Brief overview
- Symptoms: Motion-dependent groin pain, pain after prolonged sitting, limited mobility.
- Causes: Malformations of the head of the femur and/or the acetabulum that abut in places.
- Treatment: In mild cases, conservative therapy, but usually surgery
- Forms: Depending on the involvement of the acetabulum or head, a distinction is made between pincer and cam impingement; mixed forms possible
- Diagnosis: Physical examination of mobility, imaging examinations, especially X-ray and MRI
- Course of disease and prognosis: If treated in time, more severe joint damage can possibly be prevented (arthroscopic surgery); if not treated, cartilage or the joint lip are potentially damaged; in the worst case: hip joint arthrosis
- Prevention: avoid sports with special stress on the hip joint (soccer, martial arts); however, general prevention is not possible.
Description
Impingement syndrome of the hip (femoro-acetabular impingement syndrome) is a mechanical tightness between the femoral head of the thigh bone (femur) and the acetabular roof (acetabulum), which is formed by the pelvic bone.
Depending on the origin of the bony changes, doctors distinguish between pincer impingement and cam impingement.
Pincer impingement of the hip
In Pincer impingement of the hip, the femoral neck has a normal configuration. The acetabulum, on the other hand, has the deformed shape of a pincer and literally “pincers” the femoral head. This increased roofing of the femoral head within the joint space causes the femoral head and the acetabular roof to collide slightly, depending on the movement. The result is painful mechanical impingement of the hip joint.
Pincer impingement syndrome of the hip is more common in women.
Cam impingement of the hip
In a healthy skeleton, the neck of the femur has a waist below the head of the femur, giving the head of the femur more freedom of movement in the joint capsule. In cam impingement syndrome of the hip, the waist is lost due to a growth of the femoral neck bone. The bone bulge narrows the joint space, which promotes painful rubbing of the femoral neck head and the labrum of the acetabular roof.
Cam impingement syndrome of the hip is more common in young, athletically active males, with soccer players being particularly prone to it.
Symptoms
Initially, symptoms of hip impingement syndrome are often very gradual. Patients report sporadic pain in the hip joint. The pain in the groin often radiates into the thigh and intensifies with exertion.
Climbing stairs and remaining in a seated position while driving also often cause pain. In most cases, turning the bent leg inward (internal rotation with 90 degrees of flexion) also triggers or intensifies pain. So, depending on the sleeping position (side sleeper), people with hip impingement may experience pain at night because the joint has rotated awkwardly.
In many cases, sufferers adopt a protective posture in which they rotate the affected leg slightly outward (external rotation).
Causes and risk factors
Impingement syndrome of the hip most often results from bony deformity of the acetabular roof (acetabulum): The iliac bone (os ilium) forms a cup-shaped socket that, together with the femoral head of the femur, forms the hip joint.
The origin of many of the pincer impingement and cam impingement cases has not yet been adequately clarified. However, the load-dependent, bony structural changes are detectable in most affected individuals. Another possible explanation for the bony deformity is the assumption that a growth disorder in adolescence leads to a defective closure of the growth plates.
Another factor for the development seems to be excessive sports.
How is impingement syndrome of the hip treated?
The therapy concept for impingement syndrome of the hip depends on the triggering cause. Conservative therapy approaches such as immobilization of the joint, painkillers, physiotherapy and avoidance of triggering factors often relieve the symptoms, but do not eliminate the cause. For this, surgery is necessary (causal therapy).
Conservative therapy of impingement syndrome of the hip
In the early stages of the disease, conservative therapy options are especially important. Their goal is to relieve pain without invasive procedures. Anti-inflammatory painkillers such as acetylsalicylic acid or ibuprofen help.
Causal therapy of impingement syndrome of the hip.
The causal therapy approach involves treating and eliminating the triggering cause of the condition. In impingement syndrome of the hip, the physician removes the structural bone changes during a surgical procedure (arthroscopy). Pain usually improves once the mechanical tightness is removed by surgery.
Surgery is especially recommended for young patients to minimize the risk of joint stiffness later in life. The surgical procedure of first choice is arthroscopy.
Arthroscopy is the surgical procedure of first choice and has replaced open surgery. It is a low-risk, minimally invasive method that involves making two to three small (about one centimeter) incisions in the skin around the hip joint. A camera with an integrated light source and special surgical equipment are inserted into the joint through the skin incisions, allowing precise visualization of the entire joint and detection of damage.
Examination and diagnosis
The right person to contact if you suspect impingement syndrome of the hip is a specialist in orthopedics and trauma surgery. He or she will first discuss your medical history with you in detail. He may ask you the following questions:
- Do you do any sports, and if so, what kind?
- What are the symptoms of restricted mobility in the hip joint?
- Do you remember an injury or heavy exertion that was associated with the onset of pain?
- Does the pain increase when you turn your leg inward?
The doctor will physically examine you following the interview. He will test the mobility of the hip joint by asking you to put the leg in different positions. In addition, the doctor will press the bent leg against the edge of the hip socket, which usually triggers the typical pain.
Imaging tests to detect impingement syndrome of the hip include an X-ray of the pelvis, magnetic resonance imaging (MRI) and an ultrasound examination (sonography).
X-ray examination
Magnetic resonance imaging (MRI)
Magnetic resonance imaging (MRI), also known as magnetic resonance imaging, enables precise imaging of the soft tissues surrounding the hip joint. Tendons, muscles, bursa and cartilage can thus be depicted in very high resolution. The images are created during magnetic resonance imaging by combining radio waves and magnetic fields.
Before a planned surgical, reconstructive procedure, an MRI is particularly useful to better assess the surgical conditions and to better plan the planned procedure.
Sonography (ultrasound)
Sonography is a very simple and inexpensive examination method that can be used, for example, to visualize inflammation-related fluid accumulations within the bursa as well as muscular structures. Bones, on the other hand, cannot be sufficiently well imaged by ultrasound. In impingement syndrome of the hip, sonography is therefore usually only used as a supplementary examination method and not as the primary diagnostic method.
Course of the disease and prognosis
Depending on the measures performed during surgery, the period of time during which patients must take care of themselves varies. Under certain circumstances, this means that after the arthroscopy only partial weight-bearing of the hip joint with a maximum of 20 to 30 kilograms is allowed at first.
Regular physiotherapeutic treatment immediately follows the arthroscopy. Weight-bearing by jumping is recommended at the earliest twelve weeks after the hip joint operation. Sports that relieve pressure on the hip joint, such as swimming and cycling, are permitted again as early as six weeks after the operation. Six months later, all sports are usually possible again.
Consequential damage caused by impingement syndrome of the hip can only be successfully prevented with early treatment.
