When Should You Recalibrate Your Alignment? (Part 1)

Written by Bryan Potok, CPO on November 4, 2018
Last updated on November 8, 2018

Understanding the effects of proper alignment is important to your overall physical health. When your prosthetic socket is misaligned, it can create a variety of issues such as lower back pain (LBP), fatigue and physical exhaustion, among others. So, we created this Alignment Guide for you.

A below-the-knee amputee having his alignment adjusted Image from limb-loss.org

But before we jump into the nitty-gritty of knowing when to recalibrate your alignment, it’s best to discuss the basic terminologies first.

Prosthetic Socket Alignment Basics

Diagram describing flexion and extension of prosthetic sockets.

Socket flexion – is the act of placing the knee (below the knee amputee) or hip (above the knee amputee) in a more flexed posture. Simply flexing your socket 4 degrees can change everything. Flexing a prosthetic socket will move body weight forward or backward on your prosthetic foot depending upon amputation level. So, when your knee feels unstable in a below-knee or above-knee prosthesis, it’s possible that your socket is over-flexed. When viewing your BK prosthesis from the side, you should see only a minimum amount of flexion relative to a line perpendicular to the floor.

Socket extension – creates an excess load that is carried onto the heel cushion. A socket that is overextended may feel as though your knee is hyperextended or stretched too far back and will feel constrained to move into knee flexion.

Side-to-side tilting – this refers to a prosthetic socket tilting either inward or outward when viewed from the front or back. This can alter how your foot hits the ground and is the direct cause of pressure differences along the brim of your socket, as well as changes in your base of support.

Now that you’re up to speed on the basics, let’s talk about the symptoms you’re potentially experiencing.

7 signs that your prosthetic alignment may be off and your prosthetic socket is the culprit

SYMPTOM	EXPLANATION	ABOVE-KNEE AMPUTEE	BELOW-KNEE AMPUTEE
Lower back pain	This is a clear symptom that there could be issues related to your socket’s alignment.	If you wear an AK socket that doesn’t have enough flexion built into the alignment, you may find yourself hyperextending your lower back to advance your foot.	If you wear a BK prosthesis and you have too much flexion, your prosthetic leg could be shorter—especially if this change happened after receiving your prosthesis and the initial height was set.
Your knee caves in	This is a sign that the side-to-side tilt angle may be off, which opens up a whole set of issues for you.	AK amputees can and should have some valgus—which means your knee should be caving inward as you stand. However, your knee should be vertical while walking and especially when you’re on single limb support. If not, you may find that your knee unit doesn’t swing through properly. This means your leg may be shorter and, as a result, can affect your lower back.	You might find yourself experiencing outer-knee pain or pain along the end of your tibia.
Fatigue and physical exhaustion after a day of walking	You’re feeling as if you’ve been working out for 8 hours straight. This is usually a result of your foot being placed too far back or forward in relation to your socket.	Regardless if you’re wearing an AK or BK prosthesis, imagine your socket being placed or aligned right over the toe of your foot, versus in the middle. This effectively removes the toe lever and the energy storage capacity of your foot. Instead of your energy storing food giving you 12-25% energy return, it's now only capable of providing you with 2-3%. Your body has to compensate for the difference—and that’s tiring. It’s the same thing if your prosthetic socket is placed over the heel and is effectively providing a really long toe lever. You would think that the longer the toe lever is, the more energy it could store to push off. The reality is, your toe may feel too mushy now during push-off and it requires more energy to “come over your toe” as you prepare for push-off. Your toe, then, feels way too stiff. It now feels as if you’re climbing a small hill with each step. This can zap away your energy.
The foot isn’t responding	This can be related to either your socket flexion being set too much or set too little. Socket flexion can affect whether your foot is too far forward or backward relative to your socket.	Too much socket flexion moves your above-knee socket far back on the foot and creates a long toe lever. Your toe now feels stiff and hard to come over. A positive effect can be increased prosthetic knee stability if that’s what you need.	Too much below-knee socket flexion in your prosthesis will move your socket far forward over the toe. With no toe lever, your foot will feel as if it’s not responding and can potentially create unease along the front portion of your tibia.
Pressure along the front of your tibial bone	This is directly related to socket flexion.	If your above-knee prosthetic socket doesn’t have enough flexion built into the alignment, then you may experience pressure along the front end of your femur. You can tell there isn’t enough socket flexion when you realize you’re taking really long strides compared to your other side.	If you’re experiencing pressure along the front part of your tibia, there’s a high possibility of too much flexion. Removing some of the socket flexion (2-6 degree) will either relieve your tibial pressure entirely or tell you that you need a socket adjustment in the form of adding or removing sock ply. This will depend on your socket design and suspension. For instance, adding pressure or eliminating space within a vacuum system will offer you relief and comfort if you’re experiencing tibia pain or discomfort.
Pressure is present along the outside of your socket		Pressure over your femur can be an indication that your foot is too far outset and the base of your support is too broad. Move your foot inwards to help relieve any femoral pressure, as well as improve your gait from having a smaller support base.	Outside pressure, especially over your fibula head, can be a sign that your foot is too inset. This means, your base of support is too narrow. Moving your socket to the outside in small millimeter increments can have a substantial positive effect on your gait and comfort.
The shoe’s heel is wearing out on the inside		If your sneaker’s heel is wearing out on the interior heel, then you have an alignment problem. The side-to-side socket tilt can be one culprit or the socket on your prosthesis may be set too far outward, which causes your foot to contact the inner heel initially. Ideal initial contact is slight outer heel contact and then foot flat. If the side-to-side angle of your foot is causing you to ride the inside of your heel, your Prosthetist can correct this for you.

3 Types of Initial Alignment Steps for Socket Placement

1. Bench alignment – this refers to the assembly of your various components in a standardized alignment before an initial check socket fitting.

2. Static alignment – this refers to the process of observing the prosthetic alignment as the amputee is simply standing and not moving (thus the term “static), and as you shift positions over the prosthesis. After this procedure is complete, the following changes are expected: length of the leg should be correct, normal toe-out is approximate, and you should be able to stand in one position as you walk in-between the parallel bars while shifting weight comfortably and controlling your movements.

3. Dynamic alignment – if the static alignment is successful, the prosthetic leg will be tuned further, so it’s customized to the amputee’s individual walking style. If there aren’t any critical issues noted by the Prosthetist, it’s highly advisable to spend at least 10-15 minutes getting accustomed to the new prosthesis.

Make sure to have longer check socket walks with your prosthesis, as this is the perfect time for your prosthetist to explain how the new components work so you know more about your new leg. Always remember that knowledge is power, and understanding how your leg works from the get-go will enable you to determine if an alignment or recalibration should be scheduled immediately. Working out any bugs or adjustments now will save you and your Prosthetist discomfort and stress later on.

Alignment is a very intimate and intricate process that you have to go through with your Prosthetist. Changing your socket alignment can affect all other elements of alignment and not just your prosthetic socket. Proper alignment can improve your comfort and make walking more efficient.

Our next few articles will describe alignment relative to your knee and foot. Please leave a comment with any questions and/or which information relating to alignment you would like to read next.