Mechanical osteoarthritis is characterized by the presence of degenerative lesions resulting in early joint impairment due to mechanical overload, generally secondary to the alteration in mechanical axis of the extremity. Structural deformities of the lower extremity (Pawels), in any of the spatial planes, induce an abnormal distribution of mechanical loading upon the joint surfaces. OBJECTIVE 1. To demonstrate that torsion modifies the tensions in the femorotibial and femoropatellar joints. 2. To demonstrate that increased external tibial torsion induces displacement of the compression forces towards the posterior and internal zone of the femorotibial joint. MATERIALS Anatomical pieces,test bench, extensiometric gauges ,electrogoniometer,registry canal system,software METHOD Preparation of the specimens (4 frozen knees) After thawing, the tibia and fibula were embedded in a cuvette perpendicular to the floor with the help of Araldite® Positioning of the extensiometric gauges A gauge was positioned on the posterior surface of the proximal tibial epiphysis (G5), with two gauges on the anterior-internal surface (G1 and G2), and two more on the anterior-external surface (G3 and G4). Positioning of the knees on the test bench EXPERIMENTATION: Registry without tibial osteotomy from 0 to 90º with femoral anterior torsion of 15-20° Registry with flat supra-tuberosity tibial osteotomy with 10º external rotation, and maintaining femoral anterior torsion of 15 20° with 0 to 90º flexion RESULTS In the biomechanical study of the knee, a dual tension state of opposite sign has been observed in the proximal tibial epiphysis, with areas that act in terms of compression and others under traction, according to the model of Pawels. With regard to the cross-sectional plane, as central point of this Doctoral Thesis, the proximal tibial epiphysis has been shown to have certain areas operating under compression, and others under traction. This tension state is modified in relation to the location of the point of load application; on increasing external tibial torsion after coronal osteotomy (15° of external rotation), increased compression is observed in the posterior and internal zones of the tibial plateau, with increased traction in the anterior and posterior zone of the tibial plateau CONCLUSIONS On loading the lower extremity, the proximal tibial epiphysis responds in the form of a dual tension state characterized by distinct compression zones and traction zones separated by a neutral line referred to as the “core line”. Changes in tibial torsion have a direct impact upon the qualitative and quantitative distribution of the load over the proximal tibial epiphysis. With increased external tibial torsion there is increased loading in the internal and posterior zone of the tibial plateau that progressively increases with flexion. A similar change is observed at the external tibial plateau, but of opposite sign – producing “core line” deviation towards the internal and posterior zone.
|Date of Award||15 Jul 2015|
|Supervisor||Jorge Ballester Soleda (Director), Juan Cebamanos Celma (Director) & Antoni Navarro Quilis (Director)|