December 4, 2021

Anterior Cruciate Ligament (Knee)

Anterior Cruciate Ligament

Anterior Cruciate Ligament

The majority of anterior cruciate ligament ruptures occur following high velocity twisting and turning sports.  Often you will hear a pop followed by immediate swelling.  Occasionally, swelling may occur overnight, however will be localised to the knee joint.  It is a common injury in Australian Rules, touch football, skiing, rugby league/union, netball and hockey; indeed any sport involving turning on the knee.  Other injuries may be associated with this injury, eg, meniscal tear, medial collateral ligament sprain.

Rupture of the anterior cruciate ligament is a disabling injury for the sportsperson involved in pivoting and twisting sports.  In many cases an untreated rupture will result in recurrent instability and degenerative joint disease in patients who continue to remain athletically active.  Continued giving way of the knee results in meniscal and articular surface damage over time, thus increasing the degeneration within the knee joint.


The anterior cruciate ligament is one of two cruciate ligaments within the knee joint. It is composed of three bundles which are twisted (like a rope) allowing each bundle to be taut in varying degrees of knee flexion (bending). The anterior cruciate is the primary stabiliser of the knee. It has two main functions. It prevents forward displacement of the tibia on the femur and controls rotation of the tibia on the femur, thereby protecting the menisci and articular cartilage.

Acute Management:

Acute management involves RICE (rest, ice, compression, elevation), correct diagnosis and an understanding of the options for treatment, both conservative and surgical.

Conservative treatment:

Conservative treatment requires that the joint effusion (swelling) be settled, restoration of full painfree movement of the knee, maintenance/restoration of full muscle strength and control (hamstrings/quadriceps) and proprioceptive activities

(change of direction activities, balance, functional tests).  Modification of sporting activity may be required (eg change of sport/position of play).

Surgical Management:

It is usual to wait at least three weeks post injury before arthroscopic repair is performed to ensure that the joint effusion has reduced and the person has full range of movement.

Surgical Management very much depends on the choice of orthopaedic surgeon, age, sporting aspirations and commitment to rehabilitation.   Surgical repair is complex and therefore selection of a surgeon should be on the basis of experience with this procedure.  The most common technique currently used is to arthroscopically repair the ligament using part of the semitendinosus and gracilis (hamstring) tendons which are fixed into place (after the remains of the ruptured ligament are removed).

Rehabilitation post surgery is very much dependent on the surgeon and technique.   However, the initial program of physiotherapy post reconstruction involves reducing swelling/effusion, gaining full range of movement, and strength and control of muscles around the knee, involving close kinetic chain exercises.  (Open chain exercises, eg knee extensions are not allowed for at least six months post surgery).   The program is progressed regularly to increase the skill level required for sport and requires a high commitment to exercise.

Return to sport is usually within 6-12 months of surgery, however is very much dependent on the person being confident to undertake the activities required for their particular sport, having regard to acceleration/deceleration and change of direction activities at speed.