Electrochemical methods to enhance osseointegrated prostheses Abstract Osseointegrated (OI) prosthetic limbs have been shown to provide an advantageous treatment option for amputees. In order for the OI prosthesis to be successful, the titanium implant must rapidly achieve and maintain proper integration with the bone tissue and remain free of infection. Electrochemical methods can be utilized to control and/or monitor the interfacial microenvironment where the titanium implant interacts with the biological system (host bone tissue or bacteria). This review will summarize the current understanding of how electrochemical modalities can influence bone tissue and bacteria with specific emphasis on applications where the metallic prosthesis itself can be utilized directly as a stimulating electrode for enhanced osseointegration and infection control. In addition, a summary of electrochemical impedance sensing techniques that could be used to potentially assess osseointegration and infection status of the metallic prosthesis is presented.

Porous electrospun poly(ε-caprolactone)/gelatin nanofibrous mat containing cinnamon for wound healing application: in vitro and in vivo study Abstract In this study, cinnamon (cin) was loaded into poly(ε-caprolactone)/gelatin (PCL/Gel) nanofibrous matrices in order to fabricate an appropriate mat to improve wound healing. Mats were fabricated from PCL/COLL [1:1 (w/w)] solution with 1, 5 and 25% (w/v) of cinnamon. Prepared mats were characterized with regard to their microstructure, mechanical properties, porosity, surface wettability, water-uptake capacity, water vapor permeability, blood compatibility, microbial penetration and cellular response. The fabricated mats with and without cinnamon were used to treat the full-thickness excisional wounds in Wistar rats. The results indicated that the amount of cinnamon had a direct effect on porosity, mechanical properties, water uptake capacity, water contact angle, water vapor transmission rate and cell proliferation. In addition, the results of in vivo study indicated that after 14 days, the wounds which were treated with PCL/Gel 5%cin had better wound closure (98%) among other groups. Our results suggest that the cinnamon can be used as a suitable material for wound healing.

Quantitative assessment of compress-type osseointegrated prosthetic implants in human bone using electromechanical impedance spectroscopic methods Abstract Osseointegrated (OI) prostheses are a promising alternative to traditional socket prostheses. They can enhance the quality of life of amputees by avoiding fit and comfort issues commonly associated with sockets. The main structural element of the OI prosthesis is a biocompatible metallic implant that is surgically implanted into the bone of the residual limb. The implant is designed to provide a conducive surface for the host bone to osseointegrate with. The osseointegration process of the implant is difficult to clinically evaluate, leading to conservative postoperative rehabilitation approaches. Elastic stress waves generated in an OI prosthesis have been previously proposed to interrogate the implant-bone interface for quantitative assessment of the osseointegration process. This paper provides a detailed overview of the various elastic stress wave methods previously explored for in situ characterization of OI implants. Specifically, the paper explores the use of electromechanical impedance spectroscopy (EIS) to assess the OI process in compress-type OI prostheses. The EIS approach measures the electrical impedance spectrum of lead zirconate titanate elements bonded to the free end of the implant. The research utilizes both numerical simulation and experimental verification to establish that the electromechanical impedance spectrum is sensitive (between 400 and 460 kHz) to both the degree and location of osseointegration. A baseline-free OI index is proposed to quantify the degree of osseointegration at the implant-bone interface and to assess the stability of the OI implant for clinical decision making.

Sensing and actuation technologies for smart socket prostheses Abstract The socket is the most critical part of every lower-limb prosthetic system, since it serves as the interfacial component that connects the residual limb with the artificial system. However, many amputees abandon their socket prostheses due to the high-level of discomfort caused by the poor interaction between the socket and residual limb. In general, socket prosthesis performance is determined by three main factors, namely, residual limb-socket interfacial stress, volume fluctuation of the residual limb, and temperature. This review paper summarizes the various sensing and actuation solutions that have been proposed for improving socket performance and for realizing next-generation socket prostheses. The working principles of different sensors and how they have been tested or used for monitoring the socket interface are discussed. Furthermore, various actuation methods that have been proposed for actively modifying and improving the socket interface are also reviewed. Through the continued development and integration of these sensing and actuation technologies, the long-term vision is to realize smart socket prostheses. Such smart socket systems will not only function as a socket prosthesis but will also be able to sense parameters that cause amputee discomfort and self-adjust to optimize its fit, function, and performance.

The state of the art of osseointegration for limb prosthesis Abstract Osseointegration (OI) is the direct attachment of bone onto a titanium implant. Recently, the term is used to describe “transdermal” implants that allow an external prosthesis to be connected directly to the skeleton. This technology eliminates the challenges of conventional socket-based prostheses, such as skin breakdown and poor fit, which are common in patients with major extremity amputations. Osseointegration patients demonstrate encouraging improvements in quality of life and function. Patients report improvement in prosthetic use, prosthetic mobility, global health, and pain reduction on a variety of clinical assessment tools. Various implants have been developed for osseointegration for amputees. These implants use a variety of fixation strategies and surface augments to allow for successful integration into the host bone. Regardless of design, all OI implants face similar challenges, particularly infections. Other challenges include the inability to determine when integration has occurred and the inability to detect loss of integration. These challenges may be met by incorporating sensing systems into the implants. The percutaneous nature of the metal devices can be leveraged so that internal sensors need not be wireless, and can be interrogated by external monitoring systems, thus providing crucial, real-time information about the state of the implant. The purpose of this review is to (1) review the basic science behind osseointegration, (2) provide an overview of current implants, practice patterns, and clinical outcomes, and (3) preview sensor technologies which may prove useful in future generations of transdermal orthopaedic implants.

