[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.

[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.

[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.

[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.

[En-bloc spondylectomy and reconstruction for primary tumors and solitary metastasis of the spine]. / En-bloc-Spondylektomie und Defektrekonstruktion bei Primärtumoren und Solitärmetastasen der Wirbelsäule.

In primary tumors of the spine and, with limitations, solitary metastasis, the surgical approach should aim for curative treatment of the disease. Because the prognosis of malignant bone tumors is extremely limited, if an intralesional approach is performed, an extralesional en bloc resection is the treatment of choice. Therefore, it is mandatory to use an appropriate staging system. For the spine, the WBB staging system has been approved, which transfers the principles of the Enneking classification for treating primary malignant tumors of the limb to the spine. After en bloc spondylectomy, rigid and primary stable instrumented dorsoventral reconstruction must be performed - posteriorly with a dual-rod system using pedicle screws, and anteriorly in the ideal case by means of a vertebral body replacement cage. The possibility of extralesional (wide or marginal) resection of spinal tumors depends on tumor size and location. Extralesional resection and, if indicated, other neoadjuvant, adjuvant, or local therapeutic modalities have a strong positive influence on long-term survival rates. A good prognosis for primary tumors is associated with a good response to chemotherapy and extralesional resection. Solitary metastases have a much worse quod vitam prognosis. Therefore, local control of the disease in en bloc resections of solitary metastasis is a second relevant goal, although curative treatment is the primary aim.

[Surgical treatment of idiopathic scoliosis with anterior dual rod instrumentation]. / Operative Therapie der idiopathischen Skoliose mittels ventraler Doppelstabinstrumentation.

BACKGROUND: In the surgical treatment of idiopathic scoliosis both anterior and posterior correction and instrumentation techniques are available. The aim of the present study was to analyse the results of a new anterior dual rod instrumentation. PATIENTS AND METHODS: Prospective analysis of radiometric and clinical parameters of 93 patients operated on between 1996 and 2004 using the Münster Anterior Dual Rod System. RESULTS: The average curve correction was 65% (fusion length usually Cobb levels) with a preoperative Cobb angle of 59 degrees. Postoperative loss of correction amounted to 1.5 degrees (average follow-up of 36 months). Apical vertebral derotation averaged 45% in the thoracic and 53% in the lumbar spine with a subsequent correction of the rib hump of 66% and the lumbar hump of 81%. There were no revisions or neurological complications. CONCLUSION: Anterior dual rod instrumentation enables an effective and safe three-dimensional curve correction in single structural curves with only minimal loss of correction.

[Lumbar disc arthroplasty. Established technique or experimental procedure?]. / Lumbale Bandscheibenprothesen. Etablierte Technik oder experimentelles Vorgehen?

Lumbar interbody fusion used to be the most common surgical treatment for painful lumbar disc degeneration. With the technical development of total disc prostheses, replacement of the degenerated disc by a motion preserving implant has become a widely discussed alternative. The advantages of such replacement appear to include the prevention of adjacent segment disease as well as less perioperative morbidity. Three types of total disc prostheses are currently in common use. Although numerous studies have been made, a review of the literature reveals only two multicenter randomized studies comparing the outcome of disc prostheses with a control group of fusion patients. After 2 years, the available results show similar improvement after both types of surgery without significant differences. However, there is a trend towards faster recovery and improvement in disc arthroplasty patients. The long-term results of current and future randomized studies, including studies comparing results after disc arthroplasty, with results of standardized conservative therapies will determine the fate of lumbar disc prostheses.

[Surgical therapy of unspecific and specific Spondylodiscitis]. / Operative Therapie der unspezifischen und spezifischen Spondylodiszitis.

