A contusion or bruise just means some capillaries and smaller veins have burst open within muscle or fat tissue usually due to blunt trauma. You can inject into a contusion and the solution will still absorb but it may be painful and absorption may take a little longer. Make sure you aspirate so as not to inject into an active vein. I always alternate and always do glute injections. I used to have the shaking problem until I switched to a 10 cc syringe. The larger syringe is very easy for me to grip, hold, inject and aspirate with even in my left hand. I switched to 20 guage 11/2" needles and now my injections are smooth and easy. The smaller guage needle has a larger diameter and allows for smoother injections. Syringes and needles are cheap and legal to buy at any pharmacy so you should try my sizes and see how it works out for you. The cypionate is slowly time released over a 10 to 14 day time period. Why inject twice a week with a long acting ester? It does not make any sense. Try injecting only once a week with 800 mg and the equipment I recommend I bet that solves all your injection problems.