Anterior cruciate ligament (acl) injuries, treatment, training and surgery

Complete tears of the anterior cruciate ligament (ACL) – the key ligament which bonds together the upper and lower parts of the leg at the knee – account for more than two-thirds of all knee injuries in skiers and are fairly common in other sports as well.

For example, basketball players, volleyball participants, and racket-sports enthusiasts are all susceptible to the injury.

 So what should you do if your doctor examines your inflamed knee and gives you the dreaded verdict – a ruptured ACL? First, make certain that the diag nosis is correct by consulting a second doctor or obtaining an MRI (magnetic resonance imaging) of your troublesome knee. Although some doctors believe an MRI is no more accurate than a careful examination in verifying a breach in your ACL, the MRI can also document damage to the ‘menisci,’ little pads of cartilage inside the knee which provide cushioning (‘torn cartilage’ in the knee usually involves a severance of one of the menisci). The MRI information can help you decide how to exercise during the period leading up to your surgery, if you do elect to go under the knife (if the MRI shows that a meniscus is damaged in addition to the ACL, you’ll want to avoid exercises which produce an aggressive range of motion and/or wear and tear at the knee).

Of course, you may elect not to have surgery to repair your severed ACL. If your lifestyle is going to be fairly sedentary, you don’t really need a fully operational ACL (but of course, if you were truly immobile, you wouldn’t be reading this publication, either). Runners who rupture an ACL (this usually happens when they participate in another sport; ACL break-ups during running are very uncommon) will sometimes – after the knee swelling and pain diminishes – go on to run for several years without realising that a key knee ligament is missing. Eventually, though, problems usually arise, especially in higher-mileage runners, because the loss of the ACL leads to a lack of stability in the knee, which increases the risk of damage to the menisci and (ultimately) arthritis.

After an ACL tear, doctors sometimes tell patients to ‘test their knee out’ for a period of time while they’re considering the possibility of surgery. While this can help the person who exercises fairly lightly decide whether to have surgery, the strategy can also place the patient at risk of further damaging the menisci inside the knee, or eroding the cartilage caps at the ends of the femur and tibia – the two important bones which form a junction at the knee. An important point to remember is that if your sports activity produces pain, you shouldn’t blithely continue exercising. Stopping a painful workout is disappointing in the short run but far better for your health over the long term.

For the ‘high-demand’ patient who wants to return to vigorous training, especially if the preferred sports activity involves pivoting and ‘cutting,’ a reconstruction of the ACL is the best way to increase the chances of returning to near-normal activity. Apparently, you’re never too old for an ACL reconstruction; good success has been achieved with patients over the age of 40, for example.

However, there’s lots of controversy concerning HOW the ACL should be reconstructed. The first debatable point is how long to wait after the injury has occurred. Many doctors recommend waiting at least three weeks after injury before reconstruction occurs, but a consensus is emerging that the surgical procedure should not take place until good range of motion returns to the knee and the associated quadriceps muscle is strengthened. This seems to lower the risk of developing excessive amounts of fibrous connective (‘scar’) tissue in the knee after surgery.

The next dilemma concerns WHERE to get the new ACL. Since tendons and ligaments are similar in construction, cutting one of the existing hamstring tendons and placing it inside the knee to form a new ACL is an intervention which works fairly well and leaves just a very small scar in the knee area. Another popular technique is to remove the middle portion of the patellar tendon (the tendon which connects the quadriceps muscle with the lower part of the leg) and affix it inside the knee. This latter strategy permits better initial fixation of the new ACL and – somewhat surprisingly – better strength in the quadriceps during post-surgery rehabilitation, along with one negative: a potentially higher risk of patellar tendonitis. Another option is to use an ‘allograft’ – i.e., an ACL from a cadaver. This prevents damage to the patient’s patellar or hamstring tendons, but the allograft is less likely to ‘take’ inside the knee and more likely to fail during exercise, and there’s also a small risk of picking up AIDS along with the graft.

The post-surgery recuperative period and rehabilitation programme can be even more important than the surgery itself. Activities should be arranged to promote healing, upgrade flexibility in the knee, and strengthen surrounding muscles. A passive range of motion programme (stretching) following surgery aids in the healing process, promotes better nutrient flow to the cartilage caps at the ends of the femur and tibia, and prevents excess tightness from developing in the knee. A hinged knee brace which prevents hyperextension or hyperflexion should be used during the four to six weeks after surgery in order to prevent ruptures of the new ACL (stretching activities take place without the brace on, however).

 Although maintaining adequate range of motion is the primary focus immediately after surgery, strengthening is also initiated without great delay. A consensus is emerging that it’s best to perform the strengthening work in a ‘closed-chain’ manner – with the feet (or foot) firmly planted on the ground and the leg in a weight-bearing position. However, stationary bicycling is also utilized to increase leg strength and overall aerobic capacity; the bicycle seat is usually adjusted to keep the knee between 10 and 90 degrees of flexion.

About four to six weeks after surgery, the patient can progressively begin to carry out one- and two- leg squats as well as forward and backward walking with elastic resistance. Increased-resistance cycling and stair-stepping also help to renew strength in the knee area. At eight to 12 weeks, side-to-side movements are begun in order to strengthen the knee in all directions of motion.

The key point for ACL patients to remember after surgery is that every effort must be made to increase range of motion and flexibility at the knee. Knee weakness can usually be remedied by extra strengthening exercises, but increased stiffness can sometimes be permanent if not corrected by further surgery. (‘The Surgical Treatment of Knee Injuries in Skiers,’ Medicine and Science in Sports and Exercise, vol. 27(3), pp. 328-333,1995).

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