Two firms have been ordered to pay nearly £50,000 in fines and costs following an investigation into the incident on 5 January 2012 by the Health and Safety Executive (HSE).
Derby Crown Court heard Vincent Sutton, 49, from Mossley, had been delivering the 5m long rectangular frame to Delpro on the Brookfield Industrial Estate after it had been manufactured by his employer, Russell Fabrications (UK).
The frame, known as a skid, had been loaded onto a pickup truck at an angle using an overhead crane and chains, with the top end resting on a supporting bar above the driver's cab.
When the frame arrived at the Delpro plant, workers lifted it off the truck using the same chains, this time attached to a forklift truck. The chains consisted of two separate sets, one of which was significantly shorter than the other to allow for the angle of the lift.
As they lifted the frame, the shorter chains – attached to the higher side – forced their way out from the hook on the forklift truck. The frame fell around two metres to the ground and landed on Mr Sutton's left foot.
The damage was so severe that his leg eventually had to be amputated to above the knee for medical reasons.
The court was told neither of the companies had planned how they were going to safely lift the metal frame onto and off the pickup truck, and that both the truck and the lifting equipment were entirely unsuitable for the job.
Russell Fabrications (UK) also failed to make adequate arrangements for the metal frame to be transported safely.
Delpro, which designs and assembles equipment for packaging and printing industries, pleaded guilty to a single breach of the Lifting Operations and Lifting Equipment Regulations 1998 by failing to ensure the work was properly planned, appropriately supervised and carried out in safely.
The company, of Peakdale Road in Glossop, was fined £12,000 and ordered to pay £8,735 towards the cost of the prosecution on 27 February 2015.
Russell Fabrications (UK), of Wood Street, Ashton-under-Lyne, was fined £11,917 with costs of £13,734 after being found guilty of a breach of the Health and Safety at Work etc Act 1974 following a trial.
HSE inspector Scott Wynne said: "The failings of both companies contributed to this incident, which could so easily have been avoided had more thought gone into the planning of the loading, unloading and transport of the metal frame.
"The methods adopted for both the loading at Russell Fabrications (UK) Ltd and the unloading at Delpro Ltd were inherently unsafe and the vehicle used to transport the frame was unsuitable as the loading area was too small to safely accommodate it.
"Unfortunately the failings of the two companies have led to a worker suffering life changing and permanently disabling injuries."