A grown German Shepherd is usually 50 to 90 lbs and measures roughly 38 to 44 inches from nose to the base of the tail, long-bodied, with a sloped back that puts real load through the hips.
Shepherds are commonly affected by hip and elbow dysplasia, and the breed is also predisposed to degenerative myelopathy, a progressive condition of the spinal cord that shows up in the back legs. Neither is inevitable in your dog. But if you own a Shepherd, the back end is the thing to watch, and the thing to make easy.
That changes what matters in a bed. Support is only half of it. The other half is getting in and out without climbing. A tall rim she has to lift a weak hind leg over is a bed she'll eventually stop using.
Egg-crate orthopedic foam takes the pressure off the hips while she rests. A low, open front means she doesn't have to negotiate the bed to use it.