Charles Edwards

The management of traumatic spondylolisthesis of the axis.

Fifty-two patients with traumatic spondylolisthesis of the axis were admitted to the University of Maryland Spinal Injury Center between 1977 and 1982. There were fifteen Type-I fractures, twenty-nine Type-II fractures, three Type-IIa fractures, and five Type-III fractures. Associated neurological deficits were found in only four patients, although unassociated neurological deficits such as closed head injury were seen in eleven patients. Thirteen patients had other fractures of the cervical spine. Type-I fractures were stable injuries and were treated with collar protection. Most Type-II injuries were reduced with the patient in halo traction, and then immobilization in a halo vest was used. Type-IIa injuries, as they showed increased displacement in traction, were reduced with gentle extension and compression in a halo vest. Type-III injuries were grossly unstable and required surgical stabilization. All of the fractures healed, although the use of early halo-vest immobilization for displaced fractures resulted in significant residual deformity. The radiographic patterns of the fracture types and the resulting data on clinical stability suggested a correlation between the fracture type and the mechanism of injury. Type-I injuries resulted from a hyperextension-axial loading force; Type-II injuries, from an initial hyperextension-axial loading force followed by severe flexion; Type-IIa injuries, from flexion-distraction; and Type-III injuries, from flexion-compression.

Cervical Pedicle Screws : Comparative Accuracy of Two Insertion Techniques

Study Design. Independently assessed radiographic and anatomic comparison of device implantation methods. Objectives. To compare the relative accuracy of two techniques of inserting cervical pedicle screws. Summary of Background Data. In an attempt to define the anatomic risks of cervical pedicle screw insertion, image-guided stereotactic technology was shown to be superior to some other methods in vitro.— Meanwhile,in vivo experience with Abumi’s technique of screw insertion has had few clinically relevant instances of screw malposition. There has been no direct comparison between current image-guided technology and Abumi’s fluoroscopically assisted technique. Methods. The pedicles (C3–C7) of human cadaveric cervical spines were instrumented with 3.5-mm screws with either of two techniques. Cortical integrity and potential neurovascular injury were independently assessed by computed tomographic (CT) scans and anatomic dissection. A cortical breach was considered “critical” if the screw encroached on any vital structure. If any part of the screw violated the cortex of the pedicle but no vital structure was at risk for injury, the breach was classified as “noncritical.” Results. In Group I (StealthStation; Sofamor–Danek, Memphis, TN), 82% of screws were placed in the pedicle, and 18% had a critical breach. In Group II (Abumi technique), 88% of screws were placed in the pedicle, and 12% had a critical breach. No statistically significant differences were demonstrated between each group (P = 0.59). Regarding pedicle dimensions and safety of insertion, a critical pedicle diameter of 4.5 mm was determined to be the size below which a critical breach was likely, but above which there was a significantly greater likelihood for safe screw placement. The most common structure injured in each group was the vertebral artery. Conclusions. The use of a computer-assisted image guidance system did not enhance safety or accuracy in placing pedicle screws compared with Abumi’s technique. Both techniques have a noteworthy risk of injuring a critical structure if inserted into the pedicles with a diameter of less than 4.5 mm. Under laboratory conditions, pedicles with a diameter of more than 4.5 mm have a significantly greater likelihood of being safely instrumented by either technique. These data indicate that cervical pedicle screw placement is feasible, but it should be reserved for selected circumstances with clear indications and in the presence of suitable pedicle morphology.

Pseudarthrosis in adult spinal deformity following multisegmental instrumentation and arthrodesis

BACKGROUND There have been few detailed reports concerning pseudarthrosis following spinal instrumentation and arthrodesis in adults with spinal deformity since the introduction of modern segmental fixation techniques. The purposes of this study were to analyze the prevalence, risk factors, and outcome scores on the Scoliosis Research Society Instrument-24 associated with pseudarthrosis following instrumentation and arthrodesis for the treatment of spinal deformity in adults. METHODS A clinical and radiographic assessment of 232 adults with spinal deformity who were treated surgically at a single institution was conducted. The average age of the patients was 40.8 years, and the operation was a primary procedure in 150 patients and a revision procedure in eighty-two patients. All patients who underwent a long (four vertebrae or more) spinal instrumentation and arthrodesis with a minimum follow-up of two years were included in the analysis. Clinical outcomes were assessed with the Scoliosis Research Society questionnaire. RESULTS Forty patients had a pseudarthrosis. Factors that were found to be significantly associated with pseudarthrosis were preoperative thoracolumbar kyphosis of >20 degrees (p < 0.0001), an age of more than fifty-five years (p = 0.001), arthrodesis to S1 compared with arthrodesis to L5 or a cephalad level (p = 0.002), and arthrodesis of more than twelve vertebrae (p = 0.037). Patients with a pseudarthrosis had lower total outcome scores on the Scoliosis Research Society questionnaire, on the average, than those without a pseudarthrosis (p = 0.001). CONCLUSIONS The prevalence of pseudarthrosis following long arthrodesis with use of modern segmental spinal instrumentation for the treatment of spinal deformity in adults was 17%, and the clinical outcome in these patients can be negatively affected by the pseudarthrosis.

