Scoliosis may be the first symptom of the tethered spinal cord

Background:

Tethered cord syndrome (TCS) is a progressive clinical entity that arises from abnormal spinal cord tension. Scoliosis may be a unique symptom in TCS. The aim of this study is to investigate prognosis after releasing the filum terminale in scoliosis due to TCS with/without findings in magnetic resonance imaging (MRI) and to draw attention to the importance of somatosensorial evoked potentials (SSEP) on the differential diagnosis of idiopathic scoliosis versus scoliosis due to TCS with normal appearance of filum terminale and conus medullaris.

Materials and Methods:

Eleven female and seven male patients with progressive scoliosis were included in the study. They were evaluated radiologically, SSEP and urodynamical studies. Preoperative and postoperative anteroposterior full spine X-rays were obtained for measuring the Cobb''s angle. MRI was performed in all cases for probable additional spinal abnormalities. All patients underwent filum terminale sectioning through a L5 hemilaminectomy. The resected filum terminale were subjected to histopathological examination.

Results:

The mean Cobb angle was 31.6° (range 18°–45°). Eight patients (44.45%) had a normal appearance of filum terminale and normal level conus medullaris in MRI, but conduction delay and/or block was seen on SSEP. In the histopathological examination of filum terminale dense collagen fibers, hyaline degeneration and loss of elastic fibers were observed. Postoperatively none of the patients showed worsening of the Cobb angle. Three patients showed improvement of scoliosis.

Conclusion:

In TCS presented with scoliosis, untethering must be performed prior to the corrective spinal surgery. Absence of MRI findings does not definitely exclude TCS. SSEP is an important additional guidance in the diagnosis of TCS. After untethering, a followup period of 6 months is essential to show it untethering helps in stopping the progress of the scoliotic curve. In spite of non progression (curve stopped lesser than 45°) or even improvement of scoliosis, there may be no need for major orthopedic surgical intervention.     

The lumbar lordosis index: a new ratio to detect spinal malalignment with a therapeutic impact for sagittal balance correction decisions in adult scoliosis surgery

Purpose

Sagittal malalignment is frequently observed in adult scoliosis. C7 plumb line, lumbar lordosis and pelvic tilt are the main factors to evaluate sagittal balance and the need of a vertebral osteotomy to correct it. We described a ratio: the lumbar lordosis index (ratio lumbar lordosis/pelvic incidence) (LLI) and analyzed its relationships with spinal malalignment and vertebral osteotomies.

Methods

53 consecutive patients with a surgical adult scoliosis had preoperative and postoperative full spine EOS radiographies to measure spino-pelvic parameters and LLI. The lack of lordosis was calculated after prediction of theoretical lumbar lordosis. Correlation analysis between the different parameters was performed.

Results

All parameters were correlated with spinal malalignment but LLI is the most correlated parameter (r = −0.978). It is also the best parameter in this study to predict the need of a spinal osteotomy (r = 1 if LLI <0.5).

Conclusion

LLI is a statistically validated parameter for sagittal malalignment analysis. It can be used as a mathematical tool to detect spinal malalignment in adult scoliosis and guides the surgeon decision of realizing a vertebral osteotomy for adult scoliosis sagittal correction. It can be used as well for the interpretation of clinical series in adult scoliosis.     

The correlation between coronal balance and neuroaxial abnormalities detected on MRI in adolescent idiopathic scoliosis

Introduction

The indications for magnetic resonance imaging in presumed adolescent idiopathic scoliosis (AIS) have not been established, with some studies suggesting that rates of spinal cord abnormalities are low and question the use of the routine MRI in AIS.

Objective

Given the restraints on MRI resources the authors performed a retrospective audit to see if the presence of coronal or sagittal misbalance–balance could be used as a surrogate marker for the presence of spinal cord abnormalities in this patient group and hence reduce the need for unnecessary MRI scans.

Methods

We performed a retrospective review of imaging of patients with AIS at our centre over a 2-year-period. All MRI scans were reported by the senior author and the presence of spinal cord abnormalities noted. All plain films were assessed by a senior SpR and ST2 orthopaedic surgeons for Cobb angle, coronal balance, sagittal balance and Lenke classification.

Results

A total of 171 patients were identified with AIS. Of these, a total of 15 patients (9%) were found to have neural axis anomalies on MRI including syringomyelia, Chiari malformations and dural ectasia. The average Cobb angle was 44.9° with coronal balance varying from 67.2 mm left to 40.2 mm right. Sagittal balance varied from 125 mm negative to 83 mm positive. No correlation was found between coronal/sagittal misbalance and the presence of neural axis anomalies.

