Keywords:
Technical aspects, MR, CT, Musculoskeletal joint, Education and training
Authors:
J. Pires, R. Costa, J. Vasconcelos, R. Sampaio; Porto/PT
DOI:
10.1594/essr2016/P-0087
Background
The extensor mechanism of the knee is a complex biomechanical apparatus,
responsible for the stabilization of the patellofemoral joint and knee extension.
Abnormalities in joint congruence and stability lead to pathology and clinical symptoms.
There are five main interlocking factors that affect the stability and congruence of the patellofemoral joint: patellar height; patellar tendon valgus and Q angle; lateral stabilization static mechanism; medial dynamic stabilization structures; and patellar thickness.
Computed tomography (CT) has been used to measure the valgus of the patellar tendon,
assess the shape of the trochlea and the degree of patellar tilt and lateral patellar subluxation.
Magnetic resonance imaging (MRI) evaluates the major determinants of patellar stability,
the same as with CT,
and,
in the same study,
accesses cartilage damage,
soft-tissue and ligament lesions,
allowing a much more comprehensive study.
No ionizing radiation is used and the study takes only a bit longer than a routine MRI and not much longer than a CT of the knees.
Correct measurements are essential to decide surgical treatment.