Study Guide

Sacral Fractures

Key Points:

Pediatric sacral fractures are rare injuries and are usually caused by high energy trauma.
Advanced imaging should be obtained if there is any concern, based on history and physical exam findings, as these injuries may be missed with routine radiographs.
Given the higher energy typically causing these injuries, patients should be evaluated for solid organ damage.
Most pediatric sacral fractures are treated non-operatively, with operative treatment reserved for fractures with sacroiliac joint displacement or neurologic injury.
The mortality rate for patients with pediatric sacral and pelvic fractures may be as high as 25%, due to significant associated injuries.

Description:

Pediatric pelvic fractures represent 1-2% of all pediatric skeletal trauma, with an incidence of 1 per 100,000 children per year (Shaath). Sacral fractures are even more rare, with one series reporting a total of only 7 sacral fracture-dislocations and 2 sacral fractures out of 54 pelvic fracture patients spanning 1974 to 1993 (Rieger). Another retrospective review from a level I pediatric trauma center found that pediatric sacral fractures occurred in only 0.16% of nearly 5,000 pediatric trauma cases (Hart). The largest reported incidence is from a pediatric level I trauma center, where there were 9 (5.4%) sacral fractures out of the 166-patient pelvic fracture cohort (Silber). In most traumatic sacral fractures, patients do not sustain a neurological injury (Dogan). Sacral stress fractures can occur, but appear to be less common than traumatic sacral fractures, and have only been described in case reports (Grier, Hama, Haasbeek).

Clinical Findings:

Pediatric sacral fractures are typically caused by high-energy trauma, including motor vehicle accidents, auto versus pedestrian accidents, and falls from significant heights (Hart). Given the level of energy required to sustain these injuries, sacral fractures usually do not occur in isolation, and are typically accompanied by other injuries (Silber). The importance of a thorough patient history and physical examination should be stressed, since these injuries may be missed (Dogan). Edema and pain about the sacrum are usually present. Palpation of the sacrum during rectal examination produces pain. The incidence of vaginal and rectal tears is reported between 2% and 18% and early recognition is necessary for appropriate antibiotic prophylaxis to prevent infection. Attempts at reduction are discouraged due to the risk of creating rectal tears (McCarthy).

Imaging Studies:

Denis et al are credited with the classification of sacral fractures, which divides the sacrum into 3 zones based on the location of the vertical fracture line orientation as it relates to the sacral foramina. Zone I is the alar region, and lateral to the foramina. Zone II is through the foramina, and zone III is the central sacral canal region, medial to the foramina. Denis’ study showed a higher risk of neurological impairment as the zone increased (Denis). The Torode and Zieg classification has been used historically for pediatric pelvic fractures, and sacral fractures are included in their description of type IV fractures, which include fractures producing an unstable segment. Within the AO classification, sacral fracture dislocations are C1-2 and sacral fractures are C1-3.

It is difficult to identify sacral fractures in pediatric patients on plain radiographs. One series noted 9 sacral fractures that were appreciated in a CT imaging cohort, while only 3 were found on plain X-Rays (Guillamongdegui).

Plain X-Rays are typically not helpful for diagnosing sacral stress fractures. Bone scans are the most sensitive study, though MRI scans may be adequate and may allow evaluation of other associated pathology without the higher radiation dose. Single photon emission computed tomography (SPECT) or CT are also considered sensitive studies to detect sacral fractures, but also with higher radiation doses (Shah).

Treatment:

Most pediatric sacral fractures are managed with protected weight bearing, crutch assistance, and medication as needed for pain. In rare cases of significant fracture or sacroiliac joint displacement with neurological injuries, such as cauda equina syndrome, operative intervention including decompression may be warranted (Avadhani).

If needed, sacral screws can be safely utilized in children as young as 6 years old with sacroiliac joint injuries (Abdelgawad). Starr et al reported safely treating an unstable pelvic ring injury in a 20-month-old child with a right anteriorly dislocated sacroiliac joint. He utilized closed reduction and S2 iliosacral screw fixation, however, the S1 corridor was not utilized due to sacral dysmorphism (Starr).

Based on CT measurements in patients aged 2-16, a radiographically safe pathway does exist for 99% of patients for an iliosacral S1 screw, and for 89% of patients for a trans-sacral trans-iliac screw at S2. However, a safe pathway only exists in 51% of patients for an S1 trans-sacral trans-iliac screw (Burn). This highlights the need for careful preoperative CT evaluation due to variable sacral morphology prior to pursuing iliac screw fixation (Gras).

The treatment for sacral stress fractures is activity modification. Most patients can return to a normal level of activity after 4 to 6 weeks.

