M. Jason Highsmith

Safety, energy efficiency, and cost efficacy of the C-Leg for transfemoral amputees: A review of the literature

The purpose of this paper was to review the literature through a structured literature review and provide a grade of recommendation for patient safety, gait energy efficiency, and cost effectiveness of the C-Leg microprocessor-controlled prosthetic knee for transfemoral amputees. Medline (Ovid) and CINAHL (EBSCO) data bases were searched to identify potentially pertinent studies within the 1995–2009 time range. Studies were screened and sorted. Pertinent studies were rated for methodologic quality and for risk of bias. Following assessment of methodologic quality and bias risk, the level of evidence and a grade of recommendation was determined for each of three categories: Safety, energy efficiency, and cost effectiveness. A total of 18 articles were determined to be pertinent: seven for safety, eight for energy efficiency, and three for cost effectiveness. Methodologic quality was low with a moderate risk of bias in the safety and energy effectiveness categories. Studies in cost effectiveness received high scores for methodologic quality. Though methodologic quality varied across the selected topics, there was sufficient evidence to suggest increased efficacy of the C-Leg in the areas of safety, energy efficiency and cost when compared with other prosthetic knees for transfemoral amputees.

Differences in myoelectric and body-powered upper-limb prostheses: Systematic literature review.

The choice of a myoelectric or body-powered upper-limb prosthesis can be determined using factors including control, function, feedback, cosmesis, and rejection. Although body-powered and myoelectric control strategies offer unique functions, many prosthesis users must choose one. A systematic review was conducted to determine differences between myoelectric and body-powered prostheses to inform evidence-based clinical practice regarding prescription of these devices and training of users. A search of 9 databases identified 462 unique publications. Ultimately, 31 of them were included and 11 empirical evidence statements were developed. Conflicting evidence has been found in terms of the relative functional performance of body-powered and myoelectric prostheses. Body-powered prostheses have been shown to have advantages in durability, training time, frequency of adjustment, maintenance, and feedback; however, they could still benefit from improvements of control. Myoelectric prostheses have been shown to improve cosmesis and phantom-limb pain and are more accepted for light=intensity work. Currently, evidence is insufficient to conclude that either system provides a significant general advantage. Prosthetic selection should be based on a patients individual needs and include personal preferences, prosthetic experience, and functional needs. This work demonstrates that there is a lack of empirical evidence regarding functional differences in upper-limb prostheses.

Kinematic Comparison of Myoelectric and Body Powered Prostheses While Performing Common Activities

This study examined the kinematic differences of a bilateral transradial amputee using myoelectric and body-powered prostheses during select activities of daily living. First in harness suspended, body powered then self-suspended externally powered prostheses, the subjects shoulder and elbow joint movements were calculated and compared while completing an elbow range of motion test, simulated drinking from an empty cup, and opening a door. In this case, body-powered prostheses allowed for greater range of elbow flexion but required more shoulder flexion to complete the tasks that required continuous grasp. While using myoelectric prostheses, the user was able to compensate for limited elbow flexion by flexing the shoulder.

3D printed tooling for thermoforming of medical devices

Purpose – The purpose of this paper is to evaluate the performance of 3D printed materials for use as rapid tooling (RT) molds in low volume thermoforming processes such as in manufacturing custom prosthetics and orthotics.Design/methodology/approach – 3D printed specimens of different materials were produced using the Z‐Corp process. The parts were post processed using both standard and alternative methods. Material properties relevant to the 3D printed parts such as pneumatic permeability, flexural strength and wear rate were measured and compared to standard plaster compositions commonly used.Findings – Three‐dimensional printing (3DP) can replicate the performance of the plaster materials traditionally used in prosthetic/orthotic applications by using modified post process techniques. The resulting 3D printed molds can still be modified and adjusted using traditional methods. The results show that 3D printed molds are feasible for thermoforming prosthetic and orthotic devices such as prosthetic socket...

Differences in knee flexion between the Genium and C-Leg microprocessor knees while walking on level ground and ramps

BACKGROUND Microprocessor knees have improved the gait and functional abilities of persons with transfemoral amputation. The Genium prosthetic knee offers an advanced sensor and control system designed to decrease impairment by: allowing greater stance phase flexion, easing transitions between gait phases, and compensating for changes in terrain. The aim of this study was to determine differences between the knee flexion angle of persons using the Genium knee, the C-Leg knee, and non-amputee controls; and to evaluate the impact the prostheses on gait and level of impairment of the user. METHODS This study used a randomized experimental crossover of persons with transfemoral amputation using the Genium and C-Leg microprocessor knees (n=25), with an observational sample of non-amputee controls (n=5). Gait analysis by 3D motion tracking of subjects ambulating at different speeds on level ground and on 5° and 10° ramps was completed. FINDINGS Use of the Genium resulted in a significant increase in peak knee flexion for swing (5°, p<0.01, d=0.34) and stance (2°, p<0.01, d=0.19) phases relative to C-Leg use. There was a high degree of variability between subjects, and significant differences still remain between the Genium group and the control groups knee flexion angles for most speeds and slopes. INTERPRETATION The Genium knee generally increases flexion in swing and stance, potentially decreasing the level of impairment for persons with transfemoral amputation. This study demonstrates functional differences between the C-Leg and Genium knees to help prosthetists determine if the Genium will provide functional benefits to individual patients.

