Radiographic pseudoscoliosis in healthy male subjects following voluntary lateral translation (side glide) of the thoracic spine.
OBJECTIVE
To determine projected Cobb angles associated with trunk list (side shift) posture, hypothesizing that the side shift "scoliotic" curvature would be similar to true scoliotic curvature in the early stages.


METHODS
Anteroposterior (AP) radiographs of volunteers in neutral, in left, and right lateral translations of the thoracic cage (trunk list) were digitized.


METHODS
Computer laboratory.


METHODS
Fifteen healthy male volunteers.


METHODS
Not applicable.


METHODS
Cobb and Risser-Ferguson angles determined from digitizing vertebral body corners from T12 to L5 on 51 AP lumbar radiographs.


RESULTS
Using the horizontal displacement of T12 from S1, subjects could translate an average of 54.0 mm to the left and 52.5 mm to the right. The average digitized Cobb T12-L5 angle produced for the 30 translated postures was 16 degrees. Angles ranged from 2.6 degrees to 27.0 degrees. Risser-Ferguson angles averaged 10 degrees between T12 and L5. Statistical correlations were found between Cobb L1-5 and translation to the left (P=.015), Cobb T12-L5 and translation to the right (P=.024), Risser-Ferguson angle and translation to the left (P=.021), and the lumbosacral angle to the right and trunk translation to the right (P=.027).


CONCLUSIONS
During lateral translation of the thorax (trunk list), coupled lumbar lateral flexion resulted in the appearance of a pseudoscoliosis on AP radiographs. For this trunk list posture, Cobb angles are considerable (16 degrees ) and increase as the magnitude of trunk translation increases. Differentiating true structural scoliosis from this pseudoscoliosis would be clinically important. The small coupled axial rotation in trunk list is in contrast to the considerable degree of axial rotation observed in structural idiopathic scoliosis.
Harrison
Deed E
DE
Department of Medicine, University of California, Los Angeles, CA, USA.
Betz
Joseph W
JW
Cailliet
Rene
R
Colloca
Christopher J
CJ
Harrison
Donald D
DD
Haas
Jason W
JW
Janik
Tadeusz J
TJ
D000328:Adult; D015331:Cohort Studies; D006801:Humans; D017116:Low Back Pain / Q000209:etiology / Q000517:prevention & control; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*; D008297:Male; D011336:Probability; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012016:Reference Values; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D013131:Spine / Q000000981:diagnostic imaging* / Q000502:physiology; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology*