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J. Caton, G. Deschamps
76
Introduction
Since 1977 after our medical thesis in Lyon
about tears of the knee extensors (patella frac-
tures excluded) we have been using our assess-
ment index modified in 1981 after the medical
thesis of Gerard Deschamps about patella in-
fera and known as Caton - Deschamps index.
Our index
The method (fig. 4) consists of plotting the dis-
tance between the inferior edge of the patellar
joint surface and the antero-superior angle of
the tibia on sagittal X-rays (AT) and the joint
length of the patella (AP).
The value ratio AT/AP is normally equal to 1
(0.96 ± 0.134 for men and 0.99 ± 0.129 for wo-
men). When the ratio is equal or superior to 1.2
it is defined as patella alta and when the ratio is
less than or equal to 0.8 it is a patella infera but
we do operation for patella infera when the CD
ratio is inferior or equal to 0.6.
Conclusion
In our opinion the most accurate diagnosis
method for patellar height variations or patel-
lar instabilities is the Caton-Deschamps index
because this ratio relies on readily identifiable
and reproducible anatomical landmarks and is
possible regardless of the quality of the
X-rays, knee size, radiological enlargement or
position of the tibial tubercle or patellar modi-
fication and knee flexion between 10° and 80°/
used to adults and children and its calculation
quantified the necessary surgical correction of
patella alta or patella infera.
A valuable ratio for patellar
vertical height
The Caton – Deschamps Index
References
[1] BERNAGEAU J, GOUTALLIER D. Examen radio
logique de l’articulation fémoro-patellaire. In : l’actualité
rhumatologique, de Seze et coll.
Expansion Scientifique
Française, Paris, 1984.
[2] BIEDERT RM, ALBRECHT S. The patella trochlear
index: a new index for assessing patella height 2006.
Knee
surg sports traumatol arthrose 14:707-12.
[3]BLACKBURNEJS,PEELTE.Anewmethodofmeasuring
patella height.
J Bone Joint Surg (Br), 1977, 59, 241-2.
[4] BLUMENSAAT C. Die lageabweichungen und
Vezzenkungen der Kniescheibe Ergebn
Chir. Orthop, 1938,
31. 149-229.
[5] BOON-ITT SB. The normal position of the patella.
Am J
Roentgenol, 1930, 24, 389-94.
[6] BRATTSTROM H. Shape of the intercondylar groove
normally and in recurrent dislocation of the patella.
Acta
Orthop Scand, 1964, suppl 68, 1-148.
[7] BRATTSTROM H. Patella alta in non-disclocating knee
joints.
Acta Orthop Scand. 1970, 41, 578.
[8] CATON J. Les ruptures du système extenseur du genou
(fractures de la rotule exceptées). A propos de 130
observations.
Thèse médecine 1977. Lyon.
[9] CATON J, DESCHAMPS G, CHAMBAT P, LERAT JL,
DEJOUR H. Les rotules basses (Patellae inferae) – A propos
de 128 observations.
Rev Chir Orthop 1982, 317-25.
[10] CATON J. Méthode de mesure de la hauteur de la rotule.
Acta Orthop Belg 1989, 55. 385-6.
[11] CHAREANCHOLVANICH K, NARKBUNNAM R.
Novel method of measuring patellar height ratio using to
distal femoral reference point
2012 int orthop. 36. 749-53.
[12] DE CARVALHO A, HOLST ANDERSEN A, TOPP S,
JURIK AG. A method for assessing the height of the patella,
1985, Int Orthop 9:195-7.