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Undercutting decompression is a common surgical procedure for the therapy of lumbar spinal canal stenosis. Segmental instability, due to segmental degeneration or iatrogenic decompression is a typical problem that is clinically addressed by fusion, or more recently by semi-rigid stabilization devices. The objective of this experimental biomechanical study was to investigate the influence of spinal decompression alone, as well as in conjunction with two semi-rigid stabilizing implants (Wallis, Dynesys) on the range of motion (ROM) of lumbar spine segments. A total of 21 fresh-frozen human lumbar spine motion segments were obtained. Range of motion and neutral zone (NZ) were measured in flexion-extension (FE), lateral bending (LAT) and axial rotation (ROT) for each motion segment under four conditions: (1) with all stabilizing structures intact (PHY), (2) after bilateral undercutting decompression (UDC), (3) after additional implantation of Wallis (UDC-W) and (4) after removal of Wallis and subsequent implantation of Dynesys (UDC-D). Measurements were performed using a sensor-guided industrial robot in a pure-moment-loading mode. Range of motion was defined as the angle covered between loadings of -5 and +5 Nm during the last of three applied motion cycles. Untreated physiologic segments showed the following mean ROM: FE 6.6 degrees , LAT 7.4 degrees , ROT 3.9 degrees . After decompression, a significant increase of ROM was observed: 26% FE, 6% LAT, 12% ROT. After additional implantation of a semi-rigid device, a decrease in ROM compared to the situation after decompression alone was observed with a reduction of 66 and 75% in FE, 6 and 70% in LAT, and 5 and 22% in ROT being observed for the Wallis and Dynesys, respectively. When the flexion and extension contribution to ROM was separated, the Wallis implant restricted extension by 69% and flexion by 62%, the Dynesys by 73 and 75%, respectively. Compared to the intact status, instrumentation following decompression led to a ROM reduction of 58 and 68% in FE, 1 and 68% in LAT, -6 and 13% in ROT, 61 and 65% in extension and 54 and 70% in flexion for Wallis and Dynesys. The effect of the implants on NZ corresponded to that on ROM. In conclusion, implantation of the Wallis and Dynesys devices following decompression leads to a restriction of ROM in all motion planes investigated. Flexion-extension is most affected by both implants. The Dynesys implant leads to an additional strong restriction in lateral bending. Rotation is only mildly affected by both implants. Wallis and Dynesys restrict not only isolated extension, but also flexion. These biomechanical results support the hypothesis that postoperatively, the semi-rigid implants provide a primary stabilizing function directly. Whether they can improve the clinical outcome must still be verified in prospective clinical investigations.

Introduction and aim of the study The primary assumption for successful internal fixation of the spine is a stable screws fixation. Aim of this experimental examination was to point out the influences on axial pull-out strength of screws and to suggest improvements for its increase. Methods Eight specifically manufactured screw-prototypes were tested in standardized pull-out tests in comparison by pairs. An isotropic, synthetic hard-foam was used as test material. It resembled to the spongiose bone and reduced the deviation of the results. To show the transferability of the results on bone there were made pull-out tests out off calf vertebra. Results A significant increase of axial pull-out strength can be achieved by a wide external diameter, a big insertion depth, a flat angel of tooth profile and a small thread pitch. This examination could not prove a significant advantageous influence on axial pull-out strength by fast pull-out, asymmetrical "Butress-thread" or proportion of core- and external diameter difference. Conclusions Referring to the aim of this examination a wide outside-diameter can be recommended. Likewise the depth of insertion should be as deep as the anatomic conditions permit. The influence of these two factors are considerable. In contrast to other author's statements the maximum axial stability increases significantly by a small thread pitch and a flat angel of tooth profile.

Raster-stereographic and radiographic evaluation of idiopathic scoliosis without braces in a retrospective longitudinal long-term follow-up study.To investigate the reliability and accuracy of raster stereography in comparison with radiography as the gold standard, using a longitudinal long-term study design in idiopathic scoliosis, to reduce the number of radiographs required during follow-up in scoliosis patients.It has been confirmed that raster stereography produces reliable data in patients with conservatively and surgically treated idiopathic scoliosis, up to a Cobb angle of 80 degrees. This means that the method can be used to replace radiography during the follow-up in these patients. However, no data have yet been published on the use of raster stereography in a longitudinal setting during a long-term follow-up period in comparison with radiography as the gold standard.Raster stereographs and digitized anterior-posterior radiographs of 16 patients with idiopathic scoliosis were studied retrospectively in a longitudinal study design, with a mean follow-up period of 8 years (range 3 to 10 y). Lateral vertebral deviation and vertebral rotation were measured between C7 and L4 using raster stereography and radiography, compared with Cobb angles, and correlated.During the follow-up period, the Cobb angle increased on average by 13 degrees. The progression of lateral vertebral deviation measured using both techniques, and that of vertebral rotation measured with radiography, was greater than that of the Cobb angle, whereas that of raster-stereographic vertebral rotation was lower. However, there was an excellent correlation between the raster-stereographic and radiographic progression of these parameters (R2or=0.5). The mean difference between raster stereographs and radiographs was 3.21 mm for lateral vertebral deviation and 2.45 degrees for vertebral rotation.Using the parameters of lateral vertebral deviation and vertebral rotation, raster stereography accurately reflects the radiographically measured progression of idiopathic scoliosis during the long-term follow-up, but these parameters are not directly comparable with the Cobb angle. In the follow-up of scoliosis patients, the authors would recommend a raster-stereographic examination every 3 to 6 months and a radiographic examination every 12 to 18 months only, provided that raster stereography does not show rapid deterioration of the scoliosis. The patient's radiation exposure can be reduced using this approach.

