Hitesh N. Modi

Accuracy of thoracic pedicle screw placement in scoliosis using the ideal pedicle entry point during the freehand technique

Previously, we described the ideal pedicle entry point (IPEP) for the thoracic spine at the base of the superior facet at the junction of the lateral one third and medial two thirds with the freehand technique on cadavers. Here we measured the accuracy of thoracic pedicle screw placement (Chung et al. Int Orthop 2008) on post-operative computed tomography (CT) scans in 43 scoliosis patients who underwent operation with the freehand technique taking the same entry point. Of the 854 inserted screws, 268 (31.3%) were displaced; 88 (10.3%) and 180 (21.0%) screws were displaced medially and laterally, respectively. With regard to the safe zone, 795 screws were within the safe zone representing an accuracy rate of 93%; 448 and 406 thoracic screws inserted in adolescent idiopathic and neuromuscular scoliosis showed an accuracy of 89.9 and 94%, respectively (p = 0.6475). The accuracy rate of screws inserted in the upper, middle and lower thoracic pedicles were 94.2, 91.6 and 93.7%, respectively (p = 0.2411). The results indicate that IPEP should be considered by surgeons during thoracic pedicle screw instrumentation.RésuméLe point d’entrée idéal des vis pediculaires (IPEP) au niveau thoracique se situe au niveau de la facette articulaire supérieure à la jonction du tiers latéral, 2/3 médial. Nous avons mesuré l’efficacité de cette technique « à main levée » par des scanners post-opératoires sur 43 scolioses chez 43 patients opérés. 268 (31,3%) des 854 vis mises en place n’étaient pas à un niveau parfait. 88 (10,3%) et 180 (21,0%) étaient soit trop médianes soit trop latérales. Néanmoins, si l’on considère la zone de sécurité, 795 vis soit 93% étaient en zone de sécurité. 448 et 446 vis thoraciques insérées lors d’une scoliose idiopathique ou neuromusculaire de l’adolescent étaient en zone saine dans respectivement 89,9% et 94% (p = 0,6475). Le taux de précision des vis insérées à la partie supérieure ou médiane ou inférieure du pédicule thoracique était respectivement de 94,2%, 91,6% et 93,7% (p = 0,2411). Résultats : cette étude montre que la technique de mise en place des vis pediculaires à « main levée » peut être considérée comme une technique efficace au niveau thoracique.

Posterior Multilevel Vertebral Osteotomy for Correction of Severe and Rigid Neuromuscular Scoliosis: A Preliminary Study

Study Design. Prospective study. Objective. To determine the effectiveness and correction with posterior multilevel vertebral osteotomy in severe and rigid curves without anterior release. Summary of Background Data. For the correction of severe and rigid scoliotic curve, anterior-posterior combined or posterior vertebral column resection (PVCR) procedures are used. Anterior procedure might compromise pulmonary functions, and PVCR might carry risk of neurologic injuries. Therefore, authors developed a new technique, which reduces both. Methods. Thirteen neuromuscular patients (7 cerebral palsy, 2 Duchenne muscular dystrophy, and 4 spinal muscular atrophy) who had rigid curve >100° were prospectively selected. All were operated with posterior-only approach using pedicle screw construct. To achieve desired correction, posterior multilevel vertebral osteotomies were performed at 3 to 5 levels (apex, and 1–2 levels above and below apex) through partial laminotomy sites connecting from concave to convex side, just above the pedicle; and repeated cantilever manipulation was applied over temporary short-segment fixation, above and below the apex, on convex side. On concave side, rod was assembled with screws and rod-derotation maneuver was performed. Finally, short-segment fixation on convex side was replaced with full-length construct. Intraoperative MEP monitoring was applied in all. Results. Mean age was 21 years and average follow-up was 25 months. Average preoperative flexibility was 20.3% (24.1°). Average Cobb’s angle, pelvic obliquity, and apical rotation were 118.2°, 16.7°, and 57° preoperatively, respectively, and 48.8°, 8°, and 43° after surgery showing significant correction of 59.4%, 46.1%, and 24.5%. Average number of osteotomy level was 4.2 and average blood loss was 3356 ± 884 mL. Mean operation time was 330 ± 46 minutes. None of the patient required postoperative ventilator support or displayed any signs of neurologic or vascular injuries during or after the operation. Conclusion. This technique should be recommended because (1) it provides release of anterior column without anterior approach and (2) our results supports its superiority as a technique.

