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X-ray of the hip joint is now useful not only in elderly patients in whom osteoarthritis is suspected. or osteoarthritis of that jointbut also in younger patients.
Young people often come to the radiologist’s office without osteoarthritis, but (unless there is a clear problem), they examine for the presence of femoroacetabular impingement or hip dysplasia.
A plain x-ray can evaluate both a normal and dysplastic hip joint, or with signs of damage.
In addition, there may be such pathological processes such as osteoarthritis, infections or tumors.
What is the hip joint
The hip joint is one of the important joints in the human body. It allows you to walk, run and jump. It carries the weight of the body and the strength of the strong thigh muscles. However, the hip joint is also one of the most flexible joints and provides a greater range of motion than all other joints in the body except for the shoulder.
It is a globular synovial junction formed between the pelvis and femur. A round cup-shaped structure on the os coxae, known as the acetabulum, forms the socket for the hip joint. The rounded head of the femur forms the head of the joint.
Alternative Research Methods
X-ray, in our time, is the method of choice for assessing the condition, the presence of fractures and other pathological changes in adults, due to its prevalence, information content and low cost, and hence accessibility. But there are conditions that cannot be assessed only with the help of X-ray examination.
X-ray is basic diagnostic method to study the hip joint. But still, magnetic resonance imaging (MRI) is the method of choice for assessing the bone marrow, acetabulum, cartilage, and periarticular soft tissue.
Ultrasound also applies in the evaluation of periarticular soft tissues and the detection of effusion or synovial thickening. It can also be used as a method for diagnostic and/or therapeutic procedures.
MRI with intra-articular contrast (MR arthrography) has a better informperformance than conventional MRI for assessing intra-articular pathology, especially cartilage.
Computed tomography (CT) using same as x-ray ionizing radiation has a greater spatial and contrast resolution than x-rays.
It is informative for assessing general anatomical features, bone lesions hidden from x-rays, and fractures.
In the study of the hip joint, a simple x-ray should always be taken into account, which provides meaningful information, but often, yet, insufficient for making decisions about treatment tactics.
Other visualization methods provide additional information that cannot be received simple x-ray.
A very important task is to improve the methods of damage detection. cartilage tissue before they become macroscopically visible.
Research Basics
There are many different positions for taking x-rays of the hip joint. A standard examination is performed in the anteroposterior view to evaluate the space of the acetabulum and the joint, which is performed in the standing position, because this position adds information about the pelvic slope and acetabular insertion. Depending on what exactly needs to be investigated, some additional positions of a hip can be used.
For example, if femoroacetabular impingement is suspected, then the study is performed in a true axial or lateral projection. A false profile projection is used to assess the anterior acetabular coverage. For joint pathology or avascular necrosis – Lowenstein projection.
A pelvic x-ray determines whether the hip joint is normal, borderline or dysplastic, whether there are signs of degenerative or inflammatory arthropathy, avascular necrosis, calcification, tumors, etc.
The first item to consider in X-ray diagnostics is the quality control associated with symmetry, tilt and rotation.
X-ray analysis should be systematic, starting with the surrounding soft tissues, where the gluteal, iliac, and obturator fat pads should be recognized. These pads define the corresponding muscles. They should be straight forward and clearly defined. If they have a bulge, it implies a stretching of the hip joint with the presence of fluid. The x-ray must be strictly in the anteroposterior projection for this assessment to be reliable. Flexion and rotation of the hip can lead to false readings.
Indications for the study
The main indications for an x-ray of the hip joint in adults:
- fracture;
- aseptic necrosis of the femoral head;
- bacterial septic arthritis;
- osteoporosis;
- tuberculosis and brucellosis arthritis;
- dislocation of the joint;
- movement restriction.
Osteoarthritis
The main indication for an X-ray of the pelvis in adults is the detection of osteoarthritis, osteoarthritis or conditions preceding them.
Osteoarthritis is the most common joint disease. It is characterized by progressive degeneration of the articular cartilage. Most imaging results are late effects of this process. A decrease in the amplitude of the joint space, sclerosis, cysts and osteophytes are all signs of a long-standing process, so their detection is a sign of a rather long-term existence of this diagnosis.
It is currently believed that different etiological factors can lead to the same process of degeneration in the final phase.
One of these factors is the articulation of “abnormal” morphology or deformity of the acetabulum or hip.
These bone abnormalities are highly predictive of hip osteoarthritis, so there is high interest in their early detection and improved treatment options. In addition, it is important to determine in advance the “borderline” conditions in which hip dysplasia is observed.
The main features on x-ray of the hip joint are narrowing of the joint space as a result of cartilage damage, subchondral sclerosis consistent with a reparative bone reaction, osteophyte formation in areas of low joint pressure, consistent with a reparative attempt to maintain joint stability, and subchondral cysts that occur both in the head of the femur, as well as in the acetabulum.
The grading system ranges from 0 to 3, with 0 showing no evidence of osteoarthritis. The first degree shows moderate sclerosis of the acetabular head, slight narrowing of the joint space, and marginal osteophyte.
Grade II presents with small cysts in the femoral head or acetabulum, moderate joint space narrowing, and moderate loss of sphericity of the femoral head.
Grade 3 is the most severe form of osteoarthritis, which manifests as narrowing of the joint space, the formation of a large subchondral cyst, which can lead to deformity of the bony components of the joint, while secondary osteoarthritis caused by calcium pyrophosphate precipitation can be diagnosed by detecting hyaline cartilage calcification.
Acute septic arthritis
There are other pathological conditions that can affect the hip joint, and radiographs help to identify the appropriate diagnosis. Acute bacterial septic arthritis can be diagnosed by x-ray of the hip when rapid regional osteoporosis and a destructive monoarticular process develop.
In the case of tuberculous or brucellous arthritis, it appears as a slow progressive process and the diagnosis may be delayed.
Other diseases of the hip joint
Synovial chondromatosis can be confidently diagnosed by x-ray when calcified cartilaginous chondromas are visible. However, other synovial proliferative processes, such as pigmentary villonodular synovitis, require MRI for accurate diagnosis, although synovitis may be suspected on radiographs by circumstantial evidence such as soft tissue swelling and/or erosion in the femoral head, femoral neck, or acetabulum.
Radiological features of transient osteoporosis of the hip include localized osteoporosis of the femoral head and neck.
However, a definitive diagnosis must be made by MRI to distinguish it from avascular necrosis and from insufficiency or stress fractures of the femoral head or neck. In the case of aseptic necrosis of the femoral head, radiographs may show only minor signs.
Pros and cons of the method
This method is affordable and widespread, often used at the primary level of diagnosis. X-ray of the hip joint is inexpensive compared to other diagnostic methods in this field.
Almost all doctors are familiar with x-rays and are able to decipher them. Using a series of images, you can analyze the dynamics of treatment.
The disadvantages of this method are few, but still they can be significant for some patients. During the study, ionizing radiation is used, which affects the body, and although it is used in small quantities, its influence cannot be denied. This method does not allow assessing the functional state of the joints and is static.
With the help of x-rays, it is impossible to evaluate some layers and sections of tissue separately. Soft tissue can only be assessed with a contrast medium.