Conclusions

Our audit demonstrates that neither coronal nor sagittal misbalance should be used as an indicator of neural axis abnormalities.     

Chiari I malformation associated with syringomyelia: can foramen magnum decompression lead to restore cervical alignment?

Purpose

There are few researches that demonstrate the relationship between the extent of syringomyelia and sagittal alignment of the cervical spine. The purpose of this study is to investigate the correlation between the change of syrinx size and cervical alignment.

Methods

From January 2001 to June 2008, we operated on 207 patients who had syringomyelia. The associated diseases were categorized by Chiari I malformation, tumor, trauma, spinal stenotic lesion, inflammatory disease and idiopathic causes. Thirty patients who had Chiari I malformation associated with syringomyelia and who underwent foramen magnum decompression (FMD), participated in this study. We excluded patients with scoliosis, cervical instrumentation, tumor, trauma, myelomeningocele, hydrocephalus, tethered cord and congenital vertebral anomalies. Lateral radiographs in neutral and magnetic resonance imaging were taken pre- and postoperatively.

Results

Mean follow-up was 6.5 ± 1.5 years (ranged from 4.0 to 9.5 years). The mean pre- and postoperative lordosis angles at C2–C7 were −5.9° ± 1.0° and −10.4° ± 1.0°, respectively (P = 0.001). There was significant correlation between the differences of syrinx width and the cervical lordotic angles before and after surgery (P = 0.016). After FMD, syringomyelia and cervical alignment improved in 28 (93.3 %) and 25 (85.18 %) of 30 patients, respectively. There was significant correlation between recovery rate by Japanese Orthopaedic Association scores and the difference of the cervical lordotic angles before and after surgery (P = 0.022).

Conclusions

The present results demonstrate that the decrease of syrinx size by FMD may restore the cervical lordosis. We suggest that the postoperative cervical alignment might be a predictive factor for neurological outcome.     

Posterior correction of thoracic adolescent idiopathic scoliosis with pedicle screw instrumentation: results of 48 patients with minimal 10-year follow-up

Purpose

Since early 1990s pedicle screws in thoracic spine have been used in posterior correction of adolescent idiopathic scoliosis (AIS). Long-term results are scarce. We report clinical, radiological and pulmonary function results of 48 consecutive patients with 10-year minimal follow-up.

Methods

Forty-eight consecutive patients (42 females, 6 males) with 41 Lenke 1 (lumbar modifier A = 19, B = 8, C = 14), 7 Lenke 2 (lumbar modifier A = 2, B = 4, C = 1) were operated for AIS from posterior with pedicle screw alone instrumentation. Risser stage at the time of operation was 0–3 in 24, more than 3 in 24 patients. Mean age was 15.3 years. The data were prospectively collected preoperatively, at 6 weeks, 2 years and 10 years postoperatively. Cobb angle, sagittal and coronal balance, distal adjacent disc angle and lowest fused vertebral tilt were documented at all time-points. Choice of fusion levels is described. Not every vertebra was instrumented with pedicle screws. The implant density was average one pedicle screw per vertebra or 50 %. Derotation and translation of apical vertebrae on the concave side were performed for correction. The overall outcome and the outcome of different curve types were analyzed statistically.

Results

Lowest instrumented vertebra (LIV) was distal end vertebra in two-thirds of the patients and was one below distal end vertebra in one-third of the patients. The main thoracic curve correction was 63 %, from 58° ± 12° preoperative to 21° ± 9° at 6 weeks. The Cobb angle was 23° ± 10° at 2 years and 26° ± 10° at 10 years. The apical vertebral rotation improved 35 %, the non-instrumented lumbar curves improved 47 %, the distal adjacent disc angle decreased from 6° ± 3° preoperatively to −2° ± 4° postoperatively and the last instrumented vertebral tilt decreased from 23° ± 8° preoperatively to 5° ± 5° postoperatively. All these parameters remained stable up to 10-year follow-up. The scoliosis correction was not associated with any change in the preoperative thoracic kyphosis and lumbar lordosis. The  % FVC remained unchanged with 74 ± 21 % preoperatively to 74 ± 11 % at 2 years and 75 ± 10 % at 10 years. The SRS-24 score was 93 ± 18 points at 2 years and 95 ± 22 points at 10 years. There were no neurological complications, no pedicle screw-related complications.

