On X-rays, the anatomy of the hip joint looks simple and understandable even to people far from medicine, however, everything is not as banal as it seems at first glance. Although the joint consists of only two bones and visually resembles a regular hinge, its full operation includes much more than simple rotation within a strictly limited radius. The joint provides full walking, supports the body in an upright position and helps the lower limbs cope with high loads. What are the anatomical features of the hip joint, what does the normal physiology of the joint depend on and how does it change with age? Let's look at the complex issues of orthopedic anatomy more clearly and consistently.
Basic anatomy of the hip joint: bones that form the joint
The human hip joint is formed by two bones, the surfaces of which ideally coincide, like pieces of a puzzle. The acetabulum on the surface of the ilium plays the role of a kind of pocket into which the spherical process of the femur is immersed - the head, completely covered with durable and elastic cartilage. Such a complex resembles a hinge, the rotation of which is achieved due to the harmonious coincidence of the sizes and shapes of the adjacent osteochondral structures.
Soft and painless sliding between two fairly tightly adjacent bones is achieved due to the special structure of cartilaginous tissue. The combination of collagen and elastin fibers allows you to maintain a rigid and at the same time elastic structure of cartilage, and proteoglycan molecules and the water included in the composition guarantee the necessary pliability and elasticity. In addition, it is these substances that are responsible for the timely release of the optimal amount of joint fluid, which serves as a shock absorber during movement, protecting sensitive cartilage from abrasion.
The joint cavity is limited by a special capsule, the basis of which is fibrous fibers. These molecules are characterized by increased strength, so that even under great pressure the joint retains its integrity and original shape. However, this reserve is not unlimited, and, unfortunately, it is impossible to guarantee 100% the impossibility of dislocation: with inadequate loads, strong external pressure or a sharp displacement in space, such an atypical injury is quite real.
Cementless fixation of the endoprosthesis
With cementless fixation, all parts of the endoprosthesis are in direct contact with the bone. Therefore, the surfaces of the prosthesis are specially coated and processed in such a way that the endoprosthesis grows into the bone. This process is called "Osseointegration". Special bone substitutes, such as hydroxyapatite and various titanium alloys, are used to cover the endoprosthesis. All components of the endoprosthesis are pressed into the bone using the so-called 'Press-fit-Technik' technique.
This process requires a certain preparation of the bone surfaces in contact with the endoprosthesis.
- To install the endoprosthesis stem, the medullary cavity of the femur is cut out with special cutters in the shape of the endoprosthesis. After this, the leg of the prosthesis is pressed into a previously prepared cavity, which makes it possible to quickly load the leg after surgery.
- When installing a cup, a so-called 'Press-fit' cup is often used. It is driven in and seems to get stuck in the bone, because... by its design, it is larger in size than the corresponding depression. Screw cups with self-tapping external threads that are screwed into the bone are not used at Gelenk-Klinik.
Hip joint: anatomy of the ligamentous apparatus
Ligaments play a very important role in the functionality of the hip joint. It is these super-strong fibers that maintain the optimal shape of the joint, ensure adequate mobility and activity of the joint, and protect against injury and deformation. The ligamentous apparatus of the hip joint is represented by the most powerful fibers:
- The iliofemoral ligament is the most powerful and durable ligament in the human body, capable of withstanding incredible loads without tears or sprains. Experimental experiments have shown that its fibers are capable of withstanding a load comparable to the weight of 3 centners. It is thanks to this that the joint remains protected during intense training, unsuccessful movements and other unpleasant surprises that affect the mobility of the femoral joint.
- The ischiofemoral ligament is a much thinner and softer ligament that controls the degree of pronation of the femur. It is, as it were, woven into the articular capsule, located from the ischium all the way to the trochanteric fossa.
- The pubofemoral ligament is responsible for the abduction angle of the free femur of the lower limb. Its fibers, like the ischiofemoral ligament, penetrate into the articular capsule, however, they originate not at the ischium, but at the pubic joint.
- The circular ligament does not leave the joint capsule. As the name suggests, it is located in a circle, encircling the head and neck of the femur in a tight loop and secured to the anterior surface of the lower bone.
- The ligament of the femoral head is the most original in the anatomy of the hip joint. Unlike its “colleagues”, it does not directly protect the joint and does not control its mobility; the functions of this ligament are to preserve the blood vessels with which it is penetrated. This feature is explained by its location, which coincides with the trajectory of the vessels: the ligament begins at the acetabulum and ends at the head of the femur.
Anatomical features and functions of the muscular frame
The musculature of the hip joint is represented by fibers of various types and functionality. This is primarily due to the varied trajectory of movement that the hip can perform. So, if we classify muscle fibers into groups according to function, in the anatomy of the hip joint we should highlight:
- The transverse, or frontal, muscle group, which is responsible for flexion and extension of the lower limb in the pelvic area. Among them are the flexor muscles (sartorius, iliopsoas, pectineus, rectus, tensor fascia lata) and hip extensor muscles (gluteus maximus, adductor magnus, semitendinosus, semimembranosus and biceps). Thanks to their coordinated work, a person can sit down and stand up, squat down and take a vertical position, pull his legs to his chest and straighten up.
