Unusual cause of knee locking.

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Musculoskeletal Imaging

Background:

• Knee locking is a common complaint, often caused by meniscal tears or loose bodies.
• Popliteus tendon injuries are rare and can present with atypical symptoms.
• Pseudolocking, distinct from true mechanical locking, can result from inflammation and soft tissue impingement.

Purpose of the Study:

• To report a unique case of knee pseudolocking caused by a partial intrasubstance tear of the popliteus tendon.
• To highlight the diagnostic challenges and successful management of this rare injury.
• To contribute to the understanding of popliteus tendon pathology in athletes.

Main Methods:

• Case presentation of a 13-year-old semiprofessional soccer player with persistent knee locking.
• Diagnostic workup including clinical examination, Magnetic Resonance Imaging (MRI), and arthroscopy.
• Surgical intervention involving debridement of the torn tendon and inflammatory tissue.

Main Results:

• MRI and arthroscopy confirmed a partial intrasubstance tear of the popliteus tendon and associated synovitis.
• The patient experienced significant loss of knee extension (30°-90° range of motion).
• Post-operative recovery was rapid, with the patient discharged with full range of motion and weight-bearing ability on the first day.

Conclusions:

• Partial intrasubstance tear of the popliteus tendon is an unusual cause of knee pseudolocking.
• Prompt diagnosis and surgical management can effectively restore knee function.
• This case expands the differential diagnosis for knee locking symptoms in young athletes.