Biomechanical characteristics, patient preference and activity level with different prosthetic feet: a randomized double blind trial with laboratory and community testing.

Providing appropriate prosthetic feet to those with limb loss is a complex and subjective process influenced by professional judgment and payer guidelines. This study used a small load cell (Europa™) at the base of the socket to measure the sagittal moments during walking with three objective categories of prosthetic feet in eleven individuals with transtibial limb loss with MFCL K2, K3 and K4 functional levels. Forefoot stiffness and hysteresis characteristics defined the three foot categories: Stiff, Intermediate, and Compliant. Prosthetic feet were randomly assigned and blinded from participants and investigators. After laboratory testing, participants completed one week community wear tests followed by a modified prosthetics evaluation questionnaire to determine if a specific category of prosthetic feet was preferred. The Compliant category of prosthetic feet was preferred by the participants (P=0.025) over the Stiff and Intermediate prosthetic feet, and the Compliant and Intermediate feet had 15% lower maximum sagittal moments during walking in the laboratory (P=0.0011) compared to the Stiff feet. The activity level of the participants did not change significantly with any of the wear tests in the community, suggesting that each foot was evaluated over a similar number of steps, but did not inherently increase activity. This is the first randomized double blind study in which prosthetic users have expressed a preference for a specific biomechanical characteristic of prosthetic feet: those with lower peak sagittal moments were preferred, and specifically preferred on slopes, stairs, uneven terrain, and during turns and maneuvering during real world use.

Ramp descent performance with the C-Leg and interrater reliability of the Hill Assessment Index.

Background: Transfemoral amputees have decreased ability to descend ramps and hills. The Hill Assessment Index quantifies transfemoral amputee ramp performance, but interrater reliability has not been assessed. Objectives: To determine whether C-Leg use improves hill descent gait and evaluate the Hill Assessment Index’s interrater reliability. Methods: Twenty-one transfemoral amputees descended a ramp while timed and video recorded, using their nonmicroprocessor prosthetic knee. Subjects were fitted and accommodated with a C-Leg and retested. Test times were compared, and ramp performances were independently reviewed using the Hill Assessment Index by two raters. Hill Assessment Index scores were compared between knee conditions within raters for performance and between raters to assess the Hill Assessment Index’s interrater reliability. Results: Mean Hill Assessment Index scores were greater for C-Leg compared to nonmicroprocessor prosthetic knee for both raters. C-Leg resulted in faster ramp descent. Strong correlations resulted between raters on Hill Assessment Index scores for nonmicroprocessor prosthetic knee (intraclass correlation coefficient = 0.97) and C-Leg (intraclass correlation coefficient = 0.99). Conclusions: C-Leg improves Hill Assessment Index ramp descent performance and time. In descent quality, C-Leg offers the possibility of eliminating assistive device use and/or improving step length in the absence of an assistive device. C-Leg resulted in 23% gait speed increase during ramp descent. The Hill Assessment Index had very good interrater reliability but should be assessed for intrarater reliability, minimal detectable change, and validity. Clinical relevance Transfemoral amputees have difficulty ambulating on ramps. While the C-Leg has been shown to improve ramp descent, this has not been confirmed, and the Hill Assessment Index has not been studied for reliability. This study confirms that the C-Leg improves ramp descent performance and the Hill Assessment Index’s interrater reliability.

Transfemoral sockets with vacuum-assisted suspension comparison of hip kinematics, socket position, contact pressure, and preference: Ischial containment versus brimless

The objective of this study was to investigate the effect of brimless compared with ischial ramus containment (IRC) prosthetic sockets when using vacuum-assisted suspension (VAS) on persons with a unilateral transfemoral amputation (TFA). A randomized crossover design with a 2 d accommodation was used. People with unilateral TFA (n = 9 analyzed) were enrolled. Interventions were IRC VAS and brimless VAS sockets. Main outcome measures included coronal hip angle and vertical and lateral socket movement as measured by X-ray, skin pressure measured by Tekscan, and preference measured subjectively. The brimless design was statistically equivalent to IRC in all measured coronal hip angles and vertical and lateral socket displacement. The peak/stance mean pressure in the medial proximal aspect of the socket was 322 mmHg in the IRC compared with 190 mmHg in the brimless condition. Except for medial proximal pressure, no other measures reached statistical significance. All subjects reported the brimless design to be more comfortable than the IRC in short-term preference. Brimless VAS socket design may be a clinically viable choice for people with TFA.

STAIR ASCENT AND RAMP GAIT TRAINING WITH THE GENIUM KNEE

Accepted May 1, 2013. Address correspondence to M. Jason Highsmith, School of Physical Therapy & Rehabilitation Sciences, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 077, Tampa, FL 33612-4799, USA. Tel: +1-813-974-3806 (office); Fax: +1-813-974-8915; E-mail: mhighsmi@health.usf.edu Technology and Innovation, Vol. 15, pp. 349–358, 2014 1949-8241/14

A Method for Training Step-Over-Step Stair Descent Gait With Stance Yielding Prosthetic Knees: A Technical Note

90.00 + .00 Printed in the USA. All rights reserved. DOI: http://dx.doi.org/10.3727/194982413X13844488879267 Copyright  2014 Cognizant Comm. Corp. E-ISSN 1949-825X www.cognizantcommunication.com