How deep is the injection of steroid for a keloid scar from achilles surgery?

Steroid : The corticosteroid injection is placed into the dermis , the layer of skin beneath the upper portion of skin or epidermis.

Steroid in scar: Keloids can be treated with steriod injections to try to soften them. The steriod is placed directly into the scar to slow the body's ability to maintain the overgrown scar and to allow the body's natural ability to reduce the scar to prevail. Since this weakens the scar tissue, it is common for the scar to widen as it flattens. The injection should avoid the tendon itself.

Skin: Injection is into the skin or dermis as injection into the achilles itself may cause a rupture of tendon.

Extreme caution....: This is a tricky area to do steroid injections. Maybe try some topical verapamil cream first to try and reduce the keloid. It couldn't hurt to try topical first.