The anterior cruciate ligament (ACL) is an important ligament connecting the bones of the knee joint (the femur and tibia). It provides stability to the knee and prevents anterior and posterior displacement of the knee bones. For an individual who leads a sedentary life, it is possible to live without the ACL as any strain on the knee joint is minimal. For people who take part in sport, however, it is a vital part of the human body.
Who is most at risk of an ACL injury?
Those most at risk of injuring their ACL are footballers, skiers, rugby players, runners, or anybody who takes part in a medium to high contact sport.
A classic ACL injury occurs when the foot is planted on the ground and the leg continues to turn, thus twisting the knee beyond its usual limits. This kind of impact can apply enough force to rupture the ligament, hence the reason why an ACL tear or sprain is one of the most typical knee injuries for sportspeople.
ACL injury symptoms
Many individuals who suffer from an ACL injury often report they hear or feel something pop in their knee. The knee then swells up quickly, as it fills up with blood caused by bleeding from the ruptured ligament (known as haemarthrosis).
After an ACL injury, an individual will find they are unable to bear weight on the affected leg. Rest is needed, applying ice on the knee in order to reduce swelling. If they start becoming active again, and have sustained an ACL injury, their knee gives way when they put weight on it due to loss of strength.
Treating ACL tears
Individuals who do not partake in sport can be treated with physiotherapy in order to strengthen their quadriceps, without the need for ACL surgery.
For those who wish to carry on playing sports, an MRI scan is necessary in order to confirm the diagnosis. This shows if there is any damage to the menisci and other ligaments in the knee as well.
If ACL surgery is necessary, the surgeon replaces the ligament with a graft using an arthroscope in a minimally-invasive surgical procedure. The graft is often made from the patient´s own hamstring or patellar tendon tissue. A more modern technique employs the use of an allograft made up of tissue attained from a deceased donor.
The advantage of using an allograft is that the patient does not need to use their own tissue, thus avoiding donor site morbidity and pain in the area where the graft tissue would be taken from.
ACL surgery recovery time
Recovery after ACL surgery requires time and patience. It can take at least 6 months for an individual to return to an active lifestyle, and up to 9 months for a footballer.
Rehabilitation is necessary, beginning with gentle exercises before moving on to more vigorous activities to strengthen the leg muscles when the patient is ready. If an allograft is used, as the graft is made up of dead tissue it weakens during the first 3 months after surgery. Any movements involving the knees being twisted, and open chain exercises must be avoided during this time until neo-ligaments form and strength returns.