Meiko Müller

Modular design of a miniaturized surgical robot system.

Abstract Currently, there are only a small number of robotic systems used in various surgical fields. As modified industrial robot systems have shown significant limitations in the past, specialized kinematic solutions have been proposed for specific surgical applications. The majority of these systems are designed for specific applications in only a limited number of cases. The acquisition and operating costs are high, hindering the dissemination and broad clinical application of such systems. To address this problem, a modular mini-robot system is proposed, which can be easily adapted to different application-specific requirements. Therefore, the requirements of different applications have been categorized and clustered to a standardized requirement profile. Next, a modular robot based on a hybrid kinematic module structure has been developed. This concept has been implemented and tested in in vitro studies for different applications, such as revision total hip replacement and unicondylar knee arthroplasty. User-orientated tests of the intraoperative handling, as well as accuracy tests, proved the feasibility of the concept.

Smart bioimpedance-controlled craniotomy: Concept and first experiments

Craniotomy is part of many neurosurgical interventions to create surgical access to intracranial structures. The procedure conventionally bears a high risk of unintended dural tears or damage of the soft tissue underneath the bone. A new synergistically controlled instrument has recently been introduced to address this problem by combining a soft tissue preserving saw with an automatic cutting depth control. Many approaches are known to obtain the information required on the local bone thickness. However, they suffer from unsatisfactory robustness against disturbances occurring during surgery and many approaches require additional intra- or preoperative steps in the workflow. This article presents first concepts for real-time cutting depth control based on in-process bioimpedance measurements. Furthermore, sensor integration into a synergistic surgical device incorporating a bidirectional oscillating saw is demonstrated and evaluated in first feasibility tests on a fresh bovine bone specimen. Results of bipolar measurements show that the transition of different layers of bicortical bone and bone breakthrough lead to characteristic impedance patterns that can be used for process control.

Analyse der Regelungsstrategien eines Osteotomie-Instruments auf Basis multimodaler Informationen / Analysis of the Control Strategies of an Instrument for Osteotomy on the Basis of Multimodal Information

Zusammenfassung Um den Chirurgen bei der Eröffnung des Schädels in der Neurochirurgie oder des Brustbeins in der Herz- und Thoraxchirurgie zu unterstützen, wurde ein semiautomatisches, handgeführtes Sägeinstrument entwickelt. Die Schnitttiefe wird auf Basis von drei unterschiedlichen Messverfahren (Computertomographie, Ultraschall, Licht) automatisch geregelt. Nach erfolgreichen Machbarkeitsstudien zu den einzelnen Ansätzen wird in diesem Beitrag darauf aufbauend ein detaillierter Vergleich der Verfahren mit einer Untersuchung der strukturellen Vor- und Nachteile sowie Optimierungspotentiale durchgeführt. Summary To support the surgeon during opening of the skull in neurosurgery or of the sternum in cardiothoracic surgery, a semiautomatic, hand guided saw was developed. The cutting depth is automatically controlled on the basis of three different modalities (computed tomography, ultrasound, light). In addition to the general successful proof of general feasibility, the present paper provides the results of a detailed comparison of the different systems in combination with an analysis of the structural advantages and disadvantages and their individual optimization potential.

Evaluation of a new computer-assisted surgical planning and navigation system based on two-dimensional fluoroscopy for insertion of a proximal femoral nail: an experimental study.

Pertrochanteric femoral fractures are common and intramedullary nailing is an accepted method for their surgical treatment. Accurate placement of the implant is essential to ensure fixation. The conventional technique can require multiple guide wire passes, and relies heavily on fluoroscopy. A computer-assisted planning and navigation system based on two-dimensional fluoroscopy for guide wire placement in the femoral neck has been developed, in order to perform intramedullary pertrochanteric fracture fixation using the proximal femoral nail (PFNA®). The planning process was supported by a ‘zero-dose C-arm navigation’ system. The PFNA was inserted into 12, intact, femoral sawbones guided by the computer-based navigation, and into 12, intact, femoral sawbones using a conventional fluoroscopic-assisted technique. Guide wire and subsequent blade placement in the femoral neck was evaluated. The computer-assisted technique achieved a significant decrease in the number of required fluoroscopic images and in the number of guide wire passes. The obtained average blade placement accuracy in the femoral neck was equivalent to the conventional technique. The operation time was significantly longer in the navigation-assisted group. The addition of computer-assisted planning and surgical guidance to the intramedullary nailing of pertrochanteric femoral fractures offers a number of clinical benefits based on the results of this sawbone study. Further studies including fractured sawbones and cadaver models with extension of the navigation process to all steps of PFNA introduction and with the goal of reducing operation time are indispensable before integration of this navigation system into clinical practice.