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.

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.

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°, LAT 7.4°, ROT 3.9°. 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.

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: Raster-stereographic and radiographic evaluation of idiopathic scoliosis without braces in a retrospective longitudinal long-term follow-up study.Objective: 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.Summary of Background Data: 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.Methods: 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.Results: 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 (R-2 > 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.Conclusions: 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.

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.

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 < 0.001) and 19% (Pope, P < 0.001), respectively, and that of the second adjacent level by on average 16% (Farfan, P < 0.001) and 14% (Pope, P < 0.001), respectively. A tendency towards more disc height reduction (DHR) in the degenerative group was observed. Advanced age correlated with advanced DHR ( P ≤ 0.003, r = 0.5). Multiple level fusion led to a more pronounced DHR than 1-level fusion ( P = 0.028). There was a tendency towards more DHR in the first adjacent disc compared to the second. Gender, prior surgery of the fused segment and fusion level did not affect the amount of DHR. There was no correlation between the clinical outcome and DHR. Lumbar fusion is associated with DHR of adjacent discs. This may be induced by additional biomechanical stress, ongoing degeneration affecting the lumbar spine and advancing age. However, clinical outcome is not correlated with adjacent DHR.

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 artifical 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.

In Brief 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 artifical 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. A 40-year-old women successfully underwent lumbar disc arthroplasty because of severe osteochondrosis at L5–S1 and correlating discogenic lumbar back pain. After an uneventful postoperative course, she developed a symptomatic acquired lumbar spondylolysis of L5, impairing the initial clinical result and requiring additional posterior lumbar instrumentation and fusion.

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.

OBJECTIVETo analyze the correlation ratios between the spinal posture (thoracic, lordotic, and pelvic inclination) and the craniofacial morphology.MATERIALS AND METHODSThe 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.RESULTSSignificant 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.CONCLUSIONSIn 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.

Lumbal spinal stenosis is gaining more and more clinical relevance because of changing population structure and increasing demand on lifequality in the elderly. Current treatment recommendations are based on clinical experience, expert opinions and single studies rather than on proven evidence. The radiologic degree of stenosis does not correlate with the patients' clinical situation. It is not the main factor indicating surgery but rather the typical history and spinal claudication. Symptomatic patients with light to moderate complaints should undergo multimodal conservative treatment. Epidural injections, delordosating physiotherapy and medication are useful. In patients with severe symptomatic stenosis surgery is indicated after a conservative treatment of 3 months. Relevant pareses or a cauda equina syndrome are absolute indications for surgery. The general aim is to decompress sufficiently while maintaining or restoring segmental stability. A laminectomy is not necessarily required. In patients with accompanying degenerative Meyerding grade I-II spondylolisthesis or instability in functional radiographs, fusion or dynamic stabilisation are recommended in addition to decompression, depending on the patient's age and activity level.

Abstract Background The correlations between the sagittal jaw position and the cranio – cervical inclination are described in literature. Only few studies focus on the sagittal jaw position and the body posture using valid and objective orthopaedic examination methods. The aim of this study was to test the hypothesis that patients with malocclusions reveal significant differences in body posture compared to those without (upper thoracic inclination, kyphotic angle, lordotic angle and lower lumbar inclination). Methods Eighty-four healthy adult patients (with a mean age = 25.6 years and ranging from 16.1 to 55.8 years) were examined with informed consent. The orthodontic examination horizontal overjet (distance between upper and lower incisors) was determined by using an orthodontic digital sliding calliper. The subjects were subdivided in respect of the overjet with the following results: 18 revealed a normal overjet (Class I), 38 had an increased overjet (Class II) and 28 had an reversed overjet (Class III). Rasterstereography was used to carry out a three – dimensional back shape analysis. This method is based on photogrammetry. A three-dimensional shape was produced by analysing the distortion of parallel horizontal white light lines projected on the patient's back, followed by mathematical modelling. On the basis of the sagittal profile the upper thoracic inclination, the thoracic angle, the lordotic angle and the pelvic inclination were determined with a reported accuracy of 2.8° and the correlations to the sagittal jaw position were calculated by means of ANOVA, Scheffé and Kruskal-Wallis procedures. Results Between the different overjet groups, no statistically significant differences or correlations regarding the analysed back shape parameters could be obtained. However, comparing males and females there were statistically significant differences in view of the parameters 'lordotic angle' and 'pelvic inclination'. Conclusion No correlations between overjet and variables of the thoracic, lordotic or the pelvic inclination could be observed.

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.

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.

OBJECTIVE 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. MATERIALS AND METHODS 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. RESULTS 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. CONCLUSIONS 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.

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° and 82° 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° in standing to 26.3° in forward bending posture. The standard deviation of this difference was high (6.1°). 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.