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Biomedical subjects

N Südkamp

Publications and source records attributed to N Südkamp.

At least 19 recordsLinked to original sources
PubMed2007

[Biomechanical evaluation of glenohumeral stability through muscle force vector analysis. Effect of a decreased glenoid inclination in shoulders with global rotator cuff tears].

OBJECTIVES: The aim of the study was to quantify the decrease in glenohumeral stability following a global rotator cuff tear and to evaluate the effect of a decreased glenoid inclination angle through analysis of muscle force vectors in a computer model. MATERIAL AND METHODS: The lines of action of eight shoulder muscles were integrated into a standard geometric model. Muscle force magnitudes were estimated based on physiological cross-sectional area and normalized electromyographic activity. The magnitude and elevation angle of the resultant force vector was calculated at 0, 30, 60, and 90 degrees of abduction. A rotator cuff tear was simulated by reduction of the corresponding muscle force vectors. RESULTS: At 0 and 30 degrees of glenohumeral abduction a global rotator cuff tear showed a resultant force vector pointing outside the glenoid. In the computer model, decreasing the inclination angle of the glenoid by 30 degrees increased the stability in rotator cuff-deficient shoulders. CONCLUSIONS: The results of this study provide a biomechanical rationale for clinical complications of global rotator cuff tear such as superior humeral head translation. The decreased glenoid inclination simulated in the computer model may represent a biomechanical basis for the development of new operative techniques to treat global rotator cuff tears.

Biomechanical Phenomena↗
PubMed2006

Results after microfracture of full-thickness chondral defects in different compartments in the knee.

OBJECTIVE: To determine if the clinical results after microfracture of full-thickness cartilage lesions deteriorate over a period of 36 months. METHODS: Between 1999 and 2002 85 patients (mean age 39.5 years) with full-thickness cartilage lesions underwent the microfracture procedure and were evaluated preoperatively and 6, 18 and 36 months after surgery. Exclusion criteria were meniscal pathologies, axial malpositioning and ligament instabilities. Baseline clinical scores were compared with follow-up data by paired Wilcoxon-tests for the modified Cincinnati knee and the International Cartilage Repair Society (ICRS)-score. The effects of the lesion localization and Magnetic resonance imaging (MRI) parameters were evaluated using the Pearson correlation and independent samples tests. RESULTS: Both scores revealed significant improvement 18 months after microfracture (P<0.0001). Within the second 18 months after surgery there was a significant deterioration in the ICRS-score (P<0.0001). The best results could be observed in chondral lesions of the femoral condyles. Defects in other areas of the knee deteriorated between 18 and 36 months after microfracture. MRI 36 months after surgery revealed best defect filling in lesions on the femoral condyles with significant difference in the other areas (P<0.02). The Pearson coefficient of correlation between defect filling and ICRS-score was 0.84 and significant at the 0.01 level. CONCLUSIONS: Microfracture is a minimal invasive method with good short-term results in the treatment of small cartilage defects. A deterioration of the results starts 18 months after surgery and is most evident in the ICRS-score. The best prognostic factors have young patients with defects on the femoral condyles.

Adult↗
PubMed2005

Computer-assisted ankle joint arthroplasty using bio-engineered autografts.

Bio-engineered cartilage has made substantial progress over the last years. Preciously few cases, however, are known where patients were actually able to benefit from these developments. In orthopaedic surgery, there are two major obstacles between in-vitro cartilage engineering and its clinical application: successful integration of an autologuous graft into a joint and the high cost of individually manufactured implants. Computer Assisted Surgery techniques can potentially address both issues at once by simplifying the therapy, allowing pre-fabrication of bone grafts according to a shape model, individual operation planning based on CT images and providing optimal accuracy during the intervention. A pilot study was conducted for the ankle joint, comprising a simplified rotational symmetric bone surface model, a dedicated planning software and a complete cycle of treatment on one cadaveric human foot. The outcome was analysed using CT and MRI images; the post-operative CT was further segmented and registered with the implant shape to prove the feasibility of computer assisted arthroplasty using bio-engineered autografts.

