[Collected data on freehand technique instrumentation and literature comparison on fluoroscopic and CT-assisted navigation]. / Erhobene Daten zur Instrumentierung in Freihandtechnik und Literaturvergleich zu fluoroskopisch- und CT-gestützter Navigation.

BACKGROUND: A proven and frequently used surgical procedure in patients with idiopathic scoliosis (IS) is posterior transpedicular corrective spondylodesis using the freehand technique. Novel procedures with fluoroscopically and computed tomography (CT)-assisted navigation are presumed to be less risky and more accurate. OBJECTIVE: Is the freehand technique for IS safe with respect to screw-associated complications and intraoperative radiation exposure? MATERIAL AND METHODS: Prospectively collected data (2017-2018) from 39 consecutive patients (average age 18.7 years) with thoracic single curvature IS (61.7°â€¯± 13.9°) from a specialized scoliosis center were evaluated for the following parameters (mean ± standard deviation): total radiation product, fluoroscopy time, fused segments, operative time, blood loss and screw-associated complications. A comparison with data from the literature on intraoperative radiation exposure using navigation procedures was carried out. RESULTS: The total radiation product per patient was 71.7 ± 44.0 cGy*cm2, fluoroscopy time 17.4 ± 8.6 s. (7.8 segments), operative time 183.5 ± 54.2 min and blood loss 379.5 ± 183 ml. There were no screw-associated complications in the entire collective. Correction of the main curvature was 75.7%. Comparison of the data with index data from the literature showed a 1.25-12.5-fold higher radiation exposure for patients with fluoroscopically assisted navigation and 9.25-12.3-fold higher radiation exposure with CT-assisted procedures compared to the present results. CONCLUSION: The results of this study showed that with appropriate experience freehand positioning of pedicle screws is associated with comparable accuracy and less radiation exposure for patients than navigation procedures. With respect to the young age of patients, a radiation-induced long-term risk for malignant diseases should be taken into consideration.

[Surgical treatment of de-novo scoliosis]. / Operative Therapie der degenerativen Lumbalskoliose.

BACKGROUND: De-novo scoliosis is most commonly associated with chronic back pain and in 70 % of cases with neurological symptoms of the lower extremities. In recent literature, the occurrence and severity of segmental lateral listhesis has been discussed as being an important prognostic factor of sagittal and frontal deformity progression. In general, operative interventions in patients with de-novo scoliosis are associated with a high rate of complications. Therefore, conservative treatment modalities are recommended at early stages of the disease. If conservative management fails and a sufficient reduction of the patient's symptoms cannot be achieved, depending on the symptoms, a selective decompression, short-segment fusion or long-instrumented reduction and fusion are indicated. Additionally to the patient's symptoms, specific imaging diagnostics are necessary to develop an adequate surgical treatment strategy. TREATMENT: Selective decompression without fusion is indicated in patients with a fixed deformity and primarily neurologic pain or deficits. In conditions of a focal pathology as cause of significant low back pain and/or neurologic symptoms at early stages of deformity, a short segment fusion is the treatment of choice. However, short-segment fusion as a less-invasive procedure must not be performed in biplanar unbalanced patients and/or advanced de-novo scoliosis. In advanced degenerative de-novo scoliosis a long-segment reposition and fusion following an alignment correction are needed. Standardized pre-operative planning and perioperative management are highly critical to the post-operative success. CONCLUSION: All operative treatment strategies in patients with de-novo scoliosis can be successful but they require sophisticated and individual surgical indication.

[Transforaminal lumbar interbody fusion for the treatment of degenerative spondylolisthesis]. / Transforaminale lumbale interkorporelle Fusion zur Versorgung der degenerativen Spondylolisthese.

