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THR: Acetabular Component Anteversion:


- Discussion:  
     - see native acetabular anteversion and femoral anteversion and acetabular component position
     - general considerations:
              - simple visualization of length of anterior/posterior walls gives an accurate measure of native anteversion;
              - references:
                      - Femoral anteversion in THA and its lack of correlation with native acetabular anteversion.
                      - The effect of the orientation of the acetabular and femoral components on the range of motion of the hip at different head-neck ratios.
                      - Does Acetabular Retroversion Affect Range of Motion after Total Hip Arthroplasty?
                     
- The 2014 Frank Stinchfield Award: The 'landing zone' for wear and stability in total hip arthroplasty is smaller than we thought: a computational analysis.

       - effect of decreased/insufficient anteversion:          
             
- psoas tendonititis:
              - references:
                  - Influence of component positions on dislocation: computed tomographic evaluations in a consecutive series of total hip arthroplasty.
                  - Dislocation After Total Hip Arthroplasty. Causes and Prevention.
                  - Factors predisposing to dislocation after primary total hip arthroplasty. A multivariate analysis.
                  - Acetabular revision for recurrent dislocations: results in 14 cases after 3 years of follow-up.
                  - Position, orientation and component interaction in dislocation of the total hip prosthesis
                  -
Iliopsoas Impingement After Primary Total Hip Arthroplasty: Operative and Nonoperative Treatment Outcomes.

      - effect of increased/excessive anteversion: (see painful hip replacement
              - impingement will occur in hip extension/ER during the toe off phase;
              - posterior impingement (due to increased anteversion) will be increased with addition of posterior positioning of the extended rim;  
              - references:
                      - Increased anteversion of press-fit femoral stems compared with anatomic femur. 
                      - Anterior dislocation of a total hip replacement. Radiographic and CT-scan assessment. Behavior following conservative management.
                      - Posterior femoral neck impingement secondary to excess acetabular anteversion in hip resurfacing arthroplasty.
                      - The spatial location of impingement in total hip arthroplasty
                      - Cup-neck impingement due to the malposition of the implant as a possible mechanism for metallosis in metal-on-metal total hip arthroplasty.
                      - Anterior Subluxation after Total Hip Replacement Confirmed by Radiographs: Report of Two Cases
                      - Anterior Dislocation Following Primary THR by the Posterior Approach — Aetiology and Treatment
                      -
Increased Anteversion of Press-fit Femoral Stems Compared With Anatomic Femur

     - Intraoperative Determination of Component Anteversion:
              - patient position:
                     - note that it can be difficult to judge component flexion on the OR table due to patient position; 
                     - if the patient is tilted posteriorly, there will be a tendency to ream the component in retroversion (and vice versa); 
                     - in the lateral position, if the patient's pelvis is flexed relative to the torso, the surgeon the ream the component in a
                               retroverted position (if degree of anteversion is calculated off of patient's torso); 
                     - references:
                               - Accuracy of intraoperative assessment of acetabular prosthesis placement
                               - Combined Anteversion Technique for Total Hip Arthroplasty
              - Native Anteversion:
                     - Does Native Hip Anatomy Fit Recommendations for Safe Component Orientation in THA?
                     - Femoral Anteversion in THA and its Lack of Correlation with Native Acetabular Anteversion.
                     - Comparison of native anatomy with recommended safe component orientation in total hip arthroplasty for primary osteoarthritis.

              - McCollum's line extends from anterosuperior iliac spine to the sciatic notch; 
                       - this gives a reproducible landmark to help the surgeon gage the proper angle of reaming; 
                       - generally the line of reaming and cup insertion is either perpendicular to McCollum's line or is slightly anterior to the line;
                        - safe rande for flexion was 20 degrees to 40 degrees; 
                        - when cup was positioned in 20 deg flexion impingement was occasionally noticed w/ hip flexed to 90 deg & IR to 90 deg;
                        - to eliminate impingement of prosthetic neck against the prosthetic cup, flexion was increased to 30 degrees; 
              - Transverse acetabular ligament as a refererence for anteversion:
                        - The Transverse Acetabular Ligament: Optimizing Version
                        - Anteversion of the acetabular component aligned with the transverse acetabular ligament in total hip arthroplasty.
                        - Is transverse acetabular ligament an anatomical landmark to reliably orient the cup in primary total hip arthroplasty
                        - The role of the transverse acetabular ligament for acetabular component orientation in total hip replacement: an analysis of acetabular component position and range of movement using navigation software.
                        - The transverse acetabular ligament may be used to align the acetabular cup in total hip arthroplasty
                        - Acetabular component positioning using the transverse acetabular ligament: can you find it and does it help?
                        - The relationship of the orientation of the transverse acetabular ligament and acetabular labrum to the suggested safe zones of cup positioning in total hip arthroplasty.                        - Reducing the rate of early primary hip dislocation by combining a change in surgical technique and an increase in femoral head diameter to 36 mm.
                        -
Total hip replacement through a posterior approach using a 22 mm diameter femoral head : the role of the transverse acetabular ligament and capsular repair in reducing the rate of dislocation.

Postoperative Radiographic Evaluation:
       - see postoperative radiographic evaluation of cup position
       - measurement of postoperative anteversion:
              - Anteversion of the acetabular cup. Measurement of angle after total hip replacement.
              - A simplified method to determine acetabular cup anteversion from plain radiographs.

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 Influence of the sagittal balance of the spine on the anterior pelvic plane and on the acetabular orientation.