The lower limb is made up of the hip, thigh, leg and foot.

Structure of the lower limb. Two in number, the lower limbs are connected to the trunk from the pelvic girdle. Each lower limb consists of four parts:

• The hip forms the lateral protrusion of the pelvis and consists of the coxofemoral joint, connecting the femur to the pelvis through the coxal (or iliac) bone (1). Many ligaments and different muscles surround this joint.
• The thigh is made up of a single bone: the femur. The latter articulates with the hip bone, the tibia, the fibula as well as the kneecap (knee bone). The femur is surrounded by three muscle compartments: anterior, posterior and internal. The muscles of the anterior and posterior compartments are respectively innervated by the femoral nerve and the sciatic nerve. The muscles of the internal compartment are mainly innervated by the obturator nerve, but also by the sciatic and femoral nerves (3). The whole is vascularized by the femoral artery.
• The leg is made up of two bones: the tibia, located at the front and the fibula (or fibula), located at the back. It is also made up of different muscles divided into three compartments, anterior, lateral and posterior, which are respectively innervated by the deep peroneal nerve, the superficial peroneal nerve and the tibial nerve (2). The whole is vascularized by the anterior and posterior tibial arteries.
• The foot (1) is made up of 26 bones divided into 3 zones: the tarsus, making the junction between the leg and the foot, the metatarsus, middle part, and the phalanges, constituting the toes.

We distinguish certain areas of links between these parts :

• The gluteal region, or buttock, forms the posterior part between the trunk and the lower limb.
• The knee is the joint between the thigh and the leg.
• The ankle is the joint between the leg and the foot.

Weight support. Body weight is transmitted from the trunk to the lower limb through the hip joint (1).

Locomotion. The lower limbs are involved in locomotion and thus allow walking, running, jumping, etc. (1).

Balance. The structure of the lower limbs also helps to maintain a stable position (1).

Pain can be felt in the lower limbs. Their causes are varied but the most commonly affected parts are the knee, leg, and foot (1).

• Bone lesions. Severe pain in the lower limb may be due to a bone fracture.
• Bone pathologies. Lower limb pain may be due to a bone disease such as osteoporosis.
• Muscular pathologies. The muscles of the lower limbs may be subject to pain without injury such as cramping or suffer muscle injury such as straining or straining. In the muscles, tendons can also cause pain, especially during tendinopathies such as tendonitis.
• Vascular pathologies. In case of venous insufficiency in the lower limbs, a feeling of heavy legs may be felt. It is manifested in particular by tingling, tingling and numbness. The causes of heavy leg symptoms are varied. In some cases, other symptoms may appear such as varicose veins due to dilation of the veins or phlebitis due to the formation of blood clots.
• Nerve pathologies. The lower limbs can also be the site of nervous pathologies such as, for example, sciatic neuralgia. Due to damage to the sciatic nerve, the latter is manifested by intense pain felt along the limb.

Drug treatments. Depending on the pathology diagnosed, different drug treatments may be prescribed to reduce pain and inflammation as well as to strengthen bone tissue.

Symptomatic treatment. In the case of vascular pathologies, elastic compression may be prescribed to reduce the dilation of the veins.

Surgical treatment. Depending on the type of pathology diagnosed, surgery may be performed.

Orthopedic treatment. Depending on the type of fracture, the installation of a plaster or a resin can be carried out.

Physical treatment. Physical therapies, through specific exercise programs, can be prescribed such as physiotherapy or physiotherapy.

Physical examination. First, a clinical examination is performed in order to observe and assess the symptoms perceived by the patient.

Medical analysis. In order to identify certain pathologies, blood or urine analyzes can be carried out such as, for example, the dosage of phosphorus or calcium.

Medical imaging exams. An examination by radiography, by scanner, by MRI, by scintigraphy, or by bone densitometry can be carried out to confirm or deepen a diagnosis.

• Doppler ultrasound. This specific ultrasound makes it possible to observe the blood flow.

In 2013, The New England Journal of Medicine unveiled an article chronicling the new achievements of bionic prostheses. A team of researchers from the Chicago Rehabilitation Institute has successfully put a robotic leg in place on an amputee patient. The latter is able to control this bionic leg by thought. (4)