A Vancouver RMT’s Take on the “New” Knee Ligament
Post by Nicola Grice, RMT at Broadway Wellness
Your knee is one of the most important joints in your body. It is also one of the more interesting because humans are the only animals to stand with an upright posture and bear our body weight through the fully extended knee joint. Whilst most people mistakenly believe the knee is a simple hinge joint this is not true, it provides stability and allows your legs to bend (flexion), straighten (extension) and a large amount of swivel (rotation). It is made up of four parts: bones, tendons, cartilage and ligaments.
The bones are: the femur (thighbone), the tibia (shinbone) and the patella (kneecap).
The cartilage provides shock absorption when you walk, run, climb or any other impact activity. There are two types called the menisci and the articular cartilage. Neither of these have blood vessels nor can they regenerate in a natural way, which is why when it is damaged it is very difficult to repair.
The tendons connect muscles, such as your quadriceps and hamstrings, to the knee, which then contract and relax to move your knee.
A ligament is a tough strip of connective tissue that joins one bone to another bone around a joint. The knee joint ligaments help to stabilize and support the knee when it is moved into different positions. The four main ligaments of the knee are the two collateral ligaments, which resist side-to-side movement and help prevent rotation between the femur & the tibia, and the two cruciate ligaments known as the anterior (ACL) and posterior (PCL) which stop the tibia moving forward or backward respectively. Another important function of the ACL is its role in the “screw-home mechanism.” This is the name given to the action when a knee reaches full extension and just as the knee locks into hyperextension the knee rotates in an outward direction just a few degrees. This has the effect of putting most of the weight onto the cartilage, menisci, and bones of the joint while giving a rest to the muscles of the thigh and calf. Tearing of the weaker ACL is a very common sporting injury.
However, back in 1879 a French Surgeon called Paul Segond was the first to report the existence of “pearly, resistant fibrous band” connecting the outside front of the femur to the tibia. Yet it was not named and its existence was forgotten or ignored and often assumed to be part of iliotibial (IT) band. In 2013, after several years of research into ACL injuries, Belgian scientists provided the first full anatomical description of the anterolateral ligament (ALL).
So what does this all mean?
Researchers believe this newly named ligament could play an important protective role for the knee as we twist or change direction. Despite advancement in surgical techniques for ACL repair, between 10-20% of people are unable to recover fully. Interestingly, some of these patients said their knees give way as they twist or turn. Researchers now think an injury to the ALL may be partly responsible for this. They believe some people may injure the ALL at same time as the ACL, leaving the knee less stable as the leg rotates. All this now questions current medical thinking about serious ACL injuries and could signal a breakthrough in the treatment of patients with serious ACL injuries.
The knee just got a whole lot more interesting!
Further Reading
Anatomy of the anterolateral ligament of the knee
Doctors discover knee ligament
Anterolateral Ligament
Surgeons describe new ligament in human knee
Orthopaedic surgeon says anterolateral ligament not “new” but promising for ACL injuries
Ligament discovered in knee, Belgian surgeons say