outcome measures for lower limb exercise groups

Run a group exercise programme concentrating on strengthening and reconditioning for patients with arthritis hip knee or ankle. Occasionally some post POP cast removal. Looking for lower limb specific disability scales. Any ideas? We use Quebec and Oswestry for back pain clients but are looking for validated outcome measurements for lower limb problems. Thanks

I work for a company trying to introduce a system of applying graded exercises known as "Medical Exercise Therapy" and have some information on lower limb disfunction.