Ossicles of lumbar articular facets: normal variant or spondylolytic variant?
OBJECTIVE
The objective of this study was to establish the prevalence and significance of ossicles of lumbar articular facets (OLAF) in young athletes with backache diagnosed by multi-detector computed tomography (MDCT).


METHODS
The MDCT examinations of the lumbar spine carried out for suspected spondylolysis on 46 consecutive symptomatic young athletes presenting to a sports injury clinic over a 1-year period were retrospectively reviewed. OLAF study included detailed correlation with the structural and morphological stress features of the posterior neural arches. This was then compared with a control group composed of 39 patients.


RESULTS
Twenty-three OLAF were identified in 15 patients. Eleven of the 15 patients with ossicles had posterior element stress changes (PEST)/pars defects. In the control group, two OLAF were identified in two patients, one demonstrating PEST changes.


CONCLUSIONS
The high prevalence of OLAF in young symptomatic athletes compared with the asymptomatic control group is indicative of stress fractures. The non-united articular process fractures should be regarded as part of the spectrum of stress-induced changes in the posterior neural arch in the same way as spondylolysis. MDCT with volumetric acquisition and multi-planar reformation is the most reliable investigation in the diagnosis of OLAF.


CONCLUSIONS
1) This CT study supports a traumatic aetiology for lumbar articular facets ossicles.                                    2) OLAF represent part of a spectrum of stress-induced changes in the posterior neural arch.                                                     3) OLAF are associated with typical spondylolysis.                                                     4) OLAF can be overlooked on reverse gantry angle computed tomography (RG-CT).                                                     5) OLAF may account for some of the discrepancy between radionuclide and RG-CT studies.
Department of Diagnostic imaging, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, SY10 7AG, UK.
Dalavaye S
DS
Kumar
Anastasia
A
Fotiadou
Radhesh
R
Lalam
Laurence M
LM
Ginder
Stephen M
SM
Eisenstein
Bernard J
BJ
Tins
Prudencia N M
PN
Tyrrell
John M
JM
Delieu
Iain W
IW
McCall
Dai A
DA
Rees
Victor N
VN
Cassar-Pullicino
D000293:Adolescent; D000328:Adult; D001175:Arthrography / Q000379:methods*; D001416:Back Pain / Q000175:diagnosis* / Q000209:etiology; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013169:Spondylolysis / Q000150:complications / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult; D021801:Zygapophyseal Joint / Q000002:abnormalities*