Mark O'Mahony joined the Royals in the summer on a season-long loan as part of plans to bolster Noel Hunt's front line prior to the signing of Jack Marriott.
The 21-year-old striker has made 21 appearances across all competitions so far during his loan spell with Reading, he scored two goals and provided an assist.
He registered a goal and an assist in the Vertu Trophy group stages 3-1 wing against West Ham U21s in September - His second goal came in the 3-2 defeat to Carlisle United in Reading's First Round exit of the FA Cup.
His last appearance as part of a matchday squad for the Royals was in a 1-1 draw against Peterborough in December.
When asked in January ahead of the transfer window closing if the Brighton loanee is still part Richardson's plans he said: "As far as I'm aware, he's part of our squad and we'll be using him as that as well because he's a good young player but I am also very aware that players need to play football, they need to play regular because that's where their pathway is and that's how they're going to improve to be the best player that they can be so that's the same as anybody really."
Mark O'Mahony (Image: ©Jason Dawson)
Leam Richardson has since revealed to The Reading Chronicle that O'Mahony has picked up an injury and will be out of the squad for a 'lengthy' period of time.
He said: "Mark has got an knee problem.
"So, he'll be out for a lengthy period of time. He's fully committed and Brighton are fully committed.
"As soon as he's back fit and available, he'll be in and around the squad and hopefully raring to get going."
The majority of his appearances came under former Reading manager Noel Hunt who entrusted the young loanee with five league starts at the beginning of the season. In that time the Ireland youth international was unable to hit the back of the net, and even when Marriott sustained an injury in October Kelvin Ehibhatiomhan took the position of lead striker.
O'Mahony fell down the pecking order when Leam Richardson took on the role with Ehibhatiomhan leading the line, and has only played 60 minutes across five league games under the new gaffer.
His minutes were further reduced when Marriott was introduced back into the starting line-up against Luton in December, where he picked up only 20 minutes across three games.