Protrusio acetabuli

Protrusio acetabuli is an uncommon defect of the acetabulum. The acetabulum is the socket that receives the femoral head to make the hip joint. It is composed of three bones, the ilium, the ischium and the pubis. The socket is too deep and may protrude into the pelvis. ^[1]

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Classification

Protrusio acetabuli is divided into two types, primary and secondary.

Primary protrusio acetabuli

• Characterized by progressive protrusio in middle aged women
• May be associated with OA
• May be familial

Secondary protrusio acetabuli

Causes include:

may be present bilaterally in Paget's disease, Marfan syndrome,^[2] RA, AS, & osteomalacia;

• Femoral head prosthesis
• Cup arthroplasty
• Septic arthritis
• Central fracture dislocation
• Total hip replacement surgery

Signs and Symptoms

• May be asymptomatic
• Limitation of joint range of movement is the earliest sign
• Pain

Natural course

The protrusio may progress until the femoral neck impinges against the pelvis.

Diagnosis

Diagnosis is made on the basis of an anteroposterior radiograph of the pelvis that demonstrates a center-edge angle greater than 40 degrees and medialisation of the medial wall of the acetabulum past the ilioischial line.

Treatment

Joint replacement surgery is indicated for severe pain or substantial joint restriction

References

1. ^ Van De Velde S, Fillman R, Yandow S (2006). "The aetiology of protrusio acetabuli. Literature review from 1824 to 2006". Acta Orthop Belg 72 (5): 524–9. PMID 17152413.
2. ^ Van de Velde S, Fillman R, Yandow S (2006). "Protrusio acetabuli in Marfan syndrome. History, diagnosis, and treatment". J Bone Joint Surg Am 88 (3): 639–46. doi:10.2106/JBJS.E.00567. PMID 16510833.

• McBride MT, Muldoon MP, Santore RF, Trousdale RT, Wenger DR (2001). "Protrusio acetabuli: diagnosis and treatment". J Am Acad Orthop Surg 9 (2): 79–88. PMID 11281632.