Adjacent segment degeneration (ASD) is discussed to impair long-term outcome after lumbar interbody fusion. Nevertheless the amount and origin of degeneration and its clinical relevance remain unclear. Only little data is published studying quantitative disc height reduction (DHR) as indicator for ASD in long-term follow-up. Forty patients (23 men, 17 women) (group 1: degenerative disc disease, n = 27; group 2: lytic spondylolisthesis, n = 13) underwent lumbar 360° instrumentation and fusion between 1991 and 1997. Preoperative and follow-up lateral lumbar radiographs were studied. Disc heights of first and second cephalad adjacent segments were measured by Farfan’s technique and Hurxthal’s technique modified by Pope. Clinical outcome was studied using Oswestry disability index (ODI) and visual analogue scale (VAS). Age, gender, prior surgery, fusion rate and number of fusion levels were investigated as potential factors affecting the outcome. Mean follow-up was 114 (72–161) months. Clinical outcome showed an improvement of 44.6% in ODI and 43.8% in VAS with a tendency towards better results in group 2. Fusion rate was 95%. Disc height of the first cephalad adjacent segment in all patients was reduced by on average 21% (Farfan, P

Objective: To relate the differences in the posture of patients with different craniofacial morphologies. Subjects and Methods: Fifty-three adult patients with Class II and III malformations were examined by cephalometric analysis and rasterstereography. The facial depth, maxillary position, mandibular plane angle, inner gonial angle, facial axis, and lower facial height were evaluated and classified into a basal distal–mesial group and a horizontal-vertical group by means of threshold parameters. Analyzing the results of the rasterstereography, the spine's lateral perpendicular deviation, the pelvic tilt, and the pelvic rotation were calculated by means of mathematical algorithms on the basis of the three-dimensional spine profile. To determine the statistically significant correlations between the studied parameters, the t-test was applied in groups with a normal distribution, and the Mann-Whitney U-test was used in the cases of abnormally distributed variables (significance level P < .05). Results: Statistically significant differences (P < .05) in pelvic torsion were documented with respect to the facial axis and facial depth. Moreover, the differences (P < .05) between patients with a skeletal horizontal-vertical facial axis and patients with a basal distal–mesial position for the facial depth could be determined for the pelvic torsion. Conclusions: As a clinical consequence of the results, an extension of the interdisciplinary concepts within the sense of an orthopedic examination can be considered for patients undergoing a combined orthodontic-operative therapy.

Background and Purpose: The use of instrumentation in spinal infections is still a controversial issue. The aim of the present study was to evaluate the efficiency of titanium cages in the surgical treatment of severe vertebral osteomyelitis (synonym spondylodiscitis) concerning eradication of the infection as well as biomechanical aspects. Materials and Methods: The peri- and postoperative data of 43 consecutive patients with vertebral osteomyelitis who underwent single-stage posterior stabilization, anterior debridement including decompression, and anterior column reconstruction using modular titanium ring cages filled with autologous bone were analyzed retrospectively. In 29 cases, a clinical and radiological follow-up of on average 2.5 years (median 2.2 years) was available. To assess the course of spinal alignment, a detailed radiometric analysis was performed. Results: The time of symptoms prior to surgery averaged 4.6 months. Preoperatively, 37% of the patients showed neurologic compromise with partial or complete recovery in 88% after surgery. In 25 patients (58%), a germ was isolated with Staphylococcus aureus being the most frequent pathogen (44%). Except for one patient with anterior revision and exchange of the cage for persistent infection, primary eradication of the infection was accomplished in all patients. At follow-up, all infections were eradicated, and all cages appeared radiographically fused. The present loss of correction in the sagittal plane amounted 1.5° at the affected segment(s) reconstructed by cage interposition and 4.4° at posterior fusion levels. Conclusion: Single-stage posterior instrumentation and fusion combined with anterior debridement and anterior column reconstruction using modular titanium ring cages represent a safe and efficient strategy in cases of severe vertebral osteomyelitis necessitating surgery. The use of titanium cages guarantees longterm maintenance of correction without increased risk of persistent or recurrent infection.

We studied 27 patients with post-discectomy syndrome. All patients had Lumbar Interbody Fusion with titanium cages and pedicle screw fixation either as Anterior (ALIF, n=18) or as Transforaminal Lumbar Interbody Fusion (TLIF, n=9). Follow-up ranged from 24 to 94 months. The clinical and radiological data were compared. The outcome was evaluated using the Oswestry low back pain disability score and the visual analogue pain intensity scale. Outcomes were similar for all patients regardless of surgical technique and showed a significant improvement at final follow-up.

The forward bending test according to Adams and rib hump quantification by scoliometer are common clinical examination techniques in idiopathic scoliosis, although precise data about the change of axial surface rotation in forward bending posture are not available. In a pilot study the influence of leg length inequalities on the back shape of five normal subjects was clarified. Then 91 patients with idiopathic scoliosis with Cobb-angles between 20 degrees and 82 degrees were examined by rasterstereography, a 3D back surface analysis system. The axial back surface rotation in standing posture was compared with that in forward bending posture and additionally with a scoliometer measurement in forward bending posture. The changes of back shape in forward bending posture were correlated with the Cobb-angle, the level of the apex of the scoliotic primary curve and the age of the patient. Averaged over all patients, the back surface rotation amplitude increased from 23.1 degrees in standing to 26.3 degrees in forward bending posture. The standard deviation of this difference was high (6.1 degrees ). The correlation of back surface rotation amplitude in standing with that in forward bending posture was poor (R (2)=0.41) as was the correlation of back surface rotation in standing posture with the scoliometer in forward bending posture measured rotation (R (2)=0.35). No significant correlation could be found between the change of back shape in forward bending and the degree of deformity (R (2)=0.07), likewise no correlation with the height of the apex of the scoliosis (R (2)=0.005) and the age of the patient (R (2)=0.001). Before forward bending test leg length inequalities have to be compensated accurately. Compared to the standing posture, forward bending changes back surface rotation. However, this change varies greatly between patients, and is independent of the type and degree of scoliosis. Furthermore remarkable differences were found between scoliometer measurement of the rib hump and rasterstereographic measurement of the vertebral rotation. Therefore the forward bending test and the identification of idiopathic scoliosis rotation by scoliometer can be markedly different compared to rasterstereographic surface measurement in the standing posture.

