Tendo Achilles is the strongest tendon of the body. It connects the bulky Gastro-soleus muscle of calf to the posterior aspect of heel bone (calcaneum). Blood supply of Tendo Achilles is limited. Due to this paucity of circulation microinjury of the tendon from daily activity does not heal properly and accumulates. This makes it prone for degeneration and vulnerable to injury. 

Achilles tendon injury is of two type acute traumatic or chronic degenerative. Acute rupture of Tendo Achilles usually happens in young individuals when foot is forcefully moved upwards at ankle and calf muscle is engaged. Commonly associated with RTA, steeping in a hole and sports related activity. Or direct injury from a sharp object. This injury is associated with contaminated local wound and exposed cut tendon. 

Degenerative rupture of Achilles tendon happens due to tendon degeneration from non-insertional or insertional tendinosis and repeated loading of the tendon. Rupture usually occurs at 6 cm from its attachment with calcaneus. There are few risk factors associated with Tendo Achilles rupture. Male ages from 30 to 40 are more prone to injury. Sports involving running, jumping, sudden starts and stops are high risk for injury. Local steroid injection around the tendon or intake of fluoroquinolone antibiotic increases rupture risk.

Acute injuries are always painful and often patient feels a pop during the injury. Patients cannot walk or stand following injury. Chronic degenerative injuries may go unnoticeable but acute injuries are always symptomatic. Most of the time one may feel being kicked off at back of the leg, feeling a pop on snap followed by severe pain and swelling at rupture site. Inability to stand on toe tip and push off while walking. Acute injuries are very obvious on clinical examination. There is always a palpable gap indicating tendon discontinuation. may not need any investigation but if there is any risk factor for tendon degeneration then an ultrasound or MRI should be done to assess the integrity and health of tendon. 

Whenever you feel pain at back of ankle near Achilles tendon with difficulty in walking you should visit a specialist foot & ankle surgeon.

He will do a clinical examination following your history and symptom analysis. He may ask you to get an x-ray along with a MRI or USG. MRI and USG is required to evaluate degenerative status of tendon.  

For acute traumatic rupture treatment option is surgical repair of the tendon. In degenerative rupture both surgical repair and cast immobilization is recommended. Depending on patient profile and activity demand.