|SYMPOSIUM ON PELVIC TRAUMA
|Year : 2014 | Volume
| Issue : 1 | Page : 8-13
Classification of pelvic fractures and its clinical relevance
Rehan Ul Haq, Ish K Dhammi, Amit Srivastava
Department of Orthopaedics, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi, India
|Date of Web Publication||6-Jun-2014|
Rehan Ul Haq
Department of Orthopaedics, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi-110 095
Source of Support: None, Conflict of Interest: None
Pelvic fractures are one of the common cause of mortality in polytrauma patients, especially following high velocity trauma. The management in emergency requires good clinical judgment and access to radiological modalities. There are various classifications to define the pattern of injury in pelvic fractures. Previously, fracture patterns were described on the basis of anatomical fracture pattern on radiographs. With the introduction of concept of force vector and stability defined by Pennal and Tile, which was further modified by Young and Burgess, the corrective forces required to reduce such fractures were defined. With the introduction of these newer classification systems along with the introduction of external fixators, the mortality and morbidity has significantly reduced in pelvic fractures.
Keywords: Classification, pelvic fractures, ring injuries
|How to cite this article:|
Haq RU, Dhammi IK, Srivastava A. Classification of pelvic fractures and its clinical relevance. J Orthop Traumatol Rehabil 2014;7:8-13
|How to cite this URL:|
Haq RU, Dhammi IK, Srivastava A. Classification of pelvic fractures and its clinical relevance. J Orthop Traumatol Rehabil [serial online] 2014 [cited 2019 Jan 21];7:8-13. Available from: http://www.jotr.in/text.asp?2014/7/1/8/133997
| introduction|| |
Pelvic fractures constitute 3% of all skeletal injuries. ,,,,, Its incidence amongst polytrauma patients ranges from 25% to 30%. It is one of the most common causes of mortality in polytrauma patients and these rates have been found to be in the range of 16-19% in such patients. ,,,,, The most common cause of death in these patients is hemorrhagic shock or coagulopathy (60-65%), thus, control of hemorrhage is of utmost importance. Additional causes of death are sepsis in pelvic hematoma and acute renal failure. 
Management of pelvic fractures in emergency requires good quality radiographs, which is quite a task in such patients as they cannot be lifted and turned repeatedly. Anterioposterior view, oblique views and "inlet" and "outlet" views should be done. ,,,, These views provide useful information regarding pelvic ring fractures and associated sacroiliac (SI) disruption. On the basis of these views along with computer tomography (CT) scan of pelvis, we can identify stable or unstable fracture patterns, and thus manage the patient accordingly. ,,, CT scan better defines the posterior pelvic injury, better delineates rotation of fragments and comminution of the bone.
| Anatomy|| |
The pelvis is a ring with two parts; each part is formed by ilium, ischium, and pubis. These units do not have inherent stability but rely on ligamentous support for stability. The stability of pelvic ring depends on the SI joints and the pubic symphyses, both of which are fibrous joints and only allow minimal movements. The sacrum and ilium are attached to each other by short interosseous ligaments, short posterior ligaments, and long anterior ligaments. In addition to these ligaments, further stability is provided by sacrotuberous ligament (arising from lateral border of the sacrum to the ischialtubeosity) and sacrospinal ligament (from lateral border of sacrum to the spinous process of the pelvis). ,
| Classification|| |
The spectrum of pelvic fractures ranges from pubic ramus fractures, which are low energy fractures to high energy unstable fractures, which can result in massive blood loss and associated morbidity and mortality.
Fracture classification systems must identify and describe the fracture pattern, must aid in treatment protocol, and help in predicting the treatment outcome. There are classifications of pelvic fracture which adequately define the injury pattern and assist in management planning, but are associated with inter- and intraobserver variations. 
The various classification systems which are commonly used in pelvic fracture are:
- Anatomical classification by Letournel.
- Classification based on stability and deformity.
- Orthopedic Trauma Association classification - mainly useful for research.
- Classification based on vector force and associated injuries by Young and Burgess.
Anatomical Classification by Letournel
Letournel defined the fracture pattern on the basis of the area of pelvic bone involved. He divided all fractures in two groups - anterior and posterior. 
Anterior fractures include
- Ramus fractures
- Symphyseal disruption
Posterior fractures include
- Iliac wing fracture
- Iliac wing/SI joint fracture (crescent fracture)
- SI joint fracture
- Sacrum/SI joint fracture
- Sacrum fracture
This classification defined the fracture pattern, but it did not mention the stability of the fracture and therefore is not useful in deciding the management protocol or outcome of these fractures. This classification was introduced at the time when CT scans had not been introduced and there were limited surgical options for managing such fractures. Thus, most of the fractures were treated conservatively by skeletal tractions, slings, or abdominal binders.
Classification based on stability and deformity by Pennal, Bucholz, and Tile
With the introduction of external fixators, there was marked improvement in managing pelvic fractures. ,,, The concept of "force vector" causing the fracture and "counter force" required to reduce the fracture was understood. This concept was introduced by Pennel in 1961 and was further modified by Bucholz and Tiles, who added the concept of stability in the classification.
