1. Idiopathic and normal lateral lumbar curves: muscle effects interpreted by 12th rib length asymmetry with pathomechanic implications for lumbar idiopathic scoliosis
Grivas TB1, RG Burwell2, Kechagias V1, Mazioti C1, Fundas A1, D Kolovou3, Christodoulou E4
1Department of Trauma and Orthopaedics, "Tzaneio" General Hospital, Tzani and Afendouli 1 st, Piraeus 18536, Greece
2Centre for Spinal Studies and Surgery, Nottingham University Hospitals Trust, Queen’s Medical Centre Campus, Nottingham, UK
3Department of Radiology, "Tzaneio" General Hospital, Tzani and Afendouli 1 st, Piraeus 18536, Greece
4Asklepios Klinik Lindenlohe, Schwandorf, Germany

2. Introduction
The historical view of scoliosis as a primary rotation deformity (Roaf 1958) led to debate about the pathomechanic role of paravertebral muscles; particularly multifidus, thought by some to be
scoliogenic (Riddle and Roaf 1955, Fidler and Jowett 1974,1976),
counteracting (Zuk 1962, Schmitt 1981),
uncertain (Roaf 1976), or
unimportant (Milner and Dickson 1996).
Here, we address lateral lumbar curves (LC) & suggest a pathomechanic role for quadrates lumborum, (QL) in the light of a new finding, namely of 12th rib bilateral length asymmetry associated with IS & normal lateral LC
Grivas et al 1992

3. study design
Case-control &
Level of Evidence III
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4. Material and Methods Group 1 Two groups of children were studied
There was no pelvic tilt in both groups
Group 1
Postero-anterior spinal radiographs of
14 children (n= girls 9, boys 5) w\
right lumbar idiopathic scoliosis (IS) & w/
right LC less that 10 degrees, were studied,
ages 9-18, (median age 13 years).
mean Cobb angle 12º (range 5º-22º)
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5. Material and Methods Group 2
postero-anterior spinal radiographs were evaluated similarly to the children with the LC in
N= 28 children (girls 17, boys 11) w/
straight spines
ages 8-17, median age 13 years
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6. Material and Methods
The quotient of the right/left 12th rib lengths and it’s reliably was calculated
The difference of the quotient between the two groups was tested (Mann-Whitney) & the
correlation between the quotient & the Cobb angle estimated (Spearman’s rho)
Statistical analysis was done using the SPSS package
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7. The quotient’s reliability study
Results
The quotient’s reliability study
intra-observer error ±0,036 &
inter-observer error
± 0,042
in terms of 95% confidence limit of the error of measurements
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8. Results
The 12th rib was longer on the side of the curve convexity in 12 children w/ LC & equal in two lumbar scoliotics
The 12th rib quotients of the lumbar curved children were statistically significantly, (SS), greater than in those with straight spines (Mann-Whitney U = 71,000, p<0,001)
The correlation of the 12th rib quotient w/ Cobb angle was SS, (Spearman’s rho = 0,690, p<0,002)
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9. The skewness & kurtosis
Results
The skewness & kurtosis
for the quotient = 0,615 & 0,702 &
for Cobb angle 0,359 & 1,068
The 12th thoracic vertebrae did not show axial rotation in the LC or straight spine groups
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10. Conclusion
We interpret the abnormal lengthening of the convex 12th ribs as resulting from increased muscle activity on the lumbar curve convexity
Several small muscles are attached to the 12th ribs.
We focus attention here on the largest of these muscles namely, Quantrates lubrorum muscle (QL)
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11. quadrates lumborum muscle QL
Conclusion
quadrates lumborum muscle QL
attachments to the
pelvis,
12th rib
transverse processes of lumbar vertebrae
as origin & as insertion
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12. Conclusion
We suggest that the increased relative length of the 12th rib on the convexity of the LCs is an indicator of increased function of the right relative to left QL muscle
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13. we suggest two hypotheses
Conclusion
we suggest two hypotheses
The relatively increased activity of the right QL muscle causes the LCs (first hypothesis) or
counteracts the lumbar curvature as part of the body's attempt to compensate for the curvature (second hypothesis)
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14. Conclusion
These hypotheses may be tested by electrical stimulation studies of QL muscles in subjects w/ lumbar IS by revealing respectively curve worsening or correction
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15. Conclusion
The mechanism leading to relatively increased length of the right 12th ribs is attributed to mechanotransduction in accordance w/ Wolff’s & Pauwel’s Laws
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