Repeated irritation to the upper part of the shoulder joint by either the defective bone from birth (hooked acromion process), or sports or exercises in Gym. some time leads to inflammation & swelling ,pain to the subacromian bursa which is a balloon like thing that lie s between the two bones to work like shoke absorber. The primary treatment is always the rest, physiotherapy & medicines. If all fails surgery is the choice, and arthroscopic subacromian decompression is the best available tool to get relive from this. The man usually gets relive within days & goes to his regular duty without any residual problem.