Background . To optimize physiological load transfer and mechanical stability a close geometric fit between cementless stems and the bone stock is essential. To solve the problem of a geometric mismatch between the anatomic shape of the femoral canal and conventional stems custom-made implants were developed. This study determined the accuracy of implanting custom-made press-fit straight femoral stems compared to conventional cementless stems. Methods . Nine pairs of human cadaveric femurs were used to determine the extent of the endocortical area in contact with the stem. The bone–femoral component interface was measured in vitro using CT-data analysis. A software program was developed to describe the periprosthetic inner cortical bone structure, the stem surface and the proportionate implant–endosteal bone contact. Findings . The mean endosteal bone contact of both prostheses was 21.6%. The proportionate implant–endosteal bone contact for straight custom-made femoral prostheses averaged 20.98%. For the conventional cementless stems the mean proportionate contact was 22.15%. Especially in the proximal femur the desirable contact of customized implants was not achieved by closed distal press-fit. Interpretation . Compared to conventional straight cementless stems custom-made stems did not extend the endocortical contact area. The desirable “fit and fill” of the proximal femur was not achieved with straight custom-made femoral components in femurs of regular geometry.

The unilateral transforaminal approach for lumbar interbody fusion as an alternative to the anterior (ALIF) and traditional posterior lumbar interbody fusion (PLIF) combined with pedicle screw instrumentation is gaining in popularity. At present, a prospective study using a standardized tool for outcome measurement after the transforaminal lumber interbody fusion (TLIF) with a follow-up of at least 3 years is not available in the current literature, although there have been reports on specific complications and cost efficiency. Therefore, a study of TLIF was undertaken. Fifty-two consecutive patients with a minimum follow-up of 3 years were included, with the mean follow-up being 46 months (36–64). The indications were 22 isthmic spondylolistheses and 30 degenerative disorders of the lumbar spine. Thirty-nine cases were one-level, 11 cases were two-level, and two cases were three-level fusions. The pain and disability status was prospectively evaluated by the Oswestry disability index (ODI) and a visual analog scale (VAS). The status of bony fusion was evaluated by an independent radiologist using anterior–posterior and lateral radiographs. The operation time averaged 173 min for one-level and 238 min for multiple-level fusions. Average blood loss was 485 ml for one-level and 560 ml for multiple-level fusions. There were four serious complications registered: a deep infection, a persistent radiculopathy, a symptomatic contralateral disc herniation and a pseudarthrosis with loosening of the implants. Overall, the pain relief in the VAS and the reduction of the ODI was significant (P

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 Cheneau-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.

Study design A case of transient hemiplegia during posterior correction and instrumentation of scoliosis in an 18-year-old woman. Objective To present a case of transient hemiplegia most probably resulting from an arteriovenous fistula. Summary of background data Neurologic impairment in spinal surgery is a feared complication. Common reasons are direct or indirect trauma to neural elements, intraoperative hypotension, ischemia, bleeding, metabolic dysbalances, or drug effects. Review of the literature did not reveal any case of transient hemiplegia similar to the presented one in which none of the mentioned pathologies could be found. Case summary An 18-year-old woman with a right long thoracic lordoscoliosis measuring 67 degrees Cobb angle and a marfanoid phenotype underwent posterior correction and transpedicular instrumentation from T3 to L2. After uneventful correction of the deformity through rod rotation, the wake-up test revealed a right-sided hemiplegia without facial asymmetry or other neurologic abnormalities affecting structures above the spinal cord. The rods were removed, the pedicle screws left in place, and the patient was turned on her back. Within 30 minutes after extubation, the neurologic deficits disappeared completely. Extensive diagnostic workup, including magnetic resonance angiography, did not show any pathologic findings explaining the transient hemiplegia. Two weeks later, the surgical correction was completed. After rod rotation again, right-sided hemiplegia was found in the wake-up test. Leaving the correction and after finalizing surgery, the patient was turned on her back and a 5 x 3-cm mass became apparent in her right sternocleidomastoid region. Color-coded duplex sonography revealed an arteriovenous fistula between the right external carotid artery and the right internal jugular vein. After extubation, the mass disappeared and within minutes all neurologic functions returned to normal again. Conclusions Spine surgeons should be aware of arteriovenous malformations as a potential cause of neurologic disturbances.