Cervical myelopathy: current diagnostic and treatment strategies

Cervical myelopathy is a varied clinical syndromes resulting from spinal cord dysfunction. Underlying causes are numerous, but spondylosis at one or more levels is the most common etiology. Natural history studies have demonstrated a variable clinical course with gradual neurologic deterioration in a majority of patients. While prospective clinical comparisons are limited, existing literature suggests that operative management reliably arrests the progression of myelopathy and may lead to functional improvement in a majority of patients. The selection of surgical procedures must be carefully individualized based on specific clinical and radiographic factors. Whereas anterior decompression and fusion procedures at one or two motion segments have predictable results, procedures involving three or more levels are associated with increased morbidity. Newer techniques for the treatment of multilevel cervical myelopathy include anterior decompression with 360-degree fusion, hybrid corpectomy/anterior cervical discectomy and fusion techniques and the use of dynamic anterior cervical plates. An alternative technique for patients with a lordotic sagittal alignment is laminoplasty, which has a proven track record of long-term good to excellent results.

Thoracolumbar deformity arthrodesis to L5 in adults: the fate of the L5-S1 disc.

Study Design. A retrospective clinical and radiographic analysis of long adult deformity fusions terminating at L5. Objectives. To define the results of thoracolumbar fusions to L5 in adult deformity patients with critical evaluation for potential subsequent L5-S1 disc degeneration and L5 implant loosening. Summary of Background Data. Few studies have reported the results of long adult fusions to L5 and the potential for subsequent advanced L5-S1 disc degeneration is unknown. Materials and Methods. Thirty-four consecutive patients fused from the thoracic spine to L5 at a single institution were evaluated at a mean follow-up of 5.6 years (2.1–14.3 years). SRS-24 functional outcome questionnaire results were obtained for all patients at most recent follow-up. Results. By latest follow-up, subsequent advanced L5-S1 disc degeneration (SAD) developed in 19 of 31 patients (61%) assessed as having “healthy” discs before surgery. SAD was associated with a forward shift in sagittal balance (P = 0.02) and need for revision surgery (P = 0.02). Risk factors for the development of SAD were preoperative positive sagittal balance (P = 0.01), younger age (P = 0.03), and the presence of even mild radiographic degeneration before surgery (P = 0.004). Loss of L5 implant fixation occurred in six patients (18%) and was associated with deep seating of L5 within the pelvis (P = 0.0001). Inferior SRS-24 outcome measures were associated with preoperative advanced L5-S1 disc degeneration and the development of postoperative sagittal imbalance. Conclusions. Subsequent L5-S1 DDD developed in 61% of patients after long adult fusions to L5 and was associated with a significant loss of sagittal alignment and an increased likelihood for or definite need for another operation. Loss of L5 implant fixation is not uncommon, especially in patients with a deep-seated L5 vertebra.

Changes in Radiographic and Clinical Outcomes With Primary Treatment Adult Spinal Deformity Surgeries From Two Years to Three- to Five-Years Follow-up