Complications:

The mortality rate for patients with pediatric pelvic fractures has been reported as high as 25%, though most studies state a lower range of 2% to 12%, and most causes of death are from associated injuries rather than sacral or pelvic fractures. The most common cause of death is a traumatic brain injury which, is followed by thoracolumbar abdominal injuries. Hemorrhage accounts for mortality in less than 1% of pediatric cases, versus 3.4% in adults, which is attributed to the improved pliability of the vasculature and better arterial contractility in the pediatric population. The incidence of at least one associated injury with sacral fractures is 58% to 87%, with the most common associated injuries being other fractures (McCarthy).

In a retrospective review, Silber reported the femur (23.5%), the tibia/fibula (14.5%), and the clavicle (10.8%) as the most common associated fractures. MRI can be used to identify associated peripheral nerve injuries (i.e., lumbosacral plexus, sciatic nerve), which occur in less than 3% of pediatric patients with pelvic fractures. Most nerve injuries occur in patients with zone 3 injuries, and in those with posterior displacement. EMG/NCS has been used to identify affected peripheral nerves for persistent deficits (McCarthy).

References:

Abdelgawad AA, Davey S, Salmon J, Gurusamy P, Kanlic E. Ilio-Sacral (IS) Screw Fixation for Sacral and Sacroiliac Joint (SIJ) Injuries in Children. J Pediatr Orthop. 2016 Mar;36(2):117-21.

Avadhani A, Shetty AP, Rajasekaran S. Pediatric transverse sacral fracture with cauda equina syndrome. Spine J. 2010 Feb;10(2):e10-3. doi: 10.1016/j.spinee.2009.11.014. Epub 2009 Dec 29.

Blondel B, Glard Y, Launay F, Jacopin S, Jouve JL, Bollini G. Anterior dislocation of the sacroiliac joint in children: a new technique for pelvic fixation. J Pediatr Orthop B. 2011 Jul;20(4):209-11. doi: 10.1097/BPB.0b013e3283441092.

Denis F, Davis S, Comfort T. Sacral fractures: an important problem. Retrospective analysis of 236 cases. Clin Orthop Relat Res. 1988 Feb;227:67-81.

Dogan S, Safavi-Abbasi S, Theodore N, Chang SW, Horn EM, Mariwalla NR, Rekate HL, Sonntag VK. Thoracolumbar and sacral spinal injuries in children and adolescents: a review of 89 cases. J Neurosurg. 2007 Jun;106(6 Suppl):426-33.

Gras F, Gottschling H, Schröder M, Marintschev I, Hofmann GO, Burgkart R. Transsacral Osseous Corridor Anatomy Is More Amenable To Screw Insertion In Males: A Biomorphometric Analysis of 280 Pelves. Clin Orthop Relat Res. 2016 Oct;474(10):2304-11. doi: 10.1007/s11999-016-4954-5. Epub 2016 Jul 8.

Grier D, Wardell S, Sarwark J, Poznanski AK. Fatigue fractures of the sacrum in children: two case reports and a review of the literature. Skeletal Radiol. 1993 Oct;22(7):515-8.

Guillamondegui OD, Mahboubi S, Stafford PW, Nance ML. The utility of the pelvic radiograph in the assessment of pediatric pelvic fractures. J Trauma. 2003 Aug;55(2):236-9; discussion 239-40.

Hart DJ, Wang MY, Griffith P, Gordon McComb J. Pediatric sacral fractures. Spine (Phila Pa 1976). 2004 Mar 15;29(6):667-70.

Kenawey M, Addosooki A. U-shaped sacral fracture with iliac crest apophyseal avulsion in a young child. J Pediatr Orthop. 2014 Jul-Aug;34(5):e6-e11. doi: 10.1097/BPO.0000000000000139.

McCarthy J, Herman MJ, Sankar WN. (2015). Fractures of the Pelvis. Eds. Flynn JM, Skaggs DL, Waters PM (8th Edition). Rockwood and Wilkins’ Fractures in Children. p. 931. Philadelphia: Wolters Kluwer Health

Rieger H, Brug E. Fractures of the pelvis in children. Clin Orthop Relat Res. 1997 Mar;(336):226-39.

Routt ML Jr, Simonian PT. Closed reduction and percutaneous skeletal fixation of sacral fractures. Clin Orthop Relat Res. 1996 Aug;(329):121-8.

Shaath MK, Koury KL, Gibson PD, Adams MR, Sirkin MS, Reilly MC. Associated Injuries in Skeletally Immature Children with Pelvic Fractures. J Emerg Med. 2016 Sep;51(3):246-51. doi: 10.1016/j.jemermed.2016.05.031. Epub 2016 Jun 25.

Shah MK, Stewart GW. Sacral stress fractures: an unusual cause of low back pain in an athlete. Spine (Phila Pa 1976). 2002 Feb 15;27(4):E104-8.

Starr AJ, Ortega G, Reinert CM. Management of an unstable pelvic ring disruption in a 20-month-old patient. J Orthop Trauma. 2009 Feb;23(2):159-62. doi: 10.1097/BOT.0b013e31819866b5.