The stevedore was admitted to Royal Melbourne Hospital after the straddle he was operating toppled yesterday. Initial tests indicate his spinal column is intact, but he has a broken pelvis and will require an operation on his arm.
It follows an incident last month in which another stevedore was injured while using the same batch of straddles.
MUA Victorian Branch Secretary Kevin Bracken said the union had offered support to the injured worker and his family.
"Our thoughts are with our member and his family who are hoping he makes a full recovery," Mr Bracken said.
"The fact remains that waterfront workers are 14 times more likely to be killed on the job than the average Australian worker."
Mr Bracken said the run of injuries underscored the urgent need for a National Stevedoring Code of Practice for safe work on the waterfront.
"A National Stevedoring Code of Practice would improve safety and save lives on the waterfront. It is long overdue," Mr Bracken said.
"Waterfront workers need employers to stop throwing up obstacles to the establishment of a Code of Practice. We need the rules to be set hard and fast so we can minimise injuries and deaths in this dangerous environment.
"The MUA will not rest until better safety standards are established on the waterfront. The proven way to protect and boost workers' safety in dangerous workplaces is through a strong and active union presence."