Adjustable-Volume Prosthetic Sockets: Market Overview and Value Propositions

Abstract

The prosthetic socket is commonly considered to be the most important part of the prosthesis and lack of fit can lead to skin breakdown, reduction in wear, reduction in activity, and consequential deleterious health effects. Furthermore, approximately 90% of amputations are due to a vascular etiology, which affect fluid retention regularity, and even small limb volume fluctuations can lead to lack of fit. Adjustability in the socket volume has been suggested as a potential solution to common fit issues but has lacked market penetration mostly due to lack of reimbursement. Despite this there are several adjustable-volume sockets emerging on the market today including prefabricated, modular, custom with adjustable-volume component, custom with adjustable-volume feature, and adjustable-hybrid sockets. Prefabricated sockets are mass produced in common sizes and fit directly to the patient by a prosthetist using pad kits, BOA dials, or straps. Modular sockets are assembled to a patient or model with panels or struts attached to an adjustable base. Custom sockets with adjustable-volume elements are traditionally-fabricated sockets made to a model of a patient’s limb with a volume-adjustable component added or volume-adjustable feature built in. Custom-hybrid sockets are made custom to a model of the patient’s limb and incorporate several aspects of the previous socket types and include some radically-unique design aspects which cannot be limited to one category. These adjustable-volume sockets offer several advantages to traditional rigid-volume sockets for the patient, prosthetist, and providing clinic. The micro-adjustability for the patient allows them to alter fit without removing the socket, maintaining a more intimate fit throughout the day than traditional sockets. The macro-adjustability for the prosthetist allows for increased options for fit customization including the ability to reverse or undo changes without necessarily re-making the socket. This allows for the most optimal fit for the patient. Adjustable volume also present efficiencies in the fitting process by simplifying or eliminating steps including residual limb shape capture, form modification, diagnostic fabrication, iterative alteration, and definitive fabrication with the different socket types affecting different steps. Due to these factors, adjustable-volume sockets have disrupted the market to the point where reimbursement reform is needed including additional L-codes in the United States and fee-for-service or fee-for-outcome associated with prosthetic follow-up care. Prosthetic care should also be separated from durable medical equipment to allow for alternative reimbursement models. As reimbursement adapts prosthetists must adapt correspondingly to differentiate their skillset from other allied health providers including incorporating more objective methods to show superior care outcomes. This adaptation should include a continued push for state and municipal licensure of prosthetists.
 Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/35208/28346
 How To Cite: Klenow TD, Schulz J. Adjustable-volume prosthetic sockets: market overview and value propositions. Canadian Prosthetics & Orthotics Journal. 2021; Volume 4, Issue 2, No.17 https://doi.org/10.33137/cpoj.v4i2.35208
 Corresponding Author: Tyler D. Klenow, MSPO, MBA, CLPO, FAAOPMartin Bionics Clinical CareE-Mail: Tyler.klenow@martinbionics.comORCID ID: https://orcid.org/0000-0002-6372-2241

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“…Past approaches to managing residual limb volume fluctuation ranged from early adjustable sockets made of leather and lacers ( 41 , 42 ) to adding and taking off stump socks over the course of the day, the latter of which is still done today but which is not a wholly satisfactory solution ( 43 ). Research has begun to point to the current standard of care being inadequate and thoughtful approaches are beginning to emerge ( 44 ). As in past eras, these draw on an expanding palette of materials alongside seeking more widely sourced innovative elements, for example the sports equipment and high-performance garment sectors and then combining them in more complex and novel ways.…”

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“…Clinician adjustments are usually designed to alter the socket geometry to accommodate larger physiological changes without needing to redesign the socket or replace major components [46,47,51]. Together, these enable off-the-shelf and modular prosthetic sockets to be feasible, with one device potentially being suitable for a range of patients with varying residual limb sizes and shapes [15].…”

“…Offthe-shelf devices are also being developed to a lesser extent, and there is specific interest into how these can be utilised within low resource settings, to reduce the time, clinical expertise and materials which are required to fit and manufacture conventional sockets [4]. Previous reviews of adjustable sockets have categorised them by their method of manufacture: off-the-shelf, where a prosthesis is purchased pre-made to a set size with small adjustments made to suit the patient; modular, where a kit of parts is delivered to and assembled by the clinician with modifications to parts made to suit the patient; and custom, where the prosthesis is made by the clinician or manufacturer to match the patients residuum shape with no limitation on shape due to pre-made components [14,15]. This categorisation is useful for fabrication but provides no insight into how or where the shape of the socket changes when adjusted, which are significant due to how they influence the stability, comfort and tissue health dimensions listed above.…”

Adjustable prosthetic sockets: a systematic review of industrial and research design characteristics and their justifications

“…Off-the-shelf devices are also being developed to a lesser extent, and there is specific interest into how these can be utilised within low resource settings, to reduce the time, clinical expertise and materials which are required to fit and manufacture conventional sockets [ 4 ]. Previous reviews of adjustable sockets have categorised them by their method of manufacture: off-the-shelf, where a prosthesis is purchased pre-made to a set size with small adjustments made to suit the patient; modular, where a kit of parts is delivered to and assembled by the clinician with modifications to parts made to suit the patient; and custom, where the prosthesis is made by the clinician or manufacturer to match the patients residuum shape with no limitation on shape due to pre-made components [ 14 , 15 ]. This categorisation is useful for fabrication but provides no insight into how or where the shape of the socket changes when adjusted, which are significant due to how they influence the stability, comfort and tissue health dimensions listed above.…”