Why is a good socket fit so important?

There is a variety of reasons why a person can be amputated, such as traumatic injuries, congenital anomalies, vascular diseases, or cancer [1]. When a leg or other extremity is amputated or lost, a prosthesis plays a key role in rehabilitation. The goal of an amputee using a prosthetic limb is to restore function and improve physical and psychosocial functions, such as performing daily activities, optimising the quality of life, returning to work [3] and remaining independent. Thereby, a good socket fit is one of the key points to achieving it [4,5]. For a lower-limb amputee, their gait and capability to ambulate may be compromised by an ill-fitting socket, increasing the risk of falling. For upper-limb amputees, the socket connects the prosthesis to the other parts of the arm, like a wrist joint or an elbow joint, whose functionalities may be hindered by a wrong fit and poor establishment of the interface between the limb and the prosthesis.

According to previous research, most patients with an extremity amputation utilize a prosthetic device and can regain some physical function [6–8]. However, long-term disability is a big worry for people who have had an amputation. Mackenzie et al [9], showed that most patients' physical and mental performance decreased over the course of seven years after amputation, to the point that half of them classified themselves as severely impaired. Furthermore, in the case of lower-limb amputation, people become more susceptible to developing obesity, cardiovascular diseases, osteoarthritis, residual limb pain and low back pain. When the prosthesis fits comfortably, one reaches optimum functionality more successfully [5], which is a big step taken towards restoring independence, quality of life, and avoiding all the stated complications. 

A successful prosthesis depends not only on a multidisciplinary team that may accompany the patient but also on the amputee's overall health, physical and cognitive abilities [2]. 

During the lower-limb prosthetic fitting process, patients frequently return to the clinic for several changes and adjustments [2]. This iterative process and the constant changes in comfort and functionality of the prosthetic socket can be a major source of frustration for both the amputee and the rehabilitation team. It is also worth noting that there is a learning curve while utilizing the prosthesis for the first time, which is even less steep when the patient was amputated recently or has never used a prosthesis for locomotion. As a result, establishing whether a certain prosthetic device is a good fit for the patient and modifying the prosthetic socket for maximum performance and comfort may take a while. 

When evaluating how well a prosthesis fits, there are several factors to consider [2], going from weight fluctuations to the normal wear and tear of the prosthetic socket. It is crucial to meticulously observe any changes in the residual limb's shape or size. The body is constantly changing, especially when it comes to diet and exercise – and the residual limb is subjected to these alterations, which can cause the socket to become looser or tighter, exerting pressure over soft tissues repeatedly and leading to unnatural body movements and fatigue. An ill-fitting socket can cause rubbing, discomfort and even skin breakdown or ulcers, therefore, minimizing changes in the fitting is an important part of maintaining a good socket fit.  

Of course, it would be game-changing to have prosthetic sockets that would not only adapt to the residual limb as it undergoes modifications (physiological, adaptations to the new ambulation strategies) but would also repair themselves on any damage or change in their fitted shape. This is not a reality yet, although the prosthetic device world is developing fast, having these ideas in mind. For now, changes in comfort and activity may even be undetectable to users if they occur slowly over time, making current procedures for evaluating socket fit unfavourable for those with limb loss. 

Good and clear communication between the prosthetist and the amputee is essential to achieving a proper socket fit. As it is becoming clear, the most common complaint among prosthesis users is that the socket does not fit properly.

What should a prosthetist aim for, then, if it can get so complicated to understand the needs of the patient and achieve a perfectly fitting socket? One should always try to achieve the clearest communication possible with the patient, directing the effort to understand perfectly where the complaints and the discomfort come from. Then, one should use the tools at hand to derive explanations for the problems being described. If the patient is unsure about how to pinpoint a certain source of discomfort, or there may be a phantom pain or reinnervation problem associated with the amputation, it is useful to try out pressure assessment tools, along with alignment assessment platforms, for example, for trying to get a clearer picture of the problem and adequation of the intervention. Moreover, if the patient is presented with extra sources of data that is explaining what they may be feeling, the enlightenment that may come with validation or different insights will facilitate enormously the exchange of ideas between them and the practitioner, leading to better-informed decisions and mutual understanding.

