A rupture of the Achilles tendon is not an uncommon problem in sport and is very dramatic if it occurs, since the calf muscles and the connected Achilles tendon play such an important function. It is more likely to happen in explosive activities like tennis. The real issue is that the achilles tendon and the two muscles connected to it cross two joints (the knee as well as the ankle joint) and if the two joints are moving in opposite directions simultaneously, especially if suddenly (as can happen in tennis), then the probability of something failing is pretty high.
The management of an achilles tendon rupture is a bit controversial with there being two options that almost all the published research shows have got quite similar outcomes. One option is conservative and the other is surgical. The conservative option is typically putting the leg in cast that holds the foot pointing downwards a little. Usually it takes approximately six weeks to heel up and after the cast is removed, there should be a slow and gentle return to physical activity. Physical rehabilitation is normally used to assist with that. The operative option is to surgically stitch the two edges of the tendon back together, this is followed by a period in a cast that is shorter than the conservative option, and will be followed by a similar steady and slow return to sport. When longer term results are compared the final result is generally about the same, but the surgical procedure has the additional risk of surgical or anaesthetic complications which the conservative strategy doesn't have. The choice as to which method is better is going to have to be one based mostly on the experiences of the surgeon and the preferences of the individual with the rupture. There is a tendency for competitive athletes to go on the operative pathway as it is believed that this will give a improved short term outcome and get the athlete back to the sports field quicker.