Observation of Gravitationally Induced Vertical Striation of Polarized Ultracold Neutrons by Spin-Echo Spectroscopy.

We describe a spin-echo method for ultracold neutrons (UCNs) confined in a precession chamber and exposed to a |B0|=1 µT magnetic field. We have demonstrated that the analysis of UCN spin-echo resonance signals in combination with knowledge of the ambient magnetic field provides an excellent method by which to reconstruct the energy spectrum of a confined ensemble of neutrons. The method takes advantage of the relative dephasing of spins arising from a gravitationally induced striation of stored UCNs of different energies, and also permits an improved determination of the vertical magnetic-field gradient with an exceptional accuracy of 1.1 pT/cm. This novel combination of a well-known nuclear resonance method and gravitationally induced vertical striation is unique in the realm of nuclear and particle physics and should prove to be invaluable for the assessment of systematic effects in precision experiments such as searches for an electric dipole moment of the neutron or the measurement of the neutron lifetime.

Hidden discoligamentous instability in cervical spine injuries: can quantitative motion analysis improve detection?

PURPOSE: Recent literature shows that occult discoligamentous injuries still remain difficult to diagnose in the first instance. Thresholds as indicators for discoligamentous segmental instability were previously defined. But, since supine radiodiagnostic is prone to spontaneous reduction of a displaced injury, and even some highly unstable injuries reveal only slight radiographic displacement, these criteria might mislead in the traumatized patient. A highly accurate radiographic instrument to assess segmental motion is the computer-assisted quantitative motion analysis (QMA). The aim was to evaluate the applicability of the QMA in the setting of a traumatized patient. METHODS: Review of 154 patients with unstable cervical injuries C3-7. Seventeen patients (male/female: 1:5, age: 44.6 years) had history of initially hidden discoligamentous injuries without signs of neurologic impairment. Initial radiographs did not fulfill instability criteria by conventional analysis. Instability was identified by late subluxation/dislocation, persisting/increasing neck pain, and/or scheduled follow-up. For 16 patients plain lateral radiographs were subjected to QMA. QMA data derived were compared with normative data of 140 asymptomatic volunteers from an institutional database. RESULTS: Data analysis of measurements revealed mean spondylolisthesis of -1.0 mm (-3.7 to +3.4 mm), for segmental rotational angle mean angulation of -0.9° (-11.1° to +17.7°). Analysis of these figures indicated positive instability thresholds in 5 patients (31.3 %). Analysis of center of rotation (COR)-shifts was only accomplishable completely in 3/16 patients due to limited motion or inadequacy of radiographs. Two of these patients (12.5 %) showed a suspect shift of the COR. CONCLUSIONS: Our data show a high rate of false negative results in cases of hidden discoligamentous injuries by using conventional radiographic analysis as well as QMA in plain lateral radiographs in a trauma setting. Despite the technical possibilities in a modern trauma center, our data and recent literature indicate a thorough clinical and radiographic follow-up of patients with cervical symptoms to avoid secondary complications from missed cervical spine injuries.

Reinforcement of lumbosacral instrumentation using S1-pedicle screws combined with S2-alar screws.

OBJECTIVE: Increasing construct stability of lumbosacral instrumentations using S2-ala screws as an alternate to iliac screws. INDICATIONS: Revision surgery after failed lumbosacral fusion; long instrumentations to the sacrum; L5-S1 fusion without anterior support. CONTRAINDICATIONS: Lack of sacral bone stock. SURGICAL TECHNIQUE: Midline approach. The entry point for S2-ala screws is caudal to the posterior S1 foramen and close to the lateral sacral crest. Screw tract preparation for S2-ala screws necessitates 30-45° angulation in the axial plane. Biplanar fluoroscopy with inlet and outlet views ensure screw accuracy. With S2-ala screws, bicortical fixation is the goal. POSTOPERATIVE MANAGEMENT: Patients are mobilized under the surveillance of physiotherapists on day 1 and released from the hospital after 10 days. Clinical and radiographic controls are performed at 6, 12 and 24 months. RESULTS: Retrospective review of 80 patients undergoing S2-ala screw fixation. Main diagnosis was degenerative lumbar instability, adult scoliosis, high-grade listhesis, and nonidiopathic scoliosis. In 66% of patients, the instrumentation using S2-ala screws was part of a major lumbosacral revision surgery. Follow-up averaged 26 months. There were no deaths or major neurovascular complications. First time fusion rate at L5-S1 was greater than 90%. Eight patients (10%) experienced a complication which could be related to the S2-ala screws. Out of 160 S2-ala screws, 16 screws were judged to cause focal irritation and were removed, indicating a survival rate of 90% for the S2-ala screw.

[Restoration of sagittal balance in treatment of thoracic and lumbar vertebral fractures]. / Wiederherstellung der sagittalen Balance bei der Versorgung thorakaler und lumbaler Wirbelkörperfrakturen.

Posttraumatic kyphosis (PTK) is a possible consequence of a missed fracture, a wrong indication for conservative therapy or an inadequate surgical technique but PTK can also be a complication after adequate surgery. Avoidance of PTK is of importance because subsequent surgical therapy can be extensive. A thorough planning as well as surgical experience with anterior and posterior revision cases is necessary. The various types of osteotomy which allow correction of local as well as global deformities should also be mastered. Knowledge of the principles of sagittal balance and spinopelvic parameters are indispensable in the treatment of PTK. Our experience and results from the literature show that a good long-term outcome with limited complications can only be achieved when considering the biomechanical principles as well as restoration of sagittal balance.

[Relevance of surgical outpatient clinics in academic university centers to health care in Germany]. / Stellenwert einer allgemeinen chirurgischen Hochschulambulanz für die medizinische Patientenversorgung Eine ergänzende Erhebung zur "Deutschen Hochschulambulanzenstudie".

During the observation period between 2001 and 2003, all outpatient surgical therapy, including degrees of urgency, surgical care volume, regional provenance of patients, diagnoses, and referral channels were prospectively analysed at the Surgical Department of the University of Heidelberg, Germany. The data gathered do not merely describe the volume and characteristics of care encountered at this academic surgical institution but also provide further insight into the variability of resource utilisation and associated patient flow. Additionally, a retrospective evaluation using structured interviews and questionnaires was performed to differentiate and quantify patient care, teaching, and research activities. This study illustrates the high relevance of academic outpatient institutions to regional provision of general surgical care in Germany. There is a clear dominance of medical support functions, while research and teaching activities are of only minor relevance and realised particularly in subspecialty clinics. These data should give important stimuli for the future planning of health care in Germany. Outpatient clinics for general surgery appear to be an excellent basis for regional models of integrated health care delivery in the future.