I. Common causes and pathological basis of femoroacetabular impingement syndrome Femoroacetabular impingement syndrome is a group of clinical syndromes that can be caused by a variety of diseases, such as slipped femoral epiphysis at a young age, abnormal healing of femoral neck fracture, Legg-Calve-Pethes disease, congenital hip dysplasia, etc. Because of this, the diagnosis of femoroacetabular impingement syndrome requires a clear understanding of the primary etiology, and the author believes that FAI can be further divided into two categories: congenital and secondary. The congenital type can be characterized by developmental abnormalities of the femoral head and neck, such as congenital hip dysplasia, malformation of the proximal femoral pistol stem, deep acetabulum, posterior tilt of the femoral head, and posterior tilt of the acetabulum, etc. The age of onset of this type of patients is relatively young; the secondary type has no specific hip abnormalities at a young age and is commonly associated with traumatic arthritis and deformed healing after femoral neck fracture, etc. This type of patients can occur at all ages. FAI can lead to injury of the acetabular labrum, which is the most common cause of hip pain in young patients. Repeated impingement can cause damage to the acetabulum, glenoid labrum and cartilage, resulting in hip pain, which can lead to degeneration of the hip joint. It is also an important cause of osteoarthritis of the hip joint. Second, the analysis of misdiagnosis because of FAI part of the disease is relatively atypical or part of the disease is still not enough to understand, so it is often ignored by clinicians, or diagnosed as other diseases, such as femoral head necrosis, groin muscle strain, myofasciitis, hip synovitis, etc.. Since femoral head necrosis is more common in young adults and often has obvious hormonal, alcohol and other drug causes, its necrotic site is located in the weight-bearing area, however, for Ficat
I and II stage cases especially need a clear understanding of MRI examination. Due to the lack of awareness of FAI, many cases are misdiagnosed as femoral head necrosis. In terms of staging, Cam-type cases have an etiology in the neck of the femoral head, whereas Pincer-type cases are localized in the acetabulum, and therefore Cam-type cases are relatively more likely to be misdiagnosed as femoral head necrosis than Pincer-type cases. Our previous study showed that the femoral head-neck ratio was significantly reduced in FAI cases, and the reduced femoral head-neck ratio was a high risk for FAI. Third, the diagnosis of femoral acetabular impingement syndrome is experienced 1 History: Patients often have no obvious history of trauma, no history of alcohol and hormone use, but a small number of patients can be described as a particular injury in the flexion and internal rotation position of the hip. The main manifestation is groin pain, but also thigh pain and pain in the greater trochanter. The main reason for this is the need for hip hyperflexion and internal rotation in this position. Most of them have a history of recurrent attacks, and the movement of the hip joint is still restricted after the acute period. The most important manifestation is a positive impingement test, which needs to be compared with the opposite side. 9 cases in this group had bilateral onset, and all cases showed limited internal rotation during hyperflexion of the hip. For patients with bilateral onset, it is necessary to ask about previous hip activities. Most cases of FAI show progressive limitation of hip flexion and internal rotation, and it is necessary to exclude other disorders such as hip contracture and other extra-articular hip pathologies. Very few cases may combine FAI and hip contracture at the same time, so the diagnosis of FAI should be cautious. 3. Imaging: For young patients with hip pain, positive impingement test, and only mild abnormalities of the head and neck or acetabulum in hip pelvic plain film, orthopantomogram with head and neck ratio measurement, lateral hip joint or frog position film with femoral head and neck offset and a-angle measurement, for reduced head and neck ratio and a-angle greater than 55°, the possibility of FAI should be highly suspected. MRI is mandatory. The most common MR manifestation of femoral head necrosis is a speckled subchondral injury in the anterior upper part of the femoral head, which is characterized by different signal intensities on T1WI, surrounded by a low signal band, and a characteristic bilinear sign in the early stage of the disease, which consists of an outer low signal band and an inner high signal band on T2WI. CT scan + 3D reconstruction is of high value in determining the extent of preoperative molding. It has also been suggested that early diagnosis of FAI can be confirmed by bone scan, which shows abnormal concentration at the site of impingement, and magnetic resonance arthrograms have been reported.
The treatment of femoral acetabular impingement syndrome is still in the exploratory stage, and the author has performed surgery for some severe cases of FAI since 2009 and achieved good initial results, but medium- and long-term observation is still needed. However, medium- and long-term observation is needed. The choice of surgery must be made carefully, and the decision to operate should be made only if the disease has lasted for more than 6 months, and if regular analgesic treatment has not worked for more than 3 months. There are various surgical options.
Ganz et al. reported the surgical treatment of FAI by using a large ramus osteotomy and dislocating the hip joint, which allows 360° observation of the hip joint under direct vision for cephaloplasty, but the surgery is more traumatic. The surgical access for non-dislocation is decided according to the impact site. In recent years, with the maturity of arthroscopic technology, arthroscopically assisted or total arthroscopic FAI shaping surgery has also been reported more frequently, and all of them have obtained better clinical treatment purpose. In order to reduce the trauma of the surgery, we prefer the anterior approach to the hip joint for non-dislocation in cases of impingement limited to the anterior compartment. The main objective of the surgery is to perform hip arthroplasty, remove the impinging bone and treat the diseased acetabular labrum and cartilage.