Conclusion

Posterior correction of thoracic AIS with pedicle screw instrumentation is safe and produces a long-term stable correction and high patient satisfaction. An implant density of 50 % is sufficient to achieve these results. LIV can be the distal end vertebra or one below the distal end vertebra depending on the position of the distal end vertebra to the centre sacral line. The preoperative pulmonary function does not change on long term.     

Loss of apical vertebral derotation in adolescent idiopathic scoliosis: 2-year follow-up using multi-planar reconstruction computed tomography

Purpose

The objective of this study was to evaluate 2 years post-surgical loss of three-dimensional correction in adolescent idiopathic scoliosis (AIS) patients using multi-planar reconstruction computed tomography (CT).

Methods

Twenty-seven AIS patients treated by segmental pedicle screw (PS) constructs were included in this study. Correction in the axial plane was evaluated using the “relative apical vertebral rotation angle” (rAVR), defined as the difference between the axial rotation angles of the upper instrumented vertebra and the apical vertebra on reconstructed axial CT images. The Cobb angle of the main curve and apical vertebral translation was measured to evaluate the coronal correction. Thoracic kyphosis was also measured for the evaluation of sagittal profile. Measurements were performed before surgery, and 1 week and 2 years after surgery. The relationships between the correction losses and skeletal maturity, and variety of spinal constructs were also evaluated.

Results

The mean preoperative Cobb angle of the major curve was 59.1° ± 11.2° before and 13.0° ± 7.2° immediately after surgery. Two years later, the mean Cobb angle had increased significantly, to 15.5° ± 7.8°, with a mean correction loss of 2.5° ± 1.5° (p < 0.001). The mean preoperative rAVR of 28.5° ± 8.4° was corrected to 15.8° ± 7.8° after surgery. It had increased significantly to 18.5 ± 8.4 by 2 years after surgery, with a mean correction loss of 2.7° ± 1.0° (p < 0.001). The mean correction losses for both the Cobb angle and rAVR were significantly greater in the skeletally immature patients. The significant correlations were recognized between the correction losses and the proportion of multi-axial screws, and the materials of constructs.

Conclusions

Statistically significant loss of correction in the Cobb angle and apical vertebral axial rotation angle (AVR) were recognized 2 years after surgery using PS constructs. The correction losses, especially AVR, were more evident in the skeletally immature patients, and in patients treated with more multi-axial screws and with titanium constructs rather than with stainless constructs.     

Multilevel oblique corpectomy for cervical spondylotic myelopathy preserves segmental motion

Purpose

To document the neurological outcome, spinal alignment and segmental range of movement after oblique cervical corpectomy (OCC) for cervical compressive myelopathy.

Methods

This retrospective study included 109 patients—93 with cervical spondylotic myelopathy and 16 with ossified posterior longitudinal ligament in whom spinal curvature and range of segmental movements were assessed on neutral and dynamic cervical radiographs. Neurological function was measured by Nurick’s grade and modified Japanese Orthopedic Association (JOA) scores. Eighty-eight patients (81%) underwent either a single- or two-level corpectomy; the remaining (19%) undergoing three- or four-level corpectomies. The average duration of follow-up was 30.52 months.

Results

The Nurick’s grade and the JOA scores showed statistically significant improvements after surgery (p < 0.001). The mean postoperative segmental angle in the neutral position straightened by 4.7 ± 6.5°. The residual segmental range of movement for a single-level corpectomy was 16.7° (59.7% of the preoperative value), for two-level corpectomy it was 20.0° (67.2%) and for three-level corpectomies it was 22.9° (74.3%). 63% of patients with lordotic spines continued to have lordosis postoperatively while only one became kyphotic without clinical worsening. Four patients with preoperative kyphotic spines showed no change in spine curvature. None developed spinal instability.

Conclusions

The OCC preserves segmental motion in the short-term, however, the tendency towards straightening of the spine, albeit without clinical worsening, warrants serial follow-up imaging to determine whether this motion preservation is long lasting.     

Thoracolumbar fracture reduction by percutaneous in situ contouring

Purpose

Percutaneous in situ contouring is based on bilateral bending of rods on the spine, thus increasing lordosis at the fracture. It was analyzed if this technique would provide a better reduction than prone positioning and how sagittal alignment would behave.

Methods

Twenty-nine patients were operated using in situ contouring and selective anterior fusion for non-neurologic A2, A3 or B2 fractures. Clinical results were assessed prospectively using visual analog scale (VAS) and Oswestry Disability Index (ODI). The radiographic deformity correction was measured by sagittal index and regional kyphosis. Sagittal balance was assessed using kyphosis, lordosis, T9 tilt, pelvic incidence, pelvic tilt and sacral slope. Posterior wall fragment reduction was evaluated by computed tomography.

