Case Of the Week (COW) 28 April 2013
Answer:
Aseptic loosening of the metallic acetabular component of the right hip prosthesis with Left Avascular Necrosis.
Findings:
There is Aseptic loosening of the metallic acetabular component of the right hip prosthesis with periprosthetic osteolysis as evidenced by degradation of bone interface , holes in the acetabular component and radiolucent (lytic) areas in the central (1.5cms) and medial (6mm) aspect. Patchy STIR hyperintensities with subchondral irregularity and mild femoral head flattening and sclerosis seen in the left hip joint –Avascular Necrosis. Linear track noted in the left femoral neck and intertrochanteric regions – core decompression for Avascular Necrosis.
Discussion:
Total hip arthroplasty, the most commonly used type of hip replacement uses two components: a stemmed femoral component with a prosthetic femoral head and an acetabular component. Both components can be cemented or noncemented. Most modern hip arthroplasty systems are modular, with the femoral stem, head, acetabular shell, and acetabular liner being separate pieces. Aseptic loosening of prosthetic components is the most common cause for revision surgery. The loosening can be secondary to mechanical (stress) or biologic factors (degradation of the cement-bone or cementless interface resulting from the migration of wear particles. Progressive radiolucent areas greater than 1 mm at these interfaces indicate prosthesis loosening. A radiolucent area greater than 2 mm in any of the three of acetabular zones (1 = superolateral, 2 = central, 3 = medial aspect of the bone–acetabular component interface), superior or medial migration of the cup, or change in inclination of the cup is indicative of loosening.
REFERENCES: Joint Arthroplasties and Prostheses September 2003RadioGraphics, 23, 1295-1314.
Contributed By:
Dr. Babu Peter MD, DNB
Associate Professor, Barnard Institute of Radiology, Chennai
Senior Consultant Radiologist, Aarthi Scans, Chennai
Answer:
Aseptic loosening of the metallic acetabular component of the right hip prosthesis with Left Avascular Necrosis.
Findings:
There is Aseptic loosening of the metallic acetabular component of the right hip prosthesis with periprosthetic osteolysis as evidenced by degradation of bone interface , holes in the acetabular component and radiolucent (lytic) areas in the central (1.5cms) and medial (6mm) aspect. Patchy STIR hyperintensities with subchondral irregularity and mild femoral head flattening and sclerosis seen in the left hip joint –Avascular Necrosis. Linear track noted in the left femoral neck and intertrochanteric regions – core decompression for Avascular Necrosis.
Discussion:
Total hip arthroplasty, the most commonly used type of hip replacement uses two components: a stemmed femoral component with a prosthetic femoral head and an acetabular component. Both components can be cemented or noncemented. Most modern hip arthroplasty systems are modular, with the femoral stem, head, acetabular shell, and acetabular liner being separate pieces. Aseptic loosening of prosthetic components is the most common cause for revision surgery. The loosening can be secondary to mechanical (stress) or biologic factors (degradation of the cement-bone or cementless interface resulting from the migration of wear particles. Progressive radiolucent areas greater than 1 mm at these interfaces indicate prosthesis loosening. A radiolucent area greater than 2 mm in any of the three of acetabular zones (1 = superolateral, 2 = central, 3 = medial aspect of the bone–acetabular component interface), superior or medial migration of the cup, or change in inclination of the cup is indicative of loosening.
REFERENCES: Joint Arthroplasties and Prostheses September 2003RadioGraphics, 23, 1295-1314.
Contributed By:
Dr. Babu Peter MD, DNB
Associate Professor, Barnard Institute of Radiology, Chennai
Senior Consultant Radiologist, Aarthi Scans, Chennai