28th May 2023

Joint Replacement Considerations

Making the decision for a joint replacement

Often, it takes years before we finally commit to surgery and an appointment can be agreed. In the meantime, we must continue with our everyday lives, as best we can. This usually means that we adapt our movement to optimise our mobility while reducing pain. This movement becomes a learned behaviour over time, and muscles adapt to support that way of moving. Post-surgery, we need to teach ourselves to move symmetrically, with good range.


When the surgery finally happens, it could take any one of a range of different approaches. Techniques can include  incisions being made from the front, the side, or the back. Muscles can be cut or parted or moved and implant types/styles differ.


Good rehabilitation is key to a good recovery. The work of the physiotherapist can ensure successful outcomes from surgery. During our work with a range of hip replacement consultants, we noticed that physiotherapy-based rehabilitation from was fairly standard, irrespective of the surgical approach. Often, physiotherapy is only available from the hospital in the initial weeks following surgery. It takes the body between 6 to 8 weeks to fully recover from the trauma of surgery. During that time, gross movements of the joint are key to establish muscle memory and strength. This is what the physiotherapist will focus upon.

Once the body is ready, after that initial 6 to 8 weeks, then it is key to get back to good symmetrical movement and good ranges of motion. Symmetry, however, is the key, as this ensures that we do not continue with any compensatory movement that places load on joints that should not be experiencing them. Asymmetric movement can also have a detrimental effect on stability which can lead to falls.

Everything is ok, as I do not have pain any more

An eminent hip surgeon once said to me that hip replacement surgery is second in good patient feedback, only behind cataract surgery. Obviously, with cataract surgery you can see well again. Hip replacement surgery usually means that the pain that you were experiencing has gone. However, this is also part of the rehabilitation issue. Many patients want to do all the things they have missed out on while their mobility has been reduced and painful. However, the lack of pain does not mean that you have good gait. Walking or running on an asymmetric gait will load other joints and will potentially cause problems. For example, if you need a hip replacement, you will often load the opposite knee, supporting your body weight, to enable you to swing the bad hip through. Over time, bone density of the knee taking the load will change and subsequently, the knee may require attention. We are starting to see the relationship between hip replacements followed by opposite leg knee replacements in patients. Getting back to good symmetry is key!

You cannot change what you do not know

At STG Biomechanics, we have a world leading gait analysis system that uses 6 sensors placed on the body: pelvis, thighs, and calves. This is done over clothing, and we ask the person to walk a few strides. The data that we produce, in just a few minutes, shows us exactly how the person is moving. We show ranges, forwards/backwards (sagittal plane) as well as side to side (coronal plane), for all segments. We also calculate hip and knee joint ranges, along with symmetry, timing, and speed information, which is all referenced against a healthy norms database. This information allows a recommendation for rehabilitation exercise that is based upon accurate, objective data, depicting the actual issues that you have.

As a physio, it is hard to see and almost impossible to quantify, the detail in the movement of an individual. If you visually inspect the movement of a person from the side of the person, you can see movement, but it is difficult to quantify. The other side of the person is not possible to see and any abduction or adduction, which needs to be viewed from the front, cannot be seen at all. Alternatively, watching from the front does not allow you to see the ranges being achieved in that front to back movement.

STG Biomechanics Gait Analysis

Our gait analysis system provides all the range of motion information, along with symmetry, timing, and speed from a single stride. This information allows better focus on the rehabilitation required. Areas that need improvement or adjustment can be assessed during rehabilitation to ensure that your mobility is “moving in the right direction” – excuse the pun.

Our gait analysis system is a validated, class 1 medical device, so we know that the data is good and then your healthcare provider can base their work on accurate data.

Drop me an email if you would like to understand more about our gait analysis.

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