Results

After 2 years, VAS and ODI were comparable to the status prior to the accident. The sagittal index was 19.7° preoperatively, 5.3° after prone positioning and −1.1° after in situ contouring (p < 0.001). The loss of correction was 2.4°, mainly during the first 3 months. Similar observations were made for regional kyphosis. The sagittal spino-pelvic alignment was stable postoperatively. A preoperative canal obstruction ≥50 % was observed in 16 patients, and the fragments migrated anteriorly in all patients.

Conclusions

Percutaneous instrumentation and anterior fusion provides good clinical results. In situ contouring increases lordosis obtained by prone positioning. Anterior column lengthening and ligamentotaxis reduce posterior wall fragments, which decompress the canal without laminectomy. The fusion of anterior defects prevents the loss of correction and provides a stable sagittal profile. The instrumentation may be removed without damaging the paravertebral muscles and loss of correction.     

Posterior hemivertebra resection and monosegmental fusion in the treatment of congenital scoliosis

INTRODUCTION

Posterior hemivertebra resection combined with multisegmental or bisegmental fusion has been applied successfully for congenital scoliosis. However, there are several immature bones and their growth can be influenced by long segmental fusion in congenital patients. Posterior hemivertebra resection and monosegmental fusion was therefore suggested for treatment of congenital scoliosis caused by hemivertebra.

METHODS

Between June 2001 and June 2010, 60 congenital scoliosis patients (aged 2–18 years) who underwent posterior hemivertebra resection and monosegmental fusion were enrolled in our study. A standing anteroposterior x-ray of the whole spine was obtained preoperatively, postoperatively and at the last follow-up appointment to analyse the Cobb angle in the coronal and sagittal planes as well as the trunk shift.

RESULTS

The mean preoperative coronal plane Cobb angle was 41.6º. This was corrected to 5.1º postoperatively and 5.3º at the last follow-up visit (correction 87.3%). The compensatory cranial curve was improved from 18.1º preoperatively to 7.1º postoperatively and 6.5º at the last follow-up visit while the compensatory caudal curve was improved from 21.5º to 6.1º after surgery and 5.6º at the last follow-up visit. The mean sagittal plane Cobb angle was 23.3º before surgery, 7.3º after surgery and 6.8º at the last follow-up visit (correction 70.1%). The trunk shift of 18.5mm was improved to 15.2mm.

CONCLUSIONS

Posterior hemivertebra resection and monosegmental fusion seems to be an effective approach for treatment of congenital scoliosis caused by hemivertebra, allowing for excellent correction in both the frontal and sagittal planes.     

Lumbar Lordosis of Spinal Stenosis Patients during Intraoperative Prone Positioning

Background

To evaluate the effect of spondylolisthesis on lumbar lordosis on the OSI (Jackson; Orthopaedic Systems Inc.) frame. Restoration of lumbar lordosis is important for maintaining sagittal balance. Physiologic lumbar lordosis has to be gained by intraoperative prone positioning with a hip extension and posterior instrumentation technique. There are some debates about changing lumbar lordosis on the OSI frame after an intraoperative prone position. We evaluated the effect of spondylolisthesis on lumbar lordosis after an intraoperative prone position.

Methods

Sixty-seven patients, who underwent spinal fusion at the Department of Orthopaedic Surgery of Gwangmyeong Sungae Hospital between May 2007 and February 2012, were included in this study. The study compared lumbar lordosis on preoperative upright, intraoperative prone and postoperative upright lateral X-rays between the simple stenosis (SS) group and spondylolisthesis group. The average age of patients was 67.86 years old. The average preoperative lordosis was 43.5° (± 14.9°), average intraoperative lordosis was 48.8° (± 13.2°), average postoperative lordosis was 46.5° (± 16.1°) and the average change on the frame was 5.3° (± 10.6°).

Results

Among all patients, 24 patients were diagnosed with simple spinal stenosis, 43 patients with spondylolisthesis (29 degenerative spondylolisthesis and 14 isthmic spondylolisthesis). Between the SS group and spondylolisthesis group, preoperative lordosis, intraoperative lordosis and postoperative lordosis were significantly larger in the spondylolisthesis group. The ratio of patients with increased lordosis on the OSI frame compared to preoperative lordosis was significantly higher in the spondylolisthesis group. The risk of increased lordosis on frame was significantly higher in the spondylolisthesis group (odds ratio, 3.325; 95% confidence interval, 1.101 to 10.039; p = 0.033).

