The posterior cruciate ligament (PCL) and the anterior cruciate ligament (ACL) are two tough bands of fibrous tissue that connect the thighbone (femur) and the large bone of the lower leg (tibia) at the knee joint.
Like other types of sprains, PCL injuries are classified according to a traditional grading system.
- Grade I — A mild injury causes only microscopic tears in the ligament. Although these tiny tears can stretch the PCL out of shape, they do not significantly affect the knee's ability to support your weight.
- Grade II (moderate) — The PCL is partially torn, and the knee is somewhat unstable, meaning it gives out periodically when you stand, walk or have diagnostic tests.
- Grade III (severe) — The PCL is either completely torn or is separated at its end from the bone that it normally anchors, and the knee is more unstable. Because it usually takes a large amount of force to cause a severe PCL injury, patients with Grade III PCL sprains often also have sprains of the ACL or collateral ligaments or other significant knee injuries.
How long a PCL injury lasts depends on the severity of your injury, your rehabilitation program and the types of sports you play. In most cases, full recovery takes 4 to 12 months. after the Reconstruction following precaution must be taken to avoid further injury to the reconstructed ligament.
General Precautions
- Avoid exercises and activities that place excessive posterior shear forces and cause posterior displacement of the tibia on the femur, thus disrupting the healing graft.
- Throughout the rehabilitation process, limit the number of repetitions of knee flexion to lessen abrasion to the PCL graft.
Early and Intermediate Rehabilitation
- Begin exercise to restore knee flexion while in a seated position, allowing gravity to passively flex the knee and the hamstrings to remain essentially inactive.
- During squatting exercises to increase quadriceps strength:
- Avoid excessive trunk flexion, because it causes increased activity in the hamstrings.
- Avoid knee flexion past 60° to 70°, because it tends to cause posterior translation of the tibia.
- When performing open-chain exercises to strengthen hip musculature, such as resisted SLRs in standing, place resistance above the knee.
- Postpone open-chain, active knee flexion against the resistance of gravity (prone or standing) for 6 to 12 weeks.
Advanced Rehabilitation
- Postpone resistance training for the knee flexors, such as
- the use of a hamstring curl machine, for 5 to 6 months.
- When performing resisted hamstring curls, use low-loads.
- Avoid downhill inclines during walking, jogging, or hiking.
- Avoid activities that involve knee flexion combined with rapid deceleration when one or both feet are planted.
- Postpone returning to vigorous functional activities for at least 9 to 12months.
- Consider wearing a functional knee brace during high-demand activities.
