Which degenerative disorder is associated with a loss of proximal joint strength and a positive Gower's sign?

• A. Duchenne's muscular dystrophy
• B. Becker's muscular dystrophy
• C. Spinal muscular atrophy
• D. Myotonic dystrophy

Answer: (A)

Duchenne's muscular dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness, particularly affecting the proximal muscles of the body. The loss of proximal joint strength is a hallmark of this condition, where individuals struggle to perform everyday activities due to muscular weakness in areas such as the hips, thighs, and shoulders.

A positive Gower's sign is particularly significant in this context. This sign refers to the way individuals with proximal muscle weakness get up from a sitting or lying position; they may use their hands to "walk" up their legs to stand. This behavior occurs because the strength needed to rise is diminished, necessitating additional support from the arms and hands.

In contrast to Duchenne's muscular dystrophy, Becker's muscular dystrophy, while also affecting muscle strength, typically has a later onset and a slower progression. Spinal muscular atrophy primarily affects lower motor neurons, leading to weakness and muscle atrophy but usually does not produce a Gower's sign. Myotonic dystrophy presents with muscle stiffness and weakness but does not typically present with the distinct proximal weakness and Gower's sign associated with Duchenne's muscular dystrophy. Thus, this combination of characteristics firmly aligns with Duchenne's muscular dystrophy.