Rohan's sickening first-quarter collision with Cameron led to the Cats' leading goalkicker being stretchered off the ground and taken to hospital.
But with Rohan shining in attack and their back-line resolute, Geelong overcame the significant setback to post a stirring 11.12 (78) to 8.15 (63) win at GMHBA Stadium.
It came on the back of a stunning six-goal burst in the final term, marking dual premiership coach Chris Scott's 300th game at the helm in style.
The result balanced Geelong's season record at 7-7 in a year when their resolve has been regularly tested.
The Cats were out-muscled at stoppages, losing the clearance battle 47-35 as Demons midfielders Christian Petracca (33 disposals, 10 clearances) and Jack Viney (25, six) starred.
But Mitch Duncan (22 disposals, one goal), Tanner Bruhn (19, two), Mark Blicavs (19, one), Tom Atkins (19 touches), Brad Close (24) and Tom Stewart (22) all had an impact, and Geelong ran away with the game in the final term.
Stewart, Zach Guthrie and Jake Kolodjashnij impressed in defence.
The fallout could yet get worse for Melbourne (9-5), with leading goalkicker Bayley Fritsch to come under scrutiny for a dangerous tackle on Kolodjashnij.
A free kick was paid to Kolodjashnij, who was not seriously hurt in the final-quarter incident.
Cameron's injury held up play for almost 10 minutes during the opening term and left Rohan visibly upset as his teammate was assessed by medical staff before being driven off the field.
The goal-sneak responded with a team-lifting major before quarter time, steering the home side to a nine-point advantage at the first change.
Melbourne also suffered an early injury scare when Viney hurt his right shoulder but the tough midfielder soon returned to the action.
Joel Smith's two first-half goals helped the Demons snatch a one-point lead by the main break.
Rohan's second goal briefly put the Cats in front in the third term and they seized control again when Henry and Zach Guthrie kicked the first two majors of the last quarter.
Another goal to Blicavs, from a chain that began with Atkins' pressure act at the opposite end, put the Cats 12 points up in a low-scoring contest.
And when Rohan beat Steven May in a one-on-one contest moments later to run into an open goal - for his third - the Cats were just about home.
Rohan received a standing ovation as he ran to the bench and Duncan iced the game with the Cats' fifth consecutive goal.
Smith, Fritsch and Kysaiah Pickett finished with two goals each for Melbourne.
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