Biomedical subjects

C Knop

Publications and source records attributed to C Knop.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Biomechanical stability with a new artificial vertebral body implant. 3-dimensional movement analysis of instrumented human vertebral segments].

UNLABELLED: The authors present a new implant for vertebral body replacement in the thoracic and lumbar spine. The titanium implant is designated for reconstruction of the anterior column in injury, posttraumatic kyphosis or tumor of the thoracolumbar spine. The instrumentation has to be supplemented by a stabilizing implant. After positioning, the implant is distracted in situ, through which best contact to adjacent end-plates and 3-dimensional stability should be provided. The possibility of secondary dislocation or loss of correction should thereby be minimized. OBJECTIVES: We investigated the biomechanical 3-dimensional stability in vitro, using Synex in combination with an anteriorly (Ventrofix) or a posteriorly (USS) stabilizing implant. The differences between both stabilizing implants were to be determined. Synex was compared with the "Harms titanium mesh cage" (MOSS) as vertebral body replacement. METHODS: In a 3-dimensional spinal loading simulator, we determined the bisegmental (T12-L2) neutral zone (NZ), elastic zone (EZ), and range of motion (ROM) of 12 human cadaveric spines. After corpectomy of L1 we tested 4 groups of implant combinations: USS/Synex, USS/MOSS, Ventrofix/Synex, Ventrofix/MOSS. We analyzed the differences between each of the instrumentations as well as differences compared to the intact spine. RESULTS: In most directions, significantly higher stability was achieved with USS, compared with Ventrofix and the intact specimen. For axial rotation, with no instrumentation the stability of the intact spine was restored. With Synex a significantly higher stability was noted for extension, lateral bending, and axial rotation in comparison with the Harms cage. A tendency towards more stability for flexion was additionally observed with Synex. When using MOSS in combination with USS, it was necessary to perform a third operative step for induction of intervertebral compression via the posterior fixator. CONCLUSIONS: The posterior fixation was found to offer superior stability compared to the anterior one. Synex was at least comparable to MOSS for suspensory replacement of the vertebral body in the thoracolumbar spine. The evidence of higher biomechanical stability with Synex leads to the probability of a higher rigidity in vivo. Due to the distractability of Synex, a better intervertebral compression was achieved. Therefore, an additional tightening of the posterior fixator after insertion of Synex was not necessary, in contrast to the Harms cage.

Biomechanical Phenomena↗

PubMed2001

[Surgical treatment of injuries of the thoracolumbar transition--3: Follow-up examination. Results of a prospective multi-center study by the "Spinal" Study Group of the German Society of Trauma Surgery].

OBJECTIVES: Prospective, multicenter study addressing late results after operative treatment of acute thoracolumbar spinal injuries. METHODS: 682 patients (T10-L2) were included and 372 (80%) were postoperatively followed for 2 1/4 years (4-61 months). RESULTS: Comparing the initially included patients (n = 682) with the study group (n = 372), no differences were observed and results were assumed to be representative. A C-type lesion or polytrauma significantly prolonged the hospital stay. The method of operative treatment did not affect the length of the rehabilitation period. Neurological improvement was observed in 3 out of 7 patients with complete, and in 44 out of 64 (69%) with incomplete lesion. The operative method did not affect the improvement rate. The physical capacity significantly decreased. After a mean of 1/2 year of disability only 71% returned to work. 48% returned to their preoperative physical level. The mean Hannover Spine Score was 68 points (preoperative 94, p < 0.001), indicating permanent impairment of function. The angle-stable internal fixator was superior in restoration of spinal alignment and best radiological results were noted after combined stabilization. Posterior stabilization lead to high re-kyphosing. No correlations between radiologic and clinical parameters were observed. CONCLUSIONS: All treatment methods under study were appropriate for achieving comparable clinical and functional outcome. The internal fixator is superior in restoration of the spinal alignment. Best radiological outcome is achieved by combined stabilization. Merely by direct reconstruction of the anterior column the postoperative re-kyphosing is prevented and a gain in segmental angle is achieved.

Adolescent↗

PubMed2001

[Development and validation of the Visual Analogue Scale (VAS) Spine Score].

