Biomedical subjects

Darrell S Hanson

Publications and source records attributed to Darrell S Hanson.

6 recordsLinked to original sources

PubMed2006

Complications in spinal fusion for adolescent idiopathic scoliosis in the new millennium. A report of the Scoliosis Research Society Morbidity and Mortality Committee.

STUDY DESIGN: The Morbidity and Mortality database of the Scoliosis Research Society (SRS) was queried as to the incidence and type of complications as reported by its members for the treatment of adolescent idiopathic scoliosis (AIS) with spinal fusion and instrumentation procedures regarding surgical approach (anterior, posterior, or combined anterior-posterior) during a recent 3-year period. OBJECTIVE: To evaluate the incidence of surgeon-reported complications in a large series of spinal fusions with instrumentation for a single spinal deformity diagnosis and age group regarding surgical approach. SUMMARY OF BACKGROUND DATA: The SRS has been collecting morbidity and mortality data from its members since its formation in 1965 with the intent of using these data to assess the complications and adverse outcomes (death and/or spinal cord injury) of surgical treatment for spinal deformity. Surgical approaches to the management of treatment of AIS have a measurable impact on efficacy of correction, levels fused, and operative morbidity. However, there is a lack of consensus on the choice of surgical approach for the treatment of spinal deformity. METHODS: Of the 58,197 surgical cases submitted by members of the SRS in the years 2001, 2002, and 2003, 10.9% were identified as having had anterior, posterior, or combined spinal fusion with instrumentation for the diagnosis of AIS, and comprised the study cohort. All reported complications were tabulated and totaled for each of the 3 types of procedures, and statistical analysis was conducted. RESULTS: Complications were reported in 5.7% of the 6334 patients in this series. Of the 1164 patients who underwent anterior fusion and instrumentation, 5.2% had complications, of the 4369 who underwent posterior instrumentation and fusion, 5.1% had complications, and of the 801 who underwent combined instrumentation and fusion, 10.2% had complications. There were 2 patients (0.03%) who died of their complications. There was no statistical difference in overall complication rates between anterior and posterior procedures. However, the difference in complication rates between anterior or posterior procedures compared to combined procedures was highly significant (P < 0.0001). The differences in neurologic complication rates between combined and anterior procedures, as well as combined and posterior procedures were also highly statistically significant (P < 0.0001), but not between anterior and posterior procedures. CONCLUSIONS: This study shows that complication rates are similar for anterior versus posterior approaches to AIS deformity correction. Combined anterior and posterior instrumentation and fusion has double the complication rate of either anterior or posterior instrumentation and fusion alone. Combined anterior and posterior instrumentation and fusion also has a significantly higher rate of neurologic complications than anterior or posterior instrumentation and fusion alone.

Adolescent↗

PubMed2002

Sagittal plane analysis of adolescent idiopathic scoliosis: the effect of anterior versus posterior instrumentation.

STUDY DESIGN: Radiographic analysis of anterior and posterior instrumentation for adolescent idiopathic scoliosis. OBJECTIVES: To compare effects of anterior versus posterior instrumentation on sagittal plane parameters. SUMMARY OF BACKGROUND DATA: The sagittal plane is critical to the long-term success of scoliosis surgery, but few studies have compared the effect of anterior versus posterior instrumentation. METHODS: Standing, full spine lateral radiographs of 110 consecutive patients (mean age 14 years) who had surgery for adolescent idiopathic scoliosis between 1996 and 1998 at one institution with a minimum 24-month (mean 32 months) follow-up were evaluated. Fifty patients were instrumented anteriorly with single screw-rod constructs. Sixty patients were instrumented posteriorly with segmental implants (5.5 mm; hooks, wires, and/or pedicle screws). RESULTS: At the final follow-up, the proximal junctional measurement (measured between the proximal instrumented vertebra and the segment two levels cephalad) increased most with posterior instrumentation (+7 degrees increase for posterior thoracic +1 degrees increase for anterior thoracic instrumentation, P= 0.02; +9 degrees increase for posterior thoracic and lumbar instrumentation vs. +4 degrees for anterior thoracolumbar instrumentation, P= 0.03). Thoracic kyphosis (T5-T12) increased significantly with anterior versus posterior thoracic instrumentation (+4 degrees vs. -2 degrees change, P= 0.04). Lumbar lordosis (T12-S1) was enhanced with either anterior or posterior instrumentation. No significant changes in distal junctional measurement (measured between the distal instrumented vertebra and the segment two levels caudal) were noted. The C7 sagittal plumbline remained negative in all groups at the final follow-up. CONCLUSION: Anterior and posterior instrumentation had differential effects on the sagittal plane in patients with adolescent idiopathic scoliosis. However, the overall magnitude of the differences was small. Properly performed, both approaches can result in acceptable sagittal profiles.