Surgical correction and fusion using posterior-only pedicle screw construct for neuropathic scoliosis in patients with cerebral palsy: A three-year follow-up study

Study Design. It is a retrospective study of 52 neuromuscular scoliosis patients with cerebral palsy (CP). Objective. To determine the effectiveness and amount of correction using posterior-only pedicle screw construct. Summary of Background Data. Although there have been many reports in literature supporting the use of pedicle screw-only constructs for the correction of adolescent idiopathic scoliosis, similar studies have not been reported in patients with CP. Methods. We retrospectively evaluated outcomes of 52 neuropathic scoliosis patients (28 males and 24 females) with CP over minimum 2 years of follow-up. All patients underwent pedicle screw fixation without any anterior procedure for the correction. Pelvic fixation was done in 10 patients who had pelvis obliquity more than 15°. All coronal and sagittal parameters were noted after surgery and at final follow-up. Patient’s functional outcome was measured using modified Rancho Los Amigos Hospital system criteria. Complications were recorded from record sheets and any change in the ambulatory status was also recorded. Results. Mean age was 22 years at the time of operation and average follow-up was 36.1 month. Cobb’s angle was improved to 62.9% (P < 0.0001) from 76.8° to 30.1° after surgery and 31.5° at final follow-up. This correction of scoliosis (41%∼92%) was found to be statistically significant (P < 0.0001). Overall correction in pelvic obliquity was 56.2% from 9.2° before surgery to 4.0° after surgery which was 43.1% at final follow-up to 5.2°. Twenty-one patients (42%) improved their functional ability by grade 1 with 2 patients by grade 2. After the operation parent or caretakers of patients exhibited better sitting balance and nursing care. There were 32% complications in the series major being pulmonary. There were 2 perioperative deaths and 1 patient developed neurologic deficit due to screw impingement in canal, which was resolved after removal. Conclusion. We reported satisfactory coronal and sagittal correction with posterior-only pedicle screw fixation without higher complication rate in CP patients. Further long-term study is recommended to evaluate the success of pedicle screw in this population.

Surgical complications in neuromuscular scoliosis operated with posterior- only approach using pedicle screw fixation

BackgroundThere are no reports describing complications with posterior spinal fusion (PSF) with segmental spinal instrumentation (SSI) using pedicle screw fixation in patients with neuromuscular scoliosis.MethodsFifty neuromuscular patients (18 cerebral palsy, 18 Duchenne muscular dystrophy, 8 spinal muscular atrophy and 6 others) were divided in two groups according to severity of curves; group I (< 90°) and group II (> 90°). All underwent PSF and SSI with pedicle screw fixation. There were no anterior procedures. Perioperative (within three months of surgery) and postoperative (after three months of surgery) complications were retrospectively reviewed.ResultsThere were fifty (37 perioperative, 13 postoperative) complications. Hemo/pneumothorax, pleural effusion, pulmonary edema requiring ICU care, complete spinal cord injury, deep wound infection and death were major complications; while atelectesis, pneumonia, mild pleural effusion, UTI, ileus, vomiting, gastritis, tingling sensation or radiating pain in lower limb, superficial infection and wound dehiscence were minor complications. Regarding perioperative complications, 34(68%) patients had at least one major or one minor complication. There were 16 patients with pulmonary, 14 with abdominal, 3 with wound related, 2 with neurological and 1 cardiovascular complications, respectively. There were two deaths, one due to cardiac arrest and other due to hypovolemic shock. Regarding postoperative complications 7 patients had coccygodynia, 3 had screw head prominence, 2 had bed sore and 1 had implant loosening, respectively. There was a significant relationship between age and increased intraoperative blood loss (p = 0.024). However it did not increased complications or need for ICU care. Similarly intraoperative blood loss > 3500 ml, severity of curve or need of pelvic fixation did not increase the complication rate or need for ICU. DMD patients had higher chances of coccygodynia postoperatively.ConclusionAlthough posterior-only approach using pedicle screw fixation had good correction rate, complications were similar to previous reports. There were few unusual complications like coccygodynia.

False-negative transcranial motor-evoked potentials during scoliosis surgery causing paralysis: a case report with literature review.