The aim of the study was the development and validation of a new subjective rating scale for assessment of outcome in patients with thoracolumbar fractures and fracture dislocations. The VAS spine score consists of 19 score items, using 100-mm visual analogue scales. The items are answered by the patients independently of rater assessment. To measure the analogue scales and calculate the score, a computer-aided system was evolved consisting of self-developed software and digitizer board. The overall score is the mean of all items answered with values between 0 and 100. The individual score loss is calculated as the difference between the preinjury score and at follow-up with values between 0 and 100. The VAS spine score was tested for reliability with a group of 136 healthy volunteers. We performed a test-retest study with an interval of 24 h. For statistical analysis of the validity, we prospectively followed a group of 53 patients with the new outcome score. We chose patients with injuries of the thoracolumbar spine, all having been operatively treated by combined posterior-anterior stabilization and fusion between 1994 and 1996. In the reference group, the average test score was 91.95 (58-100) and 92.10 (58-100) at retest. The mean individual difference between test and retest scored 1.037 (0-8). A high reliability was proved by a strong correlation with a coefficient of 0.976 (p < 0.001). A high internal consistency of the VAS spine score was shown by a Cronbach-alpha of 0.9117. The mean score for the preinjury status of the patients was comparable to the reference group, amounting to 89.60 (21-100). The mean score at the time of implant removal was significantly (p < 0.001) decreased to 58.25 (13-97). Until the time of follow-up a significant (p < 0.001) increase was noted, and the group scored 66.08 (15-100) at follow-up. This was a significant (p < 0.001) difference compared with the preinjury status. The individual score loss averaged 24.1 (0-80). In the patient group we also noted a Cronbach-alpha > 0.95, indicating a high internal consistency. With the VAS spine score the authors have inaugurated a new tool for outcome measurement in the treatment of patients with thoracolumbar injuries. The study has proved the score to be both reliable and valid. The application of the score is helpful in analyzing the subjective outcome, and the results can be correlated with objective measures. The score is a useful tool for comparative clinical studies, addressing the outcome after different methods of treatment.

Adult↗

PubMed2001

Sucrose transporters in two members of the Scrophulariaceae with different types of transport sugar.

In order to study differences between sugar transport in oligosaccharide-translocating and sucrose-translocating species, two members of the Scrophulariaceae, Asarina barclaiana Pennell and Alonsoa meridionalis O. Kuntze, were analysed regarding minor-vein anatomy, sugar concentrations in leaves and phloem sap, and expression of sucrose transporters. The minor veins of Asarina barclaiana possess mainly transfer cells and modified intermediary cells and those of Alonsoa meridionalis have intermediary cells and ordinary companion cells. Phloem sap from these plants was collected by the laser-aphid-stylet technique. The main carbon transport forms in Asarina were sucrose and in Alonsoa raffinose and stachyose. The sum of the carbohydrate concentrations in the phloem sap of both species was as high as that in apoplastic phloem loaders. In Asarina the ratio of the sucrose concentration in the phloem to that in the cytosol of source cells was about 35 and the corresponding ratio in Alonsoa was about two. Sucrose transporter cDNAs were isolated from leaves of both species. By means of semi-quantitative reverse transcription-polymerase chain reaction, sucrose transporter mRNA was detected in different organs and also in the phloem sap. This is the first time that sucrose transporters have been found in oligosaccharide-translocating species and that the mRNA of these sucrose transporters has been localized directly in the phloem sap. Taken together, our observations indicate that Asarina is an apoplastic phloem loader, while the results for Alonsoa are ambiguous: some properties are typical of the symplastic phloem-loading mechanism, but probably a sucrose transporter is involved in loading and/or retrieval of sucrose into the phloem.

Amino Acid Sequence↗

PubMed2001

Biomechanical compression tests with a new implant for thoracolumbar vertebral body replacement.

