Conditions and treatments
ACL Injuries
One of the most studied ligaments of the knee, the anterior cruciate ligament (ACL) is responsible for controlling rotation, and translation between the thigh (femur) and leg (tibia).
In movements such as twisting and turning it is a core structure in controlling motion. Thus, when injured the biomechanics of the lower limb may change dramatically.
What causes an ACL injury?
There are several ways the ACL may tear, but the most common mechanisms are: rotating the body while the foot remains firmly on the ground (pivoting), bad landing (hyperextension, knee moving inwards) or direct contact (tackle). So people who practice activities that involve recurrent pivoting, jumping or contact have a higher risk of sustaining an ACL injury. Trying to prevent these injuries, warm-up programmes have been published, and they are effective as they may control modifiable risk factors. Nevertheless, there are other non modifiable risk factors (such as bony anatomy or hyperlaxity) that increase the risk of tear.
What are the symptoms and how is it diagnosed?
Many people hear a “pop” or a “snap” and feel the knee giving way. This is followed by intense pain, swelling, and difficulty bending/straightening the knee, or weight-bearing on the affected limb. Over time, the symptoms subside, but the person reports “I can’t trust my knee”, particularly while rotating or quickly changing directions. If left untreated, this instability leads to difficulty practising some sports or in heavy labour, as instability and further articular cartilage or meniscus injuries may develop. In the long term, the joint maybe prone to develop symptomatic osteoarthritis since there is abnormal mechanical loads in the joint, specially if there are coexisting menisci tears. Diagnosis of an ACL tear is made by a physician through careful medical examination, where symptoms are interpreted, and a systematic gait and joint analysis is performed. When an injury is suspected, an MRI scan may identify the tear, as well as assess other joint structures.
How is it treated?
Unfortunately in the vast majority of cases the ACL does not heal. Depending on the degree of instability, associated injuries, and level of activity, an ACL tear may be treated non surgically or require a surgery. Either way, the ultimate goal is to provide stability in your daily life activities, and lower the risk of further damage to the joint. The first step is to control pain, swelling and reestablishing as much range of movement of the knee as possible. Ice, pain killers, crutches are the first aid during initial assessment. After correct observation, diagnosis and understanding of your injury pattern (isolated tear, concomitant meniscal or other ligament tears) the physician will advice you on what is the best treatment.
If conservative treatment is indicated, you will start a demanding stepwise rehabilitation programme. First, pain and swelling management, joint mobilisation, and early activation of the muscles around the knee is promoted as they are impaired. Secondly, the focus will be on normalising your gait, training your balance, reestablishing your muscle activation patterns and their responses to external stimulus. Thirdly, strengthening, conditioning and proprioception training will help you dealing with the “new knee”. Finally, you will start all activities you are keen on doing, testing your ability to cope with them.
Where surgery is indicated, an ACL reconstruction is programmed to improve your quality of life, stabilise the joint, and minimise further damage of the knee. The reconstruction is done with a tendon (usually one that belongs to you: autologous) that will be replace the native ligament, being it called “graft”. There are different grafts used for the procedure, being the choice individualised. The inside of the joint is visualised through key holes in a procedure called arthroscopy. With the aid of a camera and tolls, the knee is inspected, all damaged structures are treated, and then the graft is placed and fixed. What follows is a demanding staged rehabilitation programme similar to the one described. It will be explained to you, and progression between stages will not only be guided by a timeframe that respects biological healing, but also by the state of your joint. Thus, your progression is closely monitored and tested to ensure the knee is ready for the future demands it will face. At the end, you will be given a set of prevention programmes to lower the risk of reinjury, optimise your performance, and keep you moving.
