Parturition-Induced Pubic Diastasis

Anteroposterior view of the pelvis in a recently postpartum woman shows widening of the pubic symphysis > 1 cm (double-headed arrow).

Facts: Parturition-Induced Pubic Diastasis/Pelvic Dislocation

• There is increased mobility of pubic symphysis and sacroiliac joints during pregnancy because of hormonal change
• During delivery, a rapid forceful descent of fetal head against the pelvic ring can result in this injury
• Patients experience immediate pain and audible snap during labor
• Mostly require conservative treatment with a pelvic binder, lateral recumbency and analgesics. In few cases, surgical fixation is used.

Predisposing Factors

• Multiparity
• Forceps assisted delivery, shoulder dystocia
• Maternal developmental dysplasia of the hip, prior pelvic trauma

Imaging

• Separation of pubic symphysis >1 cm
• If separation >4 cm, usually associated with SI joint disruption
• Patients may have sacral fractures, lumbosacral plexus injury, bladder/urethral injury

Reference:

Kharrazi FD, Rodgers WB, Kennedy JG. Parturition-induced pelvic dislocation: a report of four cases. J Orthop Trauma 1997;11:277-281.

Step Lightly for Kids

The Alliance for Radiation Safety in Pediatric Imaging has recently offered free materials on dose reduction for interventional radiology procedures, and patient education materials. These have been endorsed by the American College of Radiology (ACR).

"Treat kids with care:

Step lightly on the fluoroscopy pedal.

Stop and child-size the technique.

Consider ultrasound or, when applicable, MRI guidance."

On their website "ImageGently.org", slide presentations, checklists, outlines and patient brochures are available for free download.

Above image from www.ImageGently.org

Frontal Sinus Fracture

Axial CT image shows a depressed, comminuted fracture of the anterior wall of the frontal sinus. There is small hemosinus. The posterior wall is intact.
3D CT image beautifully demonstrates depression of the frontal sinus.

Facts: Frontal Sinus Fracture

• Because of density, thickness and arched configuration of the anterior wall of frontal sinus, a fracture requires considerable force
• Isolated frontal sinus fracture uncommon. Most fractures occur with other midface or intracranial injuries
• Most common cause is blunt trauma
• Late complications include aesthetic deformity, infection (sinus, intracranial), CSF leakage.

Classification

• Anterior wall fracture
• Posterior wall fracture
• Combined anterior and posterior wall fracture
• Decision for surgical exploration based on presence of displacement, depression, posterior wall involvement, CSF leakage, nasofrontal duct involvement

Imaging

• CT is the current gold standard for diagnosis
• Look for fracture comminution, depression, involvement of posterior wall, degree of displacement and nasofrontal duct injury
• Fracture extending to the base of frontal sinus and anterior ethmoid complex has a high likelihood of nasofrontal duct obstruction
• Some surgeons advocate surgical management if a posterior wall fracture displaces more than one both width (higher likelihood of dural tear, CSF leak).

Reference:

Thaller SR, McDonald WS. Facial trauma. Informa Health Care; 2004.

Joshi AS. Frontal sinus fracture. Emedicine, September 15, 2008.

Radiologic Miss and Malpractice

Error in Interpretation of Radiologic Studies

1. True miss: an obvious abnormal finding is not seen
2. True error in judgment: an abnormal (or normal) finding is not interpreted correctly

How Frequent Radiologists Make Error?

• Radiologists are far less than perfect in interpreting radiologic studies
• As many as 30% of abnormal findings are missed
• Radiologists disgree (either with themselves or with their peers) as often as 50% of the time
• However, the results shown above do not necessarily reflect the degree to which patient care is jeopardized. Some radiologic errors may translate into mismanagement of a patient or injury, many others are insignificant.

Does Radiologic Miss Constitute Malpractice?

• "Malpractice suits are based on assumption that the doctor violated his/her duty to a patient, resulting in injury and the patient should be compensated by the offending physician"
• In a malpractice case, it must be shown to the court that 1) the diagnosis was wrong, and 2) error was a result of 'negligence'
• Radiologic miss may or may not involve negligence. Unfortunately, there is no guidelines yet to easily distinguish this true negligence from simple error. The way it works in courts is that negligence "no reasonable radiologist in similar circumstances would have made the error"
• Radiologists have a duty to interpret radiologic studies reasonably but not necessarily perfectly

Reference

Berlin L. Malpractice issues in radiology. 3rd edition, 2009.

Importance of Visualization of Normal Acetabular Landmarks

Author: Aasis Unnanantana, M.D.

Figure 1: Pelvic radiograph (AP) shows a displaced left femoral neck fracture (arrow) in an old woman who fell.

Do you see anything else?

What normal bony structures do you expect to see in the acetabulum?

• Iliopectineal line
• Ilioischial line (Kohler's line)
• Acetabular roof (dome) or sourcil
• Radiographic teardrop
• Anterior wall
• Posterior wall

In this case, there is bowel gas overlying the left hemipelvis - making it difficult to assess. However, normal anatomic landmarks of the left acetabulum and pelvis are not visualized.

Same figure, with an outline of "non-visualized" acetabulum and left hemipelvis due to involvement of lytic metastasis. The patient also has a history of known renal cell carcinoma. Findings were confirmed on a CT scan.

Take Home Messages

• When normal radiographic features of acetabulum are not visualized on conventional radiographs, further imaging should be considered (e.g. additional radiographic views such as obliques, or CT) to assess the particular structures.
• Be aware of "satisfaction of search".

Reference:

Barrack RL, Booth Jr RE, Lonner JH, et al (eds). Orthopedic Knowledge Update: Hip and Knee Reconstruction 3. 2006

Line art: Rathachai Kaewlai, MD

About Guest Author: Dr. Aasis Unnanantana, MD, is a clinical fellow in orthopedics (Metabolic Bone Diseases Service) at the Hospital for Special Surgery, Cornell University, New York, NY. He is a member of orthopedic instructor at Siriraj Hospital, Mahidol University, Bangkok, Thailand.