Adolescent↗

PubMed2002

Dowel fibular strut grafts for high-grade dysplastic isthmic spondylolisthesis.

STUDY DESIGN: This is a clinical study that examines the results of partial reduction and fibular dowel graft placement for high-grade isthmic spondylolisthesis. OBJECTIVES: To demonstrate the efficacy of partial reduction and fibular dowel graft placement in the treatment of high-grade isthmic spondylolisthesis. SUMMARY OF BACKGROUND DATA: Previous literature has demonstrated difficulty in treating high-grade isthmic spondylolisthesis both with high rates of pseudarthrosis as well as neurologic complications if a complete reduction is attempted. There are no published data examining partial reduction with dowel graft placement. METHODS: Seventeen consecutive patients (mean age 20.3 years) with high-grade isthmic spondylolisthesis who were treated with posterior fusion and fibular strut grafts were studied (mean follow-up 4.6 years). Radiographs were reviewed at preoperative, immediate (within 3 months) postoperative, and ultimate (>2 years) follow-up. Parameters measured included lumbar lordosis, slip angle, Meyerding-Newman scores, and pelvic incidence. The anterior and posterior fusions were graded on a I-IV scale, and the implants (if used) were examined for failure. Clinical outcomes were measured with Oswestry and Scoliosis Research Society outcomes tools. RESULTS: There were 17 patients treated: 10 primary and 7 revision patients. All patients had posterior fusion with fibular dowel grafts (11 allograft, 6 autograft). Meyerding grade improved 1.3 grades and slip angle improved 14 degrees with no loss of correction at ultimate follow-up. Sixteen of 17 patients had solid fusions on ultimate follow-up. Clinical evaluation with Scoliosis Research Society and Oswestry tools showed high patient function and satisfaction. Complications included one case of a broken strut in a revision patient; this was then revised to an instrumented circumferential fusion. There were no cases of deep or superficial infection. There were no neurologic deficits at ultimate follow-up. CONCLUSION: Fibular strut grafting is a useful surgical adjunct in high-grade spondylolisthesis that is partially reduced. Clinical and radiographic outcomes were satisfactory. Our experience shows that there is no significant difference between allograft and autograft. All struts healed and remodeled by the ultimate follow-up, and there was only one instance of fibula fracture.

Adolescent↗

PubMed2002

Correlation of pelvic incidence with low- and high-grade isthmic spondylolisthesis.

PURPOSE: The development of isthmic spondylolisthesis is influenced by forces across the lumbosacral region of the spine. Pelvic incidence is a radiographic parameter that has been shown to be an independent parameter that influences both sagittal spinal balance and pelvic orientation. Our hypothesis then is that there is a positive correlation between pelvic incidence and spondylolisthesis. STUDY DESIGN: A radiographic analysis of cases with spondylolisthesis. OBJECTIVES: To try to assess the correlation between pelvic incidence in both low-grade and high-grade spondylolisthesis in both a pediatric and an adult population. SUMMARY OF BACKGROUND DATA: The concept of pelvic incidence has been introduced into the literature. Its exact association with spondylolisthesis has not yet been clarified. METHODS: Forty patients with spondylolisthesis were identified and divided into two groups: low-grade (Meyerding I-II) and high-grade (Meyerding III and higher). Radiographic parameters measured included lumbar sagittal alignment (T12-S1), sacral inclination, slip angle, and pelvic incidence. The spondylolisthesis was classified according to the Meyerding-Newman classifications and the slip angle. Radiographic measurements were also done in two control groups; there were 20 pediatric and 20 adult controls (mean age 11.8 years and 60.0 years, respectively). Unpaired t test analysis and Pearson correlation analysis were then done. RESULTS: Mean pelvic incidence was 47.4 degrees in the pediatric control group, 57 degrees in the adult control group, 68.5 degrees in the low-grade isthmic spondylolisthesis group, and 79.0 degrees in the high-grade isthmic spondylolisthesis group. Pelvic incidence was found to be significantly higher in the high- and low-grade spondylolisthesis groups compared with both control groups (P = 0.0001). Pelvic incidence was significantly higher in the high-grade isthmic spondylolisthesis group than in the low-grade isthmic spondylolisthesis group (P = 0.007). A significant correlation existed between pelvic incidence and Meyerding-Newman scores (P = 0.03). CONCLUSIONS: Pelvic incidence was significantly higher in patients with low- and high-grade isthmic spondylolisthesis as compared with controls and had significant correlation with the Meyerding-Newman grades (P = 0.03).

