- See:
-
Associated Transverse & Posterior Wall Frx;
-
T Shaped Fractures:
- Discussion:
- transverse frxs extend across both the
anterior and
posterior columns;
- the frx divides the innominate bone into superior segment containing acetabular roof and intact ilium, & inferior segment
consisting of single ischiopubic fragment;
-
classification:
- if both anterior & posterior columns are broken, then it is called transverse fracture, and if both columns are broken
& separated from each other, that is
T fracture;
- transverse fracture are sub-classified according to location relative to the wt bearing dome;
- transtectal: frx courses through the weight-bearing dome (WBD);
- juxtatectal: frx courses above the cotyloid fossa, so that a significant portion of the wt bearing dome is left intact;
- infratectal: frx courses below the wt bearing dome;
- transverse posterior wall frx:
- may be difficult to reduce in the presence of a transverse transtectal component, large posterior wall fragment, or w/ pubic ramus frx;
- mechanism: blow directly upon greater trochanter;
- stemming from the lateral compressive force these frx may also be assoc w/
central femoral head dislocation;
- Radiographs:
- ilioischial and iliopectineal lines are both disrupted, but there will be no involvement of the obturator ring (otherwise frx would be a
T fracture);
- assesment of stability:
- in the study by Vrahas et al 1999, a cadaveric biomechanical study was performed to determine the relative stability of anterior column,
posterior column, and transverse fractures;
- they noted that transverse acetabular fractures with medial roof-arc angle (AP radiograph) of 45 degrees or less were unstable and required ORIF;
- ref: The Effects of Simulated Transverse, Anterior Column, and Posterior Column Fractures of the Acetabulum on the Stability of the Hip Joint.
MS Vrahas MD et al.
JBJS Vol 81-A. July 1999.
- Exposure:
- Kocher-Langenback:
- most transverse frx are exposed w/ posterior approach, especially if the displacement and rotation is posterior;
- transverse frx,
posterior wall &
posterior column fractures, &
T-type fractures may be exposed using
Kocher-Langenback;
- in many cases a trochanteric osteotomy will be required inorder to optimize the exposure;
- ilioinguinal approach:
- indicated for high transverse frx and for frx w/ anterior displacment and/or w/ anterior rotation;
- the ilioinguinal approach should also be chosen for transverse fractures which course across the acetabulum from a proximal-
anterior to a distal-posterior direction;
- Reduction:
- for reduction of these frx pt is generally prone &
Kocher Langenbeck approach is used;
- reduction technqiue is similar to that used for
posterior column frx;
- usually the two screw technique is used to control displacement while rotational lever is placed to control the ischial tuberosity;
- as rotational lever is being applied, the entire ischiopubic segment is rotated rather than the
posterior column alone;
- reduction of anterior portion of
transverse frx is assessed by palpation of quadrilateral surface & pelvic brim thru
greater sciatic notch;
-
insertion of Schanz screw:
- w/ the posterior approach, reduction can be facilitated by inserting a Schanz screw into the ischium just inferior to the subcotyloid gutter;
- a T chuck is applied over the the Schanz screw, which is then used to rotate a displaced posterior column frx into a reduced position;
- the surgeon's other hand can guide the reduction by palpating the quadrilateral surface;
- Fixation:
-
lag screw spans transverse frx from a proximal to a distal direction;
- long
6.5 mm cancellous screw transverses the anterior portion of frx into the superior pubic ramus;
- lag screw is inserted into retroacetabular surface and is directed toward the
anterior column;
- following lag screw, a plate is placed along retroacetabular surface;
-
plate fixation:
- 3.5 mm reconstruction plate is applied along posterior column, immediately behind the acetabulum;
- in the report by Chang et al, the authors evaluated the strength of lag screw fixation compared with
traditional fixation techniques of transverse acetabular fractures;
- 10 cadaveric pelvic specimens with bilateral, transtectal transverse acetabular fractures were used for this study;
- right acetabular fractures were fixed with a 5-hole plate and four screws with the central hole spanning the posterior fracture site;
- left acetabular fractures were fixed with two lag screws, one each in the anterior and posterior columns,
or with a screw and wire construct stabilizing both columns;
- plate and screw construct showed significantly greater yield and maximum strength when compared with the two lag screws;
- stiffness of the lag screw method was 39% higher than that of the plating method, but this result was not statistically significant;
- ref: Comparative Strength of Three Methods of Fixation of Transverse Acetabular Fractures
Je-Ken Chang MD. CORR 2001;2001:433-441
- Screw Placement in the Ischial Tuberosity:
-
anatomical hazards:
- the internal pudendal bundle usually lies 1.5 cm from the medial posterior margin of the ischial tuberosity;
- internal pudendal bundle passes out of
greater sciatic foramen, passes around sacrospinous ligament,
over the
internal obturator muscle (just medial to the tuberosity) and then into lesser foramen;
- excessively medially angulated screws may injure the internal pudendal;
- at 2 cm below the inferior acetabular margin, hamstring origin is encountered (and therefore dissection below this point is avoided);
-
technique of insertion:
- maximal purchase is achieved w/ entry into the tuberosity 5 or 10 mm medial to the lateral margin of the tuberosity and are directed inferiorly;
- at the level of the inferior acetabular margin, direct the screw 35-40 deg caudally;
- at 1 cm below the inferior acetabular margin, direct screws 45-50 deg caudally;
- at 2 cm below the inferior acetabular margin, direct screws 50-55 deg caudally;
The Effects of Simulated Transverse, Anterior Column, and Posterior Column Fractures of the Acetabulum on the Stability of the Hip Joint*
MS Vrahas MD et al.
JBJS Vol 81-A. July 1999.