INTRODUCTION: Degenerative spondylolisthesis (DS) is a common cause of lumbal and lumbosacral pain as well as radicular pain. Retention and fusion is a good treatment option. Some patients have a symptomatic adjacent degenerative disc disease (DDD) in addition to DS. In these cases the adjacent segments should be fused as well. There are different techniques of fusion available, such as posterior with instrumentation or additional anterior support. This study evaluated results of transforaminal lumbar interbody fusion (TLIF) in patients with monosegmental DS and adjacent DDD. MATERIAL AND METHODS: A total of 28 patients with monosegmental DS and adjacent DDD were included into the study (all patients with bisegmental posterior instrumentation and fusion, 14 patients 1 level TLIF, 14 patients 2 level TLIF). Before surgery and 12 months after surgery the following measurements were made: pain (visual analog scale VAS), Oswestry disability index (ODI) and plain radiographs with radiometric analysis. In a sub-analysis patients with 1 and 2 level TLIF were compared. RESULTS: Pain reduction (average VAS from 8.7-3.1) and ODI (63% to 28%) showed significant improvements. Radiometric analysis showed a significant disc height reconstruction and a significant reduction of spondylolisthesis (TLIF level with spondylolisthesis). Bisegmental anterior support showed a significantly better relordosation compared to monosegmental anterior support. The complication rate was 21.4% including hemorrhages, dura leakage, wound infection and adjacent segment degeneration. There were no fatal complications. DISCUSSION: The TLIF procedure is a safe and effective treatment for monosegmental DS with adjacent symptomatic DDD. Clinical results (pain, function) show no difference between both kinds of fusion (dorsal fusion and instrumentation versus dorsal fusion with instrumentation and TLIF) for the adjacent DDD. However, additional anterior support is more effective for relordosation of the segment. This could have impact on the mid-term and long-term outcome or in cases of adjacent segment fusion.

[Surgical management of adult scoliosis. The challenge of osteoporosis and adjacent level degeneration]. / Die operative Behandlung der adulten Skoliose. Osteoporose und Versagen des Anschlusssegments als besondere Herausforderung bei der operativen Versorgung.

Adult scoliosis is defined as a spinal deformity with a Cobb angle of more than 10 degrees in the coronal plain in a skeletally mature patient. Patients predominantly suffer from back pain symptoms, often accompanied by signs of spinal stenosis (central as well as lateral). Asymmetric degeneration leads to asymmetric load and therefore to a progression of the degeneration and deformity as either scoliosis (0.5-1 degree per year), kyphosis, or both. The diagnostic evaluation includes static and dynamic imaging, magnetic resonance imaging, and myelo-computed tomography, as well as invasive diagnostic procedures such as discograms, facet blocks, and epidural and root blocks. The treatment, either conservative or surgical, is then tailored to the patient's specific symptomatology. Surgical management is usually complex and must take into account an array of specific problems, including the patient's age and general medical condition, the length of the fusion, the condition of the adjacent segments, the condition of the lumbosacral junction, osteoporosis, and any previous scoliosis surgery. The main goal of corrective surgery is a balancing of the coronal and sagittal planes.This review focuses on the special indications for vertebral body cement augmentation in patients with osteoporosis and the problem of adjacent level degeneration and its surgical management.

[Anterior scoliosis surgery. State of the art and a comparison with posterior techniques]. / Ventrale Skolioseoperationen. Stand der Technik und Vergleich mit dorsalen Verfahren.