AIM: The aim of this study was to evaluate the clinical and radiological results of surgical treatment of thoracic and lumbar vertebral osteomyelitis by means of one-stage extrafocal posterior stabilisation, anterior debridement, and anterior column reconstruction. METHOD: A retrospective analysis of the peri- and postoperative parameters of 62 patients with a clinical and radiographic follow-up of 2.6 years that were available for 46 patients was performed. In 42 cases, the anterior column was restored with structural bone grafts, in 20 patients, expandable titanium cages filled with morsellised autologous bone and antibiotic collagen sponges were used. To assess the course of spinal alignment a radiometric analysis was undertaken. Furthermore, the Roland-Morris score (RMS) was applied to evaluate the back pain-related disability. RESULTS: The diagnosis was made no earlier than 2.7 months after the first symptoms. Preoperatively, 40 % of the patients presented with neurological impairment, of these 76 % improved after surgery. Staphylococcus aureus was the most common pathogen isolated (32 %), Mycobacterium tuberculosis was found in 11 % of the patients. Except for one patient with revision for persistent infection and consecutive failure of the bone graft, primary eradication of the infection was achieved in all cases. At follow-up, bony fusion was radiographically observed in all patients. When using cages, the segmental loss of correction was significantly lower than when using bone grafts (1.0 vs. 4.1 degrees ). At follow-up the RMS averaged 6.6. CONCLUSION: One-stage extrafocal posterior stabilisation combined with anterior debridement and anterior column reconstruction with bone grafts or titanium cages is a safe and effective strategy for patients with vertebral osteomyelitis in need of surgery. Titanium cages have proven to be biomechanically advantageous, especially in cases of extensive destruction and are not associated with higher rates of persistence or recurrence of infection compared to autologous bone grafts.

[Prospective evaluation of braces as treatment in idiopathic scoliosis]. / Prospektive Untersuchung zur Korsettbehandlung bei idiopathischen Skoliosen.

AIM: To prospectively evaluate the results of brace treatment in idiopathic scoliosis and to define risk factors of treatment failure. METHOD: Fifty-two patients with a Cobb angle of between 25 and 40 degrees were included in the study. Prior to initiation of brace treatment with the Chêneau-Toulouse-Muenster orthesis, skeletal age and flexibility of the curve (bending films) were evaluated. The average follow-up after weaning of the brace was 42 months (36-78 months). RESULTS: An average initial Cobb angle of 31 degrees was corrected to 18 degrees (43 %) under brace treatment with a flexibility to 6 degrees Cobb angle on bending films. Three years after weaning there was an overall increase of the Cobb angle to 37 degrees on average. The apical vertebral rotation was corrected from 16 degrees to 11 degrees (31 %) and increased to 20 degrees during follow-up. Thoracic kyphosis changed from 24 degrees to 18 degrees during treatment. At the latest follow-up kyphosis had returned to the pre-treatment angle again. Twenty-two patients had a curve progression during or after brace treatment of more than 5 degrees. In 14 patients surgical correction and fusion have been indicated. There was a positive correlation between flexibility and Cobb angle correction during brace treatment and a negative correlation between Cobb angle correction during brace treatment and curve progression (p < 0.05). CONCLUSIONS: Curve progression was prevented in 58 %. Prognostic risk factors are a young age at initiation of brace treatment, a thoracic curve, unsatisfactory curve correction in the brace and a male gender.

Titanium cages in the surgical treatment of severe vertebral osteomyelitis.

The role of spinal implants in the presence of infection is critically discussed. In this study 20 patients with destructive vertebral osteomyelitis were surgically treated with one-stage posterior instrumentation and fusion and anterior debridement, decompression and anterior column reconstruction using an expandable titanium cage filled with morsellised autologous bone graft. The patients' records and radiographs were retrospectively analysed and follow-up clinical and radiographic data obtained. At a mean follow-up of 23 months (range 12-56 months) all cages were radiographically fused and all infections eradicated. There were no cases of cage dislocation, migration or subsidence. Local kyphosis was corrected from 9.2 degrees (range -20 degrees to 64 degrees ) by 9.4 degrees to -0.2 degrees (range -32 degrees to 40 degrees ) postoperatively and lost 0.9 degrees during follow-up. All five patients with preoperative neurological deficits improved to Frankel score D or E. Patient-perceived disability caused by back pain averaged 7.9 (range 0-22) in the Roland-Morris score at follow-up. In cases of vertebral osteomyelitis with severe anterior column destruction the use of titanium cages in combination with posterior instrumentation is effective and safe and offers a good alternative to structural bone grafts. Further follow-up is necessary to confirm these early results.

[Selective ventral derotation spondylodesis in idiopathic thoracic scoliosis: a prospective study]. / Selektive ventrale Derotationsspondylodese bei idiopathischen Thorakalskoliosen: eine prospektive Studie.

