Retrograde Medullary Superior Ramus Screw



- Discussion:
    - indicated for disruption of anterior pelvic ring frx: (APC II)when conditions for open forms of fixation are not optimal;
    - serve as an alternative to standard plating techniques for pubic ramus fixation;
    - in the case of pubic ramus frx in addition to symphysis dislocation, the retrograde screw is inserted first (to fix the frx) and subsequently the diastasis is fixed w/ a plate;
    - stability is comparable to reconstruction plate fixation;
    - a technique for insertion of a 4.5 mm cortical screw 80 mm long, which is inserted retrograde into the superior ramus, medial to the hip 
joint;
    - pubic ramus is preferably closed reduced prior to screw fixation;
           - otherwise open reduction is required;

- Radiographs:
      - inlet radiographs:
            - identifies the anterior pelvic ring;
            - slight variations in flouroscopic rotation help distinguish the superior and inferior pubic rami;
      - obturator oblique view:
            - this view is essential for demonstrating the safe zone for screw placement;
            - C-arm is placed on injured side;
            - is obtained from outlet view along w/ 20-30 deg lateral rotation;

- Technique:
    - stab incision is made at level of contra-lateral pubic tubercle;
    - blunt clamp is used to spread down to injured tubercle;
    - drill and drill sleeve are inserted parallel to superior ramus;
    - starting hole is just inferior to to the injured pubic tubercle and lateral to symphysis;
    - ML Chip et al recommend use of a oscillating 2.5 mm diameter 200 mm length triple fluted drill point (from Synthes);
          - be careful not to direct the drill cephalad out of the ramus;
    - use the inlet and the oblique-outlet views to direct the drill across the fracture and subsequently superior to the hip joint;
    - an appropriately sized 3.5 mm or 4.5 mm screw is then inserted;
           - it is not necessary for screws to pass above the hip joint, unless the ramus frx is lateral to the iliopectineal ramus;


- Internal Fixation of the Unstable Anterior Pelvic Ring: a Biomechanical Comparison of Standard Plating Techniques and Retrograde Medullary Superior Pubic Ramus Screw.

- The Retrograde Medullary Superior Pubic Ramus Screw for Treatment of Anterior Pelvic Ring Disruptions: a New Technique.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Thursday, September 6, 2012 12:47 pm