For more than 2 decades ventral derotation spondylodesis (Zielke VDS) as a major improvement over Dwyer instrumentation (DI) was the gold standard of instrumented curve correction and stabilization from the anterior approach. As the first available system it enables a true three-dimensional curve correction. A disadvantage is the low internal stabilization capability with a need for long-term external stabilization by means of cast and brace treatment postoperatively. Meanwhile with the development of modern single and dual solid rod systems these disadvantages can be avoided completely. Video-assisted (thoracoscopic) anterior scoliosis surgery accounts for less than 2% of anteriorly treated scoliosis cases, mainly due to a long operating time and significant learning curve.From the posterior approach the Cotrel-Dubousset instrumentation (CDI) as a polysegmentally attached posterior hook threaded dual rod system used to be state of the art for a long time, since it eliminated the disadvantages of Harrington instrumentation (HI) in terms of only one-dimensional correction and low stabilization capabilities. However even with CDI effective derotation was impossible. In posterior scoliosis surgery there is a strong trend away from hook systems towards transpedicular segmentally fixed dual rod systems not only in the lumbar spine but also in the thoracic area. Advantages of these newer techniques are shorter fusion, improved correction, and less loss of correction over time.Advantages of modern anterior instrumentation systems in comparison to posterior transpedicular instrumented dual rod systems are less blood loss, better derotation, slightly shorter fusion levels, and a better influence on sagittal plane control or improvement especially for hypokyphotic thoracic scoliosis cases. Our data also document a superior spontaneous correction of the lumbar curve after selective anterior instrumented correction (Lenke 1B+C), although other studies could not find significant differences. In our experience the neurological risk of anterior instrumented correction is also lower than that of posterior scoliosis surgery, although the morbidity and mortality data of the Scoliosis Research Society could not prove that anymore in recent years. A negative effect of anterior transthoracic scoliosis surgery in comparison to posterior surgery is a more negative effect on lung function, which improves slower after surgery and does not quite reach the levels of posterior surgery at follow-up. But new data on posterior segmental transpedicular correction and fusion also prove a lordosating effect with negative effect on lung function.

[Modern scoliosis surgery under the conditions of the German DRG-system]. / Finanzierbarkeit der modernen Skoliosechirurgie unter den Bedingungen des DRG-Systems.

In the German health system the payment of a hospital stay is standardised. The common basis is the G-DRG System (German diagnosis-related groups) in which every stay is paid by a lump sum. Scoliosis correction in our times means pedicle screw-based multilevel double rod instrumentation or anterior plate-rod instrumentation with primary stability. The outcome of those methods has improved the results of correction and decreased the complication rate but also means high costs due to the implants. Scoliosis correction is covered by DRG I06. Due to constant efforts a general improvement took place in the assessment of DRG I06. That is the reason why the losses incurred in DRG I06C could be lowered to 38% and in I06D to 22% in 2008. For an appropriate assessment further improvements are required.

Results of surgical correction of kyphotic deformities of the spine in ankylosing spondylitis on the basis of the modified arthritis impact measurement scales.

STUDY DESIGN: This is a retrospective study of patient outcome in ankylosing spondylitis patients with fixed kyphotic deformities of the spine who underwent reconstructive surgery. OBJECTIVES: To measure the multidimensional effects of reconstructive spinal osteotomy in this patient group with a questionnaire-based instrument. SUMMARY OF BACKGROUND DATA: Between 1979 and 1988, 175 ankylosing spondylitis patients underwent operative treatment for fixed flexion deformities of the spine. One hundred forty-eight of these patients answered the questionnaire correctly and were included in the study. The others either died or were lost to follow-up. METHODS: The modified Arthritis Impact Measurement Scales with eight scales and 60 items plus six additional summative questions were administered at a mean follow-up period of 4.8 years (range, 2-10 years). The modified Arthritis Impact Measurement Scale measures eight scales--mobility, physical, household, daily, social activity, pain, anxiety, and depression. The Wilcoxon and chi-square test were used for analysis. RESULTS: Forty-seven of 60 items showed significant improvement of activity levels or status. Only two items showed a significant impairment of function. Of the patients, 88.4% were very satisfied with the result of the operation; 60.9% were able to return to work. Age, sex, and type of surgical technique did not influence the results. CONCLUSIONS: The modified Arthritis Impact Measurement Scales approach shows excellent overall improvement of health status after surgery, proving the worth of reconstructive surgery in ankylosing spondylitis patients with fixed kyphotic deformities of the spine.

Pedicle screw instrumentation of the thoracic spine in idiopathic scoliosis.

