Method making it possible to produce the ideal curvature of a rod of vertebral osteosynthesis material designed to support a patient vertebral column

A method making it possible to produce an the ideal curvature of a rod (TV) for vertebral osteosynthesis equipment designed to correct a patient's vertebral column (CV), comprising the following steps:

• a) taking a sagittal preoperative x-ray (RS) of the vertebral column (CV) of the patient to be treated, extending from the cervical vertebrae to the femoral heads;
• b) on that x-ray (RS), identifying:
• the points and straight segments making it possible to calculate the so-called “pelvic” parameters, i.e., the sacral slope (SS), the pelvic version (PV) and the pelvic incidence (PI),
• the center of the plate of the first vertebra of the sacrum, called S1;
• the center of the second vertebra of the sacrum, called S2;
• the center of the lower plate of a reference dorsal vertebra, in particular the twelfth dorsal vertebra, called T12;
• the center of the lower plate of a reference cervical vertebra, in particular the seventh cervical vertebra, called C7;
• c) depicting, on the x-ray (RS), a first curved segment (SC1) beginning at the center of the plate of S1, tangent to the segment going from the center of S2 to the center of the plate of S1, passing through the centers of the bodies of the vertebrae of segment L5-L1 and ending at the center of the lower plate of said reference dorsal vertebra;
• d) depicting, on the x-ray (RS), a second curved segment (SC2) tangent to the first curved segment (SC1) at the center of the lower plate of said reference dorsal vertebra (T12), passing through the centers of the bodies of the vertebrae of the segment extending between said reference dorsal vertebra and said reference cervical vertebra and going to the center of the lower plate of said reference cervical vertebra (C7);
• e) identifying, on that x-ray (RS), the correction(s) (O1, O2) to be made to the vertebral column (CV);
• f) pivoting portions (P1, P2) of said x-ray (RS) relative to other portions of that x-ray (RS), based on the corrections (O1, O2) to be made, so as to show the correction(s) to be made to the vertebral column (CV);
• g) recalculating said first and second curved segments (SC1, SC2) based on the correction(s) made in step f) and depicting those curved segments on said x-ray (RS);
• h) determining the length of the vertebral segment to be corrected, therefore the length of each vertebral rod (TV) to be implanted;
• i) for each vertebra of that segment,
• either reading, on said x-ray (RS), the distance (DL5-DT12) from the center of the body of the vertebra to the posterior face of the pedicle of that vertebra, i.e., the entry face of a pedicle screw in that pedicle;
• or
• reading that same distance (DL5-DT12) in a previously established databank, containing, for each vertebra, the mean value, established statistically, of that distance for the type of patient in question, in particular based on the age, gender and size of that patient;
• j) performing, on said x-ray (RS), a displacement of the sagittal curvature segment determined in step g), extending over the vertebral segment to be corrected determined in step h), over the distances (DL5-DT12) read in step i) for the vertebrae in question, and recalculating the curvature of that segment in the displacement position;
• k) from a straight vertebral rod (TV), producing the curvature of that rod according to the shape of said sagittal curvature segment in said displacement position, recalculated in step j).