Fracture Characteristics

T-type fractures are supposed to have the worst long-term prognosis of all acetabular fracture types,^1,​2 possibly due to their uncommon frequency and the complexity of surgery.^{1,​3,​4,​5} Additionally, a clear approach recommendation is missing.³

Pennal pointed out that the T-type fracture had the worst prognosis in acetabular fractures involving both columns.²

Presently, no adequate studies dealing with this fracture type are available.

The typical transverse fracture component in T-type fractures is orientated through the anterior and posterior column, and divides the acetabulum into an upper iliac and a lower ischiopubic segment. The localization of the fracture line varies in height and inclination and, per definition, an intact articular part remains in connection to the iliac bone.

Comparable to pure transverse fractures, infratectal, juxtatectal, and transtectal fracture lines can be distinguished:

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  Infratectal fractures: the main fracture line is orientated through the anterior and posterior wall, across the acetabular fossa

  
  
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  Juxtatectal fractures: the main fracture line is orientated through the anterior and posterior wall, at the transition of the acetabular fossa to the cranial/superior joint surface (▶ Fig. 16.1)

  
  
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  Transtectal fractures: the main fracture line is orientated through the superior acetabulum, leaving only a small articular fragment connected to the intact iliac bone.

  
  
  
  

  

  
  

  Fig. 16.1 Schematic view of different acetabular T-type fractures with infratectal (left), juxtatectal (middle), and transtectal (right) fracture course of the transverse fracture component.

The vertical fracture component typically passes through the middle of the acetabular fossa, the obturator foramen, and ultimately through the transitional area between the ischial and inferior pubis ramus.

Additionally, a more anterior and posterior fracture course is possible, the latter often not involving the obturator foramen and the exclusively running intraosseous (▶ Fig. 16.2). Transition forms to transverse/posterior wall fractures can be present.

The femoral head is often dislocated centrally. In exceptional cases, a second fracture line divides the obturator ring or the fossa acetabuli.

In all cases, there is a complete separation of the anterior and posterior columns below the level of the transverse fracture component.

16.2 Radiological–Anatomical Criteria

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  Pelvic anteroposterior (AP) view (▶ Fig. 16.3). The characteristic lines representing the columns and therefore a transverse fracture component (iliopectineal line, ilioischial line, line of the anterior and posterior wall) are disrupted. Frequently, the distal vertical fracture component can already be seen on this view. In some cases, only the inferior ramus fracture indicates the T component as an indirect sign. The acetabular roof is involved, depending on the height of the fracture. Often, a central femoral head dislocation is present.

  
  
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  Iliac oblique view (IOV) (▶ Fig. 16.3). The extent of the fracture line at the posterior column (greater sciatic notch) becomes clear. The remaining integrity of the acetabular dome is confirmed.

  
  
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  Obturator oblique view (OOV) (▶ Fig. 16.3). The orientation of the anterior and often the whole transverse fracture line becomes clearer, and the “height” of the fracture course in the anterior column is observed. The vertical T component of the fracture is most clearly visible.

  
  
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  Computed tomography (▶ Fig. 16.3). The integrity of the iliac fossa and iliac crest are confirmed. Axial two-dimensional (2D) analysis confirms attachment of an articular part to the intact iliac bone connected to the axial skeleton. The transverse fracture component shows high variability. The presence of intraarticular fragments and marginal impactions can be analyzed. The exact fracture course of the T component can be analyzed, which runs through the inferior acetabular fossa into the obturator foramen ending either at the inferior pubis or ischium. A femur subtraction view or a medial hemipelvis three-dimensional (3D) view can help to clearly see the T-shaped fracture course.

  
  
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  Transition forms to other fracture types. The orientation of the vertical fracture component (T component) is highly variable. The most common fracture course is centrally through the acetabular fossa and the obturator ring. Transitions to transverse/posterior wall fractures can exist, when the T component is leaving the obturator segment near or proximal of the ischial tuberosity. A further special fracture type is the “transverse fracture with a fracture of the anterior wall,” which is attributed to the group of T-type fractures.