STUDY DESIGN: A prospective study of the accuracy of thoracic pedicle screw placement in patients with idiopathic scoliosis. OBJECTIVES: To evaluate the accuracy of thoracic pedicle screw placement in the surgical management of idiopathic scoliosis and to establish its risks and benefits. SUMMARY OF BACKGROUND DATA: Lumbar pedicle screw instrumentation has proven to be reliable and effective in the surgical management of scoliosis. No reports exist on the accuracy and benefits of pedicle screw instrumentation of the thoracic spine in scoliosis surgery. METHODS: One hundred and twenty thoracic pedicle screws in 32 consecutively treated patients with idiopathic scoliosis were investigated immediately after surgery by computed tomography scans that were analyzed by three examiners. RESULTS: Thirty (25%) of the screws penetrated the pedicle cortex or the vertebral body anterior cortex. Ten screws (8.3%) penetrated the medial cortex of the pedicle by an average of 1.5 mm and a maximum of 3.0 mm. Seventeen screws (14.2%) penetrated laterally by an average of 2.1 mm. There were two cases of caudad penetration. Three screws penetrated the anterior vertebral cortex, of which two also penetrated the pedicle cortex. Also, one of these three screws was replaced because of its direct proximity to the thoracic aorta. There were no neurologic complications. The correlation between the pedicle cortical penetration rate and the preoperative Cobb angle, vertebral rotation or level, or site of screw insertion was statistically insignificant (P > 0.05). Curve correction in the cases of mainly hook instrumentation averaged 52.5% versus 59.2% in the cases of mainly screw instrumentation. This difference was statistically insignificant (P > 0.05). CONCLUSIONS: Pedicle or vertebral body cortical penetration occurred with 25% of the screws but with no neurologic compromise. Curve correction was slightly greater than with hooks, but not to a statistically significant extent.

Morphometric analysis of thoracic and lumbar vertebrae in idiopathic scoliosis.

STUDY DESIGN: Prospective study on the morphometry of 337 pedicles in 29 patients with idiopathic scoliosis. OBJECTIVES: To analyze by means of computed tomographic scans the vertebral morphometry in idiopathic scoliosis treated by pedicle screw instrumentation. SUMMARY OF BACKGROUND DATA: Although several studies exist on the vertebrae's morphometry in normal spines, little is known concerning the morphometry of scoliotic vertebrae. METHODS: The pedicles' morphometry between T5 and L4 was analyzed by computed tomographic scans in 29 surgically treated patients with idiopathic right thoracic scoliosis. Measurements included chord length, endosteal transverse pedicle width, transverse pedicle angle, and pedicle length. RESULTS: The endosteal transverse pedicle width was significantly smaller (P < 0.05) on the concavity in the apical region of the thoracic spine and measured between 2.5 and 4.2 mm in the middle thoracic spine (T5-T9) and between 4.2 and 5.9 mm in the lower thoracic spine (T10-T12). In the lumbar spine, the width varied between 4.8 and 9.5 mm without significant differences between the concave and convex sides (P > 0.05). The chord length was shortest at T5, measuring 37 mm and increased gradually to 50 mm at L3 with significantly larger dimensions in male patients and on the concavity of the apical region in the thoracic spine (P < 0.05). The pedicle length varied minimally, with a range of between 20 and 22 mm, and was relatively consistent throughout the thoracic and lumbar spine. The transverse pedicle angle varied between 6 degrees in the lower thoracic spine and 12 degrees in the upper thoracic and lower lumbar spine. CONCLUSION: The morphometry in scoliotic vertebrae is substantially different from that of vertebrae in normal spines, with an asymmetrical intravertebral deformity shown in scoliotic vertebrae. Pedicle screw instrumentation on the concavity in the apical region of thoracic curves appears critical because of the small endosteal pedicle width.

Accuracy of pedicle screw placement in lumbar vertebrae.

