Anterior cruciate ligament tear

Findings

The acute episode has a history of rapid swelling, within 4-6 hours of a twist, fall or impact on the knee.

The subacute or chronic problem has a history with a causative injury in the past that was accompanied by rapid swelling of the knee. However, athletes do appear who give a past history of some trauma to the knee that did not grossly affect them at the time, but clinical examination shows them to have suffered an anterior cruciate ligament(ACL) tear.

Pain is often not a presenting symptom and words such as “jumps”, “gives way”, “unstable”, or “can’t trust it” are used. The knee may be painful on active and passive movement. Ballottement, or patellar tap, is usually positive in the acute or subacute stage, whereas a positive bulge test is more common in the chronic case because this sign is present with less fluid. Anterior draw and Lachman test are positive. Arthrometry displaying increased translation is indicative, and some surgeons use a measure of this laxity as an indication for surgery. The pivot shift may be positive, but may only be obtained with the patient anaesthetized. The quadriceps and hamstrings are often weak.

Treatment

Management of treatment is still continuos. Despite early repair, late repair, or non-surgical management, ACL rupture leads to the early onset of degenerative changes. The professional athlete will want an early return to sport and early surgery. Accompanying meniscal damage will hasten degenerative change and should be dealt with, even without the ACL being repaired. A conservative approach is to rehabilitate the knee over 6-12 weeks, and if functional control for daily living or the sport has not been achieved then reconstruct the ACL. One indicator for this control is the ability to nullify the pivot shift. If, after 6-12 weeks of rehabilitation, the athlete cannot control the pivot shift then, probably, he or she will not be able to control this instability in life or sport:

a)      Reduce the fluid by aspiration and electrical modalities

b)      Stabilize the joint with a brace or elastic support

c)      Quadriceps and hamstring strength, particularly hamstring, should be trained by isometrics and electrical modalities, progressing to closed chain exercises. Open chain exercises may be as effective.

d)     Balance and proprioceptive exercises.

e)      Training with zig-zag hopping, and big “hop and hold” landing

      f)    Hamstring ladder

g)      Cross-train for aerobic fitness

Sports

a)      Knee braces cannot be worn during competition whilst playing rugby, football and other contact sports, but may be of help in non-contact sports.

b)      Ski bindings must be able to release upwards and sideways at the toes, as well as at the heel, so that the backwards fall may be protected. Falling techniques may be taught to prevent cruciate ligament damage in skiers

Many elite games players, even in rugby, play with absent ACLs, and one often finds clinically lax cruciate ligaments, with no functional disability, when examining the knee for something unrelated. Whilst the muscles around the knee are working, the knee is held under control. It is when the knee is relaxed – when checking a ball in soccer, or releasing the skis from the slope before turning to stop – that trouble may occur. The functionally stable knee seems to be able to prevent the pivot shift from occurring, and the clinical persistence of the pivot shift during rehabilitation may be a warning that this knee will not do well with conservative management.

"Concise guide to sports injuries, 2^nd edition",Churchill Livingstone, Malcolm T.F. Read,  foreword by Bryan English