Hello dear I understand your concern Purplish color is due to healing phase of the wound called abrasion. Take orthodol tablet three times per day Apply dicofenac sodium locally Apply warm pad application Once wound heal you can take the treatment of the osteoarthritis. Generally analgesic and anti-inflammatory drug used but if will not responds and pain affect your daily routine activity then Injection of local steroid or hyaluronic acid can be used under the advice of the orthopaedics. If medicine will not respond then only option is joint replacement surgery Hope this may help you Contact HCM for further health query Best regards Dr.Sagar