This refers to the tearing of the Achilles tendon which joins the large calf muscles to the heel bone (calcaneus). Ruptures or tears may be partial or complete. They occur due to forcible contraction of the calf muscles against resistance, often as part of a dynamic lunge or starting a sprint. Similarly landing in jumping sports can cause tears. This injury is most common in athletes in their early 40's and is particularly common in people returning to sport after several years off.
You will experience a sudden intense pain at the back of the heel often associated with a loud pop. People often say it feels like they were hit with something (squash opponents often get accused of hitting their partners!). There will be immediate weakness, and an inability to go on to tiptoes. With partial tears the clinical picture can be less pronounced. You should cease sport and seek urgent medical attention, this usually means going to casualty. Rest, ice, elevation and compression can be useful to minimise bleeding.
If you think you have this condition it is well worth getting it checked out by Mr Willis-Owen. You local hospital should apply a plaster cast. This won't get better on its own!
Treatment involves first confirming the diagnosis. This is sometimes very obvious from examining you but if there is doubt an ultrasound scan or MRI scan can be useful to confirm the diagnosis. There is debate about the best form of treatment for complete tears, with the choice between a period of time in plaster casts and surgical boots, or surgery and a period of time in plaster casts and surgical boots. The surgery has some risks with wound healing, but achieves a better functional result. Avoiding surgery avoids some of the risks, but the chance of re-rupture is a little higher and some muscle strength may be lost as the tendon heals at the wrong length. Every case is different depending on the site of the tear and various factors regarding the patient. It is best to discuss the options face to face with Mr Willis-Owen as soon as possible after your injury. If you need surgery it should be done within the first week to ten days. This is a significant injury and will keep even top athletes off sport for several months.