AIM: Radiometric curve analysis of instrumented primary and spontaneous secondary curve correction after anterior correction and fusion of idiopathic thoracic scoliosis. METHOD: Sixty-four patients with idiopathic thoracic scoliosis were prospectively evaluated. All patients were operated either with the Zielke-VDS or with a primary stable double rod instrumentation with selective fusion of the thoracic curve from end-to end-vertebra. Follow-up averaged 29 months (24 - 52 months). RESULTS: The Cobb angle of the primary curve averaged 63.2 degrees preoperatively and was corrected to 21.4 degrees postoperatively with an average loss of correction of 5.3 degrees (58 % final curve correction). Apical thoracic vertebral rotation was corrected by 48 %. The secondary lumbar curve measured 38.2 degrees preoperatively (72 % correction on the bending films) and was spontaneously corrected by 57 % to 16.4 degrees without significant loss of correction in the final follow-up. Apical vertebral rotation averaged 11.3 degrees in the lumbar curve and was corrected spontaneously by 24 % to 8.6 degrees without significant loss of correction. Lumbar apex vertebra deviation showed no significant reduction. There was no case of lumbar curve decompensation in either frontal or sagittal plane. Implant related complications were observed in 7 patients (rod breakage), but no pseudarthrosis occurred. There were no neurological complications noted. CONCLUSION: Selective anterior correction and fusion in idiopathic thoracic scoliosis enables a satisfactory correction of both primary and lumbar secondary curves. The advantage of selective anterior correction and fusion of thoracic scoliosis is the short fusion length, better derotation and satisfactory correction of the secondary lumbar curve. The disadvantages of single threaded rod techniques in terms of lack of primary stability and a kyphogenic effect have been eliminated by the development of a primary stable, small size double rod instrumentation.

Comparative analysis of pedicle screw and hook instrumentation in posterior correction and fusion of idiopathic thoracic scoliosis.

Posterior correction and fusion with segmental hook instrumentation represent the gold standard in the surgical treatment of progressive idiopathic thoracic scoliosis. However, there is a debate over whether pedicle screws are safe in scoliosis surgery and whether their usage might enable a better curve correction and a shorter fusion length. The details of curve correction, fusion length and complication rate of 99 patients with idiopathic thoracic scoliosis treated with either hook or pedicle screw instrumentation were analyzed. Forty-nine patients had been operated with the Cotrel-Dubousset system using hooks exclusively ("hook group"). Fifty patients had been operated with either a combination of pedicle screws in the lumbar and lower thoracic and hooks in the upper thoracic spine or exclusive pedicle screw instrumentation using the Münster Posterior Double Rod System ("screw group"). The preoperative Cobb angle averaged 61.3 degrees (range 40 degrees-84 degrees ) in the hook group and 62.5 degrees (range 43 degrees-94 degrees ) in the screw group. Average primary curve correction was 51.7% in the hook group and 55.8% in the screw group ( P>0.05). However, at follow-up (2-12 years later) primary curve correction was significantly greater ( P=0.001) in the screw group (at 50.1%) compared to the hook group (at 41.1%). Secondary lumbar curve correction was significantly greater ( P=0.04) in the screw group (54.9%) compared to the hook group (46.9%). Correction of the apical vertebral rotation according to Perdriolle was minimal in both groups. Apical vertebral translation was corrected by 42.0% in the hook group and 55.6% in the screw group ( P=0.008). Correction of the tilt of the lowest instrumented vertebra averaged 48.1% in the hook group and 66.2% in the screw group ( P=0.0004). There were no differences concerning correction of the sagittal plane deformity between the two groups. Fusion length was, on average, 0.6 segments shorter in the screw group compared to the hook group ( P=0.03). With pedicle screws, the lowest instrumented vertebra was usually one below the lower end vertebra, whereas in the hook group it was between one and two vertebrae below the lower end vertebra. Both operative time and intraoperative blood loss were significantly higher in the hook group ( P<0.0001). One pedicle screw at T5 was exchanged due to the direct proximity to the aorta. There were no neurologic complications related to pedicle screw instrumentation. Pedicle screw instrumentation alone or in combination with proximal hook instrumentation offers a significantly better primary and secondary curve correction in idiopathic thoracic scoliosis and enables a significantly shorter fusion length.

