Hi Taffy:
You do't say what the other health considerations are, or if they are likely to affect the op itself or its outcome.
The important thing is to be very careful about how you select your surgeon and the anesthetist. Both are crucial to its outcome. The other important consideration is the type of anaesthesia you decide upon, and this decision my be based on other unrelated conditions that may affect your safety during surgery.
I had a spinal/epidural with sedation. You are out for the count, but it is not a general anaesthetic. You simply have a needle, almost a "pinprick" in the lower part of the back and in most cases, that's it, and you wake up in the recovery room. There is also the option of just having the anaesthesia without sedation. You are aware of what is going on, but probably cannot see it, because you would need to be in a best possble position on the table for the surgeon to access you hip easily.
All major surgery contains risks, the trick is to find your best surgeon and anaesthtist, check them out and then take it from there. Your GP has your medical history, and a pre op assessment will be done at the hospital so that there is double protection.
In most UK hospitals you are out of bed walking on a frame with the help of a physiotherapist, who will guide you and not permit you to do too much. You will be give pain killer first as it can be quite painful when you put your weight on the hip for the first time. Second day, you are on sticks walking the corridor and learning how to manage stairs. This is the general program, but it may vary. I was in for three nights and released on the fourth day. The first two weeks post op are challenging, but from that point on, there are gradual daily improvements. I have just started my fourth week, and am already walking outside with two sticks, but walk around the house unaided, unless I feel a little wobbly.
My first op was lateral, few restrictions and a great surgeon.
The pain that you are feeling in your knees is probably hip pain radiating from the hip. I do not know how long you have been living with this, how old you are, and which other factors need to be considered. Do you think you may have arthritis in both knees? I was told that the pain in y knee was radiating from the hip - so there you go! May not be quite so dire as you are fearing!
The main thing is that you will have a new hip/s, be pain free and mobile again, and that is the outcome.
However, as I have already said,I do not know whether you have other medical conditions that may affect the outcome or decision to go through this surgery.
I have heard of patients who have had both hips replaced in the same surgery, but that would depend on necessity and the overall condition of the patient, not to mention the recommendations of the medics.
I hope that I have helped and reassured you, just a little.