Lumbale Spinalkanalstenose

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.

Lumbale Bandscheibenprothesen

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

[Surgical therapy of unspecific and specific Spondylodiscitis]

AIM

The aim of this study was to evaluate the clinical and radiological results of surgical treatment of thoracic and lumbar vertebral osteomyelitis by means of one-stage extrafocal posterior stabilisation, anterior debridement, and anterior column reconstruction.

METHOD

A retrospective analysis of the peri- and postoperative parameters of 62 patients with a clinical and radiographic follow-up of 2.6 years that were available for 46 patients was performed. In 42 cases, the anterior column was restored with structural bone grafts, in 20 patients, expandable titanium cages filled with morsellised autologous bone and antibiotic collagen sponges were used. To assess the course of spinal alignment a radiometric analysis was undertaken. Furthermore, the Roland-Morris score (RMS) was applied to evaluate the back pain-related disability.

RESULTS

The diagnosis was made no earlier than 2.7 months after the first symptoms. Preoperatively, 40 % of the patients presented with neurological impairment, of these 76 % improved after surgery. Staphylococcus aureus was the most common pathogen isolated (32 %), Mycobacterium tuberculosis was found in 11 % of the patients. Except for one patient with revision for persistent infection and consecutive failure of the bone graft, primary eradication of the infection was achieved in all cases. At follow-up, bony fusion was radiographically observed in all patients. When using cages, the segmental loss of correction was significantly lower than when using bone grafts (1.0 vs. 4.1 degrees ). At follow-up the RMS averaged 6.6.

CONCLUSION

One-stage extrafocal posterior stabilisation combined with anterior debridement and anterior column reconstruction with bone grafts or titanium cages is a safe and effective strategy for patients with vertebral osteomyelitis in need of surgery. Titanium cages have proven to be biomechanically advantageous, especially in cases of extensive destruction and are not associated with higher rates of persistence or recurrence of infection compared to autologous bone grafts.

[Prospective evaluation of braces as treatment in idiopathic scoliosis]

AIM

To prospectively evaluate the results of brace treatment in idiopathic scoliosis and to define risk factors of treatment failure.

METHOD

Fifty-two patients with a Cobb angle of between 25 and 40 degrees were included in the study. Prior to initiation of brace treatment with the Chêneau-Toulouse-Muenster orthesis, skeletal age and flexibility of the curve (bending films) were evaluated. The average follow-up after weaning of the brace was 42 months (36-78 months).

RESULTS

An average initial Cobb angle of 31 degrees was corrected to 18 degrees (43 %) under brace treatment with a flexibility to 6 degrees Cobb angle on bending films. Three years after weaning there was an overall increase of the Cobb angle to 37 degrees on average. The apical vertebral rotation was corrected from 16 degrees to 11 degrees (31 %) and increased to 20 degrees during follow-up. Thoracic kyphosis changed from 24 degrees to 18 degrees during treatment. At the latest follow-up kyphosis had returned to the pre-treatment angle again. Twenty-two patients had a curve progression during or after brace treatment of more than 5 degrees. In 14 patients surgical correction and fusion have been indicated. There was a positive correlation between flexibility and Cobb angle correction during brace treatment and a negative correlation between Cobb angle correction during brace treatment and curve progression (p < 0.05).

CONCLUSIONS

Curve progression was prevented in 58 %. Prognostic risk factors are a young age at initiation of brace treatment, a thoracic curve, unsatisfactory curve correction in the brace and a male gender.

Titanium cages in the surgical treatment of severe vertebral osteomyelitis

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

[Objective measures of gait following revision hip arthroplasty. First medium-term results 2.6 years after surgery]

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'Aubigné Score and the radiographic analysis (centre of rotation).

RESULTS

The analysis revealed a decreased hip range of motion during gait (p < 0.0001). In the sagittal plane there was a significant decrease in the hip extension at the end of the stance phase (p < 0.0001). The control group reached a mean extension of - 7.6 degrees, the operated patients were limited by the extension deficit (+ 9.1) in step length (p < 0.0016) and velocity (p < 0.0001). Kinetic parameters indicated a reduced hip abductor moment (p < 0.0001). Compensation of gait instability was observed in an extended stance phase (p = 0.0389). The hip muscle activity was increased to stabilize the impaired hip. The changed kinematic parameters are observed with secondary impairments in knee extension and reduced dorsiflexion in ankle motion (p < 0.0001). Neither the Harris Hip score (77.8 points) nor the d'Aubigné score (14.9 points) were associated with the motion analysis (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.

[Selective ventral derotation spondylodesis in idiopathic thoracic scoliosis: a prospective study]

AIM

Radiometric curve analysis of instrumented primary and spontaneous secondary curve correction after anterior correction and fusion of idiopathic thoracic scoliosis.

METHOD

Sixty-four patients with idiopathic thoracic scoliosis were prospectively evaluated. All patients were operated either with the Zielke-VDS or with a primary stable double rod instrumentation with selective fusion of the thoracic curve from end-to end-vertebra. Follow-up averaged 29 months (24 - 52 months).

