A police manhunt is continuing for three robbers who stabbed property developer Bo Khan in the arm before yanking a £115,000 Breguet Tourbillon watch from his wrist in Mayfair.
Mr Khan, 55, said police had told him gangs were deliberately slashing the elbow tendons of victims to paralyse their arms and prevent them from fighting back.
He was targeted in Berkeley Square while with wife Karen in June.
They gave chase in a black Audi, whose driver stopped to help, but the muggers — caught on CCTV — fled down a side street.
Mr Khan, from Manchester, escaped lasting injury.
The attack took place about a mile from where student Mohammed Abdullah Al Araimi, 20, was stabbed to death in an attempt to steal his Rolex in December.