Study Design. Case report. Objective. To report a case of false-negative intraoperative motor-evoked potentials (MEP) that developed paraplegia after surgery. Summary of Background Data. Although several false-negative results have been reported with somatosensory-evoked potentials, there is no report noted with MEP. Therefore, several authors have preferred using MEPs as a gold standard in neuromonitoring. Methods. We report a case of false-negative MEP during the scoliosis surgery which is the first report showing false-negative MEPs during operation. Results. A 15-year-old girl with severe kyphoscoliosis (Cobb angle, 140°) in neurofibromatosis was operated for correction and posterior spinal fusion surgery, using pedicle screw instrumentation. Intraoperative neuromonitoring did not show any change in MEPs throughout the procedure, however, she woke-up with paraplegia. Immediate implant release could not recover her neurology functionally at last follow-up. Positive event during the operation was massive blood loss which could not show drop in MEPs as an ischemic cord injury (probable cause). Postoperative CT scan in both patients did not show any injury with pedicle screw as implants were well placed within the pedicles. Reviewing the literature, we could not find out any prospective study in animals identifying false-negative results with MEPs. Conclusion. From our experience of false-negative MEPs, we conclude that unwanted events with use of MEP in scoliosis or other spinal surgeries. We propose further prospective research on animals to solve this issue.

Treatment of neuromuscular scoliosis with posterior-only pedicle screw fixation

BackgroundTo determine whether posterior-only approach using pedicle screws in neuromuscular scoliosis population adequately addresses the correction of scoliosis and maintains the correction over time.MethodsBetween 2003 and 2006, 26 consecutive patients (7 cerebral palsy, 10 Duchenne muscular dystrophy, 5 spinal muscular atrophy and 4 others) with neuromuscular scoliosis underwent posterior pedicle screw fixation for the deformity. Preoperative, immediate postoperative and final follow-up Cobbs angle and pelvic obliquity were analyzed on radiographs. The average age of the patients was 17.5 years (range, 8–44 years) and the average follow-up was 25 months (18–52 months).ResultsAverage Cobbs angle was 78.53° before surgery, 30.70° after surgery (60.9% correction), and 33.06° at final follow-up (57.9% correction) showing significant correction (p < 0.0001). There were 9 patients with curves more than 90° showed an average pre-operative, post operative and final follow up Cobbs angle 105.67°, 52.33° (50.47% correction) and 53.33° (49.53% correction) respectively and 17 patients with curve less than 90° showed average per operative, post operative and final follow up Cobbs angle 64.18, 19.24(70% correction) and 21.41(66.64 correction); which suggests statistically no significant difference in both groups (p = 0.1284). 7 patients underwent Posterior vertebral column resection due to the presence of a rigid curve. The average spinal-pelvic obliquity was 16.27° before surgery, 8.96° after surgery, and 9.27° at final follow-up exhibited significant correction (p < 0.0001). There was 1 poliomyelitis patient who had power grade 3 in lower limbs pre-operatively, developed grade 2 power post-operatively and gradually improved to the pre-operative stage. There was 1 case of deep wound infection and no case of pseud-arthrosis, instrument failures or mortality.ConclusionResults indicate that in patients with neuromuscular scoliosis, acceptable amounts of curve correction can be achieved and maintained with posterior-only pedicle screw instrumentation without anterior release procedure.

Intraoperative blood loss during different stages of scoliosis surgery: A prospective study

BackgroundThere are a number of reasons for intraoperative blood loss during scoliosis surgery based on the type of approach, type of disease, osteopenia, and patient blood profile. However, no studies have investigated bleeding patterns according to the stage of the operation. The objective of this prospective study was to identify intraoperative bleeding patterns in different stages of scoliosis surgery.MethodsWe prospectively analyzed the estimated blood loss (EBL) and operation time over four stages of scoliosis surgery in 44 patients. The patients were divided into three groups: adolescent idiopathic (group 1), spastic neuromuscular (group 2) and paralytic neuromuscular (group 3). The per-level EBL and operation times of the groups were compared on a stage-by-stage basis. The bone marrow density (BMD) of each patient was also obtained, and the relationship between per-level EBL and BMD was compared using regression analysis.ResultsPer-level operation time was similar across all groups during surgical stage (p > 0.05). Per-level EBL was also similar during the dissection and bone-grafting states (p > 0.05). However, during the screw insertion stage, the per-level EBL was significantly higher in groups 2 and 3 compared to group 1 (p < 0.05). In the correction stage, per-level EBL was highest in group 3 (followed in order by groups 2 and 1) (p < 0.05). Preoperative BMD indicated that group 3 had the lowest bone quality, followed by groups 2 and 1 (in order), but the preoperative blood indices were similar in all groups. The differences in bleeding patterns in the screw insertion and correction stages were attributed to the poor bone quality of groups 2 and 3. Group 3 had the lowest bone quality, which caused loosening of the bone-screw interface during the correction stage and led to more bleeding. Patients with a T-score less than -2.5 showed a risk for high per-level EBL that was nine times higher than those with scores greater than -2.5 (p = 0.003).ConclusionsWe investigated the blood loss patterns during different stages of scoliosis surgery. Patients with poor BMD showed a risk of blood loss nine times higher than those with good BMD.

