° (range 36-168) to 33°±25° at the last follow-up (range 9-95 months) (P<0.0001). Pelvic obliquity improved from 19°±6° (range 10-30) to 5°±5° (range 0-14) (P<0.0001). Early complications included pneumonia, urinary tract infection, disseminated intravascular coagulation (DIC), and hypovolemic shock. Three patients required debriding and received prolonged antimicrobial therapy for deep wound infection (none required implant removal). At the latest follow-up, no patient complained of lumbar pain or worsening of ambulatory status or level of activity. Surgery employing the new pelvic rod fixation device allowed solid fusion and fixation with significant correction of multiplanar deformity, but the complication rate was high.

Pelvic Obliquity in Neuromuscular Scoliosis

retrospective comparative study (Level III). to compare the operative results of posterior fusion and a 2-stage anterior L5-S1 fusion followed by posterior fusion in neuromuscular scoliosis patients with significant pelvic obliquity (PO). PO in neuromuscular scoliosis is common and a challenging problem that affects proper sitting balance, necessarily addressing the deformity and proper maintenance of the correction. a total of 54 patients with neuromuscular scoliosis and significant PO (>10°) were divided into 2 groups. Group 1 (n = 24) was operated on for posterior fusion and pelvic fixation. Group 2 (n = 30) included patients who were subjected to a first-stage procedure consisting of a lumbosacral junction release and fusion through a midline retroperitoneal approach and then a second-stage procedure of posterior fusion and pelvic fixation. Parameters measured included length of the follow-up, number of fusion levels, age at operation, forced vital capacity, operative time, estimated blood loss, and postoperative complications. Radiologic parameters measured before surgery, after surgery at the time of discharge, and at a final follow-up included Cobb angle, T1 translation, sitting pelvic obliquity (PO) in the frontal plane, C7 plumb line, thoracic kyphosis, lumbar lordosis, and sacral inclination angle in the sagittal plane. the correction of scoliosis was similar in both groups. The preoperative PO averaged 19.5° in Group I and 22.9° in Group II (P = 0.22), which corrected after surgery to 9.7° versus 7.4° (P = 0.23), respectively. Group II correction progressively improved significantly compared to Group I (7.0° vs. 11.6° at P = 0.046) at the latest follow-up. A 40.6% correction (mean correction = 7.9) in sitting PO in Group I compared to 70.7% correction (mean correction = 5.9°) in Group II was observed (P = 0.004). The average loss of correction of PO at the final follow-up was lesser in group II, but not statistically significant (P = 0.07). anterior fusion of the lumbosacral junction followed by posterior fusion provides superior correction and maintenance of PO in patients with neuromuscular scoliosis.

Low Profile Pelvic Fixation With the Sacral Alar Iliac Technique in the Pediatric Population Improves Results at Two-Year Minimum Follow-up

Retrospective review. Anchor stability and prominence are problems with pelvic fixation in pediatric spinal deformity surgery. We compared the new sacral alar iliac (SAI) fixation technique (with a starting point in the sacral ala and in-line anchors deep under the midline muscle flap) with other methods of screw fixation. Iliac anchors have been shown to provide the best form of pelvic fixation. A trajectory from the posterior sacral surface to the iliac wings has recently been described. To our knowledge, no clinical series has compared this method of pelvic fixation in children to others. Of 32 consecutive pediatric patients who underwent SAI fixation, 2 died and 26 returned for follow-up (>2 years). Mean age at surgery was 14 years. Average screw size was 67 mm long and 7 to 9 mm in diameter. Clinical examinations, radiographs, and computed tomography scans were analyzed. Outcomes included pain over the implants, screw placement, implant prominence, radiographic lucency, need for revision, and infection. SAI patients were compared with 27 previous patients who had pelvic fixation via other screw techniques. For SAI fixation, correction of pelvic obliquity and Cobb angles were 20° ± 11° (70%) and 42° ± 25° (67%), respectively. For other pelvic fixation methods, those values were 10° ± 9° (50%), and 46° ± 16° (60%), respectively. Compared with other screws, SAI screws provided significantly better pelvic obliquity correction (P = 0.002) but no difference in Cobb correction. There were 2 lucencies adjacent to screws in both groups. Computed tomography scans of 18 SAI patients showed no intrapelvic protrusion, but 1 screw extended laterally (<5 mm). One early SAI patient required revision with larger screws, which relieved pain; there was 1 revision in the comparison group. SAI patients had no deep infections, implant prominence, late skin breakdown, or anchor migration; traditional patients had 3 deep infections (P = 0.09) and 3 instances of implant prominence, skin breakdown, or anchor migration. SAI pelvic fixation produces better correction of pelvic obliquity than do previous techniques. Radiographic and clinical anchor stability is satisfactory at 2-year follow-up.

