RADIOGRAPHIC COMPARISON

Difference between the radiographic outline and the joint with fixed axis.
At the end of the flexion it can be noticed how the outline of the model moves forward and up.
Recent studies fixed this up movement to an average value of 13,4 mm.

Difference between the radiographic outline and the joint with switched rotation.
At the end of the flexion the model is in a highly forward and upward position respect to the radiographic outline.

CONCLUSIONS

Our research clearly shows that the knee has a rotatory-translatory movement. After 30° of knee flexion the femoral condyle glides progressively forward on the tibial flat bone. This movement should be reproduced by all equipments or mechanical joints guiding the movement of the knee for physiotherapeutic reasons.
If the knee is restrained by a mechanical articulation that does not reproduce this kind of movement, the head of the bones tend to follow the trajectory of the mechanical articulation. This deviation produces tension in articular elements like the ligaments, particularly the cruciate ligaments, the capsule, the menisci and the cartilages.
Our research shows that the joint that better reproduces a movement respecting the order of the phases of rotation and gliding is the adjustable rotation radius joint. The leg and its mechanical support move on parallel trajectories to allow a perfectly correspondent contact between leg and mechanical disposal during the entire movement. This avoids all traction of the mechanical disposal on the articular structures and the beginning of tensions within the knee.
These are the main points of the Annex 1 to the Italian Legislative Decree No. 46 of February 24th, 1997 on the essential and general requirements for EC certifications

1. Disposals must be designed and constructed so as not to prejudice the patient's clinical state and safety or the user safety and health.

2. During the disposal design and construction the manufacturer must observe all the safety measures, up-to-date with the technological progress.

BIBLIOGRAPHY

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