Biomedical subjects

R Marmulla

Publications and source records attributed to R Marmulla.

23 records · Page 2Linked to original sources

PubMed1998

Computer-assisted bone segment navigation.

Computer-assisted bone segment navigation is defined as the precise 3-D positioning of geometrically mapped and mathematically described skeletal segments. These bone segments are osteotomized, fractured or prefabricated according to a surgical plan. The high-precision positioning should have an accuracy of 1 mm or better. Segment navigation should be prepared with plain computed tomography (CT) without the implantation of registration markers before CT in order to reduce the number of CTs and operations. The Surgical Segment Navigator (SSN) was developed at the University of Regensburg with the support of Carl Zeiss. This is the first system to meet these criteria. The SSN is based on an infrared positioning device which is connected to a Hewlett Packard LD Pro Workstation. Infrared transmitters are connected to individual templates which are fixed to the bone segment by osteosynthesis screws. Intraoperative correlation between surgical planning and surgical site is achieved by use of a surface-pattern of the bone segment which fits equally well to the laboratory model and the conditions encountered in the patient. The concept of the SSN was submitted by Carl Zeiss as German Patent DE 19747427 A1 in 1997. The SSN system presented here has already been applied clinically and its precision has been evaluated by bone segment navigation in human cadavers.

Bone and Bones↗

PubMed1998

[A new computer-aided surgical approach for reconstruction of the orbit].

BACKGROUND: Complex posttraumatic malpositions of the orbital walls require repositioning osteotomy. Computer tomography, stereolithography models and tele-X-rays are used in planning. However, the precision achieved in the planning phase could not so far be translated to patients (1). The Surgical Segment Navigator SSN is the first highly precise computer-assisted system to transfer laboratory planning data concerning the repositioning osteotomy of orbital walls to a surgical site. MATERIALS AND METHODS: The SSN is based on infrared technology such as the Surgical Tool Navigator STN and the Surgical Microscope Navigator SMN manufactured by Carl Zeiss. Laboratory planning data are transferred to the surgical site by measurements with infrared transmitters which are checked by an infrared camera. RESULTS: A surgical planning can be carried out exactly using the Surgical Segment Navigator. Moreover, the SSN displays hidden levels of an extensive bone segment which are not visible via a bicoronary approach (e.g. orbital floor and facial wall of the maxillary sinus) clearly on monitor and helps to navigate the complete segment. CONCLUSIONS: The Surgical Segment Navigator is the first computer-assisted system for highly precise repositioning osteotomy of the orbital walls.

Female↗

PubMed1998

[Precision control of the position of the bone segments during surgical navigation].

The Surgical Segment Navigator (SSN) which has been developed together with Carl Zeiss at the department for craniomaxillofacial surgery at the University of Regensburg, is the first system for highly precise positioning of bone segments. Before clinical application, the precision of the SSN was evaluated by navigation of cadaver bone segments which is presented in this paper. The SSN tracks intraoperatively bone segments and displays the osteotomied segments on a monitor of the SSN-workstation. All movements are documented and saved within a computer file. Thus, the SSN makes the quality assurance of intraoperative positioning of bone segments possible.

Cadaver↗

PubMed1997

Inherent precision of mechanical, infrared and laser-guided navigation systems for computer-assisted surgery.

This investigation detects the inherent precision of four navigation systems, of different structural type, for computer-assisted surgery, ranging from 0.1 to 1.8 mm: the Viewing Wand with a mechanical arm, and three new systems, the SMN microscope and STP pointer with infrared technology and the MKM system with laser autofocus. For this purpose, a new standard to detect separately the inherent deviations of navigation systems from the deviations caused by acquisition of CT data sets, is introduced. The measurements are performed within a complete three-dimensional room, consisting of three orthogonal planes of a geometric model. The method introduced is valid for regular measurements of the inherent precision of navigation systems for quality assurance in order to prevent intraoperative failure caused by insufficient potentiometers, infrared transmitters or receivers.

Computer Systems↗

PubMed1997

[Precision of computer-assisted systems in profile reconstructive interventions on the face].

In this investigation we compared the precision of different computer-aided systems for positioning osteotomized segments to reconstruct craniofacial asymmetries. The accuracy of a mechanical navigation system, a laser-guided navigation system and the precision of templates moulded on stereolithographic models are compared, using measurements on geometrical objects, anatomical specimens and clinical application. The precision of a mechanical navigation system is 0.5 mm, and a laser-guided system 0.3 mm. The accuracy of a computer and template guided application is 1 mm.

Data Collection↗