Final answer:
An abnormal Drennan angle is a diagnostic indicator of Blount's disease, with greater than 16 degrees being abnormal for children under 10 years, and greater than 11 degrees for older children and adolescents. It is critical for diagnosing and guiding the treatment of this growth disorder.
Step-by-step explanation:
The question is related to the angle measured between the metaphyseal-diaphyseal angles in the proximal tibia, which is known as Drennan's angle or the tibial metaphyseal-diaphyseal angle (MDA). This angle helps determine the presence and severity of Blount's disease (Blount's dz), a growth disorder of the tibia that causes the lower leg to angle inward, resembling a bowleg.
An abnormal Drennan angle indicates a deviation from the normal range, which can be an inflection point suggesting Blount's disease. For children younger than 10 years, a Drennan angle greater than 16 degrees is considered abnormal and an indication of Blount's disease. In adolescents and older children, an MDA greater than 11 degrees may be indicative of the condition.
It's important to diagnose Blount's disease early and accurately as it can lead to progressive lower limb deformity. Radiographic analysis and measurement of the Drennan angle is one of the key diagnostic tools for orthopedic specialists dealing with the condition. Treatment may include bracing or surgery, depending on the severity and age of the patient.
An abnormal Drennan angle is greater than 16 degrees for children under 10 and greater than 11 degrees for older children and adolescents, indicating the possible presence of Blount's disease.