Study Design. Retrospective analysis of data entered prospectively into a multicenter database—clinical and radiographic outcomes assessment. Objective. Our hypothesis is that between the 2-year and the 3- to 5-year points surgically treated adult spinal deformity patients will show significant reduction in outcomes by Scoliosis Research Society (SRS), Oswestry Disability Index (ODI), and numerical rating scale back and leg pain scores and will show increasing thoracic kyphosis, loss of lumbar lordosis, and loss of coronal and sagittal balance. Summary of Background Data. Most analyses of primary presentation adult spinal deformity surgery assess 2-year follow-up. However, it is established that in some patients unfavorable events occur between the 2-year and 5-year points. Methods. The cohort of 113 patients entered into a multicenter database with complete preoperative, 2-year, and 3- to 5-year data. All patients who had adult spinal deformity and surgical treatment represented their first reconstruction. Diagnoses were scoliosis (82.5%), kyphosis (10%), and scoliosis and kyphosis combined (7.5%). Outcome measures and basic radiographic parameters (curve size, thoracic and lumbar sagittal plane, coronal and sagittal balance) were assessed at those 3 time intervals. Complications (pseudarthrosis/implant failure, infection, and junctional deformities) were assessed at the 2-year and the 3- to 5-year (mean, 3.76 years) points. Results. The mean major curve Cobb angle (preoperative, 57°; 2-year, 29°; 3–5 year, 26°); thoracic kyphosis T5 to T12 (30°, 31°, 32°) and lumbar lordosis T12 to sacrum (48°, 49°, 51°) did not change from the 2-year to ultimate follow-up. Likewise, coronal and sagittal balance parameters were the same at 2-year and ultimate follow-up. SRS total scores and modified ODI were similar at the 2 year and final follow-up (SRS: 3.89–3.88; ODI: 19–18). Preoperative SRS total score was 3.17. Six patients demonstrated complications at the 2-year point and additional 9patients demonstrated complications at the 3- to 5-year point. Those 9 patients with complications at ultimate follow-up demonstrated significant deterioration in their ODI and SRS scores when compared with the patients who did not have complications at ultimate follow-up. Conclusion. Contrary to our hypothesis, we could not establish deterioration in mean radiographic or clinical outcomes between the 2-year and 3- to 5-year follow-up points when analyzing the group as a whole. However, for the 9 patients who experienced complications between 3- and 5-year follow-up, their outcomes were significantly worse than for the other 104 patients. One should not anticipate an overall radiographic and clinical deterioration of the outcomes of surgically treated primary presentation adult spinal deformity patients in this studied time interval. However, close to 10% of patients will experience a new complication at the 3- to 5-year point, most commonly implant failure/nonunion and/or junctional kyphosis, which will negatively effect the patient-reported outcome.

Thoracolumbar deformity arthrodesis stopping at L5: Fate of the L5-S1 disc, minimum 5-year follow-up

Study Design. A retrospective long-term follow-up study. Objective. Evaluate the fate of L5-S1 disc analyzing subsequent disc degeneration and associated risk factors for degeneration at minimum 5-year follow-up (average 9-year follow-up). Summary of Background Data. Two previous studies reported the results of long deformity fusions terminating at L5 with minimum 2-year follow-up only. Methods. Thirty-one consecutive patients with an average age of 45 years (range, 20–62 years) were fused from the thoracic spine to L5 and were evaluated at a mean follow-up of 9.4 years (range, 5–20.1 year). Patients were evaluated before surgery, after surgery, and latest follow-up with radiographs and Scoliosis Research Society Patient Questionnaire-24 scores. Disc degeneration using validated radiographic Weiner grades. Grade 0 to 1 discs were “healthy” and Grade 2 to 3 were degenerated. Patients with “healthy” discs preoperative that subsequently degenerated were designated subsequent advanced degeneration (SAD). Results. Two out of 31 patients had preoperative advanced degeneration of the L5-S1 disc (Weiner grade 2–3). Three additional patients had an early revision to the sacrum secondary to sagittal imbalance not thought to be related to SAD. Twenty-six out of 31 patients were assessed as “healthy discs” preoperative (Weiner grade 0–1) and were evaluated for SAD. By latest follow-up, L5-S1 SAD developed in 18 of these 26 patients (69%). Risk factors for the development of SAD included long fusions extending into the upper thoracic spine down to L5 (P = 0.02) and having a circumferential lumbar fusion (P = 0.02). Although preoperative sagittal balance was not significantly different between the “healthy” and SAD group, sagittal balance at follow-up was: C7 plumb >5 cm in 67% of SAD patients and only 13% of “healthy” disc patients (P = 0.009). There was a trend toward inferior Scoliosis Research Society Patient Questionnaire-24 pain scores at follow-up in SAD patients (average score 4.1 vs. 3.4, P = 0.13). Eleven out of 30 patients (35%) had subsequent spinal surgery with 7 of 31 (23%) having extension of their fusion to the sacrum. An additional 6 of 31 (19%) were considered for extension to the sacrum but comorbidities precluded surgery (3 patients) or the patients declined further surgery (3 patients). Conclusion. Advanced L5-S1 DDD developed in 69% of deformity patients after long fusions to L5 with 5 to 15 year follow-up. SAD frequently results in significant positive sagittal balance at a minimum 5-year follow-up. Long fusions to the upper thoracic spine down to L5 and circumferential fusion may further promote subsequent L5-S1 disc degeneration.

The Scoliosis Research Society Health-Related Quality of Life (SRS-30) age-gender normative data: an analysis of 1346 adult subjects unaffected by scoliosis.

