With any meniscal injury the goal is one thing, unload the meniscus.
Exercises such as quad sets and straight leg raises are static exercises that are performed early in rehab and will really not be effective when meeting a client.
Biomechanically remember with knee flexion, the tibia glides posterior as well as bringing the meniscus back(posterioly), while the collateral ligaments become on slack. With knee extension(leg extension machine for example), the opposite happens. Tibia slides up(anteriorly), meniscus slides forward and collateral ligaments become taught.
Specifically, you need to look at the type of meniscal injury.
Partial menisectomy or full menisectomies, the goal is hamstring strengthening, to provide posterior support as the hamstrings have been shown through evidenced based research, RCTs, CCT’s(randomized controlled trials, and clinical controlled trials) to be weaker. This is further supported via Vldamir Janda’s work and through the NSCA.
With a menisectomy client, hamstring strengthening, standing hip extension or reverse lunges(glute max), diagonal lunges(glute med/min), monster walks(where you tie tubing around the patients hip or above knee joint line) and the client partially lunges in a forward diagonal position, stops and keeps one foot on the floor while raising the opposite slightly off the floor and holds(great stability exercise)!! As well as one foot on 1/2 roll and performing trunk rotation with cable or diagonal wood chop with cable!
With a meniscal repair, we in Physiotherapy, want to stop at 90 degrees of knee flexion, because going past 90 degrees, creates a posterior shear.
Therefore, this type of client needs hamstring strengthening stopping at 90 degree, leg press is excellent co-contraction exercise, reverse diagonal lunges targeting the weaker glute med/minimus and compound exercises such as forward lunges with medicine ball rotation or cable keeping the toes past 90 degrees.
Try this–as this is not only evidenced based, but has really worked for me in my 12 yr career.