Multifunctional surgical tools and implants

Medical Device Projects

Novel Dental Implants

Design, fabrication and testing of a novel surgical tool and dental implant in collaboration with Boston University Dental School.

Dental implants smaller than a penny.
© Photo Fraunhofer CMI

Dental implants smaller than a penny.

Dental surgeons from Boston University are testing new tool at Fraunhofer CMI laboratories.

Dental surgeons from Boston University are testing new tool at Fraunhofer CMI laboratories.

Fraunhofer CMI engineers and Boston University surgeons collaborating.
© Photo Fraunhofer CMI

Fraunhofer CMI engineers and Boston University surgeons collaborating.

Objective

Novel Dental Implants: Tooth loss leads to local resorption of the jaw bone. The longer the tooth is missing, the more bone is lost. When using dental implants, bone augmentation with cadaver bone is the most common solution to enlarge the jawbone at the desired implant site. More than 50% of patients require bone augmentation before or during dental implant placement.

The PiezoImplant system, jointly developed by the Fraunhofer CMI and the Boston University Dental School, is based on the concept that the implant should match the shape of the available bone, thus eliminating the need for bone augmentation.

Methodology

A piezotome is a miniature bone saw vibrating at ultrasonic frequencies and sub-millimeter amplitudes. The piezotome is capable of creating various shapes of non-round cuts, thus for narrow bone ridges bone cuts can be made and flat implants may be precisely fitted. The non-round nature of the newly developed implants allows for a stronger implant to be placed into the narrow ridge of the recessed jaw bone.

During the design of the piezotomes, CMI employed advanced finite element and modal analysis tools to match the natural frequency of the piezotome tool to that of the instrument. A number of successive tools were developed to facilitate the step-by-step shaping of the implant site, beginning with a traditional round drill, continuing with a course roughing tool and finishing with a fine finishing tool.

Results

Prototypes for both implants and piezotomes have been fabricated and tested. The PiezoImplants were examined with respect to fatigue and stress distribution during and after placement. In vivo testing is currently in progress to assess the integration and functionality of the PiezoImplant. This is accomplished by placing PiezoImplants in the mouth of mini pigs and monitoring the success of the implant.

Collaborators

Serge Dibart, Boston University Dental School

Development of Endoscopic Fiber Optic Forceps

In this project, Fraunhofer CMI and their collaborators at BU worked to design a revolutionary tool for early cancer diagnosis. Researchers at Fraunhofer CMI have developed biopsy forceps for use in endoscopes and similar medical instruments with working channels. The unique feature of this device is the co-axial working channel within the forceps, which provides the ability to carry optical fibers for different diagnostic tools directly to the sample site. This allows for concurrent optical detection and surgical biopsy, providing real-time guidance for selective biopsy and potentially improving the chances of early cancer detection.

Close up of forceps jaws.
© Photo Fraunhofer CMI

Close up of forceps jaws.

Endoscopic Fiber Optic Forceps.
© Photo Fraunhofer CMI

Endoscopic Fiber Optic Forceps.

Objective

In the field of gastroenterology, the bulk of endoscopic procedures have shifted away from interventions for symptomatic disease and toward asymptomatic cancer prevention. This shift has been accompanied by a drive towards minimally invasive in situ diagnostic and therapeutic technologies. To this end, new multifunction tools are needed that integrate such technologies with minimally invasive procedures. Together with their collaborators, Fraunhofer CMI sought to design a tool that enhances the targeting of biopsies for the detection of dysplasia with the goal of significantly reducing the number of unnecessary biopsies (increased specificity), while, nonetheless, increasing the yield (sensitivity). 

Design

With our primary application in mind, we set out to design an endoscopic forceps for use in the 2.4-mm diameter working channels of most endoscopes that would incorporate its own coaxial working channel. Our principal application requires a minimum 0.4-mm diameter channel. Because it is a contact probe, the tip of the working channel must extend into the space between the jaws of the forceps. Yet, in order for the forceps to function properly, and tissue samples to be collected, the probe must retract before the jaws close to make room for the sample.