- The anteroposterior, or sagittal, muscles regulate the adduction and abduction of the leg. This group includes adductors (major, short and long adductors, gracilis and pectineus) and abductors (obturator internus, tensor fascia lata, twin, piriformis, gluteus medius and minimus) muscle fibers.
- The longitudinal muscle group coordinates the rotation of the hip. Here the supinator muscles are distinguished (gemini, piriformis, iliopsoas, quadratus, sartorius, obturator, gluteus maximus and posterior groups of the middle and small gluteal fibers) and pronators (tensor fascia lata, semitendinosus, semimembranosus, anterior group of the middle and small gluteal fibers) .
Each of the muscles represented in the anatomy of the hip joint performs not only a motor function: powerful fibers take on part of the load during movements. And the more trained they are, the better they cope with pressure, thereby unloading the joint and performing a shock-absorbing function. Thanks to this, the likelihood of injury due to unsuccessful movements is also reduced, since the muscles are more mobile and extensible than the tissues of the joint.
Nerve fibers adjacent to the hip joint
Like any joint of the human body, the hip joint is not distinguished by a high organization of the nervous system: the endings localized in this area mainly innervate the muscle fibers, regulating the degree of sensitivity and coordinated work of each muscle group in response to external influences. Conventionally, all nerve fibers of the hip region can be divided into 3 groups:
- anterior external, which includes branches of the femoral nerve;
- anterior internal - branches of the obturator nerve;
- posterior - branches of the sciatic nerve.
Each group is localized in a specific area of the thigh, for which it is responsible in the complex structure of the nervous system of the body in general and the lower extremities in particular.
Consequences
If the disease is not treated in a timely manner, it can develop to the most serious consequences in the form of a complete loss of working capacity, the inability to maintain an active lifestyle, and disability.
Moreover, it should be understood that if the affected joint is not treated, then ultimately the sick person simply will not be able to get out of bed, even to a sitting position. And this is already becoming a dangerous situation for the functioning of the entire organism as a whole. Needless to say, arthrosis without medical care in old age significantly shortens a person’s life span.
Blood circulation of the tissues of the hip joint: anatomy of the arteriovenous bed
The round ligament artery, the ascending branch of the lateral and deep branch of the medial circumflex femoral arteries, as well as certain branches of the external iliac, inferior hypogastric, superior and inferior gluteal arteries take part in the nutrition and supply of oxygen to the tissues of the hip joint. Moreover, the importance of each of these vessels is not the same and can change with age: if in youth the vessels of the round ligament carry a noticeable amount of blood to the femoral head, then over the years this volume decreases to approximately 20-30%, giving way to the medial circumflex artery.
Strengthening muscle tissue in the pelvic area
The muscles of the thigh and hip joint are strengthened by gymnastics. The exercises are aimed at making them elastic. When they are easy to pull, the risk of injury is minimal. That is why it is so important to do a twenty-minute warm-up before any physical exercise (swings, bending, twisting the torso and working out each part of the body). Morning exercises are an excellent prevention of household injuries associated with spraining, pinching and hypothermia. to choose a set of exercises to strengthen, stretch and flex the muscles of the hip joint .
A passive lifestyle and sedentary work lead to weakening of the tone and atrophy of the muscle corset. Therefore, sports, walks in the fresh air, and dancing are a great way to stay healthy and strengthen the muscles of the hip joint .
Physiological capabilities of the hip joint
The hip joint can perform movements in three planes at once - frontal, sagittal and vertical. Thanks to the structure of the joint, thought out by nature, a person can easily bend and straighten the hip, move it to the side and bring it to its original position, rotate it in all directions, and at a fairly noticeable angle, the magnitude of which can vary depending on the anatomical features and training of the ligamentous apparatus. But that’s not all: the hip joint is one of the few joints that can move from the frontal to the sagittal axis, providing the free limb with full circular motion. It is on this ability that a person’s mobility, his physical characteristics and abilities for certain sports (for example, gymnastics, athletics, aerobics, etc.) primarily depend.
The other side of the coin is the rapid wear and tear of the cartilaginous surfaces of the hip joint. The pelvic and femur bones bear the maximum load during walking, running and other types of physical activity, respectively, this pressure is transferred to the joints. The situation can be aggravated by excessively high weight, too intense physical activity, or, conversely, a passive lifestyle in which the muscular system practically does not protect the joint from deformation. As a result, the cartilage surfaces begin to wear out, become inflamed and become thinner, pain appears, and the trajectory of movement is significantly limited. Even the slightest deviation in the condition of the muscles, ligaments or bones of the hip joint can lead to serious pathology, which subsequently requires long-term and intensive treatment.
However, restoration of the full function of the joint is not always possible: in some cases, surgical intervention is required, in which the affected tissue is replaced with a prosthesis. To prevent this from happening, it is worth monitoring the condition of the musculoskeletal system from a young age, strengthening joints, training the muscle frame wisely and moderately, and taking care of proper and nutritious nutrition of the body. Only in this way can you protect your joints from destruction, and yourself from pain, stiffness of movement and tedious treatment!