Ankle Joint↗
PubMed2004

[Allogenic transplantation of human mesenchymal stem cells for tissue engineering purposes: an in vitro study].

Due to their plasticity and high proliferation capacity in vitro, human mesenchymal stem cells (MSC) are promising candidates for tissue engineering approaches of mesenchymal tissues like bone, cartilage, or tendon. Undifferentiated MSC do not express immunologically relevant cell surface markers. They inhibit the proliferation of allogeneic T-cells in vitro and elicit no immune response after allogeneic or xenogenic transplantation. Thus, MSC ought to be seen as immunoprivileged or immunomodulating cells. Here, we characterize the immune status and -behavior of MSC and MSC-derived osteogenic precursors in order to evaluate the usefulness of allogeneic MSC for tissue engineering of bone. Human MSC were isolated from bone marrow of hematologically normal voluntary donors. Osteogenic differentiation was induced by adding dexamethasone, ascorbic acid and beta-glycerophosphate. After 0, 8, 16 and 24 days, MSC were co-cultivated with allogeneic mononuclear cells. In parallel, the expression of immunologically relevant cell surface markers was monitored by flow cytometry. Undifferentiated and differentiated MSC did not stimulate allogeneic lymphocytes. MSC were negative for MHC-II, CD40, CD40L, CD80 (B7-1) and CD86 (B7-2), positive for MHC-I, and kept this expression pattern during osteogenic differentiation. Our results support the hypothesis that MSC are immunoprivileged cells which are potentially at disposal for HLA-incompatible cell replacement therapies.

Bone Regeneration↗
PubMed2003

[SCIWORA-syndrome. Case report and review of the literature].

The SCIWORA-syndrome was firstly described by Pang and Wilberger in 1982 [11]. It is characterized by a neurological injury without radiological appearance. Since the standardized use of MRI in spinal cord diagnosis, the number of the "real" SCIWORA-syndromes decreases. By the case report of a 14 years old boy falling down from a wall of 2 meters height with a complete paraplegia from Th12 without radiographic abnormality (even in MRI) we will give a short review of the literature.

Adolescent↗
PubMed2001

Reconstructed anterior cruciate ligaments using patellar tendon ligament grafts: diagnostic value of contrast-enhanced MRI in a 2-year follow-up regimen.

We analyzed prospectively the diagnostic efficacy of contrast-enhanced MRI following anterior cruciate neoligament (ACL) reconstruction. One hundred fifty-six MR examinations were performed 2, 12, 52, 76, and 104 weeks post-operatively on 68 patients with ACL transplants. Sagittal, parasagittal, and coronal images using unenhanced T1- and T2-weighted spinecho sequences, and post-contrast images utilizing T1-weighted spinecho and fat-saturated sequences, were acquired. Results were correlated with those of the pivot shift, Lachman, and a mechanical test. The MR examination criteria included morphological analysis, signal intensity, transplant contrast enhancement, secondary signs (e.g., elongation of normal ligaments), and comparison with clinically standardized test results. Two weeks post-operatively all neoligaments showed homogeneous low signal intensity on T1- and T2-weighted spinecho sequences indistinguishable from that of normal cruciate or patellar ligaments [contrast-to-noise ratio (C/N) on T1: 1.6], with a 9% percentile enhancement. At 12-52 weeks, signal intensity increased (C/N: 6.7), with a mean 50% percentile enhancement. The 1-year follow-up allowed no definite assessment of the neoligament's course. At 76 and 104 weeks, significant decrements in signal intensity (C/N: 3.0) and ligamentous percentile enhancement (25%) occurred. All patients tested displayed stable transplants 2 years post-operatively. Contrast-enhanced MRI allows accurate evaluation of morphology and function up to 3 months postoperatively and 1-2 years following ACL reconstructive surgery.

Adolescent↗
PubMed2000

[Dynamic magnetic resonance tomography (MRI): a follow-up study after femur core decompression and instillation of recombinant human bone morphogenetic protein-2 (rhBMP-2) in avascular femur head necrosis].

