Early Identification and Treatment of Developmental Trochlear Femoral Dysplasia

Joint dysplasias consist of alterations in the normal development of a joint. In these cases, the formation of the normally congruent joint surfaces is altered, producing functional abnormalities that, depending on the degree of dysplasia, can lead to a spectrum of clinical manifestations ranging from complete dislocation, subluxations, severe instabilities, and ultimately early osteoarthritis.

The most studied joint dysplasia is developmental dysplasia of the hip (CDD) where the head of the femur and the acetabulum present different degrees of malformation, giving rise to a non-congruent joint. The clinical spectrum of manifestations of this pathology varies from a complete dislocation to milder forms of dysplasia that can manifest in childhood, youth or adulthood as early osteoarthritis, sometimes requiring multiple interventions for its treatment.

Early detection methods for CDD include: the identification of prenatal risk factors (intrauterine position, family history, first-born…), exploration through specific maneuvers, and confirmation by imaging tests such as ultrasound at birth. The early treatment of CDD consists of the application of a Pavlik harness whose purpose is to keep the newborn in a full-time position (frog position) in which the head of the femur remains completely congruent with the acetabulum, allowing the dysplasia to be reversed in early ages. Thanks to these early detection methods and its early treatment (with minimal adverse effects), many of these clinical alterations that previously went unnoticed have been prevented, and whose late treatment involves surgeries with a degree of invasiveness inversely related to the time of detection of DDC.

The knee is another joint susceptible to developing dysplasia. The most frequent dysplasia of the knee joint involves the femoropatellar joint (FP) formed by the patella and the femoral trochlea. Its normal function is vital to be able to flex and extend the leg since the patella acts as a lever arm increasing the strength of the quadriceps. Therefore, it is a joint subjected to high tensile forces.

In the normal knee in extension, the concave patella is located in the most proximal part of the femur without having any contact with the convex femoral trochlea. As the knee is bent, the patella runs into the deep femoral groove (normal groove angle 135º), which acts as containment and allows it to slide distally as the knee is bent further. It is in these knee flexion positions, more than 90º, where there exist more tensional forces between both articular surfaces.