The authors present an investigation into the biomechanical functioning of a new titanium implant for vertebral body replacement (Synex). Possible indications are fractures and/or dislocations with damage of the anterior column, posttraumatic kyphosis and tumors of the thoracolumbar spine. The construction must be supplemented by a stabilizing posterior or anterior implant. For best fit and contact with adjacent end-plates, Synex is distractable in situ. We performed comparative compression tests with Synex and MOSS ("Harms mesh cage") on human cadaveric specimens of intact vertebrae (L1). The aim of the study was to measure the compressive strength of the vertebral body end-plate in uniaxial loading via both implants to exclude collapse of Synex in vivo. Twelve human cadaveric specimens of intact vertebrae (L1) were divided into two identical groups (matched pairs) according to bone mineral density (BMD), determined using dual-energy quantitative computed tomography (DE-QCT). The specimens were loaded with an axial compression force at a constant speed of 5 mm/min to failure, and the displacement was recorded with a continuous load-displacement curve. The mean ultimate compression force (Fmax) showed a tendency towards a higher reading for Synex: 3396 N versus 2719 N (non-significant). The displacement until Fmax was 2.9 mm in the Synex group, which was half as far as in the MOSS group (5.8 mm). The difference was significant (P < 0.001). The compression force was twice as high, and significantly (P < 0.05) higher with Synex at displacements of 1 mm, 1.5 mm and 2 mm. A significant (P < 0.001) correlation (R = 0.89) between Fmax and BMD was found. Synex was found to be at least comparable to MOSS concerning the compressive performance at the vertebral end-plate. A possible consequence of the significantly higher mean compression forces between 1 and 2 mm displacement might be decreased collapse of the implant into the vertebral body in vivo.

Biomechanical Phenomena↗

PubMed2001

Evaluation of the mobility of adjacent segments after posterior thoracolumbar fixation: a biomechanical study.

An investigation was conducted into the effects of double-level T12-L2 posterior fixation on the mobility of neighboring unfused segments. The segmental mobility of adjacent segments above and below the fixation in ten cadaveric human thoracolumbar spine specimens was measured before and after fixation by biomechanical testing in flexion, extension, right lateral bending, and right rotation, and the data were compared. In flexion and extension, mobility of the segment above the double-level T12-L2 posterior fixation was significantly increased (P<0.05). In the adjacent segment below the fixation, there was no significant increased mobility after fixation for each moment applied. There is evidence that the adjacent segment above a double-level T12-L2 posterior fixation becomes more mobile, and this may lead to an accelerated degeneration in the facet joints due to increased stress at this point. This could be responsible for symptoms like low back pain after spinal surgery.

Biomechanical Phenomena↗

PubMed2000

[Surgical treatment of injuries of the thoracolumbar transition. 2: Operation and roentgenologic findings].

The authors report on a prospective multicenter study with regard to the operative treatment of acute fractures and dislocations of the thoracolumbar spine (T10-L2). The study should analyze the operative methods currently used and determine the results in a large representative collective. This investigation was realized by the working group "spine" of the German Trauma Society. Between September 1994 and December 1996, 682 patients treated in 18 different traumatology centers in Germany and Austria were included. Part 2 describes the details of the operative methods and measured data in standard radiographs and CT scans of the spine. Of the patients, 448 (65.7%) were treated with posterior, 197 (28.9%) with combined posterior-anterior, and 37 (5.4%) with anterior surgery alone. In 72% of the posterior operations, the instrumentation was combined with transpedicular bone grafting. The combined procedures were performed as one-stage operations in 38.1%. A significantly longer average operative time (4:14 h) was noted in combined cases compared to the posterior (P < 0.001) or anterior (P < 0.05) procedures. The average blood loss was comparable in both posterior and anterior groups. During combined surgery the blood loss was significantly higher (P < 0.001; P < 0.05). The longest intraoperative fluoroscopy time (average 4:08 min) was noticed in posterior surgery with a significant difference compared to the anterior group. In almost every case a "Fixateur interne" (eight different types of internal fixators) was used for posterior stabilization. For anterior instrumentation, fixed angle implants (plate or rod systems) were mainly preferred (n = 22) compared to non-fixed angle plate systems (n = 12). A decompression of the spinal canal (indirect by reduction or direct by surgical means) was performed in 70.8% of the neurologically intact patients (Frankel/ASIA E) and in 82.6% of those with neurologic deficit (Frankel/ASIA grade A-D). An intraoperative myelography was added in 22% of all patients. The authors found a significant correlation between the amount of canal compromise in preoperative CT scans and the neurologic deficit in Frankel/ASIA grades. The wedge angle and sagittal index measured on lateral radiographs improved from -17.0 degrees and 0.63 (preoperative) to -6.3 degrees and 0.86 (postoperative). A significantly (P < 0.01) stronger deformity was noted preoperatively in the combined group compared to the posterior one. The segmental kyphosis angle improved by 11.3 degrees (8.8 degrees with inclusion of the two adjacent intervertebral disc spaces). A significantly better operative correction of the kyphotic deformity was found in the combined group. In 101 (14.8%) patients, intra- or postoperative complications were noticed, 41 (6.0%) required reoperation. There was no significant difference between the three treatment groups. Of the 2264 pedicle screws, 139 (6.1%) were found to be misplaced. This number included all screws, which were judged to be not placed in an optimal direction or location. In seven (1.0%) patients the false placement of screws was judged as a complication, four (0.6%) of them required revision. The multicenter study determines the actual incidence of thoracolumbar fractures and dislocations with associated injuries and describes the current standard of operative treatment. The efforts and prospects of different surgical methods could be demonstrated considering certain related risks. The follow-up of the population is still in progress and the late results remain for future publication.