OBJECT: The aim of the study was to test the use of dynamic magnetic resonance imaging study with Gd-DTPA-application and the dynamic changes of signal intensity at patients with avascular femoral head necrosis after having installed rhBMP-2 and/or decompressed the core. MATERIAL AND METHODS: Six patients with avascular necrosis of the femoral head ARCO-stage I- or II-lesions were treated surgically by femoral head core decompression. Three of these patients were additionally treated with rhBMP-2-instillation. The progression or regression could be confirmed by T1- and T2-weighted spinecho-sequences (zero, four, ten, sixteen weeks and 24 months follow up). RESULTS: Corresponding ARCO-classification with partly more sensitive measurement of vitality signs in comparison to the optical x-ray classification. The objective, quantitative measurement of signal intensity post contrast medium reduces the influence of experience and level of education. The dynamic sequences results are reproducible. CONCLUSION: The dynamic magnetic resonance imaging study after Gd-DTPA-application and the dynamic changes of signal intensity after Gd-DTPA enhancement in the necrotic areas of the femoral head were the important subject of our study and it seems, that these sequencies and the ascertainment of signal intensity changes will be an efficient method for judgement of vitality, vascularisation and perfusion after therapeutical intervention. Combination of femoral head core decompression and rhBMP-2-instillation for the purpose of osseous regeneration seems to stabilize the affection.

Adult↗
PubMed1998

Pinless external fixation. Indications and preliminary results in tibial shaft fractures.

A major drawback of conventional fixator systems is the penetration of the fixator pins into the medullary canal. The pins create a direct link between the medullary cavity and the outer environment. The new AO pinless fixator bypasses this disadvantage by clamping its trocar points onto the outer cortex without penetrating it. Thus, exposure and consequent contamination of the medullary cavity does not occur. The clinical use of this easily manageable fixator with no drilling requirement is for tibial fractures in which the general and local conditions are poor or the infrastructure of the clinic is inadequate for primary internal stabilization or both. All options for a later conversion to internal fixation remain open. For highly unstable tibial shaft fractures, the pinless fixator can be applied as an additional, minimally invasive, external, locked system to increase the stability of intramedullary nail fixation. The pinless external fixator can be combined favorably with the standard AO tubular system and is a valuable addition to the existing fixator systems.

Adolescent↗
PubMed1997

Magnetic resonance imaging in the diagnosis of acute injured distal tibiofibular syndesmosis.

RATIONALE AND OBJECTIVES: This study assessed the diagnostic potential of magnetic resonance imaging for the evaluation of the tibiofibular syndesmosis. METHODS: A total of 38 patients with an acute ankle trauma and clinical suspicion of a syndesmotic tear were prospectively studied with conventional plain film radiography and magnetic resonance imaging. Magnetic resonance imaging studies included plain T1-weighted (T1-w) and T2-weighted (T2-w) sequences and contrast-enhanced T1-w sequences 0 to 3 days after trauma. All images were read by two independent radiologists before surgical intervention. Sensitivity and specificity were determined for the two observers and the concordance of the two observers were calculated using the interobserver analysis (Kappa-Test). Intraoperative inspection (n = 21) revealed rupture of the anterior tibiofibular ligament (ATIF) in 15 patients, intact ATIF in 6 patients, and intact posterior tibiofibular ligament (PTIF) in 21 cases. Clinical and follow-up examinations revealed an intact syndesmotic complex in another 17 patients. RESULTS: Primary diagnostic criteria for diagnosing a ligamentous tear included tibiofibular diastasis in conventional plain films; nonvisualization of the ATIF; an abnormal course, a wavy, irregular contour of the ligament; increased signal intensity of the ligament in T2-w sequences, in plain T1-w sequence, and marked enhancement in T1-w after contrast. Important secondary signs were defined as joint fluid in the tibiofibular space and prolapse of interspace fat. Highest diagnostic accuracy was achieved if three or more diagnostic criteria could be visualized. Both readers performed best with the enhanced T1-weighted and the T2-weighted images in transverse orientation. The interobserver analysis resulted in high concordance: Kappa = 0.9 (confidence interval: 0.76 to 1.00) for all patients, and in Kappa = 0.76 (confidence interval: 0.45 to 1.0) for surgically treated patients. CONCLUSIONS: Magnetic resonance imaging of the syndesmotic complex is a highly sensitive and specific tool for the pretherapeutic-evaluation of syndesmotic injury.