Adolescent↗

PubMed2002

Can triggered electromyograph thresholds predict safe thoracic pedicle screw placement?

STUDY DESIGN: A prospective clinical study of thoracic pedicle screws monitored with triggered electromyographic testing. OBJECTIVE: To evaluate the sensitivity of recording rectus abdominis triggered electromyographs to assess thoracic screw placement. SUMMARY OF BACKGROUND DATA: Triggered electromyographic testing from lower extremity myotomes has identified medially placed lumbar pedicle screws. Higher thresholds indicate intraosseous placement because of increased resistance to current flow. Lower thresholds correspond to compromised pedicles with potential for nerve impingement. No clinical study has correlated an identical technique with rectus muscle recordings, which are innervated from T6 to T12. METHODS: A total of 677 thoracic screws were placed in 92 consecutive patients. Screws placed from T6 and T12 were evaluated using an ascending method of stimulation until a compound muscle action potential was obtained from the rectus abdominis. Threshold values were compared both in absolute terms and also in relation to other intrapatient values. RESULTS: Screws were separated into three groups: Group A (n = 650 screws) had thresholds >6.0 mA and intraosseus placement. Group B (n = 21) had thresholds <6.0 mA but an intact medial pedicle border on reexamination and radiographic confirmation. Group C (n = 6) had thresholds <6.0 mA and medial wall perforations confirmed by tactile and/or visual inspection. Thus, 3.9% (27 of 677) of all screws had thresholds <6.0 mA. Only 22% (6 of 27) had medial perforation. Group B screws averaged a 54% decrease from the mean as compared with a 69% decrease for Group C screws (P = 0.0160). There were no postoperative neurologic deficits or radicular chest wall complaints. CONCLUSION: To assess thoracic pedicle screw placement, triggered electromyographic thresholds <6.0 mA, coupled with values 60-65% decreased from the mean of all other thresholds in a given patient, should alert the surgeon to suspect a medial pedicle wall breach.

Action Potentials↗

PubMed2002

Correction of thoracic adolescent idiopathic scoliosis with segmental hooks, rods, and Wisconsin wires posteriorly: it's bad and obsolete, correct?

STUDY DESIGN: Forty-four consecutive thoracic idiopathic adolescent curves surgically treated between 1995 and 1999 at one institution were analyzed. All were thoracic curves; there were no lumbar curves, double major curves, or triple major curves. OBJECTIVES: To study the clinical and radiographic results for these 44 patients. SUMMARY OF BACKGROUND DATA: There is currently ongoing discussion regarding the "best treatment" for right thoracic idiopathic scoliosis. METHODS: Patients were administered preoperative and postoperative Scoliosis Research Society questionnaires. Radiographs were studied for coronal correction, sagittal correction, junctional deformities two segments above/two segments below, fusion status, loss of correction status, complications, and imbalance of curves above and below. Radiographic analysis was by two independent observers. All patients were treated with bilateral 5.5-mm CD Horizon (M-10) instrumentation. Corrective forces were translational and in situ contouring. An average of 10 hooks and 4 Wisconsin wires were used for an average of 14 fixation points per 11 segments. Follow-up was minimum 2 years to maximum 5 years, with an average of 3-year, 10-month follow-up. RESULTS: All were out of bed on postoperative day 1; none was braced after surgery. The average preoperative thoracic curve was 56 degrees; the average ultimate postoperative curve was 31 degrees (P = 0.0001). In the sagittal plane T5-T12 averaged 22 degrees preoperation and 20 degrees postoperation. For the complete study group (n = 44), the Cobb measurement (P = 0.001) and apical vertebral translation of the lumbar curve (P = 0.001) below improved. For the false double major curve (n = 11) patterns, the unfused lumbar curve averaged preoperation 46 degrees and postoperation 27 degrees (P = 0.0001). There were no neurologic deficits, no wound infections, and no respiratory complications. In regards to the Scoliosis Research Society questionnaires, significant (P < 0.05) changes preoperative to ultimate postoperative were found for questions 3, 5, 11, and 14. CONCLUSION: "Satisfactory" results were obtained in 44 patients treated with this technique. The complication rate was low and the fusion rate was high. Posterior treatment as described above produces reasonable and dependable results.

Adolescent↗