TO THE EDITOR:
After we reviewed "Magnetic Resonance Imaging of Articular Cartilage in the Knee. An Evaluation with Use of Fast-Spin-Echo Imaging (80-A: 1276-1284, Sept. 1998), by Potter et al., we decided to offer a perspective regarding the potential clinical implications of this work.
The development of a reliable method with which to accurately depict and characterize structural damage of articular cartilage, such as chondromalacia of the patella, as described by the authors, is to be lauded. However, we are concerned about the potentially perverse effect that the availability of such data may have on the unwary orthopaedic surgeon, who could be encouraged to pursue an operative course on the basis of the unproved assumption that there is a causal relationship between a structural finding (patellar chondromalacia) and symptoms (pain in the anterior aspect of the knee). We fear the acceleration of a trend among some orthopaedists to de-emphasize the history and physical examination and to rely instead on the radiologist and the use of structural imaging techniques (such as magnetic resonance imaging) to provide the diagnosis. Leaving the determination of a diagnosis of possible operative importance to the radiologist is not only lackadaisical but also potentially dangerous. This process could lead to increased numbers of potentially deleterious chondroplasties, which can, in fact, accelerate pathological symptoms in the anterior aspect of the knee.
Now that the authors have validated a reliable method with which to ascertain structural characteristics of articular cartilage, we encourage them to study a large number of asymptomatic control knees with use of magnetic resonance imaging. The purpose of such a study would be to determine the prevalence of radiographically identifiable damage to the articular cartilage in all aspects of the knee in an asymptomatic population, as has been done in studies of the meniscus2,3, the shoulder5, and the spine4,6. Such a study could provide a great service to the field of orthopaedics.
We believe that a large number of adults who are more than thirty years old have asymptomatic chondromalacia of the patella. The mere presence of patellar chondromalacia in a patient who has pain in the anterior aspect of the knee should not automatically lead to the conclusion that the chondral abnormality is the cause of the symptoms. For example, one of us (S. F. D.) has documented bilateral grade-III patellar chondromalacia that is totally asymptomatic, even during direct arthroscopic probing without intra-articular anesthesia1. We therefore urge the utmost caution regarding the clinical interpretation of the presence