Study design A prospective clinical and radiographic evaluation of 45 consecutive patients with idiopathic adolescent and adult scoliosis treated with anterior dual-rod Halm-Zielke instrumentation. Objectives Clinical and radiographic evaluation with a minimum follow-up of 2 years. Summary of background data Halm-Zielke instrumentation was developed to eliminate the disadvantages of Zielke instrumentation in terms of lack of primary stability and a kyphogenic effect. Methods All patients underwent an identical anterior surgical technique with the Halm-Zielke instrumentation of the primary curve. The system is composed of a lid-plate, which is fixed to the lateral aspect of the vertebral body with two screws: a sunk screw anteriorly and a ventral derotation spondylodesis (VDS) screw posteriorly. The lid-plate design provides the lowest possible implant profile. The longitudinal components consist of a threaded rod and a solid, fluted rod. Correction is performed with both the threaded and the solid rod. The solid rod allows derotation and correction of the sagittal plane and provides primary stability. Results Preoperative curves ranged from 35 degrees to 92 degrees Cobb angle. Final correction of the frontal plane averaged 67% within the instrumented levels and 59% for the total primary curve. The apical vertebral rotation of the primary curve was corrected by 52% on average without loss of correction during follow-up. Thoracolumbar kyphosis was present in 11 patients and corrected in all cases from an average of 20 degrees to 2 degrees after surgery and to 8 degrees at follow-up. We observed two cases of implant failure with one resulting in a pseudarthrosis. Conclusion Halm-Zielke instrumentation proved to be a major improvement of the original VDS-Zielke. It eliminates the kyphogenic effect and provides primary stability.

Aim The purpose of the study was to identify the functional impairments after revision arthroplasty by gait analysis. Methods This retrospective study compared 33 patients (mean age 58.5 years) who have undergone revision of an acetabular component (mean follow-up 2.6 years) with a group of normal control subjects. Gait analysis including recording of the three dimensional kinetics and kinematics was performed in all patients. Surface electromyography of seven leg and trunk muscles were registered bilaterally. The vertical ground reaction forces were determined by two force plates. These data were correlated with the Harris Hip Score, the d'Aubigne Score and the radiographic analysis (centre of rotation). Results The analysis revealed a decreased hip range of motion during gait (p 0.05). Deterioration in kinematics are indicated by cranialisation of the centre of rotation (p = 0.18). However, medial movement of the centre of rotation does not influence the kinematic data (p > 0.05). Conclusion Despite sufficient satisfactory clinical data the gait analysis confirmed objective impairments of the operated hip and neighboring joints. Gait instability is revealed in a decreased hip extension and deficient hip abduction.

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.

Background Despite the widespread use of radiofrequency-induced shrinkage of collagenous tissues, there have been no animal studies on the effects of postoperative immobilization after such treatment. Purpose To examine the effects of postoperative immobilization after radiofrequency energy treatment, with special emphasis on any tissue length increases. Study Design Controlled laboratory study. Methods The right patellar tendon of 60 New Zealand White rabbits was shrunk with a radiofrequency probe. Tendon length was measured intraoperatively before and after shrinkage and via radiographs immediately postoperatively and at 3, 6, and 9 weeks. Twenty rabbits were not immobilized, 20 were immobilized for 3 weeks, and 20 were immobilized for 6 weeks. Results In the nonimmobilized limbs, the tendon length increased 34.9% at 3 weeks and another 2.5% at 6 weeks, versus 11.2% at 3 weeks and 6.6% at 6 weeks in the immobilized limbs. Ten of the 20 rabbits that were immobilized for 6 weeks were sacrificed at 9 weeks and were found to have a further length increase of 10.8%. At 9 weeks, the tendons of this group were no longer significantly shorter than the tendons from rabbits that had not been immobilized. Conclusions Careful postoperative rehabilitation is imperative after radiofrequency-induced shrinkage. Without protection, exposure to normal physiologic loads places the shrunken tissue at risk of stretching out beyond the preshrinkage length. Clinical Relevance Shrunken tissue is at risk of stretching out after radiofrequency-induced shrinkage.

Objective. To determine the accuracy of rasterstereographic three-dimensional back surface analysis and reconstruction of the spine in cases of severe idiopathic scoliosis treated by anterior correction and fusion. Design. Comparison of digitized radiographic curves and rasterstereographic curves by best fit superimposition and calculation of root mean square differences as parameters of similarity. Background. Rasterstereography has been proven to be accurate in scoliosis up to 50° Cobb angle. Since 1989 the device is in clinical routine use for non-operatively treated patients and reduces the need for otherwise indispensable radiographs significantly. Methods. Fifty two patients with severe idiopathic scoliosis with Cobb angles up to 88° were examined rasterstereographically and radiographically. Forty eight pre-operative anterior–posterior radiographs and 101 post-operative anterior–posterior radiographs were digitized. Radiographic and rasterstereographic curves were compared and the root mean square differences were calculated as parameters of precision of rasterstereographic reconstruction. Results. Accuracy of rasterstereography in idiopathic scoliosis with Cobb angles between 50° and 88° is satisfactory. The root mean square difference of the radiographic and rasterstereographic curves was 6.4 mm for lateral deviation and 4.5° for vertebral rotation. After anterior scoliosis surgery the precision of the device is good. The root mean square difference for lateral deviation was 3.4 mm and 3.2° for rotation. Considering both groups an average root mean square of 4.7 mm and 3.7° was calculated. Conclusions. Accuracy in severe scoliosis up to 88° Cobb angle was satisfactory. The results of this first evaluation of surgically treated severe scoliosis showed a good accuracy after anterior surgery. The system can be used for post-operative follow up examinations and may reduce the number of X-rays considerably. In contrast to radiography, CT or MRI rasterstereography provides an objective quantification and documentation of the post-operative cosmetic improvement of the back shape in standing posture. Relevance statement Based on the findings of this study rasterstereography in future enables both objective quantification of cosmetic improvement and significant reduction of X-rays in idiopathic scoliosis with Cobb angles higher than 50° before and after anterior surgical correction and fusion.

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.