RESULTS

The Cobb angle of the primary curve averaged 63.2 degrees preoperatively and was corrected to 21.4 degrees postoperatively with an average loss of correction of 5.3 degrees (58 % final curve correction). Apical thoracic vertebral rotation was corrected by 48 %. The secondary lumbar curve measured 38.2 degrees preoperatively (72 % correction on the bending films) and was spontaneously corrected by 57 % to 16.4 degrees without significant loss of correction in the final follow-up. Apical vertebral rotation averaged 11.3 degrees in the lumbar curve and was corrected spontaneously by 24 % to 8.6 degrees without significant loss of correction. Lumbar apex vertebra deviation showed no significant reduction. There was no case of lumbar curve decompensation in either frontal or sagittal plane. Implant related complications were observed in 7 patients (rod breakage), but no pseudarthrosis occurred. There were no neurological complications noted.

CONCLUSION

Selective anterior correction and fusion in idiopathic thoracic scoliosis enables a satisfactory correction of both primary and lumbar secondary curves. The advantage of selective anterior correction and fusion of thoracic scoliosis is the short fusion length, better derotation and satisfactory correction of the secondary lumbar curve. The disadvantages of single threaded rod techniques in terms of lack of primary stability and a kyphogenic effect have been eliminated by the development of a primary stable, small size double rod instrumentation.

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

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

[Technique and results of monosegmental transpedicular subtraction osteotomy in patients with ankylosing spondylitis and fixed kyphotic deformity of the spine]

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.

3-D back surface analysis of severe idiopathic scoliosis by rasterstereography: comparison of rasterstereographic and digitized radiometric data

Rasterstereography has been shown to be a reliable method for three-dimensional surface measurement of idiopathic scoliosis with Cobb angles up to 50 degrees. In this study, 25 patients with severe idiopathic scolioses (Cobb angles 47 degrees-92 degrees) were examined before and after operation (VDS instrumentation). The a.p. radiographs were digitized according to the Drerup method. The similarity of rasterstereographic and radiometric data was quantified by the rms. differences between the rasterstereographic and radiographic curves of lateral deviation and vertebral or surface rotation. The average rms. differences were 5.8 mm for lateral deviation and 4.4 degrees for vertebral and surface rotation, which is about 40% higher than for mild to medium scolioses.

Morphometric analysis of thoracic and lumbar vertebrae in idiopathic scoliosis

The aim of this paper was to analyse the vertebral morphometry in idiopathic scoliosis with respect to pedicle screw instrumentation by means of computed tomography scans. The pedicle morphometry between T5 and L4 was analysed by computed tomography scans in 29 surgically treated patients with idiopathic right thoracic scoliosis. Measurements included chord length, endosteal transverse pedicle diameter and transverse pedicle angle. The endosteal transverse pedicle diameter was significantly smaller (P<0.05) on the concavity in the apical region of the thoracic spine. The chord length was the shortest at the fifth thoracic vertebra with significantly larger dimensions on the concavity of the apical region in the thoracic spine (P<0.05). The transverse pedicle angle varied between 6 degrees in the lower thoracic spine and 12 degrees at the upper thoracic and lower lumbar spine. The morphometry in scoliotic vertebrae is substantially different from those in normal spines with an asymmetrical intra-vertebral deformity. Pedicle screw instrumentation in the middle thoracic spine appears critical due to the small endosteal pedicle diameter, especially on the concave side.

[Long-term results of posterior correction and fusion of scoliosis using the Cotrel-Dubousset instrumentation]

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.

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

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

[Radiotherapy for pain in chronic, degenerative low back pain syndrome--results of a prospective randomized study]

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.

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

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

[Surgical correction and stabilization of neuromuscular scoliosis--2-4-year results of dorsal and one-stage ventro-dorsal operated patients]

QUESTION

In order to evaluate the outcome of the operative treatment of neuromuscular scoliosis 45 patients were studied prospectively.

METHODS

27 Patients were operated by posterior correction and fusion using the Münster Posterior Doublerod-System (MPDS) (GI). 18 Patients were treated with one-stage ventro-dorsal procedure in combination of VDS with MPDS (GII). For all patients, medical and radiographic records were available, with a minimum follow-up of 2 years. Postoperative management, bloodloss and complications will be discussed.

RESULTS

In group I the main curve (76.3 degrees), by an average flexibility of 36.1%, were corrected by 53.5% and 52.3% at follow up. The mean pelvic obliquity (7.7 degrees) averaged 53.8%. The mean major scoliosis of group II (107.1 degrees), by an average flexibility of 25%, gets improved by 61%. At most recent follow-up, the mean correction was 61.5%. The mean pelvic obliquity (23.1 degrees) averaged 73.2% and 70.6% respectively. The mean bloodloss in group I was 1840 ml and in group II 2180 ml.

CONCLUSION

The data in the current study support the benefit of the operative treatment of patients with severe neuromuscular scoliosis. The quality of life gets improved by stability in seating and standing by correction of pelvic obliquity and trunk instability.

[Scanning stereographic surface measurement in idiopathic scoliosis after VDS (ventral derotation spondylodesis)]

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.

[Factors influencing the anchoring stability of spinal bone screws--an experimental study]

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.