Hello,
I've rarely poster here tho I'm an avid reader. Please excuse if I don't follow all protocols.

This topic is close to my heart as I was diagnosed with cancer in my left arm in 2005 and lost most of the use and feeling in my left hand as a result of surgery. That was the end of over 40 years of guitar playing as I knew it. After years of missing it I began investigating smaller instruments. Sometimes called parlor guitars, these 3/4 sized instruments have scale lengths of around 23-1/2" vs regular guitars which are around 25" and up. Martin and Taylor currently make inexpensive acoustic travel instruments in this category. For jazz, you have to go back a ways and/or pay more--'50s Gibson ES-140, also Benedetto Andy. And the Les Paul Junior is a small sold body. There are others.

I'll never play 4 or 5 note jazz chords again, but instruments like these have helped me recover some of the joy of playing. I also found a small Ibanez microbass (24.8" scale) that has been very satisfying. Never played bass but always loved playing bass lines on guitar and this thing has been a blast. Mostly one note at a time helps a lot.

+1 to KHARMA's post
I have the same left hand issue with my pinky hurts on some chords,, I have just simplified my chording. I also have a frozen right shoulder and cannot play a full size accoustic anymore. 
I love Yamaha APX guitars, I had an older one that I wore out after 20 years so like a fool I sold it cheap to a person who wanted it badly..
So I found my self shopping for another small bodied Acoustic Electric.
The newer APX = I didn't like the electronics. Very uneven volume from string to string.
I love my Taylor mini GS and highly recomend that if you have $800
I also bought a Art and Luthier Folk which I play at work ( Care Facility ) for hours on end. 
You can also meet in the middle and buy a nice Jazz style electric. 
Taylor and many brands make very nice Jazz style guitars. If your just sitting on the couch thats all the volume your really need. I have an old Guild T100 I use for my couch guitar. I put flat wounds on it it is the easiest guitar I've ever played. It's loud eneough to fill a small room too. 
 
 

I have arthritis in the middle and front joints of all my fingers though most prominatly in the end joints of the middle fingers of both hands. There are certain chords I can no longer play or can do them with great difficulty. I will take 2 alleve and soak my hands in hot water followed by rubbing them down with rubbing alcohol. The limitations have forced me to rethink the chord inversions I choose. Single notes are ok for me but with some discomfort. I also play bass and have found that the much wider neck on my 5 string is a bit easier as it forces me to play a little more flat fingered. I wish you the best.
 

I just turned 64 and have arthritis (osteo), mostly in my spine but my fretting hand, index finger, middle knuckle gives me trouble after a bit sometimes. Voltaren Gel helps a lot, it kelps with knees and ankles too... not so much for the spine but I have other things for that. Voltaren Gel is a prescription med. I asked the doctor about it getting in my blood and NSAIDs building up. He said it pretty much stays where you put it, what gets in the blood is negligible. I recommend it. On a bad day you will probably just have to play through it. I hope you get relief.
J
 
EDIT> I don't know if you need an acoustic/electric but if not I find the Taylor Bog Baby a very comfortable guitar, I usually tune down a half step but that is so I can do bends more easily. I don't know how the Fender acoustic guitars play but if I were you I would try taking a trip to a Sam Ash or a GC and play guitars until you find one that works for both your finger and your body. A Line6 Variax might be a good option for you. I imagine it would be easier to play and maybe it has a decent acoustic model. If the Bog Baby works for you but you need electronics you might try the iRig Acoustic from IK. It sounds decent, amplifies through an iLOUD, and has several body models and some FX. I like it and it is only $50.00 pus $10 for the APP. Of course you can use it on any acoustic. Something to think about. I remember those old Ovations, they played like an electric but would always slide off my knee, lol.
http://www.ikmultimedia.com/products/irigacoustic/ you run it through an iPhone or iPad into any line in source, powered monitor or mixer. So, it could help your choice of guitars to not be limited to ones with onboard electronics, if that matters.
The Taylor Big Baby is a bolt neck but sounds fine to me. It is also 15/16ths size. The back is slightly bowed out, I think it gives it a little better tone.
 