Conclusions

Intraoperative lumbar lordosis on the OSI frame with a prone position was larger in the SS patients than the spondylolisthesis patients, which also produced a larger postoperative lordosis angle after posterior spinal fusion surgery. An increase in lumbar lordosis on the OSI frame should be considered during posterior spinal fusion surgery, especially in spondylolisthesis patients.     

Apical vertebral derotation in the posterior treatment of adolescent idiopathic scoliosis: myth or reality?

Introduction

Direct apical vertebral rotation represents an important goal of posterior surgery for thoracic adolescent idiopathic scoliosis (AIS), so as to obtain a better cosmetic effect and to avoid posterior thoracoplasty. However, the real effectiveness in correction of vertebral rotation, using posterior only procedures, is still open to debate. The aim of the present study is to compare the correction of axial apical rotation obtained with direct rotation procedure versus simple concave rod rotation, in patients treated by posterior fusion for thoracic AIS using pedicle screw-only construct.

Materials and methods

A retrospective review was performed on a total of 62 consecutive patients (one single institution, three different surgeons) affected by AIS, who had undergone a posterior spinal fusion with pedicle screw-only instrumentation between January 2005 and April 2008 at the reference center. All cases presented a main thoracic curve (Lenke type 1 and 2). The angle of rotation (RAsag) of the apical vertebra was measured from the preoperative and last follow-up axial CT. According to the derotation procedure, two groups were identified: a direct vertebral rotation group (DR group; n = 32 patients) and a simple concave rod rotation group (No-DR group; n = 30 patients). There were no statistical differences between the two groups, in terms of age, Risser’s sign, curve patterns, Cobb main thoracic (MT) curve magnitude and flexibility, extension of fusion, offset measurements on the coronal plane and sagittal preoperative contour.

Results

All 62 patients were reviewed at an average follow-up of 3.7 years (range 2.5–4.2 years). The DR group compared to the No-DR group showed a significantly better final correction of apical vertebral rotation (DR 63.4 % vs. No-DR 14.8 %; p < 0.05) and a greater final correction (61.3 vs. 52.4 %; p < 0.05) with better maintenance of the initial correction (−1.7° vs. −1.9°; ns) of the main thoracic curve. Concerning the coronal balance, there was the same aforementioned trend of better results in the DR group, with less final apical MT vertebra translation (DR 2.2 cm vs. No-DR 4.1 cm), greater overall change (preop-final) of lower instrumented vertebra (LIV) coronal tilt (−14.9° vs. −11.1°; p < 0.05); the final global coronal balance (C7–S1) resulted quite better in DR group, but without a significant difference. The T5–T12 kyphosis angle was quite similar in both group before surgery (DR 16.8° vs. No-DR 17.5°) and was little lower at final follow-up evaluation in direct vertebral rotation group (14.5° vs. 16.5°). The T10–L2 sagittal alignment angle was similar in each group before surgery (12.5° in DR vs. 11.8° in No-DR), and at the latest follow-up averaged 5.3° versus 8.2°, respectively. Lumbar lordosis was similar in each group before surgery (DR −42° vs. No-DR −44.1°) and at the final follow-up evaluation (−45.9° vs. −43.2°). At the latest follow-up, SRS-30 and SF-36 findings were similar between the two groups. The complication rate was higher in the simple concave rod rotation group (13.3 vs. 9.3 %), related in two cases to thoracoplasty, which was never utilized in direct rotation patients.

Conclusions

The direct vertebral rotation obtained significantly better final results, when compared to simple concave rod rotation, both concerning correction of apical vertebral rotation and magnitude of MT curve. On the other hand, the DR group presented a little reduction in T5–T12 kyphosis at follow-up, in comparison with concave rod rotation procedure. Both procedures were found to be satisfying from patients’ perspective. Nevertheless overall complication rate was higher in the simple concave rod rotation group, related mainly to thoracoplasty (2 cases), which was never necessary in direct rotation patients.     

Sagittal alignment and kinematics at instrumented and adjacent levels after total disc replacement in the cervical spine

Background

The purpose of the study was to report radiological outcomes after total disc replacement (TDR) in the cervical spine through a 24 months follow-up (FU) prospective study with a special focus on sagittal alignment and kinematics at instrumented and adjacent levels.

