1. Use trekking poles, as Dougfitz recommends - They DO help reduce the strain on hips and legs.
2. Use topical anti-inflammatory ointments before sleep and before starting out in the morning. Voltaren is VERY popular along the Camino. Another good choice is
Hidrotelial Luxoben Masaje Corporal FORTE. This is a pump ointment containing a whole bunch of holistic and organic stuff. All I know is that it sometimes works much better then Voltaren or other sports creams. Both Voltaren and Luxoben are available in ,most all farmacias in Spain. The Voltaren should also be available at home in Ireland. In Europe it is OTC (over the counter). In the US, a prescription is required.
3. Consider using a timed release, arthritis strength pain reliever of you choice and medical capabilities. I use a time-release Paracetamol / Tylenol / Acetaminophen pain reliever in the morning with breakfast (such as it is) before starting out for the day. The two, 650 mg tablets I take are good for eight-hours. That sees me through the end of my typical walking day. The eight-hours works with my end of day drinking schedule, so the two do not interfere. If I find I need more before the eight-hours are up, I take regular 500 mg extra strength tablets instead, to hold me over until "tea time..."
A chronic medical condition precludes me from taking ibuprofen or naproxen sodium. But, if you have a chronic condition, like scoliosis, consider taking an Arthritis formula, long-acting, timed-release pain reliever BEFORE your start out in the morning. If you wait until you are in pain, that sucks.
I am NOT advocating preventative pain relief if pain is not reasonably expected.
I too, have early onset arthritis and I KNOW that once I walk about 30 minutes, my hips, knees and ankles will start to ache, usually in that order. As my certainty of discomfort is near 100 percent, taking the timed release pain reliever does help prevent delay or mitigate the coming discomfort and prevent my walking day from sucking.
Finally, I am NOT aware of any sort of support that holds hips. Last year, I started form Madrid in April, but had to pull the plug on my fourth Camino at Sarria when knees, then ankles, and eventually hips, started protesting. It ceased being enjoyable.
The ONLY thing that comes to mind that MIGHT help would be something like SPANX, like a girdle, if you will. If you wear something like that, that is elastic and very supportive of your hips, it MIGHT work.
IMHO, the "snugger" it is the better it will provide support to your bad hip, but do not cut off circulation. Of course, you will be making a tradeoff of support versus comfort in the heat. Still, it is just a thought...
I hope this helps.