  
  
  
  

  

  
  

  Fig. 16.3 The pelvic AP view shows the disruption of both the iliopectineal and ilioischial lines. The IOV shows the displacement of the posterior column, and the OOV shows the displacement of the anterior column and the disruption inferior pubic ramus. Axial CT clearly shows the T component, which is additionally shown on the schematic view. The 3D-CT reconstruction confirms the T-shaped fracture.

16.3 Pathobiomechanics

Letournel stated that force transmission along the greater trochanter to the acetabulum as well as the dashboard mechanism are possible mechanisms resulting in acetabular T-type fractures.³

Lateral compression injury to the acetabulum via the greater trochanter and the femoral neck in 20 to 40 degrees internal rotation of the hip most often results in transverse acetabular fractures and sometimes in T-type fractures. Adduction or abduction influences the height of the transverse fracture component. With more adduction, more transtectal fractures can occur, whereas abduction positions lead to more infratectal fracture courses.

Clinically, T-type fractures resulted in 6.5% of cases after this mechanism.

The dashboard mechanism is a rather unusual mechanism resulting in a T-type fracture and was clinically observed in only 1.9%.

Dakin et al observed three T-type fractures after force transmission along the greater trochanter.⁶

Rupp et al experimentally confirmed, that a “dashboard” mechanism is capable resulting in a T-type fracture.⁷

16.4 Hip Joint Stability

Biomechanical data on hip joint stability after T-type fractures are missing. Letournel described a central dislocation in his series of 66 T-type fractures as the most common dislocation type (50 of 66 cases). A posterior dislocation was seen in five cases, and an anterior dislocation was observed in two cases.³

Since the transverse component of the T-type fracture corresponds to the biomechanical data for pure transverse fractures, the potential central instability can be expected. Transtectal T-type fractures are supposed to be highly unstable (see ▶ 14).

16.5 Biomechanics of the T-type Fracture

There is only one recent study that analyzed stress changes regarding pathobiomechanics of a T-type fracture.

T-type fracture was simulated in a 3D Finite Element analysis.⁸ The main stress concentration was observed in the superior acetabular region near the posterior transverse fracture part leaving the acetabular cavity. Even after stabilization, this area never resolved physiological stress, indicating that risk of posttraumatic arthrosis development starts in this region.⁸

16.6 Treatment Indications

The type of treatment depends on fracture morphology, fracture displacement, articular congruence, overall joint stability, and additional articular modifiers.

16.6.1 Conservative Treatment

Undisplaced or minimally displaced T-type fractures without free intraarticular fragments can sufficiently be treated nonoperatively. Additionally, in fractures with a very low infratectal transverse component and a roof–arc angle > 45 degrees with a congruent and stable joint, conservative treatment is possible.

In contrast, in undisplaced or minimally displaced, but potentially unstable T-type fractures with a high transverse transtectal fracture component and a low roof–arc angle, prophylactic stabilization and possibly percutaneous stabilization should be considered.

16.6.2 Operative Treatment

Operative treatment is indicated in:

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  Unstable hip joint

  
  
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  Femoral subluxation (joint incongruency)

  
  
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  Displacement > 2 mm in the weight-bearing area

  
  
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  Intraarticular fragments

  
  
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  Increasing sciatic nerve injury

  
  
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  Presence of marginal impaction

In unstable central or posterior fracture dislocations, supracondylar traction is always recommended to avoid further articular damage.

