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Cement augmentation of pedicle screws biomechanically increases screw purchase in the bone. However, clinical complications may occur. The pros and cons of the technique are discussed from different clinical perspectives.

Cement augmentation of pedicle screws biomechanically increases screw purchase in the bone. However, clinical complications may occur. The pros and cons of the technique are discussed from different clinical perspectives.

Die schwergradige Osteoporose stellt in der instrumentierenden Wirbelsaulenchirurgie ein groses Problem dar. Neben Anschlusskyphosierungen und -frakturen sind Schraubenlockerungen und Implantatausrisse ein alltagliches Problem bei der osteoporotischen Wirbelsaule. Es ist hinreichend bekannt, dass die Knochendichte neben Schraubendicke und -lange den grosten Einfluss auf die Stabilitat einer Schraube hat. Bei einer schweren Osteoporose kann durch die Zementaugmentierung die Ausrissfestigkeit einer Pedikelschraube um 96–278% verbessert werden. Bis heute haben sich zwei verschiedene Vorgehensweisen etabliert: Zementierung des Wirbelkorpers vor Einbringen der Schraube in den noch weichen Zement oder Zementaugmentierung nach Einbringung einer perforierten Schraube. Das groste Problem der Augmentierung ist das Auftreten von Leckagen. Zementleckagen konnen bei beiden Techniken auftreten. Bei der Augmentation uber die perforierte Schraube scheint aber das Problem eine geringere Rolle zu spielen, da die Zementierung bei einer beginnenden Leckage sofort beendet werden kann. Die Revision der zementierten Schrauben stellt nach aktuellen biomechanischen Erkenntnissen kein groseres klinisches Problem dar. Auch die initial zementierten Schrauben konnen im Revisionsfall 1 mm dicker gewahlt werden und ebenfalls erneut zementiert werden.

Progrediente Skoliosen ab einem Krummungswinkel von etwa 40–50° sollten durch eine Instrumentationsspondylodese korrigiert und stabilisiert werden. Dabei ist in der Regel die Fusion der strukturellen Krummung (Primarkrummung) ausreichend. Die nichtstrukturellen Krummungen (Sekundarkrummungen) sind flexibel und richten sich nach Korrektur der Primarkrummung spontan auf. Die Identifikation der Primarkrummung und ihre Abgrenzung von den Sekundarkrummungen sind dabei fur die Operationsplanung und fur den Erfolg der Operation entscheidend. Laut Lenke-Klassifikation sind alle Krummungen einer Skoliose, die auf der reversen Bending-Aufnahme eine Restkrummung von ≥25° oder eine pathologische Kyphosierung aufweisen, als strukturell einzustufen und sollten fusioniert werden. Eigene Erfahrungen und auch Berichte in der Literatur haben jedoch gezeigt, dass daruber hinaus klinische Parameter wie Schulterstand und Rippenbuckel bzw. Lendenwulst und auch andere radiometrische Grosen wie u. a. die Rotation eine entscheidende Rolle in der Festlegung der Fusionsstrecke spielen. Somit ist die Lenke-Klassifikation eine wichtige Entscheidungshilfe in der Operationsplanung, wobei in der individuellen Betrachtungsweise auch stets weitere wichtige Parameter berucksichtigt werden mussen.

In der operativen Therapie der idiopathischen Skoliose stehen sowohl dorsale als auch ventrale Korrektur- und Stabilisierungstechniken zur Verfugung. Ziel der vorliegenden Arbeit war die Analyse der Ergebnisse der ventralen Derotationsspondylodese unter Verwendung eines neueren Doppelstabsystems. Es erfolgt eine prospektive Analyse radiometrischer und klinischer Parameter von 93 Patienten, die zwischen 1996 und 2004 mit dem Munsteraner Anterioren Doppelstabsystem operativ behandelt worden sind. Bei einer kurzen Fusionstrecke von in der Regel End-zu-End-Wirbel gelang eine durchschnittliche Krummungskorrektur von 65% bei einem Ausgangswinkel von 59°. Der postoperative Korrekturverlust nach durchschnittlich 36 Monaten war mit 1,5° minimal. Die Derotation betrug thorakal 45% und lumbal 53%, wodurch sich der Rippenbuckel um 66% und der Lendenwulst um 81% korrigieren lies. Revisionsbedurftige oder neurologische Komplikationen traten nicht auf. Die ventrale Korrektur und Instrumentationsspondylodese in Doppelstabtechnik ermoglicht eine sehr gute und sichere dreidimensionale Krummungskorrektur strukturell einbogiger Skoliosen.

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.