[Technique and results of monosegmental transpedicular subtraction osteotomy in patients with ankylosing spondylitis and fixed kyphotic deformity of the spine]. / Technik und Ergebnisse der monosegmentalen transpedikulären Wirbelkörpersubtraktionsosteotomie bei Patienten mit Spondylitis ankylosans und fixierter kyphotischer Deformität.

AIM: The posterior extension osteotomy leads to a lengthening of the anterior column, which is associated with neurological complications and the risk of injuring retroperitoneal structures. Especially in high-grade syndesmophytosis the results are dissatisfactory. In this study we report on the results of an alternative procedure named the transpedicular subtraction osteotomy. METHOD: After resection of the posterior elements of the vertebra at the level of the osteotomy, a wedge of the vertebral body including the pedicles with posterior basis is resected followed by an instrumented closing wedge, which leads to relordosation. 12 patients were treated with this method and reexamined with a minimum follow-up of 2 years (2 - 6 years). The level of osteotomy ranged from T12 to L3. RESULTS: The mean segmental correction averaged 30.1 degrees (25 - 36 degrees ). The overall relordosation averaged 35.9 degrees and was related to additional correction in the adjacent segments. With this dissatisfactory a sufficient correction of spinal balance and visual axis was obtained. All patients were satisfied with the result of the operation and would undergo surgery again from a retrospective point of view. CONCLUSION: With the transpedicular subtraction osteotomy fixed kyphotic deformities of the spine in patients with ankylosing spondylitis can be corrected produce safely. The level of osteotomy is discussed and should depend upon the apex of kyphosis.

Occlusion of the left common iliac artery and consecutive thromboembolism of the left popliteal artery following anterior lumbar interbody fusion.

We report on a case of occlusion of the left common iliac artery due to arteriosclerosis and consecutive thrombotic occlusion of the left popliteal artery in a 52-year-old man following anterior retroperitoneal interbody fusion of L4--S1. Initial symptoms included leg pain and numbness of the lateral shank, which were thought to be a result of lumbar nerve root irritation from surgery. Diagnosis was not made until 13 days after surgery, when motor deficits were observed. Angiography showed occlusion of the left common iliac artery and thromboembolism of the left popliteal artery. After thromboendarterectomy of the common iliac artery and thrombectomy of the popliteal artery, motor deficits of the left foot were resolved whereas symptoms of pain and sensory deficits continued. Spine surgeons should be aware of this rare complication in cases of postoperative leg pain or of neurologic deficits in the lower extremity after anterior lumbar interbody fusions.

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.

[Surgical correction and stabilization of neuromuscular scoliosis--2-4-year results of dorsal and one-stage ventro-dorsal operated patients]. / Die operative Korrektur und Stabilisierung neuromuskulärer Skoliosen--2-4-Jahres-Ergebnisse dorsal und einzeitig ventrodorsal operierter Patienten.

QUESTION: In order to evaluate the outcome of the operative treatment of neuromuscular scoliosis 45 patients were studied prospectively. METHODS: 27 Patients were operated by posterior correction and fusion using the Münster Posterior Doublerod-System (MPDS) (GI). 18 Patients were treated with one-stage ventro-dorsal procedure in combination of VDS with MPDS (GII). For all patients, medical and radiographic records were available, with a minimum follow-up of 2 years. Postoperative management, bloodloss and complications will be discussed. RESULTS: In group I the main curve (76.3 degrees), by an average flexibility of 36.1%, were corrected by 53.5% and 52.3% at follow up. The mean pelvic obliquity (7.7 degrees) averaged 53.8%. The mean major scoliosis of group II (107.1 degrees), by an average flexibility of 25%, gets improved by 61%. At most recent follow-up, the mean correction was 61.5%. The mean pelvic obliquity (23.1 degrees) averaged 73.2% and 70.6% respectively. The mean bloodloss in group I was 1840 ml and in group II 2180 ml. CONCLUSION: The data in the current study support the benefit of the operative treatment of patients with severe neuromuscular scoliosis. The quality of life gets improved by stability in seating and standing by correction of pelvic obliquity and trunk instability.