Study of Safety and Efficacy of Diractin® for the Treatment of Osteoarthritis (OA) of the Knee

Inclusion Criteria: * Informed consent signed and dated * Age \> 45 years * Class I-III OA of the knee and subject meets American College of Rheumatology (ACR) clinical classification criteria for osteoarthritis of the knee Exclusion Criteria: * Skin lesions or dermatological diseases in the treatment area * Directly or indirectly involved in the conduct and administration of this study * Received any investigational medicinal product within 30 days prior to Screening Visit or participation in any previous clinical study with Diractin® * Pregnancy or lactation * Residents of psychiatric wards, prisons or other state institutions * Malignancy within the past 2 years * Depressive disorders requiring treatment with tricyclics, treatment with other antidepressants must be stable for 3 months prior to screening and throughout the study * Epilepsy * Schizophrenia * Neuropathic pain and any other pain condition requiring chronic use of pain medication * Known hypersensitivity or allergy (including photoallergy) to NSAID´s including ketoprofen and to ingredients of the IMP * Preexisting asthma or bronchospasm after taking aspirin or other NSAIDs * Unable to discontinue analgesic therapy including opioids, NSAID´s, tramadol, muscle relaxants, gabapentin, pregabalin, duloxetine, venlafaxine, capsaicine or other drugs approved or used for the treatment of pain for the duration of the study