Adolescent↗

PubMed2000

[Spinal fractures in the elderly and their treatment].

Spinal injuries referring to banal falls are common injuries in elderly persons. Up to 55 years of age spinal fractures are more frequent in men while its opposite in older persons. There are two typical lesions: odontoid fracture in the upper cervical spine and compression fracture in thoracolumbar spine. Odontoid fracture is the most frequent lesion in cervical spine in the elderly. This is caused by trabecular structure of dens axis and spine's stiffness in old age. Instable fractures in extension type II are most common. In many cases the instability of the lesion is hidden and can be first seen in functional examination controlled by x-ray. Conservative treatment is efficient in stable lesions type III while there is a high risk for pseudarthrosis in treatment of instable lesions in elderly with Halo Fixateur e.g. We think that the best operation for these fractures is the anterior screw fixation. If this is not sufficient because of low bone mass or early dislocation of the screws a dorsal fusion C1/C2 with trans-articular screwing e.g. should be done. Because of rare symptoms thoracolumbar fractures in osteoporosis are hidden frequently. In many cases it's not easy to distinguish acute lesions from healed fractures or tumor lesions. Neurological deficit is rare. Therefore there are just few compression fractures (A type) that have to be treated operatively. Instable lesions type B and C must be operated as well in the elderly as in the young. Because of low bone mass in elderly the dorsal instrumentation should include more than just the two injured segments. An even more adequate stabilisation is done with an additional vertebral replacement.

Aged↗

PubMed2000

Three-dimensional motion analysis with Synex. Comparative biomechanical test series with a new vertebral body replacement for the thoracolumbar spine.

The authors present a new implant for vertebral body replacement in the thoracic and lumbar spine. Synex is a titanium implant designated for reconstruction of the anterior column in injury, post-traumatic kyphosis or tumour of the thoracolumbar spine and must be supplemented by a stabilizing implant. After positioning, the implant is distracted in situ, thus ensuring best contact with adjacent end-plates and three-dimensional (3D) stability, and minimizing the possibility of secondary dislocation or loss of correction. We compared the effectiveness of the Synex implant with that of the "Harms cage" (MOSS) in combination with two alternative stabilizing instrumentations: the USS and Ventrofix. In a 3D spinal loading simulator, we determined the bisegmental (T12-L2) neutral zone (NZ), elastic zone (EZ), and range of motion (ROM) of 12 human cadaveric spines. After corpectomy of L1, we tested the four possible combinations of stabilizing instrumentation and vertebral replacement implant: USS/Synex, USS/MOSS, Ventrofix/Synex, Ventrofix/MOSS. We analysed the differences between each of the instrumentations as well as differences compared to the intact spine. Comparing the two stabilizing implants, a significantly higher stability was achieved with the USS for flexion, extension, and lateral bending, regardless of whether Synex or MOSS was used as vertebral body replacement. No differences were observed for axial rotation. In addition, no implant combination was able to restore the rotational stability of the intact spine. Comparing the vertebral body replacing implants, significantly higher stability was noted with Synex in combination with USS for extension, lateral bending, and axial rotation. No differences between Synex and MOSS were observed in combination with Ventrofix. Posterior fixation was found to offer superior stability compared to anterior fixation. Synex was at least comparable to MOSS for suspensory replacement of the vertebral body in the thoracolumbar spine. The increased biomechanical stability demonstrated for Synex suggests that a more rigid construction would also be achieved in vivo. When using MOSS in combination with posterior stabilization, the induction of intervertebral compression via the posterior fixator is recommended. This surgical step was not necessary with Synex.

Biomechanical Phenomena↗

PubMed1999

[Treatment of recurrence of fibular ligament rupture. Results of a prospective randomized study].

