General causes of tendon rupture

• Direct trauma.
• Advanced age: With advancing age, blood supply decreases. This decreased blood supply to the tendon can result in weakness of the affected tendon.
• Eccentric loading: When your muscle contracts while it is being stretched in the opposite direction, increased stress is placed on the involved tendon.
• Steroid injection into tendon: This treatment is sometimes used for severe tendonitis.

Quadriceps tendon rupture

• Direct trauma to the knee just above the patella (kneecap).
• Advanced age resulting in decreased blood supply to the inside of the tendon.
• Combination of quadriceps contraction and stretching of the muscle (eccentric loading).

Achilles tendon rupture

• Advanced age resulting in decreased blood supply to the inside of the tendon.
• Strenuous physical activity by those who are not well conditioned.
• Direct trauma.
• Unexpected forcing of the sole of your foot upward (dorsiflexion of the ankle) as in landing on your feet after jumping from a height.
• Excessive strain while pushing off with weight-bearing foot.
• Having group O blood type (This is a controversial cause-and-effect relationship.).

Rotator cuff tendon rupture (most commonly to the Supraspinatus)

• Lifting a heavy object overhead.
• Direct trauma.
• Attempting to break a fall with an outstretched hand.

Biceps tendon rupture

• Forced flexion of the arm.
• Traumatic rupture usually occurs when lifting 150 pounds or more.
• Advanced age resulting in gradual weakening of the tendon.
• May occur spontaneously.