Return to Case List with Diagnoses or Case List as Unknowns

BILATERAL PARS DEFECT
Authored By: Keith Fischer and Archana Kantawala.
Patient: 16 year old
History: 16 year old patient: baseball player with back pain.
Image Size:[small][as-submitted]

Multimedia: 303259_1_submitted.pptx
Image Size:[small][as-submitted]

Findings:

MR- Bilateral pars interarticularis defects with the right side demonstrating spondylolysis.

Plain films -Bilateral pars interarticularis defects at L5 with grade 1 anterolisthesis of L5 on S1.

Bone scintigraphy - Increased activity in the bilateral L5-S1 pars interarticularis fractures compatible with continued healing from acute fracture.

 

DDx:

Increased activity in the region of the pars may also be seen in infections, osteoid osteoma or degenerative changes.

False negative- Chronic spondylolysis or old healed defects may not show increased activity.

Diagnosis: Acute bilateral healing fracture at L5- S1.
General Discussion:

Spondylolysis is a defect in the pars interarticularis that may or may not be accompanied by forward translation of one vertebra relative to another (spondylolisthesis)

Patients with suspected spondylolysis should initially be evaluated with plain films - AP, lateral and oblique views. Lateral views are most sensitive and oblique views are most specific for detecting the pars defect.

Plain films- spondylolysis appears as a linear lucency in the pars interarticularis (see the images below). This lucency also can be seen on oblique radiographs.

Secondary signs on plain films - sclerosis of the contralateral pedicle and the presence of spina bifida occulta at the level of the lysis.

MRI, CT or SPECT bone imaging are other imaging options that should be considered for further evaluation or if plain radiographs are inconclusive.

MR imaging should be performed in thin sections at high resolution and in at least two planes - saggital and axial.

MRI - findings  vary depending on the timing of the examination -In acute stress reaction there is  increased signal on T2 images in the pars interarticularis representing marrow edema. On T1 images, there is decreased signal in the pars interarticularis.

In cases with an actual fracture of the pars interarticularis, there is discontinuity or fragmentation of the pars interarticularis best seen on sagittal T1 images. On T2 images, signal may be decreased in the pars if the process is chronic, indicating reactive sclerosis. If a pars defect is found with increased signal on T2 , this indicates a subacute process.

CT - linear lucency or defect extending through the pars interarticularis. Ocassionally, fragmentation of the pars interarticularis may be seen. Axial images will show absence of a complete bony ring at any given vertebral level.

Bone scintigraphy - increased activity in the pars interarticularis. These findings indicate an acute process.  This finding may imply the need for bracing.

If the bone scan is normal, it implies that the healing is complete and that bracing is of limited use in patient mangement.

 

Treatment is usually conservative. Physical therapy is an integral part of the patient's rehabilitation process. The most accepted protocol includes activity and exercise that reduces extension stress.

 

References:

Harvey CJ, Richenberg JL, Saifuddin A, Wolman RL. The radiological investigation of lumbar spondylolysis. Clin Radiol. Oct 1998;53(10):723-8.

Helms CA. Fundamentals of Skeletal Radiology. 2nd ed.

Comments:
No comments posted.
Additional Details:

Case Number: 303259Owner(s): Keith Fischer and Archana KantawalaLast Updated: 02-07-2013
Anatomy: Skeletal System   Pathology: Trauma
Modality: Conventional Radiograph, MR, Nuc MedAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: bsnm

Case has been viewed 21 times.
Certified by Keith Fischer on 06-10-2011

The reader is fully responsible for confirming the accuracy of this content.
Text and images may be copyrighted by the case author or institution.