Acute Disease↗
PubMed1996

Clinical experience with two types of pelvic C-clamps for unstable pelvic ring injuries.

The emergency stabilization of unstable pelvic injuries, in particular, injuries to the posterior pelvic ring, can be achieved following reduction by application of the pelvic C-clamp. This and other procedures contribute to controlling what is almost always a life-threatening blood loss. The pelvic C-clamp is a temporary measure preceding definitive treatment of the injury. If this procedure is to have an optimal and lasting effect, the clamp must be applied correctly, provide adequate compression and stability, and be easy to handle. In one year, we applied the AO and ACE pelvic clamps in 9 clinical cases. Satisfactory primary compression and stability were achieved for unstable injuries with both clamps. It was more difficult to achieve good rotational stability as required for subsequent treatment with the ACE clamp due to its construction design.

External Fixators↗
PubMed1996

[Diagnostic value of magnetic resonance tomography of the upper ankle joint--imaging of ligaments and tendons in standard slice orientation].

PURPOSE: Evaluation of the capability of high field strength MRI in depicting clinically important tendons and ligaments of the ankle joint using slice orientations parallel to the standard space directions without angulation. MATERIALS AND METHODS: 65 patients whose ankle joint complaints were not sufficiently clarified by conventional radiology sphere underwent MRI using plain T1-weighted spin echo sequences. Tendons and ligaments were classified by three independent radiologists with regard to their perceptibility on images of the different slice orientations. RESULTS: Good perceptibility of at least two-thirds of each structure with the possibility for a decision regarding continuity or rupture of the remaining part was given most frequently in the following slice orientations: Axially for the tendons of peroneus longus, peroneus brevis, tibialis posterior, flexor digitorum longus, flexor hallucis longus, tibialis anterior, extensor digitorum longus, and extensor hallucis longus muscles, and for the calcanear tendon (each over 94% of cases), anterior (68%) talofibular ligament, deltoid (77%), anterior (63%), and posterior (72%) tibiofibular ligaments and coronally for the calcaneofibular (39%) and posterior talofibular ligaments (70%). The sagittal orientation was never the favoured one. CONCLUSIONS: All tendons and ligaments of the ankle joint, except for the calcaneofibular and anterior tibiofibular ligaments, can be sufficiently visualized in the majority of cases by non-angulated spin echo sequences in standard slice orientations if the examination is performed in at least two slice directions. Thus, the minimal examination program should be: one T2-weighted sequence, T1-weighted sequences axially and in a further orientation, i.e. slightly angulated coronally for depicting the calcaneofibular ligament.

Achilles Tendon↗
PubMed1995

[Comparison of the diagnostic value of CT and MRI in injuries of the cervical vertebrae].

