Cartilage tear
The most common site for shoulder cartilage tear is at the front of the joint where your biceps tendon is attached to the cartilage rim of the shoulder cup (labrum).
Habitually overloading your biceps muscle places excessive load on this cartilage, which can lead to its degradation making it more vulnerable to tear. Studies have shown that degradation of the biceps tendon occurs some time before labral cartilage degradation. A fairly minor jerking motion may be enough to cause a frank tear.
Your triceps tendon also attaches deep into your shoulder joint to the cartilage at the back, which is also a frequent site of cartilage tear.