Foreign bodies within the knee


A foreign body is an element which has a firm texture, can move within the joint and may lead to joint locking episodes, similar to those observed in cases of extended meniscus effects. 


They may be one or many and of largely variable sizes (from a few millimetres to several centimetres). They have a firm consistency, of cartilaginous or osteo-cartilaginous origin. They change places with movement and become localised within the larger capacity zones (within the lower quadricipital cul-de-sac at the upper part of the patella, at the level of the knee's lateral sides, within the popliteal cavity at the posterior side). 

Vue : lésions endoscopiques de corps étrangers
Vue : lésions endoscopiques de corps étrangers

View: foreign body endoscopic injuries


The main etiologies are as follows:

Clinical Symptoms

Clinical symptoms are directly linked to the original illness, but foreign bodies are typically characterised by repetitive mechanical locking that often spontaneously disappears. Between locking episodes, the patient, when the foreign body is big enough (bigger than 8 to 10 mm), can finger one or several moving elements, which he/she will more willingly locate within the space below the patella or on the lateral sides of the knee. 

Paraclinical Exams

The standard radiological checkup can easily corroborate the diagnosis and identify foreign bodies, as long as they are big enough and calcified. A normal biological checkup does not rule out the existence of small or radio-transparent foreign bodies. 

Surgical Treatment

The foreign body leading to locking episodes creates major discomfort. A surgical intervention is then necessary. The purpose of this treatment is to improve the patient's comfort, but also to limit the arthrosic potential of the foreign body through the cartilaginous effects it may induce when it occupies a femoral-tibial space.

Arthroscopy constitutes the choice treatment for exploring and removing the foreign body. An anatomic-pathologic study is carried out.

This operation also allows for a biopsy of the synovium, when it has, macroscopically, an abnormal aspect.

Incapacity and rehabilitation

In cases of an isolated foreign body, the post-op follow-up is the same as that of an arthroscopic menisectomy.

In all other cases, the follow-up is linked directly to the original illness.

Post-operation complications

They are identical to those of arthroscopic menisectomy. 


The prognosis concerning foreign bodies which reveal a degenerative cartilage pathology or synovium problems depends directly on the etiology. 

Arthroscopie et corps étrangers du genou