ACL Reconstruction

Post-op rehab after ACL reconstruction

Post-operative rehab is an absolutely key part of the overall treatment of an ACL rupture. Surgical reconstruction without appropriate rehabilitation is probably a pointless exercise.

Patients may require one crutch post-operatively, just for a few days, until the pain from the procedure begins to settle. However, knee braces are not required and the graft strength and fixation should be firm immediately post-operatively.

Rehab regimes may vary considerably depending on whether other concomitant procedures are carried out at the same time as the ACL reconstruction. However, the basic standard ACL rehab regime involves:

• Day 1 – Week 6: Full weight bearing ASAP. Range of motion treatment. Muscle strengthening. Training of the reflexes (proprioception). Closed chain exercises only, ie the foot remains in contact with something (such as the floor), so that there is no hopping, skipping, jumping or running.
• Week 6 – Week 12: Commencement of open chain exercises (where the foot can leave the floor) eg running, but no sport
• Up to 9 months: Intensive focussing on muscle strengthening, proprioception and performance of sport-specific training exercises
• From 9 months: Careful return to competitive sport

Why is slow and careful rehab so important?

When tendon tissue is first harvested for a graft, as soon as the tissue is harvested it loses its blood supply. The cells within the tissue, responsible for constantly repairing the fibres of the tissue, thus die and the graft becomes little more than a biological scaffold, in which the fibres will begin to degrade and gradually rupture with time, thereby weakening the tissue.

When the graft tissue is inserted into the knee, it begins to grow a new blood supply. New cells migrate into the tissue and begin to repair and remodel the graft. Therefore, an ACL graft is nice and strong when it is first surgically implanted. However, initially the knee is weak and the reflexes impaired. As knee function improves and the patient’s confidence increases, the graft begins to degenerate and actually becomes weaker. The ‘danger zone’ is between 3 to 9 months. As the graft develops a new blood supply within the knee after surgical reconstruction, the new cells remodel the graft and it becomes stronger. By 9 months, the graft will look and function like a new ligament and should be strong enough to cope with a full return to sports.

Graph showing how the strength of the ACL graft initially drops and then gradually returns to normal as the graft grows a new blood supply and slowly remodels. The graft is at its weakest at 3 to 6 months – just when the patient is beginning to regain confidence. It is therefore essential that return to proper sport is delayed until 9 months post-op.