Outcome of treatment of pelvic ring fractures

                                   Outcome of treatment of pelvic ring  fractures

                                                     Dr KS Dhillon

Pelvic anatomy

The bony pelvis consists of the sacrum and coccyx posteriorly and two innominate bones laterally and anteriorly. The innominate bone (hip bone) consists of the iliac bone, ischial bone and the pubic bone which meet at and house the acetabulum. The two innominate bones articulate with the sacrum posteriorly via the sacroiliac joints and they meet anteriorly at pubic symphysis.
The sacrum is connected to axial skeleton superiorly and to the coccyx inferiorly. The innominate bone is connected to the lower limbs via the hip joint at the acetabulum. Hence the pelvis is able to transmit forces from the axial skeleton to the lower limbs.
Transmission of forces from the axial skeleton to the lower limbs is the primary function of the pelvis and its secondary function is to contain the pelvic organs.The concave iliac fossa, and pelvic floor muscles help support the pelvic organs.
A strong sacrospinous ligament which extends from the sacrum to the  ischial spine converts the sciatic notch into the greater sciatic foramen and lesser sciatic foramen. The lesser sciatic foramen lies between the sacrospinous ligament and the sacrotuberous which runs from the sacrum to the ischial tuberosity. Through the greater sciatic foramen passes the sciatic nerve and the piriformis muscle from the pelvis to the gluteal region. Through the lesser sciatic foramen passes the the tendon of the obturator internus, internal pudendal vessels, pudendal nerve and the nerve to the obturator internus.
The inguinal ligament extends from the anterior superior iliac spine to the pubic tubercle. Below the inguinal ligament the femoral nerve and the femoral vessels exit the pelvis to enter the thigh.
The obturator foramen lies below the acetabulum and is formed by the pubis and the ischial bones. It is covered by a membrane in the upper part of which there is an opening through which the obturator nerves and vessels exit the pelvis and into the thigh.                                  

Classification of pelvic fractures 

Fractures of the pelvis are often classified according to the classification by Young and Burgess (1) which is based predominantly on the mechanism
of injury and severity of pelvic fracture. An anteroposterior (AP) radiograph of the pelvis is the only investigation necessary for this classification.
According to this classification the fractures are divided into four categories based on the mechanism of injury. Two of the categories are further subdivided according to the severity of injury .

1.Anterior posterior compression fractures– These fractures result from a direct or indirect force in an anteroposterior direction leading to a diastasis of the symphysis pubis, with or without obvious diastasis of the sacroiliac joint or fracture of the iliac bone.

These fractures are subdivided into three grades.
Grade 1: Pubic diastasis with no or slight widening of the sacroiliac joint (SIJ). The SIJ ligaments remain intact.
Grade 2: Pubic diastasis with widening of SIJ and disruption of anterior ligaments and intact posterior ligaments.
Grade 3:  Pubic diastasis with complete SIJ disruption and torn anterior and posterior ligament but no vertical displacement of the hemipelvis.

2.Lateral compression fractures– These fractures result from lateral compression forces, which cause rotation of the pelvis inwards, leading to fractures in the sacroiliac region and pubic rami.

These fractures are subdivided into three grades.
Grade 1:Anterior transverse fracture of rami plus ipsilateral sacral compression fracture.
Grade 2: Anterior transverse fracture of rami plus ipsilateral sacral compression fracture and a fracture of the iliac wing.
Grade 3:Plus -Anterior transverse fracture of rami plus ipsilateral sacral compression fracture and a fracture of the iliac wing with a contralateral anterior posterior compression injury.

3.Vertical shear fractures–These fractures result from an axial shear force which disrupts the pubis symphysis and the SIJ and results in a vertical cephalic displacement of the hemipelvis.

4.Combined mechanism fractures– These fractures results from a combination of two of the above vector. The fracture pattern would be a combination of one or more of the above fracture types.

