The posterior cruciate ligament injuries (PCL) is rare and rehabilitation methods are varying. The purpose of the study is to explore if one rehabilitation option is preferable to one other for patients with acute PCL injury, by examining whether there will be differences in laxity in the knee joints and patient-reported knee function by three different rehabilitation protocols. A randomized controlled trial with 75 patients enrolled will be followed up 3 and 12 months after injury. The groups will be compared using kneelaxity (stress - X) and subjective knee function (KOOS, IKDC-2000)

The posterior cruciate ligament injuries (PCL) is rare and rehabilitation methods are varying. The purpose of the study is to explore if one rehabilitation option is preferable to one other for patients with acute PCL injury, by examining whether there will be differences in laxity in the knee joints and patient-reported knee function by three different rehabilitation protocols. A randomized controlled trial with 75 patients enrolled will be followed up 3 and 12 months after injury. The groups will be compared using kneelaxity (stress - X) and subjective knee function (KOOS, IKDC-2000) to indicate whether one rehabilitation alternative is preferable in terms of less knee joint laxity and improve knee function. Participants considered included in the study if he or she agrees to participate in the study by signing the informed consent. Inclusion criteria will be whether the patient has an acute isolated PCL injury. Exclusion is additional injuries of ligaments, cartilage and meniscus of the knee. Randomization to groups is done continuously.

Inclusion Criteria:

• Acute isolated PCL injury : 0- 3 weeks ( maximum 21 days) from the initial injury
• Isolated PCL rupture (grade I, II and III)
• Patient age should be between 16-60 years ( with closed epiphyseal plate )
• Understood and accepted written consent

Exclusion Criteria:

• Injury to the ACL or other ligaments in the knee
• Extensive injury to the cartilage or meniscus , requiring repairs
• Unfit to understand or to sign consent
• History of alcohol or drug abuse in the past three years
• Current serious illness or injury that makes rehabilitation difficult.