Materials and methods

Thirty-two patients, who sustained one-level TDR with a ball-and-socket arthroplasty (Discocerv^™ implant, Scient’x/Alphatec Spine, USA) were consecutively included in the study. Clinical (visual analogical scale and neck disability index) and radiological parameters were measured preoperatively and postoperatively at 3/6 months, 1-year and 2-year FU. Sagittal alignment, ranges of motion (ROM) and center of rotations (CORs) were analyzed using specific motion analysis software (Spineview^™, Paris, France). Patients CORs were compared with those of a control group of 39 normal and asymptomatic subjects.

Results

Both local and C3–C7 lordosis significantly increased postoperatively (+8° and +13° at 2 years, respectively). At instrumented level ROM in flexion–extension (FE) was measured to 10.2° preoperatively versus 7.5° at 1 year and 6.1° at 2 years. There were no differences in ROM at adjacent levels between pre and postoperative assessments. When compared with control group and preoperative measurements, we noted postoperative cranial shift of the COR at instrumented level for patients group. In contrast, there was no difference in CORs location at adjacent levels.

Conclusion

Through this prospective study, we observed that cervical lordosis consistently increased after TDR. In addition, although ball-and-socket arthroplasty did not fully restore native segmental kinematics with significant reduction of motion in FE and consistent cranial shift of the COR, no significant changes in terms of ROM and CORs were observed at adjacent levels.     

Normal morphology, age-related changes and abnormal findings of the cervical spine. Part II: magnetic resonance imaging of over 1,200 asymptomatic subjects

Purpose

The aim of this study is to establish standard MRI values for the cervical spinal canal, dural tube, and spinal cord, to evaluate age-related changes in healthy subjects, and to assess the prevalence of abnormal findings in asymptomatic subjects.

Methods

The sagittal diameter of the spinal canal and the sagittal diameter and cross-sectional area of the dural tube and spinal cord were measured on MRIs of 1,211 healthy volunteers. These included at least 100 men and 100 women in each decade of life between the third (20s) and eighth (70s). Abnormal findings such as spinal cord compression and signal changes in the spinal cord were recorded.

Results

The sagittal diameter of the spinal canal was 11.2 ± 1.4 mm [mean ± standard deviation (SD)]/11.1 ± 1.4 mm (male/female) at the mid-C5 vertebral level, and 9.5 ± 1.8/9.6 ± 1.6 mm at the C5/6 disc level. The cross-sectional area of the spinal cord was 78.1 ± 9.4/74.4 ± 9.4 mm² at the mid-C5 level and 70.6 ± 11.7/68.9 ± 11.3 mm² at the C5/6 disc level. Both the sagittal diameter and the axial area of the dural tube and spinal cord tended to decrease with increasing age. This tendency was more marked at the level of the intervertebral discs than at the level of the vertebral bodies, especially at the C5/6 intervertebral disc level. The spinal cord occupation rate in the dural tube at the C5 vertebral body level averaged 58.3 ± 7.0%. Spinal cord compression was observed in 64 cases (5.3%) and a T2 high-signal change was observed in 28 cases (2.3%).

Conclusions

Using MRI data of 1,211 asymptomatic subjects, the standard values for the cervical spinal canal, dural tube, and spinal cord for healthy members of each sex and each decade of life and the age-related changes in these parameters were established. The relatively high prevalence of abnormal MRI findings of the cervical spine in asymptomatic individuals emphasizes the dangers of predicating operative decisions on diagnostic tests without precisely correlating these findings with clinical signs and symptoms.     

Efficacy of PEEK Cages and Plate Augmentation in Three-Level Anterior Cervical Fusion of Elderly Patients

Background

To evaluate the clinical efficacy of three-level anterior cervical arthrodesis with polyethyletherketone (PEEK) cages and plate fixation for aged and osteoporotic patients with degenerative cervical spinal disorders.

Methods

Twenty one patients, who had undergone three-level anterior cervical arthrodesis with a cage and plate construct for degenerative cervical spinal disorder from November 2001 to April 2007 and were followed up for at least two years, were enrolled in this study. The mean age was 71.7 years and the mean T-score using the bone mineral density was -2.8 SD. The fusion rate, change in cervical lordosis, adjacent segment degeneration were analyzed by plain radiographs and computed tomography, and the complications were assessed by the medical records. The clinical outcomes were analyzed using the SF-36 physical composite score (PCS) and neck disability index (NDI).

