Hello and thanks for researching this important question!

You may need to seek an opinion at a major medical center, since your local vets cannot answer your questions. What to do about a TPLO failure depends on how the original surgery was performed and what has gone wrong...you likely need a specialist.

http://www.sancarlosvet.com/Other/Prof/TPLO/

Orthopedic specialists at the University of Pennsylvania in Philadelphia can be reached through the following link:

http://www.vet.upenn.edu/ryan/

Here is the referral link to Cornell University's Veterinary Hospital:

http://www.vet.cornell.edu/hospital/

These two centers should also have a referral listing for specialist nearer to your home, if available.

It may be that since the surgery performed is not in use it cannot be repaired using the same methods, but you need a consultation with someone willing to re-examine and take a creative approach to an alternative.

This search can take some time, so do not give up...you may also need to widen your distance perimeter to find such an artist.

This would be somewhat akin to finding help with a badly injured leg from, say, a car accident...there may be permament damage to the structures inside this knee. Many surgeons will feel unable to help you (and it is good when they honestly say this!), but you can come across someone who can visualize a good way to improve this condition. There must be some way to stabilize this joint...it may not be very terrific, but better than what your dear pet is coping with now.

You can also correspond with the American College of Veterinary Surgeons and ask for referrals to board certified surgeons. The most current phone number is listed as 301-718-6504.

Do continue trying to reach out to the major Orthopedic centers at the Veterinary Colleges at Penn, Cornell, Michigan State, etc...these are places with the highest concentrations of the kinds of creative engineers you need:

http://cvm.msu.edu/vth/index.htm

http://www.cvm.uiuc.edu/

Do enlist the assistance of the second opinion that you already have: they may be able to send digital pictures of the latest xrays (or mail the films...this just takes longer) to other specialists at a distance.

A workable "fix" can be very expensive. You may find relief (and even advice) through the following organizations:

www.carecredit.com

www.help-a-pet.org

www.imom.org