A study of technical changes to lower limb prostheses after initial fitting

Rommers, Gerardus M.; Vos, L. D. W.; Klein, Luiza Birck; Groothoff, Johan W.; Eisma, W.H.

doi:10.1080/03093640008726519

Cited by 10 publications

(6 citation statements)

References 16 publications

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“…The volume of the residuum changes due to weight gain or weight loss, 38 edema, 46 and muscle atrophy. 36 Consequently, the TTA prosthetic user is fitted with a new prosthetic socket approximately every 4 years. Despite new innovations in socket and liner materials and design, contemporary prostheses are not yet equipped to confront these changes.…”

Section: Introductionmentioning

confidence: 99%

Surgical and Morphological Factors that Affect Internal Mechanical Loads in Soft Tissues of the Transtibial Residuum

et al. 2009

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The residual limb of transtibial amputation (TTA) prosthetic users is threatened daily by pressure ulcers (PU) and deep tissue injury (DTI) caused mainly by sustained mechanical strains and stresses. Several risk factors dominate the extent of internal tissue loads in the residuum. In this study, we developed a set of three-dimensional finite element (FE) models that were variants of a patient-specific FE model, built from magnetic resonance imaging scans. The set of FE modes was utilized to assess the impact of the following risk factors on the strain/stress distribution in the muscle flap: (i) the tibial length, (ii) the tibial bevelment, (iii) a fibular osteophyte, (iv) the mechanical properties of the muscle, and (v) scarring in different locations and depths. A total of 12 nonlinear FE model configurations, representing variations in these factors, were built and solved. We present herein calculations of compression, tension and shear strains and stresses, von Mises stresses, and strain energy density averaged in critical locations in the muscle flap as well as volumes of concentration of elevated stresses in these areas. Our results overall show higher stresses accumulating in the bone proximity rather than in outlying soft tissues. The longer bone configurations spread the loads toward the external surfaces of the muscle flap. When shortening the truncated bones from 11.2 to 9.2 cm, the von Mises stresses at the distal edges of the bones were relieved considerably (by up to 80%), which indicates a predicted decreased risk for DTI. Decreasing the tibial bevelment mildly, from 52.3 degrees to 37.7 degrees caused propagation of internal stresses from the bone proximity toward the more superficial soft tissues of the residuum, thereby also theoretically reducing the risk for DTI. An osteophyte at the distal fibular end increased the strain and stress distributions directly under the fibula but had little effect (<1%) on stresses at other sites, e.g., under the tibia. Elevation of muscle stiffness (instantaneous shear modulus increase from 8.5 to 16.2 kPa), simulating variation between patients, and muscle flap contraction or spasm, showed the most substantial effect by an acute rise of the von Mises stresses at the bone proximity. The mean von Mises stresses at the bone proximity were approximately twofold higher in the contracted/spastic muscle when compared to the flaccid muscle. Locating a surgical scar in different sites and depths of the residuum had the least influence on the overall loading of the muscle flap (where stresses changed by <7%). Pending further validation by epidemiological PU and DTI risk factor studies, the conclusions of this study can be incorporated as guidelines for TTA surgeons, physical therapists, prosthetists, and the TTA patients themselves to minimize the onset of PU and DTI in this population. Additionally, the present analyses can be used to guide or focus epidemiological research of PU and DTI risk factors in the TTA population.

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Section: Introductionmentioning

confidence: 99%

Surgical and Morphological Factors that Affect Internal Mechanical Loads in Soft Tissues of the Transtibial Residuum

et al. 2009

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“…However, currently available suspension systems are accompanied by several problems that are linked to the continuous change in residual limb size, volume, donning, and doffing, especially in systems with a vacuum liner [ 18 , 19 ]. In other words, the socket, liner, and residual limb should be in full contact to ensure proper pressure distribution [ 20 ]. The continuous change in volume or size of the residual limb leads to the loss of contact and interruption of pressure distribution in the entire system [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Development of an Air Pneumatic Suspension System for Transtibial Prostheses

Pirouzi

Osman

Oshkour

et al. 2014

Sensors

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The suspension system and socket fitting of artificial limbs have major roles and vital effects on the comfort, mobility, and satisfaction of amputees. This paper introduces a new pneumatic suspension system that overcomes the drawbacks of current suspension systems in donning and doffing, change in volume during daily activities, and pressure distribution in the socket-stump interface. An air pneumatic suspension system (APSS) for total-contact sockets was designed and developed. Pistoning and pressure distribution in the socket-stump interface were tested for the new APSS. More than 95% of the area between each prosthetic socket and liner was measured using a Tekscan F-Scan pressure measurement which has developed matrix-based pressure sensing systems. The variance in pressure around the stump was 8.76 kPa. APSS exhibits less pressure concentration around the stump, improved pressure distribution, easy donning and doffing, adjustability to remain fitted to the socket during daily activities, and more adaptability to the changes in stump volume. The volume changes were adjusted by utility of air pressure sensor. The vertical displacement point and reliability of suspension were assessed using a photographic method. The optimum pressure in every level of loading weight was 55 kPa, and the maximum displacement was 6 mm when 90 N of weight was loaded.

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“…Despite functional differences between upper and lower limb prostheses, the key factors affecting user acceptance and function are similar (11), with discomfort and diminished prosthesis control being the leading causes of abandonment and dissatisfaction (11,12). Each socket's shape is derived from the anatomy, requiring complex design modifications based on factors such as location and level of amputation or limb absence, bony prominences and tissue consistency, the quality and load bearing capabilities of the tissues, and scars (13).…”

Section: Introductionmentioning

confidence: 99%

The Impact of Limited Prosthetic Socket Documentation: A Researcher Perspective

Olsen

Turner

Chadwell

et al. 2022

Front. Rehabilit. Sci.

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The majority of limb prostheses are socket mounted. For these devices, the socket is essential for adequate prosthetic suspension, comfort, and control. The socket is unique among prosthetic components as it is not usually mass-produced and must instead be custom-made for individual residual limbs by a prosthetist. The knowledge of what constitutes “good” socket fit is gained by expert prosthetists and technicians over years of experience, and rarely documented. The reliance on tacit knowledge makes it difficult to standardize the criteria for a well-fitting socket, leading to difficulties understanding the impact of socket fit. Despite its importance, the workflow for socket fitting is often overlooked in literature. Due to the customized nature of sockets, if information is provided in literature, generally only the type of socket and suspension mechanism is noted, with information regarding the fitting and manufacturing processes omitted. In this article, the concerns, issues and consequences arising from lack of upper and lower limb socket documentation are discussed from a researcher perspective, supported by healthcare professionals and socket fabrication specialists. Key changes are proposed to the way socket manufacturing and evaluation are documented to assist future research.

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A study of technical changes to lower limb prostheses after initial fitting

Cited by 10 publications

References 16 publications

Surgical and Morphological Factors that Affect Internal Mechanical Loads in Soft Tissues of the Transtibial Residuum

Surgical and Morphological Factors that Affect Internal Mechanical Loads in Soft Tissues of the Transtibial Residuum

Development of an Air Pneumatic Suspension System for Transtibial Prostheses

The Impact of Limited Prosthetic Socket Documentation: A Researcher Perspective

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