Results

Radiological fusion was observed at a mean of 12.3 weeks (range, 10 to 15 weeks) after surgery. The average angle of cervical lordosis was 5° preoperatively, 17.6° postoperatively and 16.5° at the last follow-up. Degenerative changes in the adjacent segments occurred in 3 patients (14.3%), but revision surgery was unnecessary. In terms of instrument-related complications, there was cage subsidence in 5 patients (23.8%) with an average of 2.8 mm, and loosening of the plate and screw occurred in 3 patients (14.3%) but there were no clinical problems. The SF-36 PCS before surgery, second postoperative week and at the last follow-up was 29.5, 43.1, and 66.2, respectively. The respective NDI was 55.3, 24.6, and 15.9.

Conclusions

For aged and osteoporotic patients with degenerative cervical spinal disorders, three-level anterior cervical arthrodesis with PEEK cages and plate fixation reduced the pseudarthrosis and adjacent segment degeneration and improved the clinical outcomes. This method is considered to be a relatively safe and effective treatment modality.     

Biomechanical study of the spinal cord in thoracic ossification of the posterior longitudinal ligament

Background

Ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine produces myelopathy. This is often progressive and is not affected by conservative treatment. Therefore, decompressive surgery is usually chosen.

Objective

To conduct a stress analysis of the thoracic OPLL.

Methods

The three-dimensional finite element spinal cord model was established. We used local ossification angle (LOA) for the degree of compression of spinal cord. LOA was the medial angle at the intersection between a line from the superior posterior margin at the cranial vertebral body of maximum OPLL to the top of OPLL with beak type, and a line from the lower posterior margin at the caudal vertebral body of the maximum OPLL to the top of OPLL with beak type. LOA 20°, LOA 25°, and LOA 30° compression was applied to the spinal cord in a preoperative model, the posterior decompressive model, and a model for the development of kyphosis.

Results

In a preoperative model, at more than LOA 20° compression, high stress distributions in the spinal cord were observed. In a posterior decompressive model, the stresses were lower than in the preoperative model. In the model for development of kyphosis, high-stress distributions were observed in the spinal cord at more than LOA 20° compression.

Conclusions

Posterior decompression was an effective operative method. However, when the preoperative LOA is more than 20°, it is very likely that symptoms will worsen. If operation is performed at greater than LOA 20°, then correction of kyphosis by fixation of instruments or by forward decompression should be considered.     

Minimally invasive partial fasciectomy for Dupuytren’s contractures

Background

Numerous options exist for the treatment of Dupuytren’s contracture. This study describes the technique and early results of partial fasciectomy through a mini-incision approach as an additional treatment option for Dupuytren’s disease.

Methods

This procedure involves the excision of diseased Dupuytren’s tissue with the use of multiple 1 cm transverse incisions. Patient demographics, digit involvement, the number of incisions required to release each digit, and complications were recorded for all patients. Range of motion data was obtained from a subgroup of patients that had at least 6 months of follow-up. A paired t test was used to compare preoperative and postoperative contracture.

Results

Sixty-seven patients underwent 75 procedures that involved 119 digits. The mean patient age at the time of surgery was 63 years (range, 33–95 years). A total of 32 digits (47 joints) were available for range of motion analysis. After a mean of 2.2 years following surgery, metacarpophalangeal joint contractures maintained correction (34° preoperatively, 19° postoperatively, p = 0.008). After a mean postoperative duration of 2.0 years, proximal interphalangeal joint contractures trended worse than preoperative levels (39° preoperatively, 45° postoperatively, p = 0.319). There was one major complication, which consisted of a nerve laceration that was identified and repaired intraoperatively.

Conclusions

Partial fasciectomy through the described mini-incision approach provides an additional surgical option for patients who desire a less invasive surgical procedure than traditional fascietomy. Although this procedure is safe and effective at achieving immediate cord release, maintenance of correction for proximal interphalangeal joint contractures remains problematic.     

The modulation of spinal growth with nitinol intervertebral stapling in an established swine model

Purpose

Anterior spinal stapling for the treatment of adolescent idiopathic scoliosis has been shown to slow progression in small curves; however, its role in larger curves remains unclear. The purpose of this study was to evaluate the effectiveness of nitinol staples to modulate spinal growth by evaluating the two-dimensional and three-dimensional morphological and histological effects of this method in a well-established porcine model.

Methods

Three immature Yucatan miniature pigs underwent intervertebral stapling. Two staples spanned each of three consecutive mid-thoracic discs and epiphyses. Monthly radiographs were obtained. Computed tomography (CT) was conducted at harvest after 6 months of growth. Measurements of wedging and height for each disc and vertebral body were conducted. Micro CT was used to compare physeal closure between stapled and non-stapled levels. Histology of the growth plate also compared the hypertrophic zone thickness for control and stapled vertebrae.

