Sharpe and Simpson, who ran Ideal Mobility Solutions, mainly sold ordinary mattress covers that were claimed to have health benefits for ailments such as bad backs and stiff joints.

BBC: Mobility aids con salesmen jailed

It will not come down until the two countries loosen their labour markets' famously stiff joints by cutting minimum wages, making hiring and firing easier, reducing payroll taxes and so on.

ECONOMIST: Jobs

Technology developed at MIT's Leg Lab, where Dilworth works, allows researchers to make robots with springy joints, not stiff ones.

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