STUDY DESIGN: The location of pedicle screws (n = 42) in four human specimens of the lumbar spine and in 30 patients (n = 131 screws) after lumbar spinal fusion was assessed using computed tomography. OBJECTIVES: To determine the accuracy of pedicle screw placement in lumbar vertebrae and the reproducibility and repeatability of the computed tomography examination. SUMMARY OF BACKGROUND DATA: Failures in the placement of transpedicular screws for lumbar fusion are reported. The evaluation of such screws using computed tomography examination has not been investigated. METHODS: After surgery, the specimens were dissected in transversal slices to observe macroscopically the location of the pedicle screw and to correlate these observations with the computed tomography images. All patients were examined by one observer. To determine the reproducibility and repeatability of the computed tomography examination, two observers studied computed tomography images of 12 patients (n = 58 screws) twice within 3 months. RESULTS: In the specimens, 10 screws were observed to penetrate the medial wall of the pedicle. This correlated fully with the images. In the patients' group, 40% of all screws penetrated the cortex of the vertebra. Of all screws, 29% penetrated the medial wall of the pedicle. From the computed tomography images, it appeared that a deviation of more than 6 mm medially was a high risk for nerve root damage. Three months after his first examination, Observer 1 documented a different position in three of 58 screws (kappa = 0.90). Observer 2 found a different position in eight screws (kappa = 0.65). The comparison between the reviews of the two observers showed a different opinion for the first evaluation, four disagreements (2-4 mm) and 17 disagreements (0-2 mm; kappa = 0.34), and for the second evaluation, four disagreements (2-4 mm) and 12 disagreements (0-2 mm; kappa = 0.43). CONCLUSIONS: Correct placement of transpedicular screws for spinal fusion seems to be more difficult than it looks. The computed tomography scanning is useful for differential diagnosis of postoperative radicular syndromes after lumbar transpedicular fixation.

Metastatic retroperitoneal paraganglioma in a 16-year-old girl. Case report, molecular pathological and cytogenetic findings.

Retroperitoneal paraganglioma is a rare tumor, especially occurring in childhood and adolescence, with a marked tendency to become biologically malignant. It has not been possible to predict the clinical outcome of paraganglioma patients by conventional histology, hence malignancy can only be demonstrated by the occurrence of metastatic lesions. Currently, only limited information on the genetics of this tumor is available. We report on a 16-year-old girl with a large retroperitoneal paraganglioma and an osseous metastasis to the first lumbar vertebra. In addition to morphological and immunohistochemical examinations, a molecular cytogenetic analysis was performed. Comparative genomic hybridization (CGH) revealed imbalanced chromosomal aberrations with a loss of chromosome 1p and a gain of 1q, indicating isochromosome 1q. A loss of chromosome 3 as well as low-level gains of chromosomes 4, 5, 6q, 11q and 13q were detected. A PCR-based microsatellite analysis of 1p confirmed the loss of heterozygosity, including NB1 and NB2 putative tumor-suppressor gene regions. Telomerase activity, which is found in the majority of malignant tumors, could not be detected. The case presented here is the first more comprehensive molecular genetic analysis of a sporadic malignant paraganglioma.

The BWM spinal fixator system. A preliminary report of a 2-year prospective, international multicenter study in a range of indications requiring surgical intervention for bone grafting and pedicle screw fixation.

STUDY DESIGN: A prospective, international, multicenter study of 400 patients who received the BWM fixator system. OBJECTIVES: To assess the effectiveness and safety of the system in the management of various conditions requiring spinal fixation and bone grafting. SUMMARY OF BACKGROUND DATA: The BWM system was developed for the management of spinal instability of all etiologies occurring in the thoracic, thoracolumbar, and lumbosacral spine. METHODS: Patients with fracture, tumor, spondylolisthesis, spondylitis, failed back, or other degenerative conditions of the spine received the BWM instrumentation as described in the study literature and were regularly reviewed for 2 years. RESULTS: The results from the first 200 patients to complete the study showed an overall graft fusion rate of 94% (95% confidence interval: 91.3%-97.6%). There were marked improvements in measures of functional ability (P < 0.001, Wilcoxon test). Before surgery, less than half the patients were capable of outdoor activity. At 2 years, 80% were able to undertake outdoor activity. There were few perioperative difficulties reported. Postoperative complications associated with major surgery were seen in 18% patients. There were 23 (2.6%) pedicle screw failures, including two loosenings, and 13 (2.5%) spacer element failures, including three loosenings. CONCLUSIONS: Clinical failure was not necessarily a consequence of component failure. The BWM fixator provided excellent stabilization during the process of bone graft consolidation. The risks of complication or component failure were no higher than those associated with similar devices.

The influence of automated percutaneous lumbar discectomy (APLD) on the biomechanics of the lumbar intervertebral disc. An experimental study.