Results

After 6 months of stapled growth, the average coronal Cobb angle of the stapled segments increased by 7.7 ± 2.0° and kyphosis increased by 3.3 ± 0.6° compared to preoperative curves. Increased vertebral wedging and decreased disc height (p < 0.001) were noted in stapled regions. Overall, 26 ± 23 % of each growth plate was closed in the stapled segments, with 6 ± 8 % closure in the unstapled levels. No difference was observed regarding the hypertrophic zone height when comparing instrumented to uninstrumented levels, nor was a difference recognized when comparing right versus left regions within stapled levels alone.

Conclusions

Six months of nitinol intervertebral stapling created a mild coronal and sagittal deformity associated with reduced vertebral and disc height, and increased coronal vertebral and sagittal disc wedging.     

Sagittal spino-pelvic alignment failures following three column thoracic osteotomy for adult spinal deformity

Purpose

Three column thoracic osteotomy (TCTO) is effective to correct rigid thoracic deformities, however, reasons for residual postoperative spinal deformity are poorly defined. Our objective was to evaluate risk factors for poor spino-pelvic alignment (SPA) following TCTO for adult spinal deformity (ASD).

Methods

Multicenter, retrospective radiographic analysis of ASD patients treated with TCTO. Radiographic measures included: correction at the osteotomy site, thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt (PT), and pelvic incidence (PI). Final SVA and PT were assessed to determine if ideal SPA (SVA < 4 cm, PT < 25°) was achieved. Differences between the ideal (IDEAL) and failed (FAIL) SPA groups were evaluated.

Results

A total of 41 consecutive ASD patients treated with TCTO were evaluated. TCTO significantly decreased TK, maximum coronal Cobb angle, SVA and PT (P < 0.05). Ideal SPA was achieved in 32 (78%) and failed in 9 (22%) patients. The IDEAL and FAIL groups had similar total fusion levels and similar focal, SVA and PT correction (P > 0.05). FAIL group had larger pre- and post-operative SVA, PT and PI and a smaller LL than IDEAL (P < 0.05).

Conclusions

Poor SPA occurred in 22% of TCTO patients despite similar operative procedures and deformity correction as patients in the IDEAL group. Greater pre-operative PT and SVA predicted failed post-operative SPA. Alternative or additional correction procedures should be considered when planning TCTO for patients with large sagittal global malalignment, otherwise patients are at risk for suboptimal correction and poor outcomes.     

Posterior scoliosis correction for adolescent idiopathic scoliosis using side-opening pedicle screw-rod system utilizing the axial translation technique

Background:

Though adequate literature is present depicting the results of pedicle screw-rod instrumentation using top loading systems for correction of adolescent idiopathic scoliosis (AIS), using the rod rotation technique, few published data is available regarding side loading systems used for a similar purpose. We report a retrospective study of a cohort of patients with strict inclusion criteria who underwent surgical correction of AIS with side-opening pedicle screw-rod posterior instrumentation using the axial translation technique of curve correction to assess the efficacy of side opening system for scoliosis correction with regards to patient satisfaction, Cobb''s angle correction and spinal balance.

Materials and Methods:

Clinical and radiological outcomes were measured in 14 consecutive patients (3 males, 11 females) with an average age of 14.0 years (range 9 to 23 years). They were followed up for an average period of 13.0 months (range – 2.2 to 28.5). All patients underwent posterior instrumentation only with pedicle screws used as anchor points. Hybrid constructs using hooks/wires or curves requiring anterior release were excluded from the study. All levels were not instrumented – more screws were put on the concavity and in the peri-apical region. Radiological evaluation was done by whole spine standing AP, lateral radiograms preoperatively and 1, 3, 6 and12 months after surgery. Cobb''s angles were measured and the spinal balance was noted. Clinical evaluation was done by SRS questionnaire. The complications were documented.

Results:

The mean preoperative Cobb''s angle was 58.35° (range – 44 to 72°), which came down postoperatively to 23.45° (range – 10 to 38°) signifying a mean correction of 59.57% (range – 26.92 to 76.17%). Clinical outcomes were evaluated using the SRS – 30 questionnaires. The values of mean pre- and postoperative scores are 3.68 and 4.18, showing an improvement of 0.5 points. Other than one patient of superficial wound infection, which healed with antibiotics, there was no major complication. No patient had neurological deterioration.

Conclusion:

Side-opening spinal instrumentation systems, using the axial translation technique, achieved good clinical and radiological outcome for patients of AIS.