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Biomedical subjects

L Bastian

Publications and source records attributed to L Bastian.

At least 37 records · Page 2Linked to original sources

Immunonutrition in patients after multiple trauma.

Severe trauma threatens the life of the victim, both directly and indirectly via immunological dysregulation during the subsequent clinical course. Inflammatory or infectious episodes may complicate the clinical course and ultimately result in sepsis and multiple organ failure, which have mortality rates of up to 80%. Immunomodulatory intervention aims to ameliorate the early hyperinflammatory phase (systemic inflammatory response syndrome, SIRS) to avoid the development of sepsis. One of the immunomodulation strategies is enteral feeding supplemented with specific nutrients, such as glutamine, n-3-polyunsaturated fatty acids, and nucleotides ('immunonutrition'), because changes in the GALT (gut-associated lymphoid tissue) immune response may contribute to intestinal dysfunction and increase susceptibility to post injury gut-derived sepsis. In a prospective, randomized, double-blind, controlled study in twenty-nine patients suffering severe trauma we were able to show that immunonutrition (arginine, n-3-fatty acids, and nucleotides) significantly reduces the number of SIRS days per patient, and also lowers the multiple organ failure (MOF) score on day 3 and days 8-11 (P<0.05). Other studies have reported a reduction in septic complications and MOF rates, shortened hospital stay, and reduction in the use of antibiotics in patients randomized to the immune-enhancing diet. This improved clinical outcome was reflected in a reduction in hospital costs. In the recovery period after trauma (1-72 h after injury) a limitation of the inflammatory response of immunocompetent cells must be achieved as quickly as possible (<72 h). The only strategy available to clinicians caring for trauma patients is immunonutrition, and this should be strongly considered as a rational approach improving immune function and reducing septic complications in critically ill or injured patients.

Enteral Nutrition↗

Late results of thoracolumbar fractures after posterior instrumentation and transpedicular bone grafting.

STUDY DESIGN: A retrospective clinical study was performed. OBJECTIVE: To study clinical and radiologic late results after posterior stabilization of thoracolumbar fractures with internal fixator and interbody fusion via transpedicular bone grafting. SUMMARY OF BACKGROUND DATA: The posterior approach, using an internal fixator, is a standard procedure for stabilizing the injured thoracolumbar spine. Transpedicular bone grafting was invented by Daniaux in 1986 for achieving an interbody fusion. Pedicle screw fixation with additional transpedicular fusion has remained controversial because of inconsistent reports and a lack of late results. METHODS: Between January 1989 and July 1992, 76 patients with thoracolumbar fractures were operatively treated, and after a mean of more than 3 years, 56 of 62 patients (90%) still alive who had their implants removed were examined. RESULTS: According to the Magerl classification, 33 patients sustained Type A, 13 Type B, and 10 Type C fractures. Three patients with incomplete paraplegia returned to normal. In one case of complete paraplegia, no change occurred. The mean operative time was 3 hours. In this study, two complications (3.6%) were observed: one iatrogenic vertebral arch fracture without consequences and one deep infection. Compared with the preoperative status, follow-up examinations demonstrated permanent physical and social sequelae: The percentage of individuals able to do physical labor was reduced by half (22 to 11 patients), whereas the share of unemployed or retired patients doubled (4 to 8 patients). At the time of follow-up examination, only 21 of 42 patients continued in sports. The assessment of reported problems and functional outcome with the Hannover spine score reflected a significant difference between the status before injury (96.6/100 points) and at the time of follow-up evaluation (71. 4/100 points) (P < 0.001).The radiographic assessment in the lateral plane (Cobb technique) demonstrated a significant (P < 0.001) mean restoration from an initial angle of -15.6 degrees (kyphosis) to +0. 4 degrees (lordosis). Serial postoperative radiographic follow-up assessment showed progressive loss of correction. At follow-up examination, a mean difference from the postoperative angle of 10.1 degrees was found (P < 0.001). Compared with the preoperative deformity, a mean improvement of 6.1 degrees (average, -9.7 degrees ) at follow-up examination was noted. The addition of transpedicular cancellous bone grafting did not decrease the loss of correction. Computed tomography scans after implant removal were performed in nine cases: Only three of nine patients showed evidence of intervertebral fusion. No correlation could be found between the Magerl classification and radiographic outcome. However, the preoperative wedge angle of the vertebral body correlated significantly with the postoperative loss of reduction. CONCLUSIONS: Because of the disappointing results from this study, the authors cannot recommend the additional transpedicular cancellous bone grafting as an interbody fusion technique after posterior stabilization in cases of complete or incomplete burst injury to the vertebral body.

Accidents, Traffic↗

[Comparative biomechanical compression trials with a new vertebral prosthetic implant].

