Thank you for your question.
Kyphosis in this age group is commonly postural. Brachial plexus
injuries have not been described to cause kyphosis. Scoliosis
and kyphosis may occur in combination but one does not cause the other one.Postural kyphosis
is treated by back muscle strengthening and training for correct posture.
Hope this is helpful. I would be happy to answer any questions you may have.