16.7 Techniques of Osteosynthesis

16.7.1 Biomechanics of Osteosynthesis

Simonian et al biomechanically analyzed the influence of different stabilization techniques in T-type fractures in eight hemipelvic cadavers.⁹ A transtectal transverse fracture with a vertical fracture component through the quadrilateral surface and the inferior pubic rami was simulated and three different types of stabilization were tested:

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  Anterior plate osteosynthesis with posterior column screw

  
  
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  Posterior plate osteosynthesis with anterior column screw

  
  
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  Anteroposterior plate osteosynthesis

Independent of the chosen type of osteosynthesis, the maximum displacements were all < 0.5 mm.

The overall stability can be increased by placement of an infraacetabular screw, inserted from anterior to posterior.^{10,​11,​12}

Recently, two Finite Element analyses were reported, simulating different stabilization constructs.^8,​13

Both analyses tested a double plate construct, an anterior column plate + posterior column screw, and an anterior column plate + quadrilateral surface screws. Both analyses found no difference regarding stiffness, stress distributions, force transfer, and displacement for all chosen constructs even in simulation of sitting, respectively.^8,​13 The optimal stabilization construct was the anterior column plate + quadrilateral surface screw construct in both analyses.

16.7.2 Approach

There are potentially four approach options for treatment of acetabular T-type fractures:

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  Posterior approach (Kocher-Langenbeck approach with/without surgical hip dislocation according to Ganz)

  
  
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  Anterior approach

  
  
  
  
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    Ilioinguinal approach

    
    
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    Intrapelvic approach

  
  
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  Extended iliofemoral approach according to Letournel

  
  
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  Simultaneous anterior and posterior approach stabilization

Comparative data on the choice of approach for T-type fractures are available from some studies.

Letournel stated in his analysis of 66 T-type fractures that 54.5% were operated via the Kocher-Langenbeck approach: the ilioinguinal approach in 16%, the extended ileofemoral approach in 12.9%, and a combined AP procedure was performed in another 16.1%.³

Data from the First German Multicenter Study analysis revealed 26 operatively stabilized T-type fractures. The Kocher-Langenbeck approach was used in 12 patients, the ilioinguinal approach in one patient, an extended approach in eight patients, and a combined AP stabilization in four patients.⁵

Matta stabilized 31 T-type fractures using the Kocher-Langenbeck approach in 61%, the ilioinguinal approach in 13%, the extended iliofemoral approach in 19%, and a combined AP procedure in 6%.¹

Briffa et al analyzed 17 patients. A posterior approach with surgical hip dislocation was used in 59% of cases, patients an intrapelvic approach in two (12%), a combined approach in 4 patients, and an ilioinguinal approach was used in one patient.¹⁴

Tannast et al reported on the data from Matta on 96 T-type fractures: 63% of the patients were stabilized using a Kocher-Langenbeck approach, 8% an ilioinguinal approach, 22% an extended iliofemoral approach, and 7% a combined AP approach.¹⁵

However, epidemiological data from Germany from the last two decades indicate that the Kocher-Langenbeck approach is less commonly performed.¹⁶ During 1991–1993, 38% of T-type fractures were stabilized using the Kocher-Langenbeck approach, increasing to 42% between 1998 and 2000 and decreasing to 27% during 2005 and 2006.

With integration and increasing use of the intrapelvic approach, these fractures are now more often stabilized using an anterior approach.^{17,​18,​19,​20,​21,​22,​23,​24} Whenever possible, a single (one-column) approach is favored^{25,​26,​27,​28,​29} (see ▶ 7).

The choice of approach in treating T-type fractures ultimately depends on the fracture morphology. However, fracture types are very heterogeneous, thus, no clear recommendations are possible.

The main problem of T-type fractures compared to pure transverse fractures is that the nonintact ischiopubic fragment results in a relevant instability between the separated fragments of the anterior and posterior column below the level of the transverse fracture component.

After reduction of one of these column fragments, the corresponding column still appears unstable. An anatomical reduction of this corresponding column by ligamentotaxis cannot be expected.