The presences of a displacement of the posterior sacroiliac complex by a fracture, dislocation or both and an avulsion fracture of the transverse processes of the lower lumbar vertebrae on plain AP radiographs of the pelvis is suggestive of pelvic instability (2). An inlet view is most useful for assessing rotational displacement/instability and an outlet view is most useful for vertical displacement/instability.

Outcome of treatment

Mortality

In the past hemorrhage was the cause of death in about two third of the patients who presented with pelvic fractures (3). Now, however the death from hemorrhage has been reduced with about one third of patients with pelvic fractures dying from hemorrhage (4). When there is major haemodynamic instability the mortality rates can reach as high as 40% to 80% (5,6). Presently the mortality rate in hemodynamically unstable patients with fractures of the pelvis remains at about 30% (7). The overall mortality varies between 10% (8) to 20% (9).
Besides hemorrhage which causes early mortality, sepsis with multiorgan failure can be the cause of late mortality in some patients with pelvic fractures (10).

Functional outcome

Unfortunately there are no ‘standard disease-specific functional outcome instruments’ that can be used to report functional outcome after pelvic fractures (11). Lefaivre et al (11) did a systematic review of literature to evaluate the ‘use and interpretation of generic and disease-specific functional outcome instruments in the reporting of outcome after the surgical treatment of disruptions of the pelvic ring’.They found that the ‘existing literature in this area is inadequate to inform surgeons or patients in a meaningful way about the functional outcomes of these fractures after fixation’.
Some of the commonly used scores used to report functional outcome after pelvic fractures include,Majeed score, the Iowa Pelvic Score, and the Medical Outcomes Study Short-Form 36-item Health Survey (SF-36).
The Majeed score (12) is a functional assessment for patients with pelvic fractures which assess five factors which are then scored to provide a clinical grade of excellent, good, fair and poor. The five factors are pain, standing, sitting, sexual intercourse and work performance. More than 85 points is excellent, 70 to 84 is good, 55 to 69 is fair and below 55 is poor outcome.
 The Iowa Pelvic Score assess, activities of daily life, work history, pain, limping,visual pain line and cosmesis. The SF-36 on the other hand is a general health assessment which assess physical functioning,  bodily pain and general health (2).
Suzuki et al (13) used the above scores to report the long term functional outcome after unstable pelvic ring fractures. They studied 57 patients (28 male and 29 female) with an average of 42.4 years who had unstable pelvic ring fractures. The average follow-up was 47.2 months (minimum 2 years). The average Injury Severity Score (ISS) of 24.6 points.Twenty-three of the patients were treated conservatively, 22 had external fixation, and 12 had  internal fixation of the fractures.
The average Majeed score was 79.7 and the average IPS was 80.7. The average ‘physical component summary of the SF-36 was 13.4 points worse than that of the population norm’. Radiological examination showed ‘average residual displacement was 7.3 mm anteriorly and 5.2 mm posteriorly’. They also found that the ‘Majeed score and the physical component summary of the SF-36 correlated with the presence of neurologic injury, and the Iowa Pelvic Score correlated with the presence of a mental disorder, posterior displacement, and neurologic injury’.
The authors concluded that Injury severity Score, fracture location and type of fracture did not influence the long term functional outcome in patients with unstable pelvic ring fractures. They found a close correlation between neurological injury and functional outcome.
Dienstknecht et al (14) reported the functional and socioeconomic long-term outcome in 109 patients with pelvic ring injuries at a minimum of 10 years follow up. The average age of the patients was 28.8 years (5 to 55) and the mean ISS was 22.7. They found that 39% of the patients had a limp, 11% required crutches and 15% of the patients had restrictions in use of car or public transport usage. Overall the outcome was worse in patients with isolated posterior and combined anterior posterior fractures as compared to isolated anterior fractures.
Papakostidis et al (15) did a systematic review of literature to compare the outcome of treatment of pelvic ring fractures by conservative means,  anterior stabilization,and posterior stabilization. They found no difference between the group as far as the incidence of severe pain, return to previous employment, functional scoring systems, or general health and wellbeing outcomes were concerned. A better walking ability was seen among patients who had surgical stabilization of the fractures. Less malunions were seen in patients who had internal fixation of posterior fractures. The relationship between quality of reduction of the fractures and the long-term functional outcomes remains unresolved.

