martially taiji ( taijiquan / tai chi ) , any qigong including bagua zhang or just some plain old silk reeling and warm ups alah chen style, will no doubt help.
I'm half looking into this for a future thesis component myself ( stretches / bodily fluid / joint repair / protein - sulfuric gluco / ph bio fluidic balance and tissue repair and construction etc) , and I sincerely believe it's a combination of both diet and stretching / light exercise.
I have seen many documentaries in this regard, but one that stands out was one on a woman 90 ish yrs old who was diagnosed with the same thing...... they told her to rest and she decided to take up pilates. That was 30 + yrs ago and she is now so healthy , the dear old grams is not only an instructor herself but practically a contortionist god bless her !!
I have theories on stretch therapy myself, but either yoga or pilates will almost definately help your wife out here .
Msm as a dietary supplement is also a great joint repair product! it works on principals of sulfur rebalance and heat / destablisation and cleansing of your intestinal contents respectively changing the quality , viscosity and ph of your bio-fluids and how they respectively stimulate various micro celluar reactions.
If you're anything like myself, and prefer more natural / less chemical cocktailed means, you can re-create the same effect via upping your soluable protein intake ( being that's where we find the bulk of our sulfur ) ( like fish / eggs as best source / milk / cheeeses / duck is a great one to occassionally incorperate / and maybe even a protein shake) ........
the reason being because joint repair is directly relative to sulfur in our bodies...unfortunately unless we OD ( over dose ) on the rdi ( reccommeded daily intake ) of protein, you won't get the sufficient amount for total immune repair ( also being somewhat relative to lymphocites ( or toxin clusters / white blood cells ) .....
protein however will tend to make us sleepy in high portions so to combat this utilising principals of catabolism ( non absorbtion into tissues and fibres etc) , and incorperating a protein cutter like hot and cold water and the heating aspect directly after (or with) protein consumption from a short shot ( 20 mls ish dry or straight ) or 2 even of the highest proof alcohol on hand ( red wine failing that)......... you will cause a very rapid and unique break down process of enzymes and your body will absorb only what is neccessary to produce this msm type principal........
to complete the effect , add a cup and it's refill of a lipid balancing tea or green tea of an evening.......... do one cold and strong in the morning ........ making sure to incorperate your wet fruit and unstarched veg fibers........and you have the same effect, but all natural.
Just beware to limit that alcohol intake to 2 shots in the morn, + 1 at night as a total max ( 2 per first hour and 1 each hour there after being safest recommended consumption ) and not only should she not get drunk from it ( being it's too cushioned in the proteinic enyzme and absorbtion is greatly lessened to near irrelevant quantity ...as opposed to anobolic metabolisation) .providing she keeps up 1.5 lt water comsumption daily and preferrably of a night ........there's no reason she should ever end up drunk nor lacking repair system function...........
not from these means anyway
Either way, at min, try her out on the stretch / pilates incorperation and she'll be back to better health in no time

:asian:
cheers
BL