"maintained better" is grammatically correct and can be used in written English.
Example: The new cleaning routine has helped the restaurant to be maintained better and keeps it consistently spotless.
By 600m the Italian was more than four seconds clear of the field and he maintained better than world record pace at nearly every turn to lead by six body lengths at the 1000m mark.
Some banks, for example, believe that their loan portfolios are less risky because they maintained better underwriting standards or operated in housing markets that did not experience a big run-up in prices.
He resided much of the time not in the capital at Luang Prabang but in Vientiane, which was located farther south and maintained better communications with the major states of the region.
Similarly, the survival of leukocytes was maintained better only with UFH and LMWH (right).
Roma VF tomato harvested at mature green stage maintained better chemical quality and marketability during storage.
The phenotype of the cells is maintained better in larger pores.
Some improvement plans — like maintaining better classroom order — could last a month.
After an abortive attempt to introduce trade monopolies, Ibrāhīm encouraged European traders by maintaining better security.
Accident-avoidance systems are designed to help the driver maintain better control of the car.
Prof Ian Bogost of the Georgia Institute of Technology says: "You could say they are doing this to maintain better creative control.
Johnson is 6 feet 7 inches and has tried to maintain better posture to relieve pressure on his scapula.
