Review Question - QID 4488

If the total hip prosthesis is inserted according to the template in Figure E, the offset will increase while the leg lengths will remain unchanged.

Restoration of limb length is essential following total hip arthroplasty. The amount of limb-length change will be the vertical distance between the center of rotation of the femoral component and the center of rotation of the acetabular component. Thus, when the femoral center of rotation on templating is inferior to that of the acetabular component, the limb will be shortened. Restoring femoral offset is also important. If the center of rotation of the prosthetic head lies lateral to that of the cup on templating, the reconstruction will produce decreased offset.

Scheerlinck et al. present a stepwise approach to hip templating through four steps. Step 1 involves identifying landmarks, step 2 involves assessing the quality of the radiograph, step 3 identifies mechanical references, and step 4 optimizes implant positioning.

Tripuraneni et al. discuss the common errors encountered when templating for total hip arthroplasty. They found the most common error was excessive limb lengthening and incomplete medialization of the acetabular component.

Della Valle et al. review hip templating. They stress the importance of pre-operative planning, but also discuss the importance of tactile feedback during the surgery in choosing the correct implants.

Illustration A shows a table of how offset and leg lengths can be changed through positioning and selection of components.

Incorrect Answers:
Answer 1: Figure A will decrease leg length and decrease offset.
Answer 2: Figure B will maintain offset but decrease leg length.
Answer 3: Figure C will decrease offset and maintain leg length.
Answer 4: Figure D will decrease leg length and increase offset.