In summary, physical rehabilitation following an amputation is a lengthy and complicated procedure, and a proper socket fit is critical for an improvement in the amputee’s quality of life. Anything that increases mobility and enhances the patient’s confidence and self-esteem may help to facilitate the necessary physical and psychological transitions that take place after amputation [10]. Also, as technology is shifting towards delivering data-driven information about the prosthetic fitting process and what it entails, it is imperative that it continues to be implemented every day in the practices and used not only to derive informed conclusions and decide on further steps in the rehabilitation process but also as a tool for inclusion of the patient in the process, as communication is key.

Adapttech aims to improve the life of lower limb amputees while providing a more efficient process for prosthetists. The purpose of our technology is to improve the efficiency and success of the fitting process for clinicians, rapidly deliver an ultra-comfortable uniquely fitted prosthesis for the patient, and bring to the market a new way to monitor the evolution of patients' residual limbs, their activity, and the quality of their day-to-day. Click here to know more about our innovative products.

References 

1. Stokosa JJ. Overview of Limb Prosthetics - Special Subjects - MSD Manual Consumer Version. Published 2021. Accessed March 18, 2022. https://www.msdmanuals.com/en-pt/home/special-subjects/limb-prosthetics/overview-of-limb-prosthetics 

2. Turner S, McGregor AH. Perceived Effect of Socket Fit on Major Lower Limb Prosthetic Rehabilitation: A Clinician and Amputee Perspective. Archives of Rehabilitation Research and Clinical Translation. 2020;2(3):100059. doi:10.1016/j.arrct.2020.100059 

3. Susanna Matsen BL, Malchow D, Matsen FA. Correlations with Patients’ Perspectives of the Result of Lower-Extremity Amputation *. Vol 82.; 2000. 

4. Darter BJ, Hawley CE, Armstrong AJ, Avellone L, Wehman P. Factors Influencing Functional Outcomes and Return-to-Work After Amputation: A review of the literature. Journal of occupational rehabilitation. 2018;28(4):656. doi:10.1007/S10926-018-9757-Y 

5. Walker J, Marable WR, Smith C, Sigurjónsson B, Atlason IF, Johannesson GA. CLINICAL OUTCOME OF TRANSFEMORAL DIRECT SOCKET INTERFACE (PART 2). CANADIAN PROSTHETICS & ORTHOTICS JOURNAL. 2021;4(1). doi:10.33137/cpoj.v4i1.36065 

6. Mcfarland L v., Winkler SLH, Heinemann AW, Jones M, Esquenazi A. Unilateral upper-limb loss: satisfaction and prosthetic-device use in veterans and servicemembers from Vietnam and OIF/OEF conflicts. Journal of rehabilitation research and development. 2010;47(4):299-316. doi:10.1682/JRRD.2009.03.0027 

7. van Velzen JM, van Bennekom CAM, Polomski W, Slootman JR, van der Woude LHV, Houdijk H. Physical capacity and walking ability after lower limb amputation: a systematic review. Clinical rehabilitation. 2006;20(11):999-1016. doi:10.1177/0269215506070700 

8. Raichle KA, Hanley MA, Molton I, et al. Prosthesis use in persons with lower- and upper-limb amputation. Journal of rehabilitation research and development. 2008;45(7):961-972. doi:10.1682/JRRD.2007.09.0151 

9. MacKenzie EJ, Bosse MJ, Kellam JF, et al. Early predictors of long-term work disability after major limb trauma. The Journal of trauma. 2006;61(3):688-694. doi:10.1097/01.TA.0000195985.56153.68 

10. Maguire P, Parkes CM. Surgery and loss of body parts. BMJ (Clinical research ed). 1998;316(7137):1086-1088. doi:10.1136/BMJ.316.7137.1086