The aim of our study was to compare the diagnostic capacities of computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnostic evaluation of acute cervical spinal column injuries. We examined 39 patients with cervical spine injury suspected either clinically or by plain radiography, or even confirmed. In 30 patients, 86 acute traumatic lesions were observed in the area of the cervical spine, 83% of which were retrospectively recognisable by CT and 95% on MRI films. In nine patients, no acute traumatic pathologic pattern could be found either by CT or by MRI or any other subsequently employed diagnostic methods. CT yielded 100% of the osseous acute traumatic findings, the degenerative lesions narrowing the spinal channel, and of the dislocations, but only 33% of the lesions of the longitudinal ligaments, 50% of intramedullary haemorrhages, 60% of paravertebral soft tissue haematomas, 83% of vertebral disc herniations of protrusions, and none of the six nonhaemorrhagic spinal cord contusions. Without exception, MRI revealed all the traumatic medullary and paravertebral soft tissue changes, dislocations, and spondylophytes narrowing the spinal channel, but only 50% of the C2-odonteous fractures, 89% of the transverse processes', and 92% of the vertebral lamina fractures. Basing on these results, after primary plain film radiograph imaging, the performance of MRI seems to be recommendable prior to CT in diagnostic evaluation of traumatic cervical spinal lesions, if possible with regard to the patient's clinical state and the global organization, unless immediate CT imaging of other body regions (i.e. of the head) is already being planned anyway, Nevertheless, MRI should not be abandoned within the overally framework of this disease pattern.

Adult↗
PubMed1995

[Diagnostic value and therapeutic consequences of computerized tomography (patient outcome research)--1: Diagnosis in traumatology].

During three months of 1993, 201 primary traumatologic patients (125 m, 76 f, x = 42.6 years) underwent 230 computed tomography examinations (= one CT of one body region) in the radiologic department of the Rudolf Virchow University Hospital. 87.0% of the CT's were performed completely without contrast media, 2.6% exclusively supported by intravenously given contrast media, 9.1% in both ways, and 1.3% after intra-articular contrast media administration. 97.4% served for primary diagnostic purposes and 2.6% for the control of therapeutic results. In 47.8% of the CT's, the principle diagnosis in the scanned body region was known before CT, i.e. by conventional X-ray examinations, but further detailed information was necessary to clarify the indication for operation and to choose the operative mode. In 52.2%, the diagnosis without CT was impossible by other, non-invasive and not more expensive methods. The CT diagnoses were correctly positive in 58.7% (suspected diagnosis verified, additional detail information...) and correctly negative in 41.3% (suspected diagnosis excluded). 60.9% of CT's demonstrated a missing indication for operation in the examined body region; in 39.1% the operation followed. The most frequently performed diagnostic methods before CT were conventional X-ray and sonography, whereas after CT further examinations were seldom needed. We conclude that traumatologic CT's contribute decisively to the reduction of costs by avoiding more expensive examination methods, avoiding redundant operations, and abridging stay duration in the hospital because of more efficient therapy planning.

Abscess↗
PubMed1995

The new unreamed AO nails for the tibia and the femur.

The advantages of the unreamed nailing technique compared to the reamed procedure are less damage to bone vascularity, lower intramedullary pressure during the operation and a fast operation time. These new solid nails with high mechanical stiffness and no central dead space have extended the nail indications for tibial as well as for femoral fractures, particularly in tibial shaft fractures with severe soft tissue damage and in polytraumatized patients with a femoral shaft fracture. Besides these advantages the new AO unreamed femur nail has a modular proximal interlocking system, which increases significantly the range of indications for nailing. Not only very high subtrochanteric femur fractures can be stabilized with greater stability, but also combined ipsilateral fractures of the shaft and the proximal femur can be treated with this new nail. The first clinical results of the AO unreamed nails for the tibia as well as for the femur are very encouraging. The unreamed nails prove to be excellent implants in the treatment of long bone fractures of the lower extremity.

Adult↗
PubMed1994

Routine application of the pinless external fixator.

One serious disadvantage of conventional fixator systems is the need to open the medullary space, hence creating a direct communication with the exterior. The new pinless external fixator does not have this major disadvantage, because the fixator clamps simply rest on the cortical bone without penetrating it. Clinically, this easily managed system is intended for fractures of the tibia in cases in which primary internal fixation is precluded either by precarious local or general conditions or by infrastructural problems. In such situations the new pinless fixator is an excellent device with which to achieve good stabilization of the fracture rapidly, while leaving open all options for subsequent alteration of treatment. If the surgeon decides to convert to locked intramedullary nailing, the pinless fixator facilitates the new approach, because it can be used as a distractor and makes it unnecessary to transfer the patient to a fracture table.

Adult↗