With his slicked back hair and carefully practised smile, he might look your ordinary Los Angeles surgeon. However Dr Shahab Mahboubian does not specialise in age-defying face lifts, boob jobs or any other Hollywood-loved op. Instead, he focuses solely on lengthening limbs — an eye-watering procedure which can make someone six inches taller. Yet it can cost up to $170,000 (£134,000).