In vitro biomechanical testing was performed to analyze the axial and tangential fixation strength of pedicle screws versus pedicle and laminar hooks in the human thoracic spine. Bone mineral density of each tested vertebra was determined.To study the fixation strength of pedicle screws and hooks in the thoracic spine in relation to bone mineral density.Biomechanical properties of pedicle screws have proven to be superior in the lumbar spine, but there is a paucity of data concerning the thoracic spine in particular with regard to bone mineral density.In 72 human thoracic vertebrae standard pedicle hooks between T4 and T8 and supralaminar hooks between T9 and T12 were tested against pedicle screws in pairs in one vertebra each. The bone mineral density of each vertebra was determined by means of quantitative computed tomography. Screws and hooks were loaded either axially strictly longitudinal to failure or in a coronal plane strictly perpendicular to the longitudinal axis nondestructively. A total of 78 pullout tests and 66 tangential loadings were performed.The correlation of bone mineral density and fixation strength was significant for pullout strength of pedicle screws (P0.001) and pedicle hooks (P0.001). The average pullout strength of the pedicle screws was significantly higher than that of pedicle hooks (P = 0.003) and supralaminar hooks (P = 0.02). The difference was not significant if bone mineral density was100 mg hydroxylapatite/mL. The average tangential elastic and permanent displacement of pedicle screws was significantly lower than that of pedicle (P0.001) and laminar hooks (P = 0.002).Pedicle screws may be beneficial for instrumentation of the thoracic spine because they are significantly more resistant to axial and tangential loadings than pedicle and laminar hooks on the condition that bone mineral density is100 mg/mL hydroxylapatite.

AIM Radiographic analysis of long-term results following CDI. METHODS Retrospective analysis of radiographs of 43 patients with idiopathic right thoracic scoliosis with an average follow-up of 82 months. Extensive radiographic analysis with special regard to curve correction in the frontal and sagittal planes. RESULTS The average Cobb-angle of the preoperative primary curve was 61.6 degrees (min.: 40 degrees, max.: 84 degrees ), the correction postoperatively was 51.1 % representing 29.9 degrees. Due to the loss of correction of 7.1 degrees, the overall outcome was 39.9 % by the time of follow-up. More than 90 % of the loss of correction occurred within the first 2 years. The lumbar secondary curve correction was 47.2 % (preop.: 37.5 degrees; postop.: 19.8 degrees ). Average fusion length was 11 segments, fusion usually ended two vertebrae below the end vertebra. Translation of the apex was corrected by 38.8 % (preop.: 4.9 cm; postop.: 3.0 cm), tilt of the last instrumented vertebra by 44.2 % (preop.: 18.2 degrees; postop.: 10.16 degrees ). The amount of derotation was negligible (preop.: 24.1 degrees; postop.: 22.6 degrees ). The readjustment of a preoperative pathologic sagittal profile, meaning a thoracic hypokyphosis, was successful in 12 out of 15 cases. Blood loss, duration of operation and complications were documented. CONCLUSION CD-Instrumentation in scoliosis surgery offers a long-lasting suffcient correction of the fronal and a good correction of the sagittal plane. Stability of correction is achieved 2 years after operation.

Background: Several studies have provided data on the vertebral morphology of normal spines, but there is a paucity of data on the vertebral morphology in patients with idiopathic scoliosis. Methods: The morphology of the pedicles and bodies of 307 vertebrae as well as the distance between the pedicles and the dural sac (the epidural space) in twenty-six patients with right-sided thoracic idiopathic scoliosis were analyzed with use of magnetic resonance imaging and multiplanar reconstruction. Results: A distinct vertebral asymmetry was found at the apical region of the thoracic curves, with significantly thinner pedicles on the concave side than on the convex side (p < 0.05). The degree of intravertebral deformity diminished farther away from the apex, with vertebral symmetry restored at the neutral level. In the thoracic spine, the transverse endosteal width of the apical pedicles measured between 2.3 mm and 3.2 mm on the concave side and between 3.9 mm and 4.4 mm on the convex side (p < 0.05). In the lumbar spine, the pedicle width measured between 4.6 mm at the cephalad part of the curve and 7.9 mm at the caudad part of the curve. The chord length and the pedicle length gradually increased from 34 mm and 18 mm, respectively, at the fourth thoracic vertebra to 51 mm and 25 mm, respectively, at the third lumbar vertebra. The transverse pedicle angle measured 15° in the cephalad aspect of the thoracic spine, decreased to 7° at the twelfth thoracic vertebra, and increased again to 16° at the fourth lumbar vertebra. The width of the epidural space was

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 Munster 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.

Aim of study A low-dose radiotherapy with 5 Gy on the lumbar spine in patients with chronic low back pain was investigated. Method 31 patients with non-radicular low back pain since three years at the age of at least 50 years (64.3 years on average) were treated. A psychosomatic etiology of pain was excluded. 5 Gy or 0.5 Gy (placebo dose) were applied in five fractions to the lumbar spine including the facet joints. The pain was evaluated by means of the Oswestry-Disability-Score before, six weeks after therapy, and every three months during the follow-up (22.4 months on average). Drug therapy, physiotherapy, and physical treatment were continued. Results According to the randomised distribution, 18 patients were treated with 5 Gy and 13 patients with 0.5 Gy. The Friedman-Test did not reveal any significant difference (p > 0.05) of the Oswestry-Disability-Index before and after therapy for both single questions and the sum of questions in both groups. Conclusion No significant decrease of the Disability Index after radiotherapy on the lumbar spine with 5 Gy could be demonstrated in the verum and placebo group. The authors do not recommend radiotherapy in cases of chronic low back pain. Individual successes have to be attributed to conservative treatment or placebo effects.

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.

