Answer :
Final answer:
Based on the description of symptoms and the negative straight leg test, the diagnosis for the young patient's condition aligns with Ankylosing spondylitis, given the characteristic worsening of symptoms at night and improvement with activity, without evidence of trauma or localized tenderness.
Explanation:
The young patient's symptoms of back pain and tightness, which improve during the day but worsen at night without any preceding trauma or tenderness, and a negative straight leg test, point towards a diagnosis of Ankylosing spondylitis (AS). This condition typically lacks the acute onset associated with herniated discs or the physical trauma often linked to lumbar strain. Additionally, the absence of rapid degenerative changes or localized tenderness that would be characteristic of degenerative disc disease further supports AS as the most likely diagnosis. Ankylosing spondylitis is characterized by its chronic course and its tendency to cause stiffness and pain in the axial skeleton, particularly noticeable in the mornings and at night with improvement upon activity. The patient's presentation closely aligns with the symptomatic pattern of worsening symptoms at rest and nocturnal pain, typical of AS.