Previous studies concerning ruptures of the lateral ligaments of the ankle dealt with acute first ruptures. There are a few articles about chronic instability of the ankle but no prospective investigations have been reported concerning the treatment of recurrent ruptures. Good results were obtained following after non-operative treatment of acute ruptures of the fibular ligaments of the ankle joint. This prospectively randomized study was commenced to test whether recidivations of the rupture of the lateral ligaments can also be treated non-operatively or if they are in need of operative repair. The second question to be answered was whether these injuries should be treated differently depending on the treatment of the first rupture. From December 1986 to November 1989, 109 patients with a recidivation of a rupture of the ankle joint lateral ligaments were included in this prospective trial at the Department of Trauma Surgery, Hannover Medical School. They were divided into two groups depending on the therapy used to treat the first injury: The relapse was classified as a second-stage-rupture in cases where treatment of the first ligament rupture did not involve an operation and as a rerupture if the initial rupture was surgically repaired. Half of each group was treated randomly either with surgical ligament repair or without. A total of 100 patients (92%) at an average age of 24 years (11 to 49 years) was seen for follow-up examination one year after the relapse: The follow-up included the patient's subjective assessment, a clinical examination, and stress radiography. A 70 point score was used for evaluation of the total result. Two wound infections requiring reoperation were observed in the operative treatment groups. The follow-up examination revealed better results in both operative treatment groups (A and C), which was statistically significant (P < 0.05). Patients with a second-stage-rupture showed a significantly higher (P < 0.001) stability by stress radiography after surgical treatment (group A) in contrast to non-operative treatment (group B). In addition, the subjective and clinical results indicated a tendency towards better results which were not statistically significant (P < 0.09 and P < 0.07). In cases of rerupture the patient's subjective assessment revealed significantly more (P < 0.05) complaints after non-operative treatment (group D). Clinical results were comparable, and radiologic assessment showed a tendency towards higher joint stability after surgical treatment (group C), although it was not statistically significant (P < 0.07). Based on the results presented, the authors recommend the surgical repair of ankle joint ligaments in cases of second-stage- or rerupture.

Adolescent↗

PubMed1999

[Surgical treatment of injuries of the thoracolumbar transition. 1: Epidemiology].

The authors report on a prospective multicenter study with regard to the operative treatment of fractures and dislocations of the thoracolumbar spine. 18 traumatologic centers in Germany and Austria, forming the working group "spine" of the German Society of Trauma Surgery, are participating in this continuing study. Between September 1994 and December 1996 682 patients (64% male) with an average age of 39 1/2 (7-83) years were entered. The entry criteria included all patients with acute and operatively treated (within 3 weeks after trauma) fractures and dislocations of the thoracolumbar spine (Th 10-L 2). Part 1 of this publication outlines the protocol and epidemiologic data. The incidence of fractures and dislocations of the thoracolumbar spine and associated injuries were recorded according to a standardized protocol, as well as the different operative methods and complications, duration of hospital stay, rehabilitation and incapacity. The analysis of the clinical social and radiological course was a second focus. The most frequent mechanism of injury was a fall (50%) or traffic accident (22%). Most of the fractures occurred at the L 1 level (49%). All injuries were classified according to the ASIF (AO) classification. 65% sustained an A-type fracture (compression fracture). Associated injuries were observed in 35% and 6% were polytraumatized. Extremities and thorax were most frequently affected. Younger age and traffic accidents lead more often to C-type fracture (fracture dislocation) and polytrauma. An increased number of multisegmental or multilevel lesions were observed in polytraumatized patients. There were 16% with incomplete paraplegia (Frankel/ASIA B-D) and 5% with complete paraplegia (Frankel/ASIA A). The rate of patients with initial neurologic deficits significantly increased with the severity of spinal injury according to the Magerl classification. Until discharge a neurologic improvement (at least 1 Frankel/ASIA grade) was observed in 32% of the partially paralyzed (Frankel/ASIA B-D) and in 12% of the patients with complete paraplegia (Frankel/ASIA A). A neurologic deterioration occurred in 3 patients (0.4%). As a base for further follow-up and late results the individual starting point was determined by collecting relevant data of the patients' history: 277 (40.6%) patients suffered from simultaneous diseases, one half was spine related. At the time of injury 559 (82.0%) patients were employed; 429 (62.9%) doing manual work. 369 (54.1%) patients stated sportive activities before the injury and 561 (82.3%) designated their "back function" as normal. For the time before injury the patients scored an average of 93.4 points in the Hannover Spine Score (0-100 points concerning complaints and function of the back/spine).

