Relative Strength of Pylon-to-Socket Attachment Systems Used in Transtibial Composite Sockets

Graebner, Richard H.; Current, Thomas

doi:10.1097/jpo.0b013e3180cfe8da

Cited by 14 publications

(26 citation statements)

References 3 publications

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“…7 The second study found that for socket reinforced with carbon weighing between 616 -795g, failure occurred between 4247-5663 N. 5 Different material lay-ups and socket attachment methods were found to increase the strength of laminated composite socket. 5,7,9 This study also concluded that modular components began to fail above 5400 N of force. 5 The sockets tested at Condition II in the current study, weighed between 410-450 g and broke between 4384 and 6505 N. This is approximately double the load reported by the first study and similar to results in the second study, despite sockets in this study weighing much less.…”

Section: Laminated Composite Socketsmentioning

confidence: 99%

“…2,3,4 The Prosthetist is responsible for choosing fabrication techniques that provide adequate strength and safety to their patients while maximizing function. 5 Currently, their decisions are not grounded on an evidence-based foundation as minimal evidence is available.…”

Section: Introductionmentioning

confidence: 99%

“…ISO 10328: Prosthetics-Structural testing of lower-limb prostheses is the test standard that is most commonly used to test prosthetic sockets. 5 ISO 10328 includes both static and cyclic strength tests applied in two different loading conditions, Condition I: instant of maximum loading occurring early in the stance phase of walking, and Condition II: instant of maximum loading occurring late in the stance phase of walking, for three different weight limits, P3 body mass below 60 kg, P4 body mass below 80 kg, and P5 body mass above 100 kg. 6 Previously, this standard has been used in to evaluate the strengths of different socket attachment methods as this is frequently the point of failure in transtibial prostheses.…”

Section: Introductionmentioning

confidence: 99%

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An Investigation of the Structural Strength of Transtibial Sockets Fabricated Using Conventional Methods and Rapid Prototyping Techniques

Pousett¹,

Lizcano

Raschke³

2019

Can. Prosthet. Orthot. J.

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BACKGROUND: Rapid Prototyping is becoming an accessible manufacturing method but before clinical adoption can occur, the safety of treatments needs to be established. Previous studies have evaluated the static strength of traditional sockets using ultimate strength testing protocols outlined by the International Organization for Standardization (ISO). OBJECTIVE: To carry out a pilot test in which 3D printed sockets will be compared to traditionally fabricated sockets, by applying a static ultimate strength test. METHODOLOGY: 36 sockets were made from a mold of a transtibial socket shape,18 for cushion liners with a distal socket attachment block and 18 for locking liners with a distal 4-hole pattern. Of the 18 sockets, 6 were thermoplastic, 6 laminated composites & 6 3D printed Polylactic Acid. Sockets were aligned in standard bench alignment and placed in a testing jig that applied forces simulating individuals of different weight putting force through the socket both early and late in the stance phase. Ultimate strength tests were conducted in these conditions. If a setup passed the ultimate strength test, load was applied until failure. FINDINGS: All sockets made for cushion liners passed the strength tests, however failure levels and methods varied. For early stance, thermoplastic sockets yielded, laminated sockets cracked posteriorly, and 3D printed socket broke circumferen-tially. For late stance, 2/3 of the sockets failed at the pylon. Sockets made for locking liners passed the ultimate strength tests early in stance phase, however, none of the sockets passed for forces late in stance phase, all broke around the lock mechanism. CONCLUSION: Thermoplastic, laminated and 3D printed sockets made for cushion liners passed the ultimate strength test protocol outlined by the ISO for forces applied statically in gait. This provides initial evidence that 3D printed sockets are statically safe to use on patients and quantifies the static strength of laminated and thermoplastic sockets. However, all set-ups of sockets made for locking liners failed at terminal stance. While further work is needed, this suggests that the distal reinforcement for thermoplastic, laminated and 3D printed sockets with distal cylindrical locks may need to be reconsidered. LAYMAN’S ABSTRACT 3D printing is a new manufacturing method that could be used to make prosthetic sockets (the part of the prosthesis connected to the individual). However, very little is known about the strength of 3D printed sockets and if they are safe to use. As Prosthetists are responsible for providing patients with safe treatments, the strength of 3D printed sockets needs to be established before they can be used in clinical practice. The strength of sockets made using current manufacturing methods was compared to those made using 3D printing. Strength was tested using the static portion of the ISO standard most applicable for this situation which outlines the forces a socket must take at 2 points in walking–when the foot is placed on the ground (early stance) and when the foot pushed off the ground (late stance). Sockets made for two prosthetic designs (cushion and locking) were tested to determine if one is safer than the other. All sockets made for cushion liners passed the standard for forces applied statically. However, different materials failed in different ways. At early stance, thermoplastic sockets yielded, laminated composite sockets cracked and 3D printed sockets broke circumferentially. At late stance other components failed 2/3 of the time before the sockets were affected. This provides initial evidence that sockets made for cushion liners are statically safe to use on patients. Sockets made for locking liners failed around the end, showing that 3D printing should not be used to create sockets with the design tested in this study. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/31008/24937 How to Cite: Pousett B, Lizcano A, Raschke S.U. An investigation of the structural strength of transtibial sockets fabricated using conventional methods and rapid prototyping techniques. Canadian Prosthetics & Orthotics Journal. 2019; Volume2, Issue1, No.2. DOI: https://doi.org/10.33137/cpoj.v2i1.31008 CORRESPONDING AUTHORBrittany Pousett, BSc, MSc, Certified Prosthetist,Head of Research at Barber Prosthetics Clinic,540 SE Marine Dr, Vancouver, British Colombia V5X 2T4, Canada.Email: brittany@barberprosthetics.com

