The patient presented with a long history of bilateral hip pain that was gradually getting worse. Symptoms were especially troublesome during sexual intercourse. An AP radiograph of the pelvis was taken.
The patient presented with a long history of bilateral hip pain that was gradually getting worse. Symptoms were especially troublesome during sexual intercourse. An AP radiograph of the pelvis was taken.
Protrusio acetabuli represents bulging of the acetabular floor into the pelvis. It is defined as follows:
1. The acetabular dome passes medial to Kohler's line, which is a line drawn from the pelvic border of the ilium to the medial border of the body of the ischium.
2. The centre edge (CE) angle is greater than 35 degrees. The CE angle is the angle subtended by one line drawn from the acetabular edge to the centre of the femoral head and a second line perpendicular to the line joining the centres of the femoral heads.
Protrusio acetabuli is probably the result of remodelling of weak, medial acetabular bone after multiple, recurring stress fractures. Primary and secondary forms has been described. The primary protrusio (idiopathic form) is usually seen in middle-aged women with bilateral involvment in one third of cases. The secondary form is associated with diseases causing weakening of the acetabular floor. Unilateral involvment is seen in trauma (central fracture dislocation), infective arthritis (tubercular and septic), fibrous dysplasia, and Marfan's syndrome. Bilateral involvement is seen in rheumatoid arthritis, juvenile chronic arthritis, osteomalacia and rickets, Paget's disease, Marfan's syndrome, ankylosing spondylitis and osteoarthritis (occasionally). The secondary form may also result from total hip replacement, cup arthroplasty or femoral head prosthesis. The deformity may progress until the femoral neck touches the side of the pelvis. Treatment is total hip replacement with bone grafting to build up the medial wall of the acetabulum.
Bilateral idiopathic protrusio acetabuli
1. On the anteroposterior (AP) radiograph of the pelvis, the medial margins of both acetabula appear protruded inward, with the apex of the acetabulum extending beyond Kohler’s line (a line drawn from the medial cortex of the ilium to the medial cortex of the ischium).
2. The bilateral center-edge (CE) angles are increased, exceeding 35°, indicating increased coverage of the femoral head by the acetabulum.
3. The femoral head is seen extending further into the pelvis. Although there is protrusio of the acetabulum, the joint space is still visible, without significant joint surface destruction or marked proliferative changes.
Based on the patient being a 28-year-old female, clinical symptoms of bilateral hip pain (especially noticeable during sexual intercourse), and the above X-ray findings, the following diagnoses or differential diagnoses are considered:
Taking into account the imaging findings, patient age, and clinical symptoms, the most likely diagnosis is: Bilateral Acetabular Protrusion (more likely primary).
To exclude secondary causes such as rheumatoid arthritis or other metabolic bone disorders, it is recommended to conduct further laboratory tests (inflammatory markers, immunological examinations, bone metabolism indicators) and, if necessary, MRI or CT imaging to assess the integrity of the medial acetabular wall.
1. Conservative Treatment:
・ Pain Management: Select appropriate anti-inflammatory and analgesic medications (e.g., NSAIDs) to relieve pain and inflammation.
・ Weight Management: Avoid excessive weight gain to reduce load on the hip joints.
・ Physical Therapy: Use warm therapy, ultrasound, or other modalities to improve local circulation and alleviate pain.
2. Surgical Treatment:
・ In cases of severe symptoms or significant joint destruction, total hip arthroplasty (THA) may be considered. Intraoperative bone grafting can help reconstruct the medial acetabular wall and prevent excessive medial migration of the prosthesis.
・ For younger patients or those with relatively preserved joint cartilage, if conservative treatment is ineffective, evaluate for hip preservation procedures and acetabular reconstruction.
3. Rehabilitation and Exercise Prescription (FITT-VP Principle):
・ Frequency: At least 3–4 sessions per week of hip-focused rehabilitation exercises.
・ Intensity: Low-to-moderate intensity based on individual tolerance, such as walking in water or lower-extremity strength exercises. Avoid movements with excessive rotation or extreme flexion/extension.
・ Time: Each session can last 20–30 minutes. If pain is significant, sessions may be divided, for instance 10 minutes each time, 2–3 times per day.
・ Type: Emphasize low-impact aerobic activities that protect the hip joint, such as elliptical training, modified low-resistance cycling, or aquatic therapy (water walking, leg lifts in water, etc.).
・ Progression: As symptoms improve and joint stability increases, gradually extend exercise duration and frequency. In strength training, start with light resistance for hip abduction, adduction, and extension exercises, and progressively increase as tolerated.
・ Volume & Pattern: Adjust overall exercise volume according to daily pain levels and fatigue. Encourage intermittent rest and avoid prolonged excessive weight-bearing.
4. Special Precautions:
・ Due to structural changes of the hip in acetabular protrusion, avoid any movements that may excessively stress the femoral neck or acetabulum.
・ For any special movements (including sexual positions), consult with a physical therapist or specialist to find positions that minimize pain and reduce the risk of joint damage.
This report is merely a reference analysis based on the current imaging and clinical history. It does not replace an in-person consultation or the diagnostic and treatment advice of a professional medical institution. Patients should make final decisions regarding diagnosis and treatment in consultation with their healthcare provider and based on their individual condition.
Bilateral idiopathic protrusio acetabuli