INTRODUCTION So far only radiometric and clinical methods have been available for the evaluation of results after anterior scoliosis surgery. Rasterstereography has proved to be a reliable method for three-dimensional surface measurement of conservatively treated idiopathic scoliosis patients. Therefore, patients treated operatively with anterior instrumentation were examined using rasterstereography to determine the three-dimensional correction of the spinal deformity. The aim was to measure back shape deformity, in particular derotation, and thus cosmetic improvements. METHODS 31 patients with idiopathic thoracic, thoracolumbar and lumbar scoliosis (Cobb angle 57.2 degrees) were examined with raster stereography preoperatively, postoperatively and after follow-up (25.2 months) in a standardized standing posture. Standing radiographs were compared with raster stereography. RESULTS The mean Cobb angle was reduced from 57.2 degrees to 17.2 degrees, the rasterstereographic maximal surface rotation from 16.5 degrees to 10.8 degrees, and the vertebral rotation according to Perdriolle from 29.2 degrees to 16.7 degrees. During follow-up the Cobb angle increased to 20.8 degrees, and surface rotation to 11.3 degrees. Vertebral rotation remained constant. Lordosis and kyphosis angles changed only slightly. CONCLUSION Rasterstereography is a suitable tool for analyzing the three-dimensional correction of spinal deformities after anterior scoliosis surgery. In particular, the cosmetic improvement is clearly demonstrated. The measurement of surface rotation allows objective quantification of the obtained derotation.

Symptomatic degenerative central lumbar spinal stenosis (LSS) is a frequent indication for decompressive spinal surgery, to reduce spinal claudication. No data are as yet available on the effect of surgery on the level of activity measured with objective long-term monitoring. The aim of this prospective, controlled study was to objectively quantify the level of activity in central LSS patients before and after surgery, using a continuous measurement device. The objective data were correlated with subjective clinical results and the radiographic degree of stenosis. Forty-seven patients with central LSS and typical spinal claudication scheduled for surgery were included. The level of activity (number of gait cycles) was quantified for 7 consecutive days using the StepWatch Activity Monitor (SAM). Visual analogue scales (VAS) for back and leg pain, Oswestry disability index and Roland-Morris score were used to assess the patients' clinical status. The patients were investigated before surgery and 3 and 12 months after surgery. In addition, the radiographic extent of central LSS was measured digitally on preoperative magnetic resonance imaging or computed tomography. The following results were found preoperatively: 3,578 gait cycles/day, VAS for back pain 5.7 and for leg pain 6.5. Three months after surgery, the patients showed improvement: 4,145 gait cycles/day, VAS for back pain 4.0 and for leg pain 3.0. Twelve months after surgery, the improvement continued: 4,335 gait cycles/day, VAS for back pain 4.1 and for leg pain 3.3. The clinical results and SAM results showed significant improvement when preoperative data were compared with data 3 and 12 months after surgery. The results 12 months after surgery did not differ significantly from those 3 months after surgery. The level of activity correlated significantly with the degree of leg pain. The mean cross-sectional area of the spinal canal at the central LSS was 94 mm(2). The radiographic results did not correlate either with objective SAM results or with clinical outcome parameters. In conclusion, this study is the first to present objective data on continuous activity monitoring/measurements in patients with central LSS. The SAM could be an adequate tool for performing these measurements in spine patients. Except for leg pain, the objective SAM results did not correlate with the clinical results or with the radiographic extent of central LSS.

A 15-year-old girl developed a progressive paraparesis over a period of six months, secondary to spinal cord compression by a lipomatous mass and anomalies of the vertebral column. Clinically, a right hemihyperplasia affecting the trunk and lower limb was evident, as well as a right convex lumbar scoliosis. CT and MRI demonstrated severe spinal cord compression resulting from intraspinal lipomatosis, overgrowth of right facet joints (T8 to L5), and kyphoscoliosis. Surgical decompression was undertaken. A lumbar scoliosis of 48 degrees was partially corrected by means of dual-rod instrumentation. The neurological deficit improved significantly, and ambulation was progressively restored. The patient carried the diagnosis of Proteus syndrome for several years, but reevaluation of clinical features prompted the diagnosis of Hemihyperplasia Multiple Lipomatosis syndrome (HHML). This rare sporadic disorder is often confused with Proteus syndrome. As in Proteus syndrome, spinal cord compression in patients with HHML can result from lipomatous infiltration and/or significant spinal abnormalities including kyphoscoliosis and overgrowth. HHML and Proteus syndrome are discussed and compared with special emphasis on spinal and orthopaedic pathologies.

Study design A case of acquired lumbar spondylolysis following lumbar disc arthroplasty L5-S1 in an 40-year-old woman and review of the literature. Objectives To present and discuss a case of acquired lumbar spondylolysis after implantation of an artificial disc L5-S1 that may have impaired a good clinical result requiring additional posterior lumbar instrumentation and fusion in order to improve understanding of this condition and to propose an effective method of surgical management. Summary of background data Lumbar disc arthroplasty is a possible surgical option for patients with degenerative disc disease. Acquired spondylolysis is a rare but known complication of spinal fusion but has never been described as a consequence of mobile disc arthroplasty. The authors present the first case in the literature who developed this complication. Methods A 40-year-old woman with severe osteochondrosis L5-S1 and discogenic lumbar back pain underwent implantation of an artificial disc. Surgery and postoperative course were uneventful and the patient improved significantly as for back pain and mobility. Eighteen months after surgery, the patient was again admitted to our outpatient clinic for back pain that had slowly increased over time. Results The radiologic workup showed a new spondylolysis L5 without a spondylolisthesis. Because of unsuccessful conservative treatment, the patient underwent posterior lumbar instrumentation and fusion L5-S1, leading to a significant pain reduction and a good clinical outcome. Conclusion Spine surgeons should be aware of the possibility of lumbar disc arthroplasty to induce acquired spondylolysis impairing good clinical results.

