Acetabular protrusion: treating this hip disorder

morning stiffness caused by hip pain

A protrusion means a forward movement or an advanced position of an organ. Different organs in various regions of the body can be prone to this problem. This is the case of the eyeball, the brain, the tongue, the intervertebral discs or the acetabulum. In this article, we will focus on the protrusion of the acetabulum.

What is a acetabular protrusion ? What is it due to? What are its signs? How to make your diagnosis? How to treat it? The answers below.

What is an acetabular protrusion?

In order to better understand what an acetabular protrusion is, it is advisable to make a small reminder on theanatomy of the acetabulum.

Also called the "acetabulum", the acetabulum corresponds to the articular cavity of the coxal bone of the pelvis or the iliac bone (wing of the pelvis). This cavity accommodates the head of the femur and forms with it the hip joint. Endowed with a rounded shape, the acetabulum gives the movement of the femur a great amplitude.

The acetabulum is formed more precisely of 3 bony structures.

  • On its posterior part there is theischium or coxal bone. There are two types: the coxal bone located on the left and the coxal bone located on the right. Together with the coccyx and the sacrum, these two bones form the pelvic girdle or the pelvis.
  • On its upper part, we find theilium or ilium. This is the part of the hip that protrudes.
  • On its anterior part, there is the pubis which is formed by two bones, including a wide bone and a flat bone that constitute the pelvis.

So, the acetabular protrusion refers to an abnormal protrusion of the articular surface of the iliac bone. It can also be referred to by other names: "Otto's disease", "Otto's pelvis" or "Chrobak's pelvis".


More precisely, the Otto's disease corresponds to a malformation of the hip. It is a structural anomaly which associates a reduction in the articular amplitudes as well as a too deep hip. This malformation is called “internal dysplasia”.

In case of the presence of internal dysplasia, in addition to the hip, we also notice a much deeper acetabulum than normal.

To know everything about hip dysplasia in babies, see the following article.

To learn all about hip dysplasia in adults, see the following article.

Causes of an acetabular protrusion

La acetabular protrusion is characterized by depression of the bottom of the acetabulum. Until now, the exact cause of this internal dysplasia remains unknown. But the lesion could be linked to joint degeneration associated with osteoarthritis (coxarthrosis). This type of lesion mainly affects women.

Hip osteoarthritis means osteoarthritis of thehip joint or hip. the Chrobak basin is one of the pathological mechanisms of this type of osteoarthritis. In 5 to 8% of cases of coxarthrosis, it is found involved with a high prevalence in women and generally with bilateral involvement.

A Hip osteoarthritis secondary to Otto's pelvis can be characterized as follows.

  • It is an osteoarthritis with usually slow evolution.
  • It is a condition that reduces hip mobility and generates mild pain at the onset of the disease.
  • It is a joint malformation in which the pain can increase in intensity as the osteoarthritis progresses.

Symptoms of an acetabular protrusion

At the onset of the joint malformation, the Otto's disease is not painful. It is during the degradation of the articular cartilage, which tends to evolve towards osteoarthritis, that the pain appears.

The patient may experience mechanical pain. These gradually settle in the groin or buttocks. This results in a limitation of the activities of the hip as well as the abduction movements of the lower limbs (the fact of spreading them apart).

It is suspected that a Chrobak pelvis may cause dystocia. This corresponds to difficulty during childbirth. In case of structural abnormality of the acetabulum, the pelvis is narrowed.

Diagnosis of an acetabular protrusion

When auscultating the patient as part of the Otto basin, the doctor assesses the pain and observes the decrease in joint mobility.

La pelvic x-ray is the reference examination for internal dysplasia. But sometimes it is difficult to identify osteoarthritis. As this can be located in an unusual way, it can go unnoticed, which usually happens.

If there is any doubt about the diagnosis, the doctor performs an infiltration test carried out under radiological control. This test confirms joint pain.

Treatment of an acetabular protrusion


Le treatment of an acetabular protrusion does not rely on surgery. Surgery cannot repair the joint defect. It is even possible to take care of it in order to relieve its symptoms.

Anti-osteoarthritis treatments

The anti-osteoarthritis treatments can be offered for management of internal dysplasia. These have the effect of delaying the development of coxarthrosis in order to minimize the degradation of the joint.

Other types of medication may be prescribed to ease the pain:

  • of analgesics such as paracetamol: doctors recommend them as first-line because it has a good efficacy/risk ratio;
  • of anti-inflammatory level 1 such as ibuprofen or coxibs: they are prescribed only if paracetamol proves to be insufficient or ineffective against pain.

The implantation of a prosthesis

When the evolution of osteoarthritis is too advanced, the management consists of the implantation of a total hip prosthesis. The purpose of this implantation is to lateralize the protrused hip.

This type of treatment may require the use of an additional bone graft. If this is the case, the large bone should be placed beforehand to reduce the depth of the hip as much as possible.

To know everything about the total hip prosthesis, see the following article.

Wearing foot orthotics

Plantar orthoses ensure the maintenance of good alignment of the lower limbs. They also contribute to the improvement of stability when walking. To avoid various hip problems and ensure better balance of the pelvis, a heel lift can be helpful in cases of significant leg unevenness.


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