The achilles tendon is the largest tendon in the body but also the weakest in terms of the stress placed on it. For example when a person jumps up and lands the Achilles tendon experience upto 90% of the force required to rupture it. So a little bit of weakening of it can go a long way.
Common problems include:
Achilles tendonitis: Inflammation around the tendon itself often due to overuse.Treated with rest, PT, heel lifts and NSAIDs (MOtrin etc.)
Non/Insertional Achilles Tendonosis: Thicken of the tendon when compared to the opposite achilles. Painful may have an inderlying tear which requires MRI or ultrasound evaluation. May require rest/bracing, injectionsand ocasional if unresponsive surgery.
Bursitis/Pump bump: Painful lump on the back of the heel . Maybe due to a bony bump, a bursal sack (of fluid) or both. Treated with shoe changes or surgical removal.