Bernoulli-Assisted Percutaneous Removal of an Intra-articular Foreign Body: A Case Report

A 4-year-old child presented with an intra-articular broken sewing needle in her knee. It was removed arthroscopically using a spinal needle percutaneously placed posterior to the tibia in line with the long axis of the sewing needle. The stylet was partially withdrawn to allow the sewing needle to lay within the spinal needle hollow. When the stylet was removed, the foreign body was propelled through the spinal needle by the increased velocity of the outflowing fluid and decreased pressure (Bernoulli's principle) and was caught in a specimen container.

This percutaneous technique is one of several for removing a small foreign body.