Can the caudal extent of fusion in the surgical treatment of scoliosis in Duchenne muscular dystrophy be stopped at lumbar 5?

Instrumentation and fusion to the sacrum/pelvis has been a mainstay in the surgical treatment of scoliosis in Duchenne muscular dystrophy (DMD) and is recommended to correct pelvic obliquity. The caudal extent of instrumentation and fusion in the surgical treatment of scoliosis in DMD has remained a matter of considerable debate, and there have been few studies on the use of segmental pedicle screw instrumentation for this pathology. From 2004 to 2007, a total of 28 patients with DMD underwent segmental pedicle screw instrumentation and fusion only to L5. Assessment was performed clinically and with radiologic measurements. All patients had a curve with the apex at L2 or higher preoperatively. Preoperative coronal curve averaged 74 degrees, with a postoperative mean of 14 degrees, and 17 degrees at the last follow-up. The pelvic obliquity improved from 17 degrees preoperatively to 6 degrees postoperatively, and 6 degrees at the last follow-up. Good sagittal plane alignment was recreated after surgery and maintained long term. In 23 patients with a preoperative L5 tilt of less than 15 degrees, the pelvic obliquity was effectively corrected to less than 10 degrees and maintained by adequately addressing spinal deformity, while five patients with a preoperative L5 tilt of more than 15 degrees had a postoperative pelvic obliquity of more than 15 degrees. Segmental pedicle screw instrumentation and fusion to L5 was effective and safe in patients with DMD scoliosis with a minimal L5 tilt (<15 degrees) and a curve with the apex at L2 or higher, both initially and long term, obviating the need for fixation to the sacrum/pelvis. Segmental pedicle screw instrumentation and fusion to L5 was safe and effective in patients with DMD scoliosis with stable L5/S1 articulation as evidenced by a minimal L5 tilt of less than 15 degrees, even though pelvic obliquity was significant. There was no major complication. With rigid segmental pedicle screw instrumentation, the caudal extent of fusion in the treatment of DMD scoliosis should be determined by the degree of L5 tilt. This method in appropriate patients can be a viable alternative to instrumentation and fusion to the sacrum/pelvis in the surgical treatment of DMD scoliosis.

Two-year results for scoliosis secondary to Duchenne muscular dystrophy fused to lumbar 5 with segmental pedicle screw instrumentation

BackgroundInstrumentation and fusion to the sacrum/pelvis has been a mainstay in the surgical treatment of scoliosis in patients with Duchenne muscular dystrophy since the development of the intrailiac post. It is recommended for correcting pelvic obliquity. However, caudal extent of instrumentation and fusion has remained a matter of considerable debate. This study was performed to determine the efficacy and safety of stopping segmental pedicle screw constructs at L5 during surgical treatment of scoliosis associated with Duchenne muscular dystrophy (DMD). MethodsFrom May 2005 to June 2007, a total of 20 consecutive patients underwent posterior spinal fusion and segmental pedicle screw instrumentation only to L5 for scoliosis secondary to DMD. All patients had progressive scoliosis, difficulty sitting, and back pain before surgery. A minimum 2-year follow-up was required for inclusion in this study. Assessment was performed clinically and with radiological measurements. The Cobb angles of the curves and spinal pelvic obliquity were measured on the coronal plane. Thoracic kyphosis and lumbar lordosis were measured on the sagittal plane. These radiographic assessments were performed before surgery, immediately after surgery, and at a 3-month interval thereafter. The operating time, blood loss, and complications were evaluated. Patients were questioned about whether they had difficulty sitting and felt back pain before surgery and at 6 weeks, 1 year, and 2 years after surgery. ResultsA total of 20 patients, aged 11–17 years, were enrolled. The average follow-up period was 37 months. Preoperative coronal curves averaged 70° (range 51°–85°), with a postoperative mean of 15° (range 8°–25°) and a mean of 17° (range 9°–27°) at the last follow-up. Pelvic obliquity improved from 13° (range 7°–15°) preoperatively to 5° degrees (range 3°–8°) postoperatively and 6° (range 3°–9°) at the last follow-up. Good sagittal plane alignment was recreated and maintained. Only a small loss of correction of scoliosis and pelvic obliquity was noted. The mean operating time was 271 min (range 232–308 min). The mean intraoperative blood loss was 890 ml (range 660–1260 ml). The mean total blood loss was 2100 ml (range 1250–2880 ml). There was no major complication. All patients reported that difficulty sitting and back pain were alleviated after surgery. ConclusionSegmental pedicle screw instrumentation and fusion only to L5 is safe and effective in patients with DMD scoliosis of <85° and pelvic obliquity of <15°. Good sagittal plane alignment was achieved and maintained. All patients benefited from surgery in terms of improved quality of life. There was no major complication.

