Radiology Corner – Lumbar Spine and Lumbosacral Junction

By: Terry R. Yochum, DC, DACBR, Fellow, ACCR and Michael S. Barry, DC, DACBR

Figure 1.

Figure 1.

History

This adult male patient reports with a history of trauma to the upper lumbar spine and lumbosacral junction after a severe fall. Can you find any fractures? If so, where are they? (See next page.)

Diagnosis

Fractures of the left first, second and third transverse processes and a complete horizontal fracture through the second sacral segment with altered bone alignment.

Sacral Fractures

Sacral fractures usually occur as a result of a fall upon the buttocks, direct trauma, or in association with pelvic fractures. Isolated fractures of the sacrum are uncommon, and a diligent search for an associated fracture in the pelvic ring or symphysis pubis is often beneficial. Two types are horizontal and vertical.

Horizontal (Transverse) Fractures. These are the most common types of sacral fractures. The most common location is at the level of the third and fourth sacral tubercle, which are near the lower end of the sacroiliac joint. The fracture line is frequently difficult to identify due to overlying intestinal contents, which may require reexamination or enema. Careful identification of the cortex outlining each sacral foramen (“foraminal lines”) should be scrutinized for disruption or distortion. The lateral radiograph occasionally demonstrates the fracture with disruption of the anterior cortex (as present in our case). Often, the lower segment of the sacrum may be displaced or angled forward.

Figure 2.

Figure 2.

A horizontal fracture of the upper sacrum, affecting the first or second sacral segments, may occur from high falls, such as attempts at suicide (“suicidal jumper’s fracture”).

Vertical Fractures. These usually occur as a result of indirect trauma to the pelvis with more than 50% suffering pelvic organ damage. They are visible in the frontal radiograph but not the lateral view. The cephalic tilt view, tomography, or CT may be necessary in order to demonstrate the vertical fracture line, which usually runs nearly the entire length of the sacrum. The normally symmetrical transverse sacral foraminal lines should be carefully scrutinized for detection of the fracture line.

Transverse Process Fractures

Transverse process fractures are the second most common fracture of the lumbar spine, with compression fracture being the most common. They occur from avulsion of the paraspinal muscles usually secondary to a severe hyperextension and lateral flexion blow to the lumbar spine. The most common segments to suffer transverse process fractures are L2 and L3.

Radiographically, the fracture line appears as a jagged radiolucent separation, usually occurring close to its point of origin from the vertebra. Frequently, the separated fragment is displaced inferiorly. If the fracture line is horizontal, close inspection for a transverse or “Chance fracture” should be performed. Fractures often occur at multiple levels. Fractures of the fifth lumbar transverse processes are frequently found in association with pelvic fractures, particularly fractures of the sacral ala or disruption of the sacroiliac joint. Occasionally, loss of the psoas shadow may occur secondary to hemorrhage. Ossification within this hemorrhage (myositis ossificans) can result in bony bridging between the transverse processes (lumbar ossified bridging syndrome [LOBS]). Renal damage may occur, which may be associated with hematuria.

A fracture of the transverse process can be simulated by overlying fat lines or intestinal gas or by developmental nonunion, especially at L1 where the psoas margins crosses the tip of the transverse process. Oblique or tilt views may be necessary to rule out fracture.1–5

References

  1. Yochum TR, Rowe LJ. Essentials of Skeletal Radiology, 2nd ed. Baltimore, MD: Williams & Wilkins, 1996.
  2. Furey WW. Fractures of the pelvis with special reference to associated fractures of the sacrum. AJR 1942; 47:89.
  3. Jackson H, Kam J, Harris JH et al. The sacral arcuate lines of upper sacral fractures. Radiology 1982; 145:35.
  4. Ebraheim NA, Savolaine ER, Skie MC et al. Longitudinal fracture of the sacrum: Case report. J Trauma 1994; 36:447.
  5. Osti OL, Fraser RV. Osseous bridging of the lumbar intertransverse processes after trauma. Spine 1992; 17:362.

About the Authors

Dr. Terry R. Yochum is a second generation Chiropractor and a cum laude graduate of the National College of Chiropractic, where he subsequently completed his radiology specialty. He is a Diplomate of the American Chiropractic Board of Radiology and served as its vice-president and president for seven years (1983-1990).

Dr. Michael S. Barry is a 1988 cum laude graduate of Palmer College of Chiropractic. He completed a three-year radiology residency at Logan College of Chiropractic following two years of clinical practice in Las Vegas, Nevada. He received his diplomate in radiology from the American Chiropractic Board of Radiology in 1992.