Study design Prospective clinical study. Objective To evaluate the clinical and radiographic result of the transforaminal lumbar interbody fusion (TLIF) as an alternative new technique in degenerative and isthmic lower grade spondylolisthesis. Summary of background data TLIF is a new alternative surgical technique used for spinal fusion avoiding the ventral approach and can theoretically prevent typical complications, such as those seen in anterior and posterior lumbar interbody fusion. Materials and methods There were 19 degenerative, 19 isthmic, and 1 dysplastic spondylolistheses operated on with TLIF. The clinical follow-up used the Oswestry Disability Index, the radiologic follow-up radiograph, analyzing segmental lordosis, intervertebral space, reduction, and fusion rate. The minimum follow-up was 24 months, mean clinical follow-up was 50 months, and radiologic follow-up was 35 months. Results The medium of the Oswestry Disability Index in all patients decreased from 23.5 to 13.5 points, in isthmic spondylolistheses from 20.5 to 10.95 after 2 years. The radiographic fusion rate was 94.8%. The sagittal translation was reduced from 23% to 15%. There were 3 (7.6%) serious postoperative complications observed, which required operative revision. Conclusions TLIF is a safe and effective method to treat low-grade spondylolisthesis, which can theoretically prevent typical complications of anterior and posterior lumbar interbody fusion. The results of isthmic spondylolistheses were significantly better compared to degenerative spondylolistheses.

The aim of this study is to determine correlations between the parameters of body posture in the sagittal profile and sagittal jaw position by obtaining objective and valid three-dimensional measurements of the dorsal profile by means of rasterstereography.Fifty-three adults with Class II or III malocclusions were examined, and six angular parameters were determined. For the sagittal analysis of body posture, the Fleche Cervicale and Lombaire as well as trunk inclination were evaluated.Statistically significant correlations (P.05) were found between Facial Axis and Fleche Cervicale, Mandibular Plane angle and Fleche Cervicale, and Facial Depth and the Fleche Cervicale.It can be concluded that the mandible seems to have a greater effect on body posture than other craniofacial parameters. As a clinical result of this study, patients with severe malocclusions should be examined interdisciplinarily before orthognathic surgery is performed to minimize postural influence on the altered jaw relationship after surgery.

For anterior correction and instrumentation of thoracic curves single rod techniques are widely used. Disadvantages of this technique include screw pullouts, rod fractures and limited control of kyphosis. This is a prospective study of 23 consecutive patients with idiopathic thoracic scoliosis treated with a new anterior dual rod system. Aim of the study was to evaluate the safety and efficacy of this new technique in the surgical treatment of idiopathic thoracic scoliosis. To the best knowledge of the authors, this is the largest series on dual rod dual screw instrumentation over the entire fusion length in thoracic scoliosis. Twenty-three patients with an average age of 15 years were surgically treated with a new anterior dual rod system through a standard open double thoracotomy approach. Average clinical and radiological follow-up was 28 months (24-46 months). Fusion was carried out mostly from end-to-end vertebra. The primary curve was corrected from 66.6 degrees to 28.3 degrees (57.5% correction) with an average loss of correction of 2.0 degrees at Cobb levels and of 1.3 degrees at fusion levels. Spontaneous correction of the secondary lumbar curve averaged 43.2% (preoperative Cobb angle 41.2 degrees ). The apical vertebral rotation was corrected by 41.1% with a consecutive correction of the rib hump of clinically 66.7%. The thoracic kyphosis measured 29.2 degrees preoperatively and 33.6 degrees at follow-up. In seven patients with a preoperative hyperkyphosis of on average 47.3 degrees thoracic kyphosis was corrected to 41.0 degrees . This new instrumentation enables an entire dual rod instrumentation over the whole thoracic fusion length. It offers primary stability without the need of postoperative bracing. Dual screw dual rod instrumentation offers the advantages of a high screw pullout resistance, an increased overall stability and satisfactory sagittal plane control.

STUDY DESIGN Clinical, rasterstereographic, and radiographic evaluation of spontaneous vertebral derotation of secondary curves in idiopathic scoliosis following selective anterior correction and fusion of the primary curve. OBJECTIVE To quantify spontaneous vertebral derotation in secondary curves after selective anterior correction with attention to cosmetic outcome. SUMMARY OF BACKGROUND DATA While the derotational effect of anterior instrumentation techniques on the instrumented curve is well understood, there is a paucity on data of the rotational behavior of the noninstrumented secondary curves. METHODS A total of 43 patients with idiopathic scoliosis (16 with thoracic curves in group 1 and 27 with thoracolumbar/lumbar curves in group 2) underwent selective anterior instrumentation. Vertebral rotation was analyzed before surgery and, on average, 20 months after surgery using digital radiometric rotation analysis, back shape analysis with rasterstereography, and scoliometer measurement. RESULTS In Group 1, there was a significant spontaneous vertebral derotation of the secondary lumbar curves by 14.2% (range from 12.7 degrees to 10.9 degrees) in the digital radiometric rotation analysis, surface derotation amounted to 49% (range from 9.6 degrees to 4.9 degrees) in the rasterstereography, and to 70% in the clinical scoliometer measurement (range from 8.0 degrees to 2.4 degrees ). In group 2, there was an increase of rotation of the noninstrumented secondary thoracic curves by 30% (range from 5.0 degrees to 6.5 degrees ) in digital radiometry, by 32.9% in the rasterstereography (range from 8.5 degrees to 11.3 degrees), and a 28.3% increase in scoliometer measurement (range from 6.0 degrees to 7.7 degrees). CONCLUSION Selective anterior instrumentation and fusion of primary thoracic curves results in satisfactory spontaneous vertebral and high surface derotation of the secondary lumbar curves. However, in primary thoracolumbar or lumbar curves, an increase of both vertebral and surface rotation of the secondary thoracic curve was noted. This increase can impair cosmetic outcome.

