Fracture Characteristics
Definition
Associated anterior column/wall plus posterior hemitransverse fractures are partially articular fractures with a transverse fracture component, characterized by an anterior segmental fracture (wall) or a separation of the anterior column from the posterior column in combination with only a posterior transverse fracture line. Per definition, a variable articular part remains connected to the axial skeleton.
Historically, associated anterior column plus posterior hemitransverse fractures are rare acetabular fractures with a suspected incidence of approximately 5%.1 However, with increasing frequencies of geriatric acetabular fractures, this fracture type is supposed to be more common.
Overall, Letournel distinguished six different subgroups:
Associated anterior wall fracture with a complete/incomplete posterior hemitransverse fracture
Associated anterior column plus posterior hemitransverse fracture
Low anterior column fracture (below the level of the anterior inferior iliac spine)
Intermediate anterior column fracture (between anterior inferior iliac spine [SIAI] and anterior superior iliac spine [SIAS])
High anterior column fracture (above the level of the SIAS)
Associated anterior column plus incomplete posterior hemitransverse fracture
Pediatric fractures
The primary fracture line affects the anterior wall or the anterior column. Here, the most relevant displacement is observed, whereas the posterior column fracture is usually less displaced.
The posterior transverse fracture line is orientated horizontally and meets the anterior column/wall fracture at an angle of nearly 90 degrees.
Part of the articular surface of the acetabular roof is always connected to the intact iliac bone (different than both-column fractures; see ▶ 17). The morphology of the fracture of the anterior wall or of the anterior column corresponds to the isolated fractures.
13.2 Radiological–Anatomical Criteria
Pelvic anteroposterior (AP) view (▶ Fig. 13.1, ▶ Fig. 13.2, ▶ Fig. 13.3). The characteristic lines of the anterior hemipelvis, such as the iliopectineal line and the anterior wall line, are disrupted. The ilioischial is disrupted due to the transverse fracture component and its relation to the teardrop figure is changed. When the posterior fracture is displaced, the ischiopubic segment is internally rotated, resulting in better visualization of a disruption of the posterior wall line. Further characteristics correspond to anterior wall or column fractures.
Iliac oblique view (IOV) (▶ Fig. 13.1, ▶ Fig. 13.2, ▶ Fig. 13.3). The posterior transverse component is clearly visualized and runs horizontal, typically ending in the area of the sciatic spine up to the superior part of the greater sciatic notch. Anterior fractures extending into the iliac fossa or to the iliac crest become visible.
Obturator oblique view (OOV) (▶ Fig. 13.1, ▶ Fig. 13.2, ▶ Fig. 13.3). The extent of displacement, the fracture characteristics with localization of fracture lines involving the pubic rami and the iliopectineal line, and their relation to the acetabular roof become visible. Occasionally, an additional fracture line lateral to the acetabulum is present. This fracture can be misinterpreted as a both-column fracture (pseudo spur sign). The exact fracture course involving the obturator foramen is cleared.
Computed tomography (▶ Fig. 13.1, ▶ Fig. 13.2, ▶ Fig. 13.3). The main fracture line is analyzed, starting cranially, to confirm the diagnosis of an anterior column fracture. Three-dimensional (3D)-CT provides an optimal view of the exact fracture morphology, analysis of the fragment size and possible additional injuries, and the extent of involvement of the quadrilateral surface—the latter especially using a medial hemipelvic view. The most proximal fracture line is identified. Sagittal reconstructions allow analysis of quadrilateral surface involvement.
In addition to the number of fragments of the anterior column/wall, the extent of anterior displacement (central or anterior) is visualized. Comminution zones are often present in the area of the obturator canal. The hemitransverse component is identified as a posterior part of a typical transverse fracture (posterior vertical fracture line on axial CT). The posterior ischiopubic segment can be internally rotated around a vertical axis. In the upper sections, often a fracture line in the acetabular fossa is seen, corresponding to distal parts of the posterior wall articular surface.
In some images, the T-structure of this fracture type can be seen (▶ Fig. 13.2b). On the axial images, the main fracture line is horizontally orientated, separating the anterior from the posterior column. Additionally, a sagittal fracture line appears in the inferior posterior articular area. 3D-CT with a medial hemipelvic view confirms the typical fracture lines.