Segmental pedicle screws instrumentation and fusion to L5 for spinal deformity secondary to Duchenne muscular dystrophy: results with a minimum of 2 years follow-up

Background Traditional treatment recommendations in the surgical treatment of scoliosis in Duchenne muscular dystrophy have included instrumentation and fusion to the sacrum/pelvis to correct pelvic obliquity and to restore the sitting balance of the trunk. However, caudal extent of instrumentation and fusion has remained a matter of considerable debate. This study was performed to determine the efficacy and safety of stopping segmental pedicle screw constructs at L5 in the surgical treatment of scoliosis in Duchenne muscular dystrophy (DMD), with mild pelvic obliquity (<15°).

A Biomechanical Comparison of Different Types of Lumbopelvic Fixation

Comparative biomechanical testing in calf spines. To biomechanically evaluate 4 techniques of lumbosacral fixation. Pelvic fixation is a problematic area, and currently, the preferred method of pelvic fixation is controversial. Clinically, iliac screws have demonstrated decreased rod breakage rates, and better correction of pelvic obliquity than unthreaded rods (Galveston technique), but several modern methods of iliac fixation have not been compared. A total of 32 male calf spines were tested under axial rotation, flexion/extension, and lateral bending. Following intact testing, specimens were instrumented in the following groups: group 1-Modified Galveston technique with rods connected directly to iliac screws (no S1 fixation); group 2-S1 screws and iliac screws with offset connectors distal to S1; group 3-S1 screws and iliac screws with offset connectors coupled to the longitudinal rod between L6 and S1; and group 4-S1 and S2 screws without iliac fixation. Pedicle screws were placed from L3 to L6. Following nondestructive testing, specimens were fixed at the cephalad aspect of the construct and flexed to failure, with peak failure moment (Nm). Group 1 demonstrated significantly more flexion/extension than groups 2, 3, 4 (P<0.001). There were no significant differences between groups for lateral bending or axial rotation at L3-S1 or L6-S1. During destructive testing, group 4 showed a significant reduction in peak failure compared to group 1 (P<0.001), group 2 (P=0.001), and group 3 (P<0.001). There was no significant difference between groups 1, 2, and 3 and all specimens failed at the distal fixation. With extension of instrumentation across the lumbosacral junction, our results indicate significant improvement in stability with the use of S1 screws and iliac screw fixation. Furthermore, there does not appear to be any significant difference in the location of the connector for the iliac screw.

Pressure Mapping as an Outcome Measure for Spinal Surgery in Patients With Myelomeningocele

A retrospective analysis of prospectively collected data on a cohort of 19 myelomeningocele patients undergoing spino-pelvic deformity surgery. To examine if greater curve correction with third generation spinal implants correlate with improved pressure distribution and resolution, or prevention of skin ulcerations in myelomeningocele patients. Children born with myelomeningocele have often complex spino-pelvic deformities leading to skin ulcerations. A cohort of 19 consecutive wheelchair dependent patients with myelodisplastic spinal deformities, who underwent spinal surgery, was prospectively followed with regular pressure mappings for a minimum of 2 years. Standard spino-pelvic radiologic measurements were obtained. Sitting pressure mappings were obtained over the study period using the Force Sensitive Applications from Vista Medical (Winnipeg, Manitoba, Canada). Statistical analysis was done using SAS (SAS Institute Inc, Cary, NC). Paired t-test and Wilcox on Signed Rank test was used where applicable. Significance was taken to be P<0.05. Surgery significantly corrected radiographic parameters, specifically, Cobb angle (52%), pelvic obliquity (89%), and to a lesser degree pelvic tilt. Stratifying the data based on fixation type showed that the M-W construct was able to significantly correct pelvic obliquity. While significant changes in radiographic variables were observed after surgery, this was not the case with the various pressure mapping variables. Only minor changes after surgery were observed in the average pressure, maximum pressure, and variable coefficient of pressure. What was observed was an improvement in the overall distribution from anterior/posterior and right/left. While the values only approached statistical significance (P=0.053) for right/left, however, this did not appear to be clinically significant regarding skin ulceration. Despite significant surgical corrections in radiographic parameters, these resulted in small changes in pressure distributions and do not appear to influence skin ulceration in the myelomeningocele patient. Pressure mapping may not be a useful tool in predicting outcome of spinal surgery. Factors which were proven to influence pressure distribution are the sagittal pelvic orientation and also achieving coronal spine balance.