Periacetabular Osteotomy



Periacetabular Osteotomy


Rachel Yvonne Goldstein

Michael B. Millis





INDICATIONS/CONTRAINDICATIONS



  • Age: There is not a set age range for this procedure; instead, upper and lower limits for a periacetabular osteotomy are dependent on hip maturity and viability.



    • Lower limit: open triradiate cartilage


    • Upper limit: none specific to age


  • Indications



    • Symptomatic, congruous acetabular dysplasia


    • Mechanical instability correctable by acetabular redirection


    • Lateral and anterior center edge angles less than 20


  • Contraindications



    • Absolute



      • Hinged abduction


      • Tonnis grade 2, or worse, osteoarthrosis


      • Severe limitation of motion


      • Uncontrolled inflammatory joint disease


      • Active joint infection


      • Joint incongruity


    • Relative



      • Correctable muscular weakness


      • Negative patient-related factors


GOALS



  • Normalize Tonnis acetabular roof angle (0 to 10 degrees)


  • Correct subluxation


  • Normalize mechanical stability


ANATOMIC CONSIDERATIONS



  • Important landmarks



    • Iliopectineal eminence: marks the medial-most extent of the acetabulum


    • Infracotyloid groove: just distal to the acetabulum where the obturator externus tendon lies; this is the site of the anterior ischial osteotomy


    • Anterior superior iliac spine (ASIS)


    • Anterior inferior iliac spine (AIIS)


    • Apex of the greater sciatic notch


    • Ischial spine


  • Posterior column



    • Triangular and thickest just posterior to the acetabulum


    • Becomes thinner closer to sciatic notch


    • Optimal plane for the posterior column is angled obliquely to the medial cortex and perpendicular to the lateral cortex of the ischium posterior column.



PREOPERATIVE PLANNING



  • Clinical



    • History



      • Pain: May be insidious onset



        • Localized to the following:



          • Groin


          • Lateral aspect of hip


          • Anterolateral thigh


          • Buttock


        • Activity-related pain



          • Walking


          • Running


          • Standing


          • Impact activities


          • Pivoting on affected side


          • Prolonged sitting


        • Night pain


        • Mechanical symptoms



          • Locking


          • Catching


          • Instability


        • Gait disturbance



          • Limping



            • Antalgic gait: shortened stance phase


            • Abductor lurch/Trendelenburg gait


        • Limited walking distance


      • Physical examination



        • Limp



          • Antalgic gait


          • Abductor lurch/Trendelenburg gait


        • Standing Trendelenburg sign


        • Hypermobility


        • Range of motion



          • Steady the pelvis with one hand


          • Feel for “soft” endpoints


        • Specific testing



          • Anterior-posterior impingement tests


          • Apprehension test


          • Abductor strength testing


  • Imaging



    • Radiographs



      • Anterior-posterior (AP) view of the pelvis with patient standing the beam centered on the femoral heads (Fig. 21-1A)



        • Allows for assessment of lateral coverage using the lateral center edge angle (Fig. 21-1B)


        • Demonstrates inclination of the weight-bearing zone of the acetabulum (Fig. 21-1C)


      • False-profile view of both hips (Fig. 21-2A)



        • Assesses the anterior coverage of the femoral head (Fig. 21-2B)


        • Look for anterior joint space narrowing


      • Maximum abduction with internal rotation AP view of both hips (Fig. 21-3)



        • Mimics the correction that can obtained with the PAO


        • Demonstrates the congruence of the articulation


    • CT scan



      • Generally only required for complex deformities


    • MRI (Fig. 21-4)



      • Evaluate intra-articular structures for labral tears and articular cartilage damage


      • “Biologic” techniques, such as delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), can be used to assess cartilage health.


      • With associated cuts through the femoral condyles, can be used to assess version


  • Arthroscopy (Fig. 21-5)



    • If intra-articular pathologies, such as labral tears, Cam lesions, or loose bodies, are present, consideration should be given to concomitant treatment with arthroscopy.







      FIGURE 21-1 A. Standing anterior-posterior radiograph of the pelvis with the beam centered on the femoral head. B. Lateral center edge angle. The center edge angle is obtained by drawing a vertical line through the center of the femoral head perpendicular to the horizontal line extending through the center of both femoral heads. A line is then drawn from the center of the femoral head to the most superolateral point of the acetabulum. Normal values are greater than 25. Twenty to 25 degrees are considered borderline, and a lateral center edge angle of less than 20 degrees is considered diagnostic of acetabular dysplasia. C. Tonnis (acetabular roof) angle. Measured between the horizontal and an oblique line from the most medial point of the weight-bearing acetabulum to the most lateral point of the acetabulum. Normal values are less than 10 degrees. Used to evaluate the orientation of the acetabular roof in a coronal plane.






      FIGURE 21-2 A. False-profile view. The view is obtained with the patient standing and the pelvis rotated 65 degrees relative to the film. B. Anterior center edge angle. It is measured by drawing a vertical line through the center of the femoral head and an oblique line running from the center of the head to the most anterior point of the acetabulum. Used to determine the anterior and superior coverage of the femoral head on the false-profile view. Normal values are greater than 25 degrees.







      FIGURE 21-3 Von Rosen view. Maximum abduction with internal rotation AP view of both hips.






      FIGURE 21-4 A. dGEMRIC MRI coronal view showing hypertrophied labrum (white arrow) consistent with acetabular dysplasia. B. dGEMRIC MRI radial view showing calculation of the alpha angle, an indicator of asphericity of the femoral head.






      FIGURE 21-5 Arthroscopic view of a patient with acetabular dysplasia. Note the large, hypertrophied labrum (L). The femoral head (H) appears to the right.



    • Can be performed in the same surgical setting as the PAO


    • Allows visualization of the joint and treatment of intra-articular pathology


    • Never indicated in isolation in the treatment of symptomatic acetabular dysplasia


SURGICAL TECHNIQUE

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Jun 13, 2016 | Posted by in ORTHOPEDIC | Comments Off on Periacetabular Osteotomy

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