Adolescent↗

PubMed1999

[Inter-observer reliability in the classification of thoraco-lumbar spinal injuries].

The purpose of a fracture classification is to help the surgeon to choose an appropriate method of treatment for each and every fracture occurring in a particular anatomical region. The classification tool should not only suggest a method of treatment, it should also provide the surgeon with a reasonably precise estimation of the outcome of that treatment. But to use a classification before its workability has been proved is inappropriate and can lead to confusion and more conflicting results. Any classification system should be proved to be a workable tool before it is used in a discriminatory or predictive manner. The radiographs of fourteen fractures of the lumbar spine were used to assess the interobserver reliability of the AO classification system. The radiographs and CT scans were reviewed in twenty-two hospitals experienced with spinal trauma. The mean interobserver agreement for all fourteen cases was found to be 67% (41-91%), when only the three main types (A, B, C) were used. The corresponding kappa value of the interobserver reliability showed a coefficient of 0.33 (range, 0.30 to 0.35). The reliability decreased by increasing the categories. For some injuries the interobserver reliability was found to be over 90% and also for the recommended therapeutic procedure there was an acceptable agreement. But the decision between an posterior approach alone or an additionally anterior procedure seems to be the most important question in treatment of spinal injuries at that time.

Accidents↗

PubMed1999

[Transpedicular implantation of screws in the thoracolumbar spine. Results of a survey of methods, frequency and complications].

Pedicular fixation has found great acceptance as a modality for spinal fusions. Being a "blind technique" it is associated with a potential high risk of neural and vascular morbidity. In an attempt to evaluate and/or establish a uniformly accepted concept of surgical management we designed a questionnaire composed of seventeen questions dealing with different pre-, intra- and postoperative procedures in transpedicular fixation. This was sent to 31 experienced surgeons organized in the working group "spine" of the german trauma association. Half of the answers to each question were similar. The other half however, showed a wide variation of thought. It is thus deduced that although some concepts are frequently applied there is no general agreement to an optimal method of surgical handling. Most surgeons use conventional operative cushions for positioning the patients (22/31). Access is usually proceeded by sharp dissection of the lumbodorsal fascia using a scalpel instead of catheterization (21/31), consciously avoiding traumatisation of paravertebral muscle insertion to the transverse processes (22/31), as well as sparing the dorsal branch of segmental arteries (25/31). Intraoperative orientation is attained by inspection coronary and fluoroscopy sagittal (15/31). Most surgeons remove cortical bone using a Rongeur (22/31), transpedicular drill hole is prepared by means of a k-wire (11/31), for orientation again the fluoroscope is made use of (15/31). On perforating the medial boundary of the pedicle thirteen operators correct the direction on drilling, on perforating the lateral boundary twelve medialise the screws on fixation, and eleven surgeons would leave the screws in place if firm holding is warranted. Half of the questioned surgeons simply lateralise the screws if cerebrospinal fluid leaked from the drill holes. If a malposition of the pedicle screws is not suspected no control computer tomography is performed (21/31). Regarding these facts a comparative evaluation of the different techniques used in transpedicular fixation is lacking. In our opinion further multicenter evaluation is necessary to establish a unified method and thus optimize postoperative results.

Bone Plates↗

PubMed1999

[Transpedicular fusion of the thoraco-lumbar junction. Clinical, radiographic and CT results].