Twenty human lumbar motion segments were prepared and tested in an electromechanical materials testing machine in order to investigate the biomechanical changes, i.e. intradiscal pressure, radial extension and height of the intervertebral disc, after automated percutaneous lumbar discectomy (APLD) developed by Onik. The biomechanical data were statistically analyzed with the Friedman test (significance level p < 0.05). The APLD lasted 45 minutes in every segment. The mean weight of material removed was 4.6 g. The removal of 4.6 gram of nucleus pulposus material reduced the height of the disc by an average of 1.42 mm. The intradiscal pressure also decreased by an average of 5.7 bar. The radial bulge increased by an average of 0.45 mm. Our results show that the mechanism improving radicular pain in patients with herniated disc after treatment with percutaneous nucleotomy is still in question. While clinical studies show an improvement of 70% to 85% of patients treated with APLD for herniated disc, this in vitro study showed clearly that radial bulge increases after removal of nuclear material. We postulate that loss of height of the disc and, as a consequence, reduction of tension in the affected nerve root, plays a major role with regard to this improvement.

Pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine.

While the biomechanical properties of pedicle screws have proven to be superior in the lumbar spine, little is known concerning pullout strength of pedicle screws in comparison to hooks in the thoracic spine. In vitro biomechanical pullout testing was performed to evaluate the axial pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine with regard to surgical correction techniques in scoliosis. Nine human cadaveric thoracic spines were harvested and disarticulated. To simulate a typical posterior segmental scoliosis instrumentation, standard pedicle hooks were used between T4 and T8 and supralaminar hooks between T9 and T12 and tested against pedicle screws. The pedicle screws were loaded strictly longitudinal to their axis; the hooks were loaded perpendicular to the intended rod direction. In total, 90 pullout tests were performed. Average pullout strength of the pedicle screws was significantly higher than in the hook group (T4-T8: 531 N versus 321 N, T9-T12: 807 N versus 600 N, p < 0.05). Both screw diameter and the bone mineral density (BMD) had significant influence on the pullout strength in the screw group. For scoliosis correction, pedicle screws might be beneficial, especially for rigid thoracic curves, since they are significantly more resistant to axial pullout than both pedicle and laminar hooks.

Augmentation of ventral derotation spondylodesis according to Zielke with double-rod instrumentation. Preliminary report on two-year results of thoracolumbar curves.

The advantages of VDS according to Zielke with excellent 3-dimensional correction and shorter fusion levels in comparison to posterior instrumentation techniques are well known. A disadvantage is the necessity of long postoperative immobilization in a body cast or brace due to lack of primary stability. The aim of the VDS double-rod instrumentation is augmentation of the system with the possibility of postoperative treatment without plaster cast or braces. Following thoracolumbophrenotomy and ligation of the segmental vessels double-hole vertebra clamps are inserted. First VDS screws are placed in the posterior holes of these plates. With a 4-mm threaded compression rod correction is obtained by centripetal compressive forces on the nuts. Next VDS screws for the 5-mm threaded rod are inserted into the anterior holes of the vertebral clamps. The rod is implanted in a slightly compressive manner and augments the system. In a prospective study 8 patients, 4 with idiopathic and 4 with neuromuscular scoliotic deformities, underwent this surgical procedure and now have a follow-up of 2 years. Curves ranged from 45 degrees to 131 degrees Cobb angle. All patients were treated without plaster casts or braces postoperatively, but with only a semielastic vest for 4 to 6 months. Unusual intra- and postoperative complications have not been noted. Correction of the primary curve averaged 69.4% at follow-up. Tilt of the caudal end vertebra was corrected 75% to an average of 6.3 degrees. Spontaneous partial correction of the upper secondary curve was noted in all cases. Rod fracture of the 5-mm rod without fracture of the 4-mm rod at this level was seen in 1 patient without loss of correction. Solid fusion was achieved at every level in all patients. The sagittal plane was not adversely affected by the instrumentation. However, larger patient numbers and a longer follow-up are necessary.