Pennal et al.,  described the fracture pattern on the basis of mechanism of injury:
- Anteroposterior compression (APC) injury
- Lateral compression (LC) injury
- Vertical shear (VS) injury pattern
All classifications prior to this were dependent on radiographs for describing the pelvic injuries. They only gave documentation of individual fracture pattern and were not found to be useful in further management of patients. With the introduction of this classification the concept of force vector was introduced, which aided in the surgical management of patients.
Bucholz described three fracture patterns. 
Displaced anterior ring fractures with minimally displaced, stable fracture, or incomplete tearing of anterior SI ligament.
Anterior pelvic ring injury associated with rotational opening of SI joint with disruption of only SI ligament.
Complete disruption of anterior and posterior hemipelvis.
Tile modified the Pennel classification, and categorized the injuries as "stable" and "unstable". The alphanumeric system defined by Tiles is one of the most commonly used classifications.
It is ability of pelvic ring to withstand physiologic forces without abnormal deformation. Forty percent of the pelvic stability is provided by the anterior ring and 60% by posterior ring. Stability of the pelvis following trauma is assessed by clinical and radiological parameters. ,,
Clinically, stability is examined by pelvic compression and distraction test.
Radiological criteria of instability are: ,,,
- SI displacement of 5 mm in any plane
- Posterior fracture gap (rather than impaction)
- Avulsion of fifth lumbar transverse process, lateral border of sacrum (sacrotuberous ligament), or ischial spine (sacrospinous ligament).
According to Tiles classification [Figure 1], fracture pattern was classified as follows:
|Figure 1: (a) Stable fractures. (b1 and b2) Rotationally unstable and vertically stable. (c) Rotationally and vertically unstable|
Click here to view
- Type A: Stable fracture.
These are the fractures with intact soft tissues around the pelvis, not disrupting the ligaments. It includes - avulsion fractures and transverse fracture of sacrum and coccyx.
- Type B: Rotationally unstable, but vertically stable.
These fractures are rotationally unstable and vertically stable. There is less than 1 cm rotation of the hemiplevis. These types of injuries are caused by external or internal rotational forces. The external rotational forces produce 'open book' injury pattern. There is disruption of pubis symphysis associated with unilateral or bilateral SI joint disruption. The posterior SI ligaments remain intact, thus the pelvis is vertically stable.
- Type C: Rotationally and vertically unstable.
These injuries are characterized by disruption of posterior SI ligaments as well as pelvic floor, this result in gross displacement of pelvis. These injuries are due to VS forces, resulting in the mark displacement of the SI joint. There is complete disruption of both SI and sacrotuberous ligament leading to rotationally and vertically unstable fracture pattern.
Orthopedic Trauma Association Classification is a further modification of the Tiles classification:
- A - Lesion sparing (or with no displacement of) the posterior arch
- B - Incomplete disruption at posterior arch; partially stable
- C - Complete disruption of posterior arch; unstable
- A-1 - Fracture of innominate bone; avulsion
- A-2 - Fracture of innominate bone; direct blow
- A-3 - Transverse fracture of sacrum and coccyx
Type B - Partially stable pelvic ring injuries
- B-1 - Unilateral partial disruption of posterior arch, external rotation ("open book" injury)
- B-2 - Unilateral, partial disruption of posterior arch, internal rotation (LC injury)
- B-3 - Bilateral, partial lesion of posterior arch
Type C - Complete disruption of posterior arch
- C-1 - Unilateral, complete disruption of posterior arch
- C-2 - Bilateral, ipsilateral complete, contralateral incomplete
- C-3 - Bilateral, complete disruption
This classification system has been found to be advantageous in comparing studies in literature rather than being used in emergency situation.
Young and Burgess classification
The concept of direction of forces causing fracture, associated instability of pelvis and its surgical management was further refined by the introduction of this classification. In association with clinical examination, this classification provided the logical approach to the pelvic trauma management. 
Four mechanisms of injury were defined in this classification  [Figure 2].
|Figure 2: LC = Lateral compression injury, APC = anteroposterior compression injury, VS = vertical shear force injury|
Click here to view
- Lateral compression (LC) (implosion)
- Anteroposterior compression (APC) (external rotation)
- Vertical shear (VS)
- Combined injury
Koo et al. and Furey AJ et al., found that inter- and intraobserver reliability of this classification is better than Tiles classification. ,
The pattern of fracture and mechanism of injury according this classification are as follows:
- LC fracture of anterior ring plus:
LC-I - Compression fracture of anterior sacrum
LC-II - Iliac wing fracture posteriorly (unstable)
LC-III - Windswept pelvis(contralateral SI joint injury)
- APC APC-I - Partial disruption
APC-II - Posterior SI ligaments intact
APC-III - Posterior SI ligaments disrupted
- VS - Cephalad and posterior displacement
- Combined mechanism - LC and VS most common
| Lc injury|| |
The LC fracture is the most common pattern in pelvic fractures. ,,
LC-I fracture pattern
The direction of force of injury is from the side and is associated with either horizontally oriented pubic fracture and/or impacted fracture of the sacrum. Thus, this fracture pattern is associated with impacted fracture of posterior SI complex and may be unstable [Figure 3].