The aim of this retrospective study was to determine the late result after operative treatment of acute thoracolumbar fractures and fracture dislocations. 29 patients, treated between 1988 and 1995 at the Department of Trauma Surgery, Hannover Medical School with posterior stabilization and interbody fusion with transpedicular cancellous bone grafting, were reexamined 3 1/2 years after surgery. The incorporation and effect on the fusion was analyzed with spiral CT scan after implant removal and the patients were seen for clinical and conventional radiologic examination. We treated 24 type A, 4 type B and 1 type C lesion according to the Magerl classification. 27 patients were stabilized with an internal fixator, 2 with a plate system. The mean operative time totalled 2:50 hours, the intraoperative fluoroscopy time averaged 4:07 minutes and a mean blood loss counted 376 ml. 4 patients out of 6 with an incomplete neurologic lesion (Frankel/ASIA D) improved to Frankel/ASIA grade E. 2 complications were observed: 1 delayed wound healing and 1 venous thrombosis with secondary pulmonary embolism. Compared to the preoperative status our follow-up examinations demonstrated permanent social sequelae: The percentage of individuals able to do physical labor was reduced (15 to 5 patients; p < 0.01) whereas the share of unemployed or retired patients increased (2 to 12 patients; p < 0.01). The assessment of complaints and functional outcome with the "Hannover Spinal Trauma Score" reflected a significant difference (p < 0.001) between the status before injury (96.6/100 points) and at the time of follow-up (64.4/100 points). The correlation between the "Hannover Spinal Trauma Score" and the finger-ground-distance was found to be significant (Coefficient Spearman = -0.71; p < 0.01). The radiographic assessment of the segmental kyphosis (Cobb technique) demonstrated a significant (p < 0.001) mean restoration from an initial angle of -15.2 degrees (kyphosis) to -3.4 degrees (kyphosis). Serial postoperative radiographic follow-up showed progressive loss of correction; at follow-up examination we found a mean of 7.8 degrees (p < 0.005). In 16 patients with an additional posterior fusion with autogenous bone grafting an analogous loss of correction was noted. CT scans after implant removal demonstrated an interbody fusion and incorporation of the transpedicular bone graft in 10 (34%) patients. In another 10 (34%) patients the CT scans proved the interbody fusion at the anterior and posterior wall of the vertebral body via direct contact due to collapse of the disc space. In these patients the bone graft was not incorporated and no central interbody fusion could be found. In 9 (31%) patients neither interbody fusion nor incorporation of the transpedicular graft was achieved. A frequent interbody fusion could not be achieved with the technique of transpedicular bone grafting. In case of incomplete or complete thoracolumbar burst fractures the authors recommend a combined operation with restoration of the anterior column with a strut graft or body replacement.

Female↗

PubMed1999

[Effect of a crosslink or cerclage on the mechanical stability of an internal fixator].

This study was performed to evaluate the effect of a cerclage or a crosslink on internal fixator mechanical stability in an unstable spine injury model. Nine human thoracolumbar spine specimens were instrumented either with an internal fixator alone (T12-L2) or together with a cerclage or a crosslink. Four modes of loading were used: flexion, extension, lateral bending, and axial rotation. Moments itself were generated using a specially designed loading jig and loading system. The maximum moment applied was 10 Nm, three load-unload cycles were performed. The flexibility was measured by a motion tracker and range of motion (ROM), elastic zone (EZ) and neutral zone (NZ) were calculated. Statistical analysis was performed using the paired t-test (p < 0.05). For flexion, extension and lateral bending all devices were significantly more stable (p < 0.01), for axial rotation all devices were significantly less stable compared to the intact specimen (p < 0.01). But the crosslink provided significantly more stability compared to the internal fixator alone (p < 0.001). The complete device, i.e. internal fixator + crosslink, was significantly more stable compared to internal fixator + cerclage (p < 0.05). In this study the use of a cerclage had no additional effect in stabilizing the internal fixator. The operative and financial expenditure using a crosslink seems to be justified in fractures with a high rotationally instability, i.e. in type A-3-, B-, and C-injuries according to Magerl et al. [18].

Bone Plates↗

PubMed1998

[Complex injuries of the spine].

3 different types of complex spinal trauma are defined: Type I means a multilevel contiguous or non contiguous unstable injury, type II is described as a spinal injury with concomitant thoracic or abdominal lesion, type III stands for the coincidence of spinal injury and polytrauma. Overlapping of different types occurs. Type I: The incidence amounts according a german multicenter study to about 2.5%. Multilevel injuries need to be stabilized for a long distance from posterior. With a thorough analysis the segments to be fused are determined. Type II: The leading thoracic injury is a lung contusion which occurs in up to 50% of the cases. A CT scan of the thorax during the first diagnostic screening is recommended. Early reduction and stabilization from posterior should be aimed at. During the first two weeks anterior procedures are contraindicated. Abdominal injuries are to be found in 3-4% of all spinal injuries. All organs could be affected. A typical constallation is the "seat-belt syndrome" with lesions of the upper abdominal organs and a flexiondistraction injury of the upper lumbar spine. The main problem is to make the diagnosis of both components initially. Most of the patients may be treated in one operation by first taking care of the abdominal injury and than stabilizing the spine. The prognosis of this combination is favorable. Type III: In 17-18% of all polytraumatized patients lesions of the spine are to be diagnosed. From these only one third need surgical care. From 680 patients with operatively treated fractures of the thoracolumbar junction 6.2% were polytraumatized according to the multicenter study mentioned above. The risk of missing a spinal injury in polytrauma totals approximately 20%. Surgical stabilization should be performed in the primary phase (day-1-surgery). Additional injuries, potentially time consuming operations with a high blood loss sometimes necessitate a different approach. Non stabilized spinal injuries apparently do not have the same negative effect on the whole organism as long bone fractures. In the early phase of treatment on the C-spine only anterior procedures and on the thoracolumbar spine only posterior techniques should be applied.