Study Design. Prospective, cross-sectional study. Objective. To determine Scoliosis Research Society (SRS)-30 health-related quality of life (HRQOL) reference values by age and gender in an adult population unaffected by scoliosis thereby allowing clinicians and investigators to compare individual and/or groups of spinal deformity patients to their generational peers. Summary of Background Data. Normative data are collected to establish means and standard deviations of health-related quality of life outcomes representative of a population. The SRS HRQOL questionnaire has become the standard for determining and comparing treatment outcomes in spinal deformity practices. With the establishment of adult SRS-30 HRQOL population values, clinicians, and investigators now have a reference for interpretation of individual scores and/or the scores of subgroups of adult patients with spinal deformities. Methods. The SRS-30 HRQOL was issued prospectively to 1346 adult volunteers recruited from across the United States. Volunteers self-reported no history of scoliosis or prior spine surgery. Domain medians, means, confidence intervals, percentiles, and minimum/maximum values were calculated for six generational age–gender groups: male/female; 20–39, 40–59, and 60–80 years of age. Results. Median and mean domain values ranged from 4.1 to 4.6 for all age–gender groups. The older the age–gender group, the lower (worse) the reported domain median and mean scores. The only exception was the mental health domain scores in the female groups which improved slightly. Males reported higher (better) scores than females but only the younger males were significantly higher in all domains than their female counterparts. In addition, all male groups reported higher Mental Health domain scores than their female counterparts (P = 0.003). Conclusion. This study reports population medians, means, standard deviations, percentiles, and confidence intervals for the domains of the SRS-30 HRQOL instrument. Clinicians must be mindful of age–gender differences when assessing deformity populations. Generational decreases noted in the older adult volunteer scores may provide a basis for future investigators to interpret observed score decreases in patient cohorts at long-term follow-up.

The problems and limitations of applying evidence-based medicine to primary surgical treatment of adult spinal deformity.

Study Design. Assessment of peer-reviewed literature and personal experience with publications and grant organization. Objective. This is an analysis of the current status of evidence-based medicine for primary adult spinal deformity to answer the question of whether surgical treatment benefits patients. Summary of Background Data. A limited number of evidence-based studies have been performed for primary adult scoliosis and spinal deformity surgery. None of these studies is ideal. Methods. This is an assessment of current literature and study group methodology in an attempt to provide an evidence-based medicine approach for the study of primary presentation adult scoliosis and related spinal deformity. Results. Many reasonable studies exist; however, there are no current definitive studies that answer the question posed above. There are many obstacles, both financial and organizational, to producing an “ideal” study. Most smaller studies suggest that surgical treatment of primary adult scoliosis benefits the patient. However, there is no multicenter prospective randomized study to answer this question. Conclusion. A multicenter funded study is needed to answer appropriate questions.

Age-gender matched comparison of SRS instrument scores between adult deformity and normal adults: are all SRS domains disease specific?

Study Design. Prospective, observational study. Objective. To further validate the Scoliosis Research Society (SRS) instrument by comparing scores of adult deformity patients with no prior history of spine surgery to the scores of normal adult volunteers in age-gender matched groups. Summary of Background Data. Efforts have been made to validate the SRS questionnaire in adolescent and adult deformity patients. An important psychometric attribute of any quality of life tool is its ability to discriminate between subjects with and without the condition of interest. Discriminate validity of the SRS questionnaire has not been established in the primary (no prior surgical treatment) adult deformity population. Methods. The SRS questionnaire was issued prospectively to 935 primary adult deformity patients with a diagnosis of idiopathic or de novo scoliosis and minimum Cobb angle of 30° (average Cobb angle: 54°; range: 30°–132°). Five hundred forty-three patients were treated nonsurgically while 392 patients underwent surgical intervention. Baseline SRS scores of the deformity population were compared to 1222 volunteers with no history of spine disease randomly sampled from the US population. Analysis between the 2 populations was broken down into 6 age-gender groups: male/female; 20–40, 41–60, 61–80 years of age. Results. SRS domain scores of the deformity subgroups demonstrated significant statistical differences from their corresponding age-gender matched normative group. The only exceptions were the mental health domain in the older males, 61–80 years of age. The average SRS subscore for each age-gender subgroup was less than the tenth percentile in the corresponding normative population, indicating substantial limitations in these patients. Conclusion. Our findings confirm the SRS instrument has excellent discriminate validity in the adult population. It appears to be disease-specific in the domains of pain, appearance and activity in adult spinal deformity patients who have not had prior surgery.