The medical world is cheering a cheap stem-cell treatment that can help most arthritis patients avoid knee replacements. The procedure that two Indian doctors have developed helps re-grow cartilage in the knee. Dr. V. Thirumal Selvan and Dr. SH Jaheer Hussain have perfected a procedure that takes 90 minutes. The patient has to spend only one night in the hospital. And the doctors attached to the Trauma and Orthopedic Specialty Hospital (Tosh) in Chennai have done 400 successful stem-cell treatment procedures over four years. And at $2,550, the procedure is economical when compared to knee replacement costing up to $11,400. The doctors say that the procedure, however, does not cure all types of arthritis.