Electrochemical skin conductance is sensitive and has clinical utility in patients with untreated or poorly controlled diabetes

Shape memory alloy actuation of non-bonded piezo sensor configuration for bone diagnosis and impedance based analysis Abstract In the recent years, there has been a growing interest in research community towards the application of smart materials for bio-medical structural health monitoring. Amongst the smart materials, directly bonded piezo sensors (DBPS), based on the electro-mechanical impedance (EMI) technique, have been successfully employed for the above purpose. The principle behind the EMI technique is that high frequency excitations (typically > 30 kHz) generated by a surface bonded PZT patch are used to detect changes in structural drive point impedance caused by cracks or any other type of damage. Bone healing and damage have been shown to be successfully monitored using the DBPS. However, in most of the diagnostic cases of live human and animal subjects, directly bonding a PZT patch is always an irritant or hazard for a live subject. To circumvent direct bonding, the authors have developed and experimentally demonstrated a non-bonded piezo sensor (NBPS) configuration as a good alternative to DBPS while maintaining the effectiveness of measurement well within discernible limits. This paper presents further improvement in the NBPS configuration aiming at autonomous operation of the gripping mechanism using shape memory alloy (SMA) wires. The experiments are performed on replicas of femur bone in healthy and osteoporosis state. This paper shows the effective use of SMA clamping for bone identification and its damage assessment in comparison to earlier mechanical gripping using jubilee clamps. This paper also covers impedance based identification applied to SMA and clamp based NBPS configurations. In place of raw admittance signatures, effective drive point impedance is utilized for the purpose of bone diagnostics which provides a more realistic assessment of the condition of bone.

A compact-sized surface EMG sensor for myoelectric hand prosthesis Abstract Myoelectric prosthesis requires a sensor that can reliably capture surface electromyography (sEMG) signal from amputees for its controlled operation. The main problems with the presently available EMG devices are their extremely high cost, large response time, noise susceptibility, less amplitude sensitivity, and larger size. This paper proposes a compact and affordable EMG sensor for the prosthetic application. The sensor consists of an electrode interface, signal conditioning unit, and power supply unit all encased in a single package. The performance of dry electrodes employed in the skin interface was compared with the conventional Ag/AgCl electrodes, and the results were found satisfactory. The envelope detection technique in the sensor based on the tuned RC parameters enables the generation of smooth, faster, and repeatable EMG envelope irrespective of signal strength and subject variability. The output performance of the developed sensor was compared with commercial EMG sensor regarding signal-to-noise ratio, sensitivity, and response time. To perform this, EMG data with both devices were recorded for 10 subjects (3 amputees and 7 healthy subjects). The results showed 1.4 times greater SNR values and 45% higher sensitivity of the developed sensor than the commercial EMG sensor. Also, the proposed sensor was 57% faster than the commercial sensor in producing the output response. The sEMG sensor was further tested on amputees to control the operation of a self-designed 3D printed prosthetic hand. With proportional control scheme, the myoelectric hand setup was able to provide quicker and delicate grasping of objects as per the strength of the EMG signal.

A novel pectoral muscle segmentation from scanned mammograms using EMO algorithm Abstract Mammogram images are majorly used for detecting the breast cancer. The level of positivity of breast cancer is detected after excluding the pectoral muscle from mammogram images. Hence, it is very significant to identify and segment the pectoral muscle from the mammographic images. In this work, a new multilevel thresholding, on the basis of electro-magnetism optimization (EMO) technique, is proposed. The EMO works on the principle of attractive and repulsive forces among the charges to develop the members of a population. Here, both Kapur’s and Otsu based cost functions are employed with EMO separately. These standard functions are executed over the EMO operator till the best solution is achieved. Thus, optimal threshold levels can be identified for the considered mammographic image. The proposed methodology is applied on all the three twenty-two mammogram images available in mammographic image analysis society dataset, and successful segmentation of the pectoral muscle is achieved for majority of the mammogram images. Hence, the proposed algorithm is found to be robust for variations in the pectoral muscle.

A hybrid method for fundamental heart sound segmentation using group-sparsity denoising and variational mode decomposition Abstract Segmentation of fundamental heart sounds–S1 and S2 is important for automated monitoring of cardiac activity including diagnosis of the heart diseases. This pa-per proposes a novel hybrid method for S1 and S2 heart sound segmentation using group sparsity denoising and variation mode decomposition (VMD) technique. In the proposed method, the measured phonocardiogram (PCG) signals are denoised using group sparsity algorithm by exploiting the group sparse (GS) property of PCG signals. The denoised GS-PCG signals are then decomposed into subsequent modes with specific spectral characteristics using VMD algorithm. The appropriate mode for further processing is selected based on mode central frequencies and mode energy. It is then followed by the extraction of Hilbert envelope (HEnv) and a thresholding on the selected mode to segment S1 and S2 heart sounds. The performance advantage of the proposed method is verified using PCG signals from benchmark databases namely eGeneralMedical, Littmann, Washington, and Michigan. The proposed hybrid algorithm has achieved a sensitivity of 100%, positive predictivity of 98%, accuracy of 98% and detection error rate of 1.5%. The promising results obtained suggest that proposed approach can be considered for automated heart sound segmentation.