An unusual cause of locking.

Area of Science:

• Orthopaedic Surgery
• Radiology
• Medical Imaging

Background:

• A case report detailing a delayed diagnosis of a foreign body in the knee joint.
• Highlights the challenges in identifying intra-articular plastic fragments.
• Emphasizes the long-term consequences of undetected foreign bodies.

Observation:

• A patient presented with persistent knee locking symptoms 21 years post-injury.
• Initial and serial radiological investigations, including X-rays and MRI, were unremarkable.
• Clinical suspicion led to arthroscopic examination.

Findings:

• Arthroscopy revealed a retained plastic foreign body within the knee joint.
• Successful surgical removal of the plastic fragment was achieved.
• Post-operative resolution of intermittent knee locking symptoms.

Implications:

• Underscores the critical role of clinical suspicion in diagnosing persistent joint symptoms, even with normal imaging.
• Suggests that certain plastic foreign bodies may not be readily detected by standard radiological modalities.
• Highlights the effectiveness of arthroscopy in diagnosing and treating intra-articular foreign bodies missed by initial investigations.