Sagittal plane correction in "King-classified" idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

INTRODUCTION AND AIM OF THE STUDY: Whereas Harrington instrumentation (HI) has demonstrated satisfactory frontal plane correction, sagittal plane realignment is difficult. Sagittal plane control is reported to be easier with Cotrel-Dubousset instrumentation (CDI). This study was undertaken to determine if in our series sagittal realignment was achieved with CDI in idiopathic curves classified according to King. MATERIAL AND METHODS: Ninety-seven patients with idiopathic scoliosis classified according to King and treated with CDI underwent coronal and sagittal plane analysis by an unbiased observer. The sagittal curves were measured with the Cobb method from T4-T12 (normals: +25 to +40 degrees) and L1-L5 (normals: -40 to -55 degrees). The thoracolumbar junction (TJ) was divided into an upper TJ (T10-T12) and a lower TJ (T12-L2) with normals between 0 and +10 degrees for the former and 0 and -10 degrees for the latter. RESULTS: In all types of scoliosis with associated thoracic hypokyphosis a significant realignment could be achieved, ranging from 8 degrees in King 1 and 3 curves to 19 degrees in King 4 curves. In normokyphotic curves no significant changes of the thoracic spine were measured postoperatively. Concerning the upper TJ, pathological lordosis was corrected by 7 degrees on the average, whereas correction of kyphosis ranged from 8 to 18 degrees Cobb. Pathologic kyphosis and hyperlordosis of the lower TJ showed a mean correction of 7 degrees and 11 degrees, respectively. There was no significant direct influence of CDI on the sagittal plane of the lumbar spine. CONCLUSION: The data from this study suggest that correction in the sagittal plane can be achieved with CDI in King-classified scoliotic deformities.

Influence of the running shoe sole on the pressure in the anterior tibial compartment.

The objective of the study was to evaluate the influence of a negative shoe sole on the intracompartmental pressure in the anterior tibial compartment. In 35 volunteers, the compartment pressure was documented during a 20-min. run on a treadmill with conventional running shoes and with running shoes with a negative sole. Besides the documentation of the compartment pressure we also performed a gait analysis. The comparison of gait cycle between the conventional shoe and the shoe with a negative sole showed remarkable differences. With the conventional shoe, plantar flexion after initial contact was 16 degrees compared to 6 degrees with the special shoe. Duration of plantar flexion with the normal shoe was 0.17 sec. compared to 0.1 sec. with the special shoe. The intraindividual comparison of the individual pressure curves revealed evident differences in most of the subjects. The comparison of maximum pressures of each volunteer after running with the normal shoe as well as with the special shoe showed a decrease in the maximum pressure level when using the special shoe. The maximum pressures with the normal shoe (59.7 +/- 9.1 mm Hg) were significantly higher than with the special shoe (36.5 +/- 11.8 mm Hg) (p < 0.001). The comparison of the mean pressure showed similar results. With the normal shoe a mean pressure of 47.1 mm Hg (+/- 9.0 mm Hg) was measured compared to 29.8 mm Hg (+/- 11.0 mm Hg) with the special shoe (p < 0.001). Regarding the subjective comfort of the special shoe 18 subjects did not find any difference in comparison with the normal shoe.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of tumors of the spine.

Thirty-one patients with spinal tumors underwent reconstructive surgery with our spinal instrumentation system (MPDS and MADS), with or without our new vertebral tumor prosthesis. The characteristics of the spinal tumors were analysed statistically and the treatment outcome was evaluated. There were 4 benign tumors, 6 malignant tumors, and 21 metastatic tumors. The malignant tumors involved the sacrum more frequently than the benign tumors (p = 0.0098). Metastatic tumors involved the thoracic spine more frequently than benign or malignant tumors (p = 0.0161). The average number of affected vertebrae was 1.2 in the benign tumors, 1.8 in the malignant tumors, and 2.4 in the metastatic tumors. The metastatic tumors had a tendency to involve the anterior or middle part of the spine more frequently than the benign or malignant tumors (statistically not significant). After surgery, neurological improvement was noted in 8 patients, nochange in 19 patients, and impairment due to resection of the nerve roots in sacral tumors in 4 patients.