 
 
 

Try a guitar with a more rounded radius if your doing chording.  Original old Fenders had a 7.25 radius instead of the modern 9.5 radius.  Test different neck radius' and also width until you find the combination that is most comfortable.  Fender, Gibson and PRS are easy to look up specs.  Then go to a music store and try models you know the specs.
 
You hand will tell you which is best.
 

Ricebug
... 
Now, where is my In-A-Gadda-Da-Vida lead sheet?!?!
...

PM/track down forum member bitflipper. He and his band played a 30-minute version of IAGDV in Augsburg, Germany when I was stationed there in 1971. I bet he could help you out! 

I haven't read all the posts above so I don't know if this is a repeat...
 
Consider using a Capo. That will reduce the action across the board and might demand less work from your hand.

I came down with rheumatoid arthritis a number of years ago.  My doctor put me on heavy doses of ibuprofen that not only helped my arthritis but also raised my blood pressure to sky high levels..  After hitting the books I stopped taking ibuprofen and started the over the counter Glucosamine &  Chondroitin (Glucosamine hydrochloride 1500 mg - Chondroitin sulfate sodium - 1200 mg) tablets.  I can now play guitar again and my blood pressure is normal.  YMMV
 
A pedal guitar has been mentioned as a playing option. You might want to try raising your strings with extension nut,
http://www.stewmac.com/Materials_and_Supplies/Nuts_and_Saddles/Grover_Perfect_Guitar_Extension_Nut.html
 
buying a slide
http://www.stewmac.com/Materials_and_Supplies/Accessories/Capos_and_Slides/Shubb-Pearse_Guitar_Steel.html
 
and play some slide guitar.  This just might be an inexpensive alternative to purchasing a pedal guitar.
 
Just my thoughts.

I don't go with taking pain killers to solve the problem,, 
That will probably kill you sooner than the arthritis would. 
Medical doctors prescribe pharmaceutical, it's just good business practise. 
I'm going to go to a Naturepath and see what they can do with the alternatives. 
Diet is a big part of reducing inflammation in general. 
It might mean giving up dairy and Wheat or something like that but I'm willing to give it a try. 
 
Yes taking up slide guitar is an option, any type of slide including pedal steel , but there is lots of music played with bottleneck and slide techniques. 
 
Take up playing bass, Bass does not bother my hands at all because there's no string tension. 
Take up the drums , the keyboard ,,, just about a million ways to play on really. 
 
As far as guitars go, a shorter scale lenth helps. Taylor makes 12 frets that are very easy to play. My Taylor GS mini it very easy on full chords.
I bought this Yamaha 3/4 size student acoustic for my grandson. I am now looking for more 3/4 sized guitars for my self. I once had this old Fender ?? musitang?? that was small. 
I

MarioD
After hitting the books I stopped taking ibuprofen and started the over the counter Glucosamine &  Chondroitin (Glucosamine hydrochloride 1500 mg - Chondroitin sulfate sodium - 1200 mg) tablets.  I can now play guitar again and my blood pressure is normal.  YMMV
 

In addition to the above, which many of my friends take for knee pain, neuralgias, sciatica, etc...I have found curamed (a turmeric product) to be possibly very good for my salivary gland cancer and radiation side effects as a natural anti-inflammatory.
 
Also, when I had a neck neuralgia in the 90s, I gave up red meat and became mostly vegetarian. Among the really good food groups for anti inflammatory are any alliums especially garlic, capsaicin, black pepper, turmeric...That really helped, red meat is horrible for arthritis.
 
The transition to a veggie diet takes a while, it took us a year or so, start with one meal a week, but I had help learning to cook from my wife's Asian friends where meat is just a small ingredient in stir fries and I learned a lot from Lidia's Kitchen (Italian) on PBS.
 
I agree natural is the way to go :)