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Year |
2001 |
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Question Number |
61 |
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Category |
Select |
Question
61. A 50-year old patient with rheumatoid Arthritis has protrusio acetabuli. The best method of surgically reconstructing the acetabulum during hip arthroplasty involves:
1. using cement with a metal-backed acetabular component
2. using the femoral head as a structural graft with cementless component
3. using cancellous autograft with cementless acetabular component
4. performing concentric reaming with a bipolar prosthesis
5. placing the acetabular component medially on host bone
Figures
Answer (click for answer)
The correct answer is (3) using cancellous autograft with cementless acetabular component. (1) is incorrect because there is too much particle production when using a cemented, metal backed component (3 interfaces for wear and particle production?lysis: liner-cup, cup-cement, cement-bone). The Rheumatoid femoral head’s innate lack of structural integrity (poor bone quality) mack it a poor choice for an en-bloc structural graft with a cementless component. Concentric reaming and bipolar placement is incorrect for many reasons, including the lack of attention to the medialization that has occurred in the protrusio hip (with subsequent inadequate soft-tissue tensioning, lack of adequate lateral offset, and weak abductors?Trendelenberg gait). (5) is also incorrect because it likewise does not address the medialized acetabulum, nor the fact that the medial wall is extremely thin and will not support the stress of a component, resulting in a high risk of component protrusion through the remaining medial wall into the pelvis.
Reference: Callaghan, et al. OKU: Hip & Knee Reconstruction. Rosemont, IL. AAOS. 1995. pp. 215-225.