UNLABELLED: The authors present a new titanium implant for replacement of the vertebral body (Synex). Possible indications would be fractures or dislocations with destruction of the anterior column, posttraumatic kyphosis as well as tumors in the throracolumbar spine. The construction has to be completed by a stabilizing implant. For best fit and contact to adjacent end-plates Synex is distractable in situ. The possibility of secondary dislocation or loss of correction should thereby be minimised. OBJECTIVES: 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 a caving of Synex in vivo. METHODS: 12 human cadaveric specimens of intact vertebrae (L1) were divided in 2 similar groups (matched pairs) according to bone mineral density (BMD), determined using DE-QCT. The specimens were loaded with axial compression force at a constant speed of 5 mm/min to failure and the displacement was recorded with a continuous load-displacement curve. RESULTS: The mean ultimate compression force (Fmax) showed a tendency towards a higher result testing Synex with 3396 N versus 2719 N (non significant). The displacement until Fmax was 2.9 mm in group S (Synex), which was half as long as in group M (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 a displacement of 1 mm, 1.5 mm and 2 mm. A significant (p < 0.001) correlation (R = 0.89) between Fmax and BMD was found. CONCLUSIONS: Synex was found to be at least comparable to MOSS for suspensory replacement of the vertebral body at the thoracolumbar spine. A possible consequence of the significantly higher mean compression forces between 1 and 2 mm displacement might be a decreased segmental deformation or loss of correction.

Adult↗

[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↗

[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↗

[Post-traumatic osteoid osteoma. Case report and review of the literature].

Osteoid osteoma is a painful benign bone neoplasm that is rarely described after trauma but should be suspected. A case of osteoid osteoma 19 years after a tibial fracture is presented. The patient had pain in the tibia for 6 years before the osteoid osteoma was confirmed. He had been operated on twice for suspected osteomyelitis although the clinical symptoms suggested an osteoid osteoma. The radiographic appearance as well as a bone scan confirmed the diagnosis. Removal of the nidus resulted in immediate pain relief. A precise preoperative diagnosis of the lesion based on clinical findings, standard radiographs, high-resolution CT, and bone scan is mandatory. It is important to recognize this uncommon entity to avoid morbidity associated with a prolonged delay in diagnosis.

Adult↗

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↗

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↗

Mathematical model for the natural history of human papillomavirus infection and cervical carcinogenesis.

The authors constructed a Markov model as part of a systematic review of cervical cytology conducted at the Duke University Evidence-based Practice Center (Durham, North Carolina) between October 1997 and September 1998. The model incorporated states for human papillomavirus infection (HPV), low- and high-grade squamous intraepithelial lesions, and cervical cancer stages I-IV to simulate the natural history of HPV infection in a cohort of women from ages 15 to 85 years. The age-specific incidence rate of HPV, and regression and progression rates of HPV and squamous intraepithelial lesions, were obtained from the literature. The effects of varying natural history parameters on cervical cancer incidence were evaluated by using sensitivity analysis. The base-case model resulted in a lifetime cervical cancer risk of 3.67% and a lifetime cervical cancer mortality risk of 1.26%, with a peak incidence of 81/100,000 at age 50 years. Age-specific distributions of precursors were similar to reported data. Lifetime risk of cancer was most sensitive to the incidence of HPV and the probability of rapid HPV progression to high-grade lesions (two- to threefold variations in risk). The model approximates the age-specific incidence of cervical cancer and provides a tool for evaluating the natural history of HPV infection and cervical cancer carcinogenesis as well as the effectiveness and cost-effectiveness of primary and secondary prevention strategies.

Adolescent↗

[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↗

The coracoacromial ligament: anatomical and biomechanical properties with respect to age and rotator cuff disease.

The coracoacromial ligament (CAL) plays an important role in the pathoetiology of the subacromial impingement syndrome especially in those patients who do not have bony abnormalities. A total of 40 shoulders were dissected to determine the anatomical and biomechanical properties of the CAL in shoulders with either intact rotator cuffs or rotator cuff disease, taken from cadavers of persons who were of various ages at death. The specimens from cadavers with rotator cuff degeneration had a shorter lateral and medial band of the CAL than those of the specimens taken from shoulders with intact rotator cuffs. The cross-sectional area of the lateral band was also enlarged in older specimens with rotator cuff degeneration. Analysis of the structural properties showed a higher load to failure and a higher stiffness in the younger than in older specimens. In material properties, there was a higher failure stress in specimens with normal rotator cuffs than in the specimens with rotator cuff disease but only in older specimens. The decreased material properties in older specimens with rotator cuff disease may be caused by the previously reported histological differences with tissue disorganization and a lack of parallel bundle orientation associated with rotator cuff disease.

Adult↗

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↗

[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↗

[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↗

[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↗

[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↗

[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↗