Diagnostic radiology and magnetic resonance imaging (MRI) are the most important imaging tools in the evaluation of benign bone tumors. Computed tomography (CT) is an additional tool for bony lesions, such as in cases of confirmation of the diagnosis of osteoid osteomas. For benign bony lesions three-stage skeletal scintigraphy is an optional additional diagnostic tool. The identification of benign or semimalignant bone tumors is not always clear; therefore percutaneous biopsy is necessary in most cases. In benign spinal tumors an intralesional curettage with reconstruction and stabilization is sufficient. In cases of semimalignant tumors, e.g. giant cell tumors localized in the spine, an en bloc resection is necessary because of the high recurrence rate.

Indications for surgical treatment of idiopathic scoliosis are progressive curves greater than 40-50 degrees. In most cases, fusion of only the primary (structural) curve(s) is sufficient due to the flexibility and spontaneous correction of the secondary curves. Therefore, it is crucial to identify both primary and secondary curves. According to the Lenke classification, all curves with a residual curve of more than 25 degrees on the bending films and those with a pathological kyphosis are regarded as structural and should be fused, whereas the nonstructural curves can be left unfused. However, according to reports in the literature and to the author's experience, clinical parameters such as shoulder level and rib or lumbar hump as well as radiometric criteria such as rotation are relevant as well. In summary, the Lenke classification is an important and helpful tool for analysing idiopathic curves and determining fusion length, even though each scoliosis case needs to be evaluated individually, especially taking clinical parameters into account.

In spinal fusion procedures, the local bone that is resected serves as the base bone graft for attaining biological fusion. The local bone is frequently not sufficient and requires supplementary grafting. Autologous bone transplantation is still regarded as the gold standard but might cause additional complications; also, autograft resources are limited. Alternatively, allografts and a wide variety of different bone substitutes are available.The bone substitutes currently used in scoliosis surgery are presented, and their clinical significance is elucidated by a review of the literature. Furthermore, our own experiences and clinical practice are compared with those in the literature and are critically discussed. The recently growing number of scientific publications reporting on bone substitutes reflects the immense interest and relevance of this issue. In scoliosis surgery, calcium phosphate ceramics together with bone marrow aspirate are increasingly applied.Although harvesting of autologous bone continues to be the accepted standard to extend the local autograft in scoliosis surgery, there is a clear trend toward the use of bone substitutes.

Posterior correction and fusion of scoliosis with multisegmental instrumentation systems was developed by Cotrel-Dubousset in the 1980s. Initially correction and instrumentation was performed using hooks only. Later pedicle screws were implemented first for the lumbar and then for the thoracic spine. Nowadays instrumentation based on pedicle screws only is well established for posterior scoliosis surgery. Biomechanical studies demonstrated higher pull-out forces for pedicle than for hook constructs.In clinical studies several authors reported better Cobb angle correction of the primary and the secondary curves and less loss of correction in pedicle screw versus hook instrumentations. Furthermore, pedicle screw instrumentation allows fewer segments to be fused, especially caudally, and thus saving mobile segments. In most of these publications there were no differences in operation time, blood loss and complication rates. In summary, there is better curve correction without an increased risk using multisegmental pedicle screw instrumentation in modern posterior scoliosis surgery.

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.

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.Prospective analysis of radiometric and clinical parameters of 93 patients operated on between 1996 and 2004 using the Münster Anterior Dual Rod System.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.Anterior dual rod instrumentation enables an effective and safe three-dimensional curve correction in single structural curves with only minimal loss of correction.

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.

Halm-Zielke Instrumentation (HZI) was developed to eliminate the disadvantage of ventral derotation spondylodesis (VDS)-Zielke in terms of lack of primary stability and in order to simplify sagittal plane control. Within a prospective clinical trial started in 1993, we have studied whether HZI fulfills these demands. HZI is an anterior double-rod system with a two screw per vertebral body fixation. The longitudinal components consist of a threaded VDS rod and a solid rod, which are attached to a hinge-conducted lid plate. Twenty-nine consecutive patients with idiopathic scoliosis and curves ranging from 36 degrees to 92 degrees were treated with HZI. The follow-up period ranged from 1 to 4 years. Correction of the frontal plane within the instrumented levels averaged 71.6% and 70.5% postoperatively and at follow-up, respectively. Derotation averaged 53.7% and mean correction of the tilt of the lowest instrumented vertebra was 69.5% at final follow-up. Thoracolumbar kyphosis was present in eight patients and was always completely corrected from +18.8 degrees to 3.3 degrees on average. One implant-related complication involved a screw breakage 18 months postoperatively without adverse effects. There was no case of pseudoarthrosis. All patients were mobilized without any additional external immobilization in terms of a brace or cast, and were allowed to go swimming for physiotherapeutical purposes immediately after wound healing. This study proves that HZI is a primary stable implant to perform VDS. Implant-related disadvantages typical of VDS are eliminated. Thereby, the period of rehabilitation is shortened by many months due to avoidance of cast and brace treatment.