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Section: Laminated Composite Socketsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Investigation of the Structural Strength of Transtibial Sockets Fabricated Using Conventional Methods and Rapid Prototyping Techniques

Pousett¹,

Lizcano

Raschke³

2019

Can. Prosthet. Orthot. J.

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show abstract

“…Applying the standard used to evaluate nearly all of the components to which a socket is attached was a natural choice. Further, there is some historical precedent for the use of ISO 10328 [4,6,[11][12] and continuing with this trend allows for comparisons between this study and those that preceded it.…”

Section: Limitationsmentioning

confidence: 99%

“…All 10 sockets tested in the study failed to pass the ISO 10328 static test [4]. The socket performance may have been influenced by the type of distal adapters [4,6]. The results from Current et al indicate that the type of reinforcement material contributes to a socket's ultimate static strength performance, with carbon fiber producing higher strengths than fiberglass [4].…”

Section: Introductionmentioning

confidence: 99%

Strength evaluation of prosthetic check sockets, copolymer sockets, and definitive laminated sockets

Gerschutz

Haynes²,

Nixon³

et al. 2012

JRRD

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Abstract-A prosthesis encounters loading through forces and torques exerted by the person with amputation. International Organization for Standardization (ISO) standard 10328 was designed to test most lower-limb prosthetic components. However, this standard does not include prosthetic sockets. We measured static failure loads of prosthetic sockets using a modified ISO 10328 and then compared them with the criteria set by this standard for other components. Check socket (CS) strengths were influenced by thickness, material choice, and fabrication method. Copolymer socket (CP) strengths depended on thickness and fabrication methods. A majority of the CSs and all of the CPs failed to pass the ISO 10328 ductile loading criterion. In contrast, the strengths of definitive laminated sockets (DLs) were influenced more by construction material and technique. A majority of the DLs failed to pass the ISO 10328 brittle loading criterion. Analyzing prosthetic sockets from a variety of facilities demonstrated that socket performance varies considerably between and within facilities. The results from this article provide a foundation for understanding the quality of prosthetic sockets, some insight into possible routes for improving the current care delivered to patients, and a comparative basis for future technology.

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Potential use of natural fiber-reinforced polymer biocomposites in knee prostheses: a review on fair inclusion in amputees

Kumar

Bhowmik

2022

Iran Polym J

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Relative Strength of Pylon-to-Socket Attachment Systems Used in Transtibial Composite Sockets

Cited by 14 publications

References 3 publications

An Investigation of the Structural Strength of Transtibial Sockets Fabricated Using Conventional Methods and Rapid Prototyping Techniques

An Investigation of the Structural Strength of Transtibial Sockets Fabricated Using Conventional Methods and Rapid Prototyping Techniques

Strength evaluation of prosthetic check sockets, copolymer sockets, and definitive laminated sockets

Potential use of natural fiber-reinforced polymer biocomposites in knee prostheses: a review on fair inclusion in amputees

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