[A soccer player with an unstable knee].

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Radiology

Background:

• Knee instability is a common complaint in athletes following traumatic injury.
• Congenital anomalies of the knee, though rare, can predispose individuals to ligamentous issues.

Observation:

• A 19-year-old male soccer player experienced left knee instability after a rotational injury.
• Physical examination revealed leg length discrepancy.
• Magnetic Resonance Imaging (MRI) demonstrated findings suggestive of congenital anterior cruciate ligament (ACL) absence.

Findings:

• The patient underwent successful anterior cruciate ligament (ACL) reconstruction.
• Post-operative assessment indicated regained knee stability.

Implications:

• Congenital ACL absence should be considered in the differential diagnosis of knee instability, particularly in young athletes with suggestive imaging.
• Surgical reconstruction can effectively address instability caused by congenital ACL deficiency.
• This case highlights the importance of comprehensive evaluation including imaging for diagnosing rare orthopedic conditions.