How long does it take to recover from a posterior cruciate ligament sprain?

Usually 3 months. If the ligament is incompletely torn it usually heals in 2-3 months. Complete tears or grade 3 sprains may require reconstruction. Functional instability is the determining reason for surgery.
3 months. It depends on the level of severity, but healing usually progresses about 8% to 10% per week for 10 to 12 weeks. You might recover from a mild injury in as little as 2 to 3 weeks, but typically its more on the order of 2 to 3 months. Physical therapy (rehab) is an important part of recovering as quickly and as fully as possible.