Transition forms to other fracture types. An incomplete anterior fracture component reaching the iliac fossa can be present (transition to the T-type fractures). Also, the hemitransverse component can be incomplete (transition to anterior column fractures). In the presence of an anterior column fracture, an additional anterior wall fragment can be present. Pediatric fractures can show an anterior column fracture in association with an epiphysiolysis of the posterior column.
Fig. 13.1 (a) Typical associated high anterior column plus posterior hemitransverse fracture reaching the iliac crest (arrows). The hemitransverse component is undisplaced and leaves the posterior column at the sciatic spine. (b) CT evaluation confirms the separation of both columns as indicated by the transverse fracture line. The hemitransverse component is only visible in the inferior layers. Sagittal reconstructions show a typical L-shaped fracture configuration. 3D-CT clearly points out the fracture course.
Fig. 13.2 (a) Displaced low anterior column fracture with a slightly displaced posterior hemitransverse fracture. (b) 3D image of this fracture shows the main anterior pathology at the anterior wall as part of an anterior column fracture. The typical hemitransverse component is shown on the view from inside the hemipelvis.
Fig. 13.3 Anterior column fracture with a displaced posterior hemitransverse component reaching the upper part of the greater sciatic notch. Part of the articular surface is connected to the axial skeleton.
13.3 Pathobiomechanics
Letournel proposed a lateral force acting along the femoral neck as the mechanism for an associated anterior column plus posterior hemitransverse fracture.2 This fracture type was the second most common after this mechanism following both-column fractures.2 A neutral rotated hip position was postulated in contrast to a slight internal rotation that causes both-column fractures. A dashboard mechanism did not result in this fracture type.
Dakin et al observed associated anterior column plus posterior hemitransverse fractures with a frequency of 11.1% after this lateral mechanism (3.7%).3
Clinical Relevance
The typical mechanism that results in an associated anterior column plus posterior hemitransverse fracture is a load transmission along the femoral neck due to a side impact.
13.4 Hip Joint Stability
The extent of fracture instability is regularly a function of the instability of the anterior column. The lower the fracture, the more stable the joint. Instability is increased in fractures with a high posterior hemitransverse component, leaving the greater sciatic notch proximally.
13.5 Biomechanics of Anterior Column Fractures
No biomechanical data are available for associated anterior column plus posterior hemitransverse fractures.
13.6 Treatment Indications
The type of treatment depends on fracture displacement, articular modifiers, and the fracture instability.
13.6.1 Conservative Treatment
Conservative treatment is only recommended in near undisplaced fractures without additional intraarticular injuries. Especially, undisplaced high anterior column fractures with an additional minimally displaced posterior fracture component can be sufficiently treated by conservative functional concepts.
Minimally invasive procedures can be an option (see ▶ 22).
13.6.2 Operative Treatment
Operative treatment is indicated in:
Articular displacement > 2 mm
Unstable hip joint
Femoral subluxation/dislocation
Intraarticular fragments
Extended superior dome involvement
Presence of marginal impaction
In femoral head dislocation, emergency treatment consists of closed reduction by supracondylar traction with one-seventh to one-tenth of body weight.
13.7 Techniques of Osteosynthesis
13.7.1 Biomechanics of Osteosynthesis
No biomechanical data are available regarding stability of different types of osteosynthesis.
13.7.2 Approach
Operative stabilization of associated anterior column plus posterior hemitransverse fractures is usually performed using the intrapelvic or ilioinguinal approach. Especially in fractures with an undisplaced posterior fracture component, reduction is easily performed using the second window of the ilioinguinal approach. Associated anterior column plus undisplaced posterior hemitransverse fractures are observed in approximately 60% of this fracture type.2
In fractures with severe posterior displacement or with a multiply fractured posterior component, an extended approach or an anterior plus posterior approach has to be considered.
13.7.3 Reduction Techniques
Ilioinguinal Approach
The reduction technique depends on the level of the upper end of the anterior fracture line and the displacement of the posterior column.