The prevalence and radiological findings in 1347 elderly patients with scoliosis

In order to determine the epidemiology of adult scoliosis in the elderly and to analyse the radiological parameters and symptoms related to adult scoliosis, we carried out a prospective cross-sectional radiological study on 1347 adult volunteers. There were 615 men and 732 women with a mean age of 73.3 years (60 to 94), and a mean Cobb angle of 7.55 degrees (sd 5.95). In our study, 478 subjects met the definition of scoliosis (Cobb angle > or = 10 degrees ) showing a prevalence of 35.5%. There was a significant difference in the epidemiological distribution and prevalence between the age and gender groups. The older adults showed a larger prevalence and more severe scoliosis, more prominent in women (p = 0.004). Women were more affected by adult scoliosis and showed more linear correlation with age (p < 0.001). Symptoms were more severe in those with scoliosis than in the normal group, but were similar between the mild, moderate and severe scoliosis groups (p = 0.224) and between men and women (p = 0.231). Adult scoliosis showed a significant relationship with lateral listhesis, vertebral rotation, lumbar hypolordosis, sagittal imbalance and a high level of the L4-5 disc (p < 0.0001, p < 0.0001, p = 0.002, p = 0.002, p < 0.0001 respectively). Lateral listhesis, lumbar hypolordosis and sagittal imbalance were related to symptoms (p < 0.0001, p = 0.001, p < 0.0001 respectively).

Evaluation of the three-dimensional deformities in scoliosis surgery with computed tomography: efficacy and relationship with clinical outcomes.

Study Design. Prospective radiological and clinical study with scoliosis patients. Objective. To determine the pre- and postoperative differences in the three-dimensional (3D) parameters and relationships with the outcome in scoliosis surgery. Summary of Background Data. Despite a proven important role of the 3D deformities in scoliosis, it is warranted to confirm the efficacy of these measurements, which carry a cost burden and radiation hazard. Methods. Fifty adolescent idiopathic scoliosis patients who underwent correction surgery were enrolled in this study. Pre- and postoperative whole spine radiographs and computed tomography were performed. The vertebral rotation (VR), rib hump index (RH), sternal shift (SS) on computed tomography were measured at the level of the apex in each patient. In addition, the patients described the SRS 30 (scoliosis research society 30) and ODI (owestry disability index) score. And, the differences in the parameter and the relationships between the radiological and clinical outcomes were analyzed. Results. There was significant decrease in the coronal curvature, RH, and SS after surgery (P < 0.0001). In addition, the VR decreased postoperatively but that was not significant (P = 0.236). There were significant relationships between the parameters in the coronal curvature, VR, RH, and SS, pre- and postoperatively (P < 0.05). However, regarding the pre- and postoperative differences, only the changes in the SS were related to changes in the coronal curvature (P = 0.006). In addition, there were significant relationships between the parameters and outcomes. The changes in ODI were related to changes in the coronal curvature, VR, RH, and SS (P < 0.0001, P = 0.039, P < 0.0001, P = 0.019, respectively). However, the changes in the SRS was only related to the changes in SS (P < 0.0001). Conclusion. There were significant correlations between the VR, RH, and SS with the coronal curvature, pre- and postoperatively. In addition, there were significant correlations between the 3D deformities and outcomes. Computed tomography based measurements of 3D deformities can provide useful information in planning, and predicting the outcome of corrective surgery.

Quantitative assessment of mineralization in distraction osteogenesis

ObjectivesThe most important decision in distraction osteogenesis is the timing of fixator removal. Various methods have been tried, such as radiographic appearance of callus and bone mineral density (BMD) assessment, but none has acquired gold standard status. The purpose of this study was to develop another objective method of assessment of callus stiffness to help clinicians in taking the most important decision of when to remove the fixator.Materials and methodsWe made a retrospective study of 70 patients to compare the BMD ratio and pixel value ratio. These ratios were calculated at the time of fixator removal, and Pearson’s coefficient of correlation was used to show the comparability. Inter- and intra-observer variability of the new method was also tested.ResultsGood correlation was found between BMD ratio and pixel value ratio, with a Pearson’s coefficient of correlation of 0.79. The interobserver variability was also low, with high intra-observer reproducibility, suggesting that this test was simple to perform.ConclusionPixel value ratio is a good method for assessing callus stiffness, and it can be used to judge the timing of fixator removal.