Total knee arthroplasty (TKA) is performed more than 7.000 times a year in Finland most often for osteoarthritis (OA). While pain is predictably reduced, function does not typically ever reach that of age-matched, uninjured subjects. Quadriceps weakness has been implicated in the development and progression of knee OA and is a significant problem after TKA. Advance to return to normal daily activities is not sufficient to restore knee function or quadriceps strength after TKA.

The aim of this study is to assess the effectiveness of progressive exercise program restoring knee strength, mobility and improving the functional outcome after primary TKA.

Many studies have shown, that after TKA pain decreased significantly, but muscle strength of the operated knee did not recover and may stay under the preoperative level. To find out the effects of progressive exercise program we will perform 6 weeks after TKA a randomized clinical trial of lower extremity strength training using two subgroups of people: traditional exercise group and progressive exercise group.

Inclusion Criteria:

• primary unilateral TKA for knee osteoarthritis

Exclusion Criteria:

• Rheumatoid arthritis, fibromyalgia, bilateral TKA, heart or lung disease, which prevent training, unstable serious disease (cancer), reduced co-operation (drug, alcohol abuse, mental illness)