Sexual dysfunction

Sexual dysfunction can present in various forms and includes erectile dysfunction (ED), dyspareunia, loss of sensation, ejaculatory dysfunction, and restricted motion during intercourse (16). Metze et al (16) in retrospective review studied the incidence of male sexual dysfunction after pelvic fractures. Sixty one percent of the patients reported limitations in sexual function and persistent erectile dysfunction was found in 19% of the patients.Posterior ring disruptions appeared to increase the risk of persistent erectile problems, probably due to nerve injury.
In literature the overall mean reported incidence of sexual dysfunction after pelvic fractures is 35.9% in men and 39.6% in women.There is limited consensus  on the definition of sexual dysfunction,and on the methods and timing of assessment, as well as on its management (17).

Urological injury

Urologic injuries commonly associated with pelvic fractures include injuries of the urethra, corpora cavernosa (penis), bladder, and bladder neck (18). Injuries to the urinary bladder usually result from shearing force or direct laceration by bone fragments and usually extraperitoneal. Urethral disruption can lead to urethral strictures, incontinence, and impotence. The impotence associated with pelvic fractures is usually of vascular origin and not due to neurologic injury. The management of urethral injury associated with pelvic fractures remain controversial. Some believe in early primary realignment is carried out (18).
There are others who believe that primary suturing of the disrupted urethral ends has the greatest complication rates of incontinence (21%) and impotence (56%), as compared to suprapubic cystostomy and delayed repair (19).

Neurologic injury

Reilly et al (20) did a clinical review of 90 unstable pelvic fractures treated during a 3-year period. Of these 90 patients, 83 were available for follow up examination. They found neurologic injuries in 21 % of the patients. Sensory deficit alone was present in 37% of the patients and the rest (63%) had both sensory and motor deficit. Some neurologic improvement was seen in all patients at one year follow up. Fifty three percent of the patients showed full recovery. Improvement in function took about one year in most instances but they found that L5 function was least likely to recover fully.

Venous thromboembolism

In patients with pelvic fractures the incidence of proximal vein thrombosis is between 25% to 35% with symptomatic pulmonary embolism (PE) occurring in 2% to 10% of the patients, and fatal PE in 0.5% to 2% of the patients (21).
Sharma et al (22) studied the incidence of deep vein, in 507 patients with at least one risk factor for venous thromboembolism, using venous duplex scans. They found that that the highest incidence of deep vein thrombosis (DVT) was seen in patients with pelvic fractures, in patients with previous venous thromboembolism, spinal cord injury and significant head injury (AIS > 2). They also found that deep-vein thrombosis was asymptomatic in 68% of patients and pulmonary embolism (PE)  was silent in 63% of the patients.
Steele et al (23) studied the efficacy low molecular weight heparin (LMWH) in the prevention of thromboembolism in patient with pelvic and acetabular trauma. They reported a 10% overall incidence of proximal DVT and a 5%  incidence of pulmonary embolism. They found that patients who received  LMWH within 24 hours of injury had a 3% incidence of DVT and incidence rose to 22% in patients who had who received LMWH more than 24 hours after the injury. There were ten patients who developed a proximal DVT and
five had a symptomatic PE, one of which was fatal. They recommended the use of LMWH within 24 hours in patients with pelvic and acetabular trauma.
Barrera et al (24) did a systematic review of literature for the Cochrane group to evaluate the role of thromboprophylaxis in trauma patients. They found no evidence that thromboprophylaxis reduces mortality or PE. However there was some evidence that thromboprophylaxis prevents DVT.

References

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