Anatomy & Organs

Retinaculum patellae – structure, function & diseases

Retinaculum patellae

The patellar retinaculum is an important part of the ligament system that is responsible for holding the kneecap . The most important function is to prevent patellar luxation .

What is the patellar retinaculum?

If you take the translation of the Latin terms as a basis for the German, the term is already very aptly defined. Patella means the kneecap and retinaculum means the holder, accordingly we are dealing with a holder of the kneecap.

Correctly, the use of the plural is more correct, since there are a total of 3-4 such straps on the knee. The longitudinal portions, which carry the suffix longitudinale, occur regularly on the anterior inside and outside of the knee. The transverse reins, with the suffix transversale, often exist on the outside, while they can be detected on the inside in only 30% of people. Similar retaining straps are also found in other places on the human body, for example on the foot in the area of ​​the ankle and on the upper extremity at the wrist.

Their form and function distinguish them from the retinacula patellae. They are arranged in a semicircle and are used to attach the long tendons of the flexor and extensor muscles.

Anatomy & Structure

The retinacula patellae are assigned to the connective tissue in the narrower sense. They have abundant collagen fibers that give the structure high tensile strength. The fibers are grouped in bundles that line up in the main direction of pull.The longitudinal lateral parts arise mainly from tendon material from the vastus lateralis muscle and the rectus femoris muscle, both of which are parts of the quadriceps femoris muscle. They run closely along the patella and attach laterally next to its end tendon on the tibia. They are connected to the outer edge of the kneecap with connective tissue bridges.

The transverse fibrous cords that run to the lateral surface of the femur in the area of ​​the lateral ligament derive their tissue material primarily from the iliotibial band, a tendon plate that extends from the pelvis across the outside of the thigh to the tibia .

The inner retinacula are extensions of the tendon of the vastus medialis muscle, which also belongs to the quadriceps femoris muscle. The longitudinal reins brush the inside edge of the patella and attach to the top of the tibia, medial to the quadriceps tendon. The transverse fiber strands run from the medial edge of the patella to the lateral end of the femur in the area of ​​the medial ligament.

All parts have grown together with the joint capsule in different areas .

Function & Tasks

Together with all other tissue structures, the retinacula patellae form a thin covering layer that only insufficiently shields the underlying structures from external mechanical influences. Together with the tendons of the quadriceps , they assume a special protective function when stabilizing the knee joint. The deeper layers have grown together with the capsule and reinforce it next to the kneecap and in the area of ​​the inner and outer ligament.

All ligaments are very important for stability and control of the kneecap during movement. The patella runs in a groove on the front of the femur. It has a matching ridge on its underside, which slides in this groove when bending and stretching. Bone guidance in this joint is not very pronounced, so other structures must provide backup to prevent dislocation of the kneecap. The retinacula patellae play a prominent role. The longitudinal reins, which have grown together with it, form a kind of guide rail. The transverse fibers prevent or make it difficult for the patella to move to the opposite side. The medial parts protect against outward dislocation, the lateral ones against inward dislocation.

Since the longitudinal cords arise from the extensor tendons and run parallel to the tibia, they have the same function as these, but only to a lesser extent. When the patella tendon tears, the quadriceps fail completely. However, a small residual extension is still possible via the retinacula if they are not damaged. The term reserve stretch apparatus appears in the literature in this context.

Diseases

In certain traumas, the retinacula can also be affected. Sudden overstretching with severe flexion can tear the ligaments and anterior joint capsule. The result is pain and instability of the patella with a risk of dislocation.A comminuted kneecap fracture can result in the loss of all retinacula function. They lose their tension because the continuity of the bones to which they are attached is no longer present. This also affects the tightening of the joint capsule.

A typical disease that primarily affects the kneecap but is secondarily aggravated by insufficient retaining ligaments is chondropathia patellae . Often an incongruence of the two articular surfaces on the patella and on the femur is the reason why the patella tends to slip outwards. When the securing ligaments and muscles are unable to prevent displacement, dislocation can occur. The insufficiency of the ligament structures is often due to a congenital weakness of the connective tissue or the result of a traumatic dislocation, which can lead to massive tearing.

A typical sports injury, which in rare cases also affects the retinacula that attach to the shinbone, is a ruptured patellar tendon. On the one hand, this damage can be caused by an abrupt and massive contraction of the quadriceps with simultaneous flexion of the knee, as occurs when suddenly stopping from a full run or landing after a jump. On the other hand, additional weight loading during explosive knee extension can also be responsible for the tear, such as in a full instep or volleyball in soccer. If the trauma is very great, sometimes one or both retinacula tear off.

Lisa Newlon
Website | + posts

Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.