الفهرس 
Anatomy of the Knee JointOnly 14 pages are availabe for public view
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Abstract
MRI may alter the treatment of anterior cruciate ligament (ACL) injury by allowing confident diagnosis or exclusion of an ACL tear in patients with equivocal physical examination findings.
MR arthrography combines the techniques of arthrography with MR imaging to benefit from the added imaging information afforded by intra-articular distention.
It allows unparalleled evaluation of capsuloligamentous structures, small chondral defects, and loose bodies, and is particularly useful in young, competitive athletes whose lifestyle depends on accurate diagnosis.
For direct arthrography of the knee, 1 ml of gadolinium contrast agent is diluted in a 250 ml normal saline IV bag. A 21 gauge needle is inserted into the patellofemoral joint via either medial or lateral approach with the patient on the MR table.
Indirect MR arthrography of the knee consists of a standard intravenous dose of gadolinium contrast agent.
The knee is then exercised for fifteen minutes by placing the patient on an exercise bicycle. The patient is then returned to the MRI suite where the same pulse sequences are utilized as for direct MR arthrography.
MR imaging is the modality of choice for evaluation of failed ACL graft reconstruction surgery.
Meniscal, ligamentous, and cartilage repair procedures of the knee are increasing in prevalence as are MR imaging examinations of patients after such procedures.
Therefore, it is important to be able to recognize the normal MR imaging appearance of the knee after the more common procedures, as well as complications associated with such procedures.
ACL graft complications such as abnormal tunnel positioning, roof impingement, partial and complete graft tears, arthrofibrosis, tunnel synovial cysts, iliotibial band friction syndrome, hardware loosening, and infection may be reliably assessed at MR imaging.
MR arthrography can accurately depict the presence of anterior cruciate ligament graft tears. Localized anterior arthrofibrosis and graft impingement were less accurately detected and showed greater observer variability.
Arthrography is a very safe procedure and complications are unusual. The most serious complication is an infection of the joint. This is usually caused by organisms from the patient’s skin being transferred into the joint and for this reason the procedure should not be carried out if there is broken or infected skin overlying the joint.