To analyze the correlation ratios between the spinal posture (thoracic, lordotic, and pelvic inclination) and the craniofacial morphology.The sample consisted of 53 healthy adults (32 women, 21 men; mean age 24.6 years). Six angular skeletal measurements (facial axis, mandibular plane angle, inner gonial angle, lower facial height, facial depth, and maxilla position) were determined based on the analysis of lateral head cephalographs. Rasterstereography was used for a precise reconstruction of the back sagittal profile. From the profile parameters, the upper thoracic inclination, the thoracic angle, the lordotic angle, and the pelvic inclination were determined. The correlations to the craniofacial morphology were calculated by means of the Pearson and Mann-Whitney U-test.Significant correlations could be obtained with respect to the facial axis and the lordotic angle, the facial axis and the pelvic inclination, the inner gonial angle and the lordotic angle, the inner gonial angle and the pelvic inclination, the mandibular plane angle and the lordotic angle, the mandibular plane angle and the pelvic inclination, as well as the facial depth and the pelvic inclination.In the case of postural disorders of the back shape, an interdisciplinary treatment approach seems to be of clinical value. Further prospective studies are necessary to prove how changes in craniofacial parameters can affect the postural balance of an individual.

Rasterstereography enables to reduce the number of radiographs in the conservative treatment of idiopathic scoliosis (Cobb angles below 50 degrees). The aim of the present study was to evaluate the use of rasterstereography in severe scoliosis before and after anterior surgery. The results show that the accuracy (as compared to radiographs) is lower in the pre-operative rasterstereographs. However, after operation the Cobb angles were less than 50 degrees in all cases and the accuracy of the rasterstereographs was similar to that of non-operated scolioses. This finding might allow a significant reduction of post-operative radiographs.

Rasterstereography delivers only indirect information about the three-dimensional shape of the spine. Therefore, validation with radiologic methods is necessary, in particular in severe scolioses above 50 AE Cobb. Comparison with conventional a.p. radiographs yielded satisfactory results for scolioses up to 50 AE Cobb, but only in frontal view, i.e. in two dimensions. A true three-dimensional validation is possible only with MR tomography, however this is difficult due to severe technical limitations. In the present study 26 patients with Cobb angles between 26 AE and 116 AE were examined both with MR tomography and rasterstereography. Comparing the shape of the spinal midline as measured by the two methods we found that a) the gross 3-d shape of the spinal midline is well reproduced by the rasterstereographic model, b) the lateral rms error is about twice as large as with conventional radiographs and c) that the rms errors increase with increasing Cobb angle. This means that the rasterstereographic model reconstruction must be modified for severe scolioses.

To determine the accuracy of rasterstereographic three-dimensional back surface analysis and reconstruction of the spine in idiopathic scoliosis treated by posterior correction and fusion.Prospective imaging study of 25 patients with idiopathic scoliosis who underwent posterior correction and fusion and were followed for one year.In an earlier study published in this journal rasterstereography has proved to be an accurate imaging modality for quantifying the changes in the three-dimensional shape of the spine and posterior rib cage after anterior correction and fusion. Goal of the present study was to determine the accuracy for the more common posterior correction and fusion with attention paid to the presence of the posterior implants and scarring.Twenty-five patients with idiopathic scoliosis with maximum Cobb angles of 78 degrees were examined by rasterstereography and radiography. Seventy-one anterior-posterior radiographs were digitised. Twenty-four were preoperative and 47 postoperative radiographs. Rasterstereographic and radiographic curves were compared by best-fit superimposition. Root-mean-square differences were calculated as parameters of accuracy.The accuracy of rasterstereography in severe idiopathic scoliosis with Cobb angles between 48 degrees and 78 degrees was satisfactory with root-mean-square differences of 5.8 mm for the lateral deviation and 4.8 degrees for vertebral rotation. Following posterior correction the accuracy was good. The root-mean-square difference was 4.5 mm for the lateral deviation and 4.3 degrees for vertebral rotation.The accuracy obtained for posteriorly-operated scolioses between 50 degrees and 80 degrees was similar to the findings for scolioses operated via anterior approach, as well as those with curves up to 50 degrees Cobb angle. Therefore rasterstereography can be used postoperatively to reduce the number of radiographs and radiation exposure. Additionally, the method provides an objective quantification of the postoperative improvement in the cosmesis of the back shape.In the treatment of severe idiopathic scoliosis rasterstereography provides both a considerable reduction of X-rays and an objective documentation of the cosmesis before after scoliosis surgery.

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.

The results of an open Bankart procedure with use of suture anchors were evaluated in 85 shoulders in 83 patients. The mean age was 30 years (range, 16-59 years). The mean number of preoperative dislocations was 18.5. Patients were evaluated prospectively by the Rowe score. Eighty-five shoulders were followed for 1 year and seventy-seven for at least 2 years. The mean follow-up was 3.5 years (range, 1-8.3 years). The Rowe score increased from 30 to 92 points. An excellent or good result was found in 81 of 85 shoulders after 1 year and in 68 of 77 shoulders after 2 years. Seven redislocations occurred, four due to a new trauma. Two patients had recurrent subluxations, one due to a new trauma.

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 ( P0.05). 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 ( P0.0001). 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.