Cavani, 31, hobbled off after scoring from the penalty spot in PSG's 1-0 win over Bordeaux at the Parc des Princes on 9 February.
A club statement on Sunday said the striker had sustained damage to a tendon in his hip. "The tests carried out have shown an injury in the right hip. The treatment and the amount of recovery time will depend on how he reacts over the next few days."
Meunier joined Cavani on the sick list following the victory which extended PSG's lead to 13 points over second placed Lille.
The 27-year-old Belgium international suffered a slight concussion following a collision with the Bordeaux striker François Kamano.
Cavani's strike on Saturday took his tally to 17 in Ligue 1. He has also netted twice during the group stages of the Champions League.
PSG will travel to Old Trafford without the services of Neymar. The 222 million euro striker is sidelined until at least April with a foot injury suffered during PSG's 2-0 win over Strasbourg in the Coupe de France on 23 January.
However there was a ray of light for the PSG boss Thomas Tuchel. Defensive midfielder Marco Verratti emerged from the Bordeaux match unscathed. The 26-year-old Italian had been out for three weeks nursing an ankle injury.
"Verratti can play and will play," said Tuchel. "I'm worried because we are missing key players. For the big games in the Champions League, it is absolutely necessary to have key players with a lot of experience".
PSG have been eliminated from the Champions League at the last 16 stage for the past two seasons
Last year under Unai Emery they lost to the eventual champions Real Madrid. In 2017 against Barcelona, Emery's men contrived to squander a 4-0 advantage from the first leg ultimately losing 6-5 on aggregate.
Tuchel, 45, was brought in with great fanfare to eclipse Emery's record.
However, while the Spaniard steered PSG to a domestic treble of league title, Coupe de France and League Cup in 2018, Tuchel will not be able to emulate such feats as his side were beaten in the last eight of the League Cup by Guingamp.
When the draw for the last 16 was made, PSG were favourites to advance against an increasingly clueless and dishevelled Manchester United side.
But with the dismissal of United boss Jose Mourinho in December, the Old Trafford outfit has been reinvigorated.
Former United striker Ole Gunnar Solskjaer has been drafted in and he has led the squad to 10 wins and a draw in all competitions.