KATHMANDU (Reuters) - A man with an artificial leg reached the summit of Mount Everest on Tuesday with a colleague who had conquered the peak just seven days earlier. Nepal‘s tourism ministry said Tom Whittaker, a 49-year-old British-born American who is an outdoor pursuits instructor living in Prescott, Arizona, reached the highest point on earth, 8,848 metres (29,028 feet) above sea level, at 7.00 a.m. (0145 GMT). Whittaker lost his right kneecap and foot in a car accident and wears an artificial leg fitted below the knee. He told Reuters in March that he was determined to be the first disabled person to climb Everest and show what the disabled can accomplish. He said that it takes him 30-35 percent more energy to climb mountains than able-bodied people. Whittaker scaled Everest by the standard Nepalese route via the southeast ridge during Tuessday night. He had left his highest cammp, at 7.900 metres (26,000 feet), at 11 p.m. Whittaker reached the top with four Nepalese sherpas — Lhakpa Tshering, Da Sonam, Tashi Tshering and Norbu — and another American, Jeffrey Rhoads, who had already accomplished the feat on May 20 but decided to do it again with his disabled friend. Rhoads, 43, is a photographer and mountain guide from Pocatello, Idaho. The men stayed at the top of the world for 20 minutes. Whittaker had told Reuters he would be using an oxygen tank during the last two days of his final push for the top. On May 20, he climbed as high as 8,230 metres (27,000 feet) before having to turn back because of a pulmonary infection. He had also attempted Everest in the spring of 1995 from the Tibetan side of the mountain.