Tannast et al recommend that the localization and extent of displacement should indicate the choice of the approach. A larger anterior fracture displacement of the transverse component requires rather an anterior approach, whereas relevant posterior displacement should result in choice of a posterior exposure.²⁹

Thus, the Kocher-Langenbeck approach is indicated for fractures with severe posterior displacement and a more undisplaced anterior fracture component. Intraoperatively, fluoroscopic and/or palpatory control of reduction of the anterior column fragment through the greater sciatic notch is recommended, as the anterior column fragments cannot be directly seen using this approach. An additional anterior stabilization is highly recommended, such as, by anterior column screw. In cases with insufficient control of reduction of the anterior part or presence of extensive intraarticular pathology, extension of the Kocher-Langenbeck approach by bigastric trochanteric osteotomy with surgical hip dislocation is reasonable.²⁶ This leads to the further advantage of direct visual and palpatory control of reduction of the complete articular surface. In addition, intraarticular hardware placement can be safely avoided.³⁰

In some cases, using the Gibson approach, dissection of the triceps coxae muscle and the piriformis muscle can be avoided.

Anterior approaches, intrapelvic or ilioinguinal, are recommended in severe anterior displaced T-type fractures with additional anterior intraarticular pathology.^19,​22

The intrapelvic approach offers adequate visualization, palpation, manipulation, and reduction of the posterior column component. Direct reduction of the anterior fracture can be sufficiently performed. A further advantage of using this approach is the ability to insert long periarticular screws, both supra- and infraacetabular, to increase the overall stability.

Letournel recommended the extended iliofemoral approach especially for T-type fractures with a transtectal transverse component or in delayed fracture treatment.³ The ilioinguinal approach was only recommended for exceptional cases. Presently, an extended approach is avoided, due to the relatively high complication rate and unsatisfactory long-term results.^31,​32

Alternatively, in the presence of additional posterior (e.g., posterior wall fracture) or intraarticular pathology (e.g., free fragments, marginal impactions) or relevant anterior and posterior displacement, a combined AP approach (simultaneous or sequential) is considered.³³

For a simultaneous approach, positioning in a semilateral position is recommended, which allows adequate tilting of the operating table. As an advantage, simultaneous manipulation and stabilization of both the anterior and posterior fracture fragments is possible.

Using a sequential combined approach, it has to be noted that the primary stabilization material does not affect the secondary osteosynthesis. The potential disadvantage is the increased blood loss, longer surgery time, etc.

16.7.3 Reduction and Stabilization Concept

The sequence of fracture reduction depends on the chosen approach. A single approach is generally favored. Correspondingly, the reduction techniques using the Kocher-Langenbeck approach with/without surgical hip dislocation according to Ganz and using an anterior approach (e.g., intrapelvic or ilioinguinal approach) are described.

Posterior Approach (Kocher-Langenbeck Approach)

Various instruments are available for reduction. The following are most frequently used^26,​29 (▶ Fig. 16.4):

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  Long-pointed reduction forceps (Weller clamp)

  
  
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  Ball spike pusher

  
  
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  Farabeuf clamps

  
  
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  Reduction forceps according to Jungbluth

  
  
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  Different Matta clamps

  
  
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  Asymmetrical reduction forceps

  
  
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  Colinear clamp

  
  
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  5-mm Schanz screw with T-handle

In addition, laminar spreaders and various raspatories or periosteal elevators are used.²⁹

First step: Mobilization of the posterior column fragment

First disimpaction of this fragment is performed by insertion of laminar spreaders and/or raspatories. Rotational displacement can be corrected using a Schanz screw inserted into the ischial tuberosity and joystick manipulation with an attached T-handle (▶ Fig. 16.5). Alternatively, distraction can be performed using a Farabeuf or Jungbluth forceps.

