Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 May;37(5):443-50.
doi: 10.1007/s00256-008-0449-0. Epub 2008 Feb 19.

Radiological Findings and Healing Patterns of Incomplete Stress Fractures of the Pars Interarticularis


Radiological Findings and Healing Patterns of Incomplete Stress Fractures of the Pars Interarticularis

Andrew J Dunn et al. Skeletal Radiol. .


Objective: The objective was to retrospectively record the CT and MRI features and healing patterns of acute, incomplete stress fractures of the pars interarticularis.

Method: The CT scans of 156 adolescents referred with suspected pars interarticularis stress fractures were reviewed. Patients with incomplete (grade 2) pars fractures were included in the study. Fractures were assessed on CT according to vertebral level, location of cortical involvement and direction of fracture propagation. MRI was also performed in 72 of the 156 cases. MRI images of incomplete fractures were assessed for the presence of marrow oedema and cortical integrity. Fracture healing patterns were characterised on follow-up CT imaging.

Results: Twenty-five incomplete fractures were identified in 23 patients on CT. All fractures involved the inferior or infero-medial cortex of the pars and propagated superiorly or superolaterally. Ninety-two percent of incomplete fractures demonstrated either complete or partial healing on follow-up imaging. Two (8%) cases progressed to complete fractures. Thirteen incomplete fractures in 11 patients confirmed on CT also had MRI, and 92% demonstrated oedema in the pars. Ten out of thirteen fractures (77%) showed a break in the infero-medial cortex with intact supero-lateral cortex, which correlated with the CT findings. MRI incorrectly graded one case as a complete (grade 3) fracture, and 2 cases as (grade 1) stress reaction. Six fractures had follow-up MRI, 67% showed partial or complete cortical healing, and the same number showed persistent marrow oedema.

Conclusions: Incomplete fracture of the pars interarticularis represents a stage of the evolution of a complete stress fracture. The direction of fracture propagation is consistent, and complete healing can be achieved in most cases with appropriate clinical management. CT best demonstrates fracture size and extent, and is the most appropriate modality for follow-up. MRI is limited in its ability to fully depict the cortical integrity of incomplete fractures of the pars, but the presence of marrow oedema on fat-saturated T2-weighted sequences is a useful means of detecting acute spondylolysis.

Similar articles

See all similar articles

Cited by 14 articles

See all "Cited by" articles


    1. Clin Orthop Relat Res. 2005 May;(434):46-54 - PubMed
    1. Radiology. 1982 Dec;145(3):737-42 - PubMed
    1. Radiology. 1989 Feb;170(2):489-93 - PubMed
    1. Clin J Sport Med. 2005 Mar;15(2):79-86 - PubMed
    1. AJR Am J Roentgenol. 1985 Nov;145(5):1039-44 - PubMed

LinkOut - more resources