The first step consists of a step-by-step reduction of the anterior column fracture according to the proximal-to-distal rule. The second step is usually the reduction of the posterior hemitransverse component, if necessary.
Various instruments are available for reduction. The following reduction instruments are most frequently used (▶ Fig. 13.4):
Long-pointed reduction forceps (Weller forceps)
Short-pointed reduction forceps (Backhaus forceps)
Matta clamp
Ball spike pusher
Colinear reduction forceps
Fig. 13.4 Typical reduction instruments for associated high anterior column plus posterior hemitransverse fractures: Farabeuf forceps, two Matta forceps, ball spike pusher, colinear clamp.
Iliac Fossa Reduction
First, reduction starts at the iliac crest. After appropriate cleaning of the fracture line, ad latus displacement due to muscle interposition of the iliacus or gluteus muscles within the cortical layers has to be corrected. A small Hohmann retractor can support the reduction maneuver by inserting its tip below the cortex of the fragment, which has to be reduced. By rotation against the opposite cortex using a Kapandji-like maneuver, reduction can be achieved (▶ Fig. 13.5). Alternatively, this maneuver can also be performed using the Farabeuf forceps. De-rotating, distracting, and final compression allow anatomical reduction (▶ Fig. 13.6).
Fig. 13.5 Insertion of a raspatory or Hohmann retractor to reduce the ad latus displacement of the iliac fossa fracture component (shown in a both column example).
Fig. 13.6 Iliac crest reduction using the Farabeuf forceps by rotational movements as well as distraction and compression.
For reduction of the fracture at the iliac crest, a long-pointed reduction forceps (Weller forceps) or the Backhaus forceps is typically used (▶ Fig. 13.7). For better grip at the cortex, small 2.0-mm drill holes can be created on each side of the fracture. It is essential that this reduction is perfect, as any mistake results in an ongoing malreduction reaching the joint.
Fig. 13.7 Reduction of the iliac crest using a large-pointed reduction forceps.
Temporary Fixation at the Iliac Crest
Temporary fixation at the iliac crest is performed using the reduction forceps. Alternatively, K-wire fixation or a 3.5-mm screw fixation is performed.
Pelvic Brim Reduction
The next reduction step takes place at the pelvic brim. In addition, the same techniques are used as described for intermediate anterior column fractures (see ▶ 12).
Prerequisite for pelvic brim reduction is the reduction of the femoral head out of its medial position. Normally, longitudinal traction alone allows reduction. Lateral traction by percutaneous insertion of a Schanz screw into the femoral neck can support the reduction maneuver. Reduction aids are the colinear forceps, Matta clamps, or the ball spike pusher.
It is important to understand the typical fracture course because the main anterior column fracture line typically is infrapectineal, parallel to but just below the pelvic brim. Thus, direct perpendicular pressure from the iliac fossa allows optimal fracture compression (▶ Fig. 13.8).
Fig. 13.8 Reduction of the anterior column close to the acetabulum using a ball spike pusher after screw fixation at the iliac crest. The typical fracture pattern is shown.
Subsequent to reduction, a step-by-step fixation protocol is recommended, which depends on the most proximal localization of the fracture:
Screw (plate) osteosynthesis iliac crest
Screw (plate) osteosynthesis iliac fossa and/or pelvic brim
Reduction posterior hemitransverse fracture
Inguinal/suprapectineal plate osteosynthesis
As a rule, in high anterior column fractures, indirect reconstruction and fixation are performed according to the proximal-to-distal rule. Fixations starts, as already described, at the iliac crest and then progresses to the joint area using isolated screws or small plates. Finally, and inguinal neutralization or buttress plate completes the osteosynthesis.
Screw (Plate) Osteosynthesis Iliac Crest
In fractures, starting at the iliac crest, after anatomical reduction, a 3.5-mm screw fixation perpendicular or slightly oblique to the main fracture line is recommended (▶ Fig. 13.9). This allows further fine-tuning with possible rotation around these screws. Long screws, up to 80 mm length, running between both cortices are possible (see ▶ 12).
Fig. 13.9 Lag screw osteosynthesis of an intermediate fragment and additional reduction of the main anterior column fragment.
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