Second step: Joint inspection

Mobilization of the posterior column fragment allows at least posterior direct visualization into the joint to remove intraarticular fragments so surgeon can address posterior marginal impaction zones. Articular fragments have to be removed or, if possible, should be stabilized, depending on their size. Marginal impactions have to be elevated and possibly supported with autologous bone grafts. Labral lesions have to be expected at the fracture level. Accordingly, the labrum should be evaluated regarding injury or avulsions. Cleaning of the fracture surfaces is performed with removal of hematoma.

Third step: Reduction of posterior column component

Exact visualization and controlled reduction of the posterior column can be exclusively performed using a posterior approach or with additional surgical dislocation of the hip joint.

For reduction of the column fragment against the intact portion of the superior ilium, different reductions techniques can be used. These essentially correspond to the techniques for isolated posterior column fractures (▶ Fig. 16.6).

While manipulating this main fragment, the gluteal neurovascular bundle has to be protected. After fracture debridement, manipulation techniques as described for fracture disimpaction (step 1) are used to perform the definitive reduction. The course of the sciatic nerve has to be respected.

The Farabeuf forceps (▶ Fig. 16.6) or the Jungbluth forceps are used, depending on the size of the operative field.

With one screw placed on each side of the fracture (Farabeuf: 3.5-mm cortical screws, Jungbluth: 4.5-mm cortical screws) these forceps can perform distraction, rotation, and gain compression. The measured screw length should be enlarged approximately 5–10 mm for sufficient bicortical placement and relevant space to fix the forceps to the screw head.

Performing compression with these reduction forceps as well as slight rotational movements allows reduction. Additional distraction is possible with the Jungbluth clamp.

Alternatively, instead of using the Farabeuf or Jungbluth forceps, the long-pointed reduction forceps (Weller forceps) can be used. Drilling of a 2.5-mm cortical hole on each side of the fracture can be helpful in obtaining optimal hold of the forceps branches.

Also, the long asymmetrical reduction clamp can be used or the Matta clamps. Again, the close relation of the sciatic nerve to these clamps has to always be considered.

Additionally, a precontoured plate that is fixed at the ischial tuberosity can support the reduction maneuver, especially in older fractures where more extensive reduction forces have to be applied (▶ Fig. 16.6). Using this reduction maneuver, the final plate position or placement of an additional lag screw has to be planned.

Stabilization Technique

Subsequent to the reduction, a step-by-step fixation strategy is recommended:

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  Lag screw fixation and reduction control

  
  
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  Posterior plate osteosynthesis

  
  
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  Anterior fixation concepts

Fourth step: Posterior lag screw fixation

Fixation of the reduced posterior column fragment is performed using a lag screw in a cranial-to-inferior direction as in isolated posterior column fractures, according to Letournel.³ Depending on the size of the operative field and already placed reduction forceps, an opposite screw direction is possible. When placing this screw (▶ Fig. 16.7), the later plate position for definitive fixation has to be considered. This plate should not interfere with the planned anterior stabilization so as to not lock anterior stabilization. Control of reduction has to be performed either by fluoroscopy or by palpation. Palpation of the posterior quadrilateral surface (posterior column) can be digitally performed through the greater sciatic notch.

Fifth step: Posterior plate osteosynthesis

In order to neutralize the potential shear forces, a reconstruction plate close to the acetabular rim, as in posterior wall or posterior column fractures, is fixed (▶ Fig. 16.7). In general, fixing the plate with two screws on each fracture side, at the ischial tuberosity and supraacetabular, is sufficient. In an unstable situation or posterior comminution, a second plate can be placed and fixed at the posterior margin close to the greater sciatic notch. Typically, a small and straight four-hole plate, which allows dynamic compression, is preferred. While fixing this plate, it has to be considered not to interfere with the following anterior stabilization.

The anterior fracture can be stabilized percutaneously using an anterior column screw only after radiological confirmation of an anatomically reduced anterior column fragment (▶ Fig. 16.8).

Related posts:

Epidemiology Classification of Acetabulum Fractures Indications and Planning Pure Transverse Fractures Approaches Radiological Diagnostics

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