Adolescent↗

PubMed1998

[Reduction and positioning of cervical spine injuries].

Prerequisites for successful reduction of cervical spine injuries are an exact analysis and classification of every lesion. In locked dislocations disc protrusion should be excluded prior to reduction by MRI or CT-scan. For manual reduction and closed manipulation by the trauma surgeon we use a halo-ring which is applied in local anaesthesia and fluoroscopic control. The anatomic position is maintained by a halo-fixator until surgery. Skeletal traction is used mainly for locked dislocations and late malalignements. Traction is provided by a halo-ring and weights up to 20 kg. Repeated clinical and neurological examinations are necessary to rule out overdistraction of the spine or neurologic deterioration. The weight may be reduced after reduction to 2 kg. For intraoperative positioning and reduction of cervical spine injuries we designed a special device which is connected to the halo ring and allows to fix the head and spine in any desired position. It may be used in prone or supine position of the patient. Operative reductions are rarely necessary on the cervical spine. Typical indication are fractures of posterior elements of the spine preventing closed reduction. Reduction manoeuvers depend on the kind of injury and are mainly composed of traction and a reversal of the trauma mechanism. The most severe complication is a neurologic deterioration. Reports in literature about 13 patients having sustained such a fate are showing the following: In most cases disc material dislocated in the spinal canal during reduction could be made responsible for the catastrophic course. Especially at risk are patients with open reduction from a posterior approach.

Cervical Vertebrae↗

PubMed1998

[Ventral interbody spondylodesis in injuries of the cervical spine. Indications, surgical technique and results].

Lower cervical spine injuries with instability of the anterior and/or posterior column can be treated by anterior interbody fusion and plate fixation. Plates available for anterior instrumentation of the lower cervical spine can be divided into locking or non-locking systems with uni- or bicortical screw purchase. Our biomechanical comparative testing of different screw fixation systems demonstrates improved stability with the use of bicortical purchase. Clinical studies, however, have proven high fusion rates without loss of correction and a low implant related morbidity with the use of unicortical as well of bicortical plate systems. Correct reduction and intraoperative positioning of the unstable cervical spine is crucial to avoid implant related complications. Also, limitations of anterior instrumentation for the treatment of specific lesions of the lower cervical spine have to be considered, e.g. in complex lesions with axial instability or in fracture dislocations with ankylosing spondylitis. Changes or alterations of adjacent segments can be reduced by the use of plates with correct lengths, contact of uninjured adjacent discs with implants should be avoided. A comparative analysis of two patient collectives--89 patients (1972-1983) and 102 patients (1987-1994), all of them treated with bicortical plate fixation--revealed different results in terms of implant failure, operative reduction and loss of correction. All but one surgical fusions had healed radiologically. Implant related complications during the first 3 months after the initial operation were lower in the latter group, only 3 out of 102 patients (3%) with implant loosening versus 7 our of 89 patients (8%) with implant breakage or loosening required surgical revision. In all cases technical errors could be detected. Clinical follow-ups with personal examination was performed in 144 patients: 57 of 72 survivors of series I (79%) after an average time of 11 years 9 months and 87 out of 94 survivors of series II (85%). The radiologic examination revealed 2 patients with screw breakage in series I, one patient with an asymptomatic implant loosening in series II. Only one case was observed with a loss of correction after loosened and early removed hardware. In all other patients there was no difference of radiologic angles between postoperative X-ray and follow-up. 16 patients, 12 of series I, 4 of series II, were fused in a kyphotic position after insufficient preoperative reduction. Radiologic alterations of adjacent segments, i.e. spondylophyts or "spontaneous" fusions, were observed in more than 50% of all patients of both series. However, complaints or persistent pain did not correlate with radiologic findings. Also in both series there was a high percentage of patients with mild, residual neck pain in spite of a very good radiologic result. Only in a very few cases the complaints had to be treated by drugs.

Adolescent↗