In cerebral spastic tetraplegia or diplegia, 13 knees with fragmentation of the lower pole of the patella were compared with 58 knees without fragmentation on lateral roentgenograms. A ratio of the longitudinal patellar length to the maximal length transversing it may be used as a parameter of fragmentation. The limit of such a ratio without fragmentation was 2.5.
It is considered that the ratio should be measured regularly in children walking with spastic lower extremities and that treatment of their abnormal posture is necessary to maintain walking ability before the ratio approaches 2.5.