Most endoscopic forceps have a scissor-like design, with a pin that both jaws pivot about. To make room in the design for the inner working channel, we essentially moved the pivot to the edges of the forceps. In addition to clearing space for a central working channel, relocating the hinge to the edge of the forceps increases the force the jaws can generate at closure with respect to the scissor-style design. This improves its ability to successfully sample tissue, and allows for low cost material choices.

Results

The jaws of our forceps are attached to the main body by a thin (0.050-mm) stainless steel strip that acts as a flexible hinge. The jaw and ferrule assembly is affixed to the end of a guide tube, the other end of which is joined to the forceps handle. The guide tube is flexible enough to follow bends in the endoscope’s working channel, yet stiff enough to resist buckling during operation. Because it is built of few parts, low cost assembly during manufacture is possible. 

Prototypes were assembled for animal studies. Initial clinical testing of prototype units has revealed that adequate mucosal biopsies can be obtained successfully. This novel tool is not only useful during diagnosis, but could also function during surgical interventions to properly guide ablation of dysplastic tissue once it has been detected.

Academic Collaborators

Satish K. Singh, Gastroenterology, Boston University School of Medicine, Boston, MA

Irving J. Bigio, Biomedical Engineering, Boston University, Boston, MA

Acknowledgement

This project was funded by the Boston University-Fraunhofer Alliance for Medical Devices, Instrumentation and Diagnostics.

Integrated Device for in vivo Fine Needle Aspiration Biopsy and Elastic Scattering Spectroscopy in Preoperative Thyroid Nodules

Fraunhofer CMI and their research collaborators designed and fabricated a prototype probe of a medical device for initial clinical studies.

Fine needle aspiration tool.
© Photo Fraunhofer CMI

Fine needle aspiration tool.

Introduction

Thyroid nodules are a frequent clinical finding and the most common endocrine malignancy is thyroid cancer. The standard of care in the management of a patient with a thyroid nodule is to perform a preoperative fine needle aspiration (FNA) biopsy of the suspect nodule under ultrasound imaging guidance. In a significant percentage of the cases, cytological assessment of the biopsy material yields indeterminate results, the consequence of which is diagnostic thyroidectomy. Unfortunately, 75–80% of diagnostic thyroidectomies following indeterminate cytology result in benign designation by postsurgery histopathology, indicating potentially unnecessary surgeries. Clearly, the potential exists for the improvement in patient care and the reduction of overall procedure costs if an improved preoperative diagnostic technique was developed.  

Elastic scattering spectroscopy (ESS) is an optical biopsy technique that is mediated by optical fiber probes and has been shown to be effective in differentiating benign from malignant thyroid tissue in ex vivo surgical tissue samples. The goal of the current research was to integrate the ESS fiber optic probes into a device that can also collect cells for cytological assessment and, thus, enable concurrent spectroscopic interrogation and biopsy of a suspect nodule with a single needle penetration. The primary challenges to designing the device included miniaturizing the standard ESS fiber optic probe to fit within an FNA needle and maintaining the needle’s aspiration functionality. 

Results

Fraunhofer CMI and their collaborators demonstrate the value of the fabricated prototype devices by assessing their preliminary performance in a clinical study with >120 patients. The devices have proven to be clinically friendly, collecting both aspirated cells and optical data from the same location in thyroid nodules and with minimal disruption of clinical procedure. In the future, such integrated devices could be used to complement FNA-based cytological results and have the potential to both reduce the number of diagnostic thyroidectomies on benign nodules and improve the surgical approach for patients with thyroid malignancies, thereby, decreasing healthcare costs and improving patient outcomes. 

Publication

Briggs J, A'amar O, Bigio IJ, Rosen J, Lee ST, Sharon A, Sauer-Budge AF. Integrated Device for in vivo Fine Needle Aspiration Biopsy and Elastic Scattering Spectroscopy in Pre-Operative Thyroid Nodules. Journal of Medical Devices. 2014;8(June):021003.

Academic Collaborators

Irving Bigio, PhD, Department of Biomedical Engineering, Boston University

Jennifer Rosen, MD, Department of Surgery, Medstar Washington Hospital Center.

Stephanie Lee, MD, Department of Medicine, Section of Endocrinology, Diabetes, and Nutrition, School of Medicine, Boston University

Funding

This project was funded in part by the BU – Fraunhofer Alliance for Medical Devices, Instrumentation, and Diagnostics.