Considerations about the knee arthrography for detection of meniscal tears

Abstract

Dear Editor,We have read with great interest the article entitled:‘‘The value of magnetic resonance imaging in our currentmanagement of ACL and meniscal injuries’’ [14]. Weagree with authors that magnetic resonance (MR) would bebeneficial in those patients where the clinical diagnosis of ameniscal tear is unclear and that it is expensive andrequires a long waiting time of 6–8 weeks. Some authors[15] report that MR findings do not always agree withsurgical findings and that false-positive and false-negativediagnoses may be due to MR interpretation error or due tothe insensitivity of MR in detecting some tears. In partic-ular, among meniscal types of lesions, radial lesions aredifficult to visualize on MRI [2]. In our opinion a relativelyold technique, low-cost and quick to perform, such as thedouble-contrast arthrography (Fig. 1) should be reminded,at least under a perspective historical view, for detection ofmeniscal tears, in particular for radial tears. As reported byFreiberger et al. [4], the arthrographic finding of a radialtear is subtle and the only abnormality detected is a relativeincrease in density of the inner portion of the wedge, whosearea has a relatively sharply defined outer margin, so thatthe difference in the density is easily identified as a radialtear. After this consideration, it should be pointed out thatwhereas MR and CT are high costs procedures, arthrog-raphy is relatively inexpensive and does not needscheduling [6]. Although it is an invasive method, double-contrast arthrography permits to evaluate meniscal tearswhen patients are operated on with metal devices in theirbody (namely: artificial heart valves, cochlear ear implants,intracranial aneurysm clips, tattoos made from iron oxidepigments, cardiac pacemakers, prosthetic hip and knees,metal body piercings and so on). In fact MR is contrain-dicated in the presence of internal metallic objects, becausethe constant strong magnetic field used for MR canpotentially pull on any ferromagnetic metal object, there-fore shifting its position. Accidents are uncommon, butmost accidents that do occur are potentially severe, namely :burns, ecchymosis, extrusion of a magnetic implant,anaphylactoid reactions to MR intravenous contrast agentsand even death [1]. While MR can cause long-termclaustrophobia [1] from the patient being within theenclosed space of the MR machine, Otto and Kallenber-ger [11] describe knee arthrography as a safe procedurethat cause very little discomfort to the patient. Thijn [13]reports double-contrast arthrography as superior toarthroscopy in the diagnosis of medial meniscus lesion,provided that the arthroscopy is carried out only from theanterolateral side. In our opinion this is an interestingdiagnostic aspect, considering that bucket-handle tearsinvolve the medial meniscus more frequently than thelateral meniscus [16]. Stoker [12] and Kempf [7] report95% diagnostic accuracy of the double contrast arthrog-raphy in lesions of the menisci, highlighting its role indemonstrating certain areas of the menisci which arevisualized with difficulty on arthroscopy. This aspect isconfirmed by Evans et al. [3] where the difficulty of thearthroscopist in reaching the posterior horn of the medial