Le knee is the biggest joint from the body. It is essential to our mobility and stability. During certain movements, such as climbing stairs, the knees support 4 to 5 times the weight of the body¹. Therefore, they can be easily weakened and damaged by various repetitive movements performed in certain trades or certain sports. The consequence is the occurrence of musculoskeletal problems that cause pain and limit mobility.

The knees are often abused by sportsmen and high-level athletes, who strain them repeatedly and subject them to blows and contacts. One third of sports injuries also relates to the knees⁸. Professions that require you to be in a squatting or kneeling position often (more than half an hour per day), to get up often from these two positions, to climb stairs frequently or to carry heavy loads also increase the risk of suffer from knee pain.

To fully understand what follows, it may be useful to refer to our Anatomy of the joints: basic concepts sheet which illustrates and defines the different elements that make up a joint.

Musculoskeletal disorders of the knee group together many problems (see diagram).

• Sprain, which is the stretching of a ligament (the fibrous tissue that connects bones together);
• The tendinopathies (or tendonitis), that is to say the attack of the tendon, this “cord” which connects the muscles to the bones. In the knee, several tendons can suffer trauma or tears;
• Lesions of the menisci, two small, crescent-shaped cartilages located between the tibia and femur in each knee;
• The hygroma or bursite of the knee, which corresponds to the inflammation of the “bursae”, small pockets present in the knee whose role is to facilitate the sliding of the tendons;
• La nerve compression which descends to the side of the calf (external popliteal sciatic nerve).

Types

This sheet describes the 3 most common musculoskeletal disorders of the knee: femoro-patellar syndrome and iliotibial band friction syndrome, often found in athletes, as well as bursite du genou, caused by frequent and prolonged kneeling position or direct trauma.

These 3 types of ailments are linked to overuse of the knee and manifest themselves gradually. They are rarely the immediate result of accidental trauma or contact shock, which instead results in ligament and meniscus injuries.

Patellofemoral syndrome

It is estimated that a quarter of athletes suffer from this syndrome at one time or another. Patellofemoral syndrome is characterized by irritation of the cartilages of the knee joint. knee, between the femur (the thigh bone) and the kneecap (see diagram). Usually, symptoms appear when the joint is surutilisée or that it is stressed too strongly, as when suddenly increasing the intensity of an exercise, or when there is a misalignment between the patella and the femur.

Main causes:

• A sag of the foot arch (the arch of the foot), which distorts the alignment of the knee, is a common cause. Hereditary or biological factors are at the origin of the problem;
• An imbalance of muscle forces exerted on the kneecap, which produces misalignment during movement, is also a common cause;
• La repeated practice one of the following activities: going up or down stairs, running on an uphill slope, going for long hikes, frequent squatting or participating in activities where you have to jump frequently (basketball, volleyball) ball, dance…). These activities are a problem for people with misalignment of the kneecap and for those who are poorly prepared physically;
• Un knee trauma following a fall on the kneecaps or a traffic accident.

Iliotibial band friction syndrome

This type of injury appears in the long term as a result of repeated practice of flexions and D’knee extensions. The athletes most at risk are long-distance runners (4% to 7% are affected⁷) and cyclists. Irritation and inflammation occur as a result of repeated rubbing of two structures of the knee, in its outer part: the long fibrous band located on the outer face of the thigh (the iliotibial band) and a protuberance of the femur (the thigh bone). This condition is sometimes referred to as “windshield wiper syndrome” because the sensation of the strip rubbing the bone under the skin is often compared to that of the wiper squeaking on the windshield. repetitive.

Main causes:

• A problem ofknee alignment is very common;
• A lack of flexibility the iliotibial band and the muscles attached to it (the tensor fascia lata and the gluteus maximus) are almost always involved;
• The practice of activities that require repeated flexes and extensions knee, such as cross-country running, mountain hiking, and cycling.

Knee bursitis

Bursitis is the inflammation or thickening of a bursa, a kind of small pad filled with fluid that helps reduce friction between the bones, tendons, and muscles inside the knee. There are 11 bursas in each knee, but bursitis most often occurs in front of the kneecap (prerotular bursitis).

Main causes:

• Frequent working in support on the knees is a major factor in bursitis, because it causes thickening of the bursa in the long term. This type of bursitis is sometimes called the “cleaning lady’s knee”;
• The falls on the knees (volleyball, wrestling…) can cause sudden inflammation of the bursa;
• La running can cause inflammation of the anserine bursa located on the inner side of the knee, just below the joint.

Possible complications

An untreated knee injury can degenerate into Chronic Pain. A process of compensation by the non-painful leg often sets in, which can lead to other biomechanical problems.

Prevalence

The musculoskeletal disorders of the knee are extremely common, both in athletes and in all workers. The prevalence is difficult to estimate, but a synthesis of studies examining the role of work in relation to knee disorders indicated that 19% of the working population (all professional sectors combined) complained of knee pain occurring in the 12 previous months³.