How does a leg amputation affect the rest of the body?

If you lose a leg your whole body becomes more ineffective.

At the Back to the Future Rehabilitation Conference back in February, Carolyn Hirons, chartered physiotherapist at Pace Rehabilitation, said something extremely simple, and borderline obvious. However, it occurred to many delegates in the room that they didn’t know exactly how the body might be impacted, beyond the affected area, following the amputation of a limb.

Making use of the expertise of Carolyn and other specialists, we have put together a list of just some of the many ways the rest of the body can be affected by a leg amputation.

Postural changes

Carolyn said at the Back to the Future conference that a big problem for leg amputees is a long-term change in posture, which causes a whole host of associated issues.

An amputation, even when a prosthetic leg is fitted, will naturally lead to a big shift in the individual’s centre of gravity and a reduction in the body’s base of support. As a result, the supporting leg will often rotate, while the pelvic girdle retracts and elevates. This is at the same time as the shoulder girdle dipping or undergoing ‘depression’ and many major muscle groups, such as the abdominals, becoming weaker.

As you can imagine, this fundamental shift in the body’s biomechanics can have quite an impact on amputees. In fact, Limbs4Life suggests the force going through an amputee’s intact leg is up to 23% greater than the force going through their amputated side when using a prosthesis.

Osteoarthritis/severe joint pain

These postural changes make amputees up to three times more likely to contract osteoarthritis in their healthy leg, which is an irreparable condition that affects the joints. Osteoarthritis leads to the thinning of the cartilage, which protects the joint. As a result, bony growths develop, along with pain, stiffness and swelling.

Osteoporosis

In addition, the postural changes and uneven weight distribution affecting amputees makes them more likely to develop osteoporosis, a disease that causes bones to weaken and become more at risk of fracturing.

Back pain

According to academic research carried out in 2005, 81% of transfemoral (above-knee) amputees who attended a regional rehabilitation centre suffered with chronic lower back pain, along with 61% of transtibial (below-knee) amputees.

Phantom pain

The same study also found that 89% of all the amputees that suffered from lower back pain also suffered from a phenomenon called phantom pain.

Phantom pain refers to pain felt by an amputee from what feels like the limb that has been amputated. Some sufferers describe brief flashes of mild pain, while others have to constantly live with severe pain.

According to the NHS, there are three main theories as to why this phenomenon occurs:

• The peripheral theory suggests the result of nerve endings around the stump forming clusters called ‘neuromas’ and sending abnormal electrical impulses to the brain.
• The spinal theory puts forward the idea that phantom pain is caused by chemical changes in the central nervous system as a result of a lack of sensory input from the amputated limb. This confuses the brain and triggers symptoms of pain.
• The central theory proposes that the brain ‘remembers’ the amputated limb and its associated nerve signals. The symptoms of pain are caused by the brain trying to recreate the memory of the limb but failing as it does not receive the feedback from the limb that it was expecting.

Contractures

This term refers to the restriction of movement of soft tissues as a result of structural changes to the body’s connective tissues. The soft tissue surrounding a joint is usually elastic and stretchy, but if it becomes shortened, it can seriously restrict the motion of the joint.

In below-knee amputees this typically happens at the knee, where it becomes unable to straighten, and at the hip joint. This makes it difficult to fit, and wear, a prosthesis and can lead to significant pain and fatigue. In addition, contractures often lead to shorter steps and an inefficient gait, putting yet more pressure on the back.

Of course, these are not the only potential physical after-effects of a leg amputation, but it does demonstrate the huge range of subsequent issues and medical conditions amputees often have to live with on a daily basis.

It also reinforces the importance of physiotherapy for amputees. As Carolyn herself said at the Back to the Future Conference:

You wouldn’t give a state-of-the-art car to someone who can’t drive and expect them to know what to do.

An amputee’s whole body - not just the affected area - changes fundamentally and permanently following an amputation and the fitting of a prosthesis. As a result, they have to learn how to use it again to avoid the potential health risks mentioned in this post, which is where physiotherapy is often invaluable.