|Figure 3: Lateral compression (type I) injury pattern, showing impaction of sacrum with superior and inferior pubic rami fracture ipsilaterally|
Click here to view
LC II fracture pattern
With increasing lateral force on the anterior pelvis, the major fracture fragment is rotated inwards, with anterior sacrum acting as the pivot. This gives rise to the disruption of the posterior SI joint associated with or without oblique fracture of posterior ilium extending lateral to the SI joint [Figure 4].
|Figure 4: Lateral compression (Type II) injury. Oblique fracture of posterior ilium, superior and inferior pubic rami with posterior dislocation of hip, and fracture shaft of femur|
Click here to view
LC III fracture pattern
This is the most severe form of LC fracture. There is further continuation of LC force which continues on the contralateral pelvis. This lateral force becomes a distracting force for the contralateral hemipelvis and causes its external rotation. This external rotation occurs due to SI, sacrotuberous, and sacrospinous ligament disruption. This leads to unstable pelvic injury with associated hemorrhage and neurological injury [Figure 5].
|Figure 5: Lateral compression (Type III). Posterior iliac blade with both rami fracture and associated sacrospinous ligament tear|
Click here to view
| Apc fracture|| |
The direction of force is from the front of the pelvis. These forces disrupt the anterior pelvis and as the force vector progresses there is disruption of posterior pelvis leading to unstable pelvic injury.
| Type i injury|| |
There is vertical fracture of pubic rami with rupture of the ligament of pubic symphysis, associated stretching of posterior ligaments. There is less than 2.5 cm of symphyseal diastasis [Figure 6].
|Figure 6: Anteroposterior compression injury (Type I). Shows rupture of pubic symphisis ligament (<2.5 cm symphyseal diastasis)|
Click here to view
| Type ii injury|| |
Additional anteroposterior force causes splaying of anterior pelvis with external rotation of iliac wings. The iliac wings hinge at the posterior SI joint. There is rupture of sacrotuberous, sacrospinous, and symphyseal ligaments with intact posterior SI ligaments (open book pattern). Symphyseal diastasis of more than 2.5 cm is seen, vertical stability is maintained [Figure 7].
|Figure 7: Anteroposterior compression injury pattern (Type II). Shows symphyseal diastasis >2.5 cm, with disruption of sacrospinous,|
sacrotuberous, and symphisis ligaments
Click here to view
| Type iii injury pattern|| |
There is complete disruption of all ligaments associated with posterior SI ligament. This results in rotational instability and lateral displacement of pelvis. This type of injury pattern is highly unstable and is associated with highest rate of vascular injuries [Figure 8]. ,
|Figure 8: Anteroposterior compression injury pattern (Type III). Shows complete disruption of all ligaments along with posterior SI ligament and SI disruption|
Click here to view
| Vs injury pattern|| |
This injury occurs because of fall from height on the extended lower limbs. There is associated disruption of sacrospinous, sacrotuberous, SI, and pubic symphysis ligaments, which leads to gross instability of the pelvis more commonly in the cephaloposterior direction. This injury is also associated with neurovascular injury and hemorrhage [Figure 9].
|Figure 9: Vertical shear injury pattern. Shows complete disruption of all ligaments in ipsilateral side associated with disruption of pubic symphisis, with vertical displacement of hemipelvis|
Click here to view
| Complex fracture pattern|| |
This fracture pattern is seen in 23% of all cases of pelvic fracture. The direction of force vector is both in anteroposterior and lateral plane. ,
This classification is useful in predicting the resuscitation requirements and further surgical reconstruction because of the better understanding of the structures injured and energy the pelvis has absorbed. For example, APC injuries are associated with bladder and other visceral organ injuries, which are associated with extensive blood loss. On the other hand, LC-I type injury rarely require surgical intervention.
| Clinical relevance of classification|| |
Classification system helps in predicting hemodynamic stability, pelvic instability, visceral, and genitourinary injuries. It also helps in understanding the mechanism of injury, force vector of injury, and surgical tactic for reduction. ,,,
The definitive management is decided on the basis of clinical features and fracture pattern.
Following indications are considered for conservative treatment:
- Most LC and anteroposterior type I injuries are treated conservatively
- Pubic symphysis diastasis less than 2.5 cm
- Pubic rami fracture with no posterior displacement.
Patients are kept on protected weight bearing and followed up by serial radiographs and clinical examination.
Absolute indications of surgery: ,,
- APC-III, LC-III, and VS type of fracture pattern
- Open pelvic fractures
- Associated visceral injury
- Hemodynamic instability
A total of 20-25% of mortality is seen in APC-III fracture pattern followed by LC-III pattern (7%). ,
These unstable pelvic fractures are managed in casualty by application of anterior or posterior pelvic external fixators, depending on the fracture pattern. ,,,,,,
In case of vertical instability, associated traction is also given by using upper tibial skeletal traction or Ganz fixator system.
In conclusion pelvic fractures are one of the major causes of mortality in polytrauma patients. With the advent of classification system along with better imaging modalities (CT scan), there has been marked improvement in management and rehabilitation of patients.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]