[Precise sacroiliac joint screw insertion without computed tomography, digital volume tomography or navigation systems]. / Sichere Verschraubung des Iliosakralgelenks ohne intraoperative Computertomographie, digitale Volumentomographie oder Navigationssystem.

OBJECTIVE: Improvement of sacroiliac positioning of screws by detailed preoperative planning with a DICOM (Digital Imaging and Communications in Medicine-the international standard to store and process medical imaging information) workstation in the absence of advanced technical facilities like intraoperative computer tomography (CT), digital volume tomography (DVT) or a navigation system. INDICATIONS: Mono- or bilateral non- or minor displaced, longitudinal sacral fractures type Denis I and II and pelvic ring fractures (Orthopedic Trauma Association) OTA type B possibly in combination with a ventral procedure. CONTRAINDICATIONS: Displaced sacral fractures type Denis II and III, fractures with central comminution and circulatory unstable patients to be stabilized in the context of emergency care. SURGICAL TECHNIQUE: Preoperative calculation of virtual conventional standard view X­rays with the CT dataset using common DICOM software (e.g., Siemens via® or Sectra®). Typical landmarks such as screw entry point and end point are projected into the virtual X­rays. Intraoperative navigation is performed by comparing the virtual standard views with fluoroscopic images of the C­arm, thereby, simplifying the operative procedure. POSTOPERATIVE MANAGEMENT: Postoperative CT scan, pain adapted partial weight bearing and X­rays of the pelvic ring after 6 and 12 weeks. RESULTS: Over a 13 month period, an orthopedic surgeon inserted 26 sacroiliac screws in 19 patients utilizing the described method. Postoperative CT scans revealed that all except three screws were precisely positioned without any bone perforation. Of these three screws one had a grade one perforation and two had a grade two perforation according to Smith. No revision was necessary and no neurological deficits were detected. The operating time was on average 33 min and duration of radiation 3.8 min.

Desmoplastic fibroma of the mandible in young children-a case series.

Desmoplastic fibromas are rare, benign, but aggressive lesions, affecting predominantly young people, with an affinity for the mandible. Four patients with desmoplastic fibromas of the mandible, seen between 1995 and 2015 with long-term follow-up, were identified. Three were treated by wide mandibular resection and immediate reconstruction with rib grafts, and one was treated with chemotherapy. In the three resected cases, there has been no recurrence and all rib grafts were successfully incorporated. The case treated by chemotherapy has persistence of the tumour, but it is not progressing. Desmoplastic fibromas in young children respond well to wide mandibular resection and immediate reconstruction with rib grafts. Chemotherapy may halt progression.

Grouping in pitch perception: evidence for sequential constraints.

Evidence is presented that sequential auditory grouping constraints apply to the perception of pitch. Experiment 1 shows that the pitch changes produced by mistuning the fourth harmonic of a 90-ms 12-harmonic 155-Hz fundamental complex tone are substantially reduced when the complex is preceded by four 90-ms tones at the same frequency as the mistuned component. Both the pitch changes and their reduction by the tonal sequence precursor remain when the mistuned component and the precursor are presented contralateral to the remaining components. Experiment 2 shows that reducing the level of the same mistuned component reduces the size of the pitch change, but only if the mistuned component is presented ipsilaterally. To the extent that adaptation can be equated with a physical reduction in level, this result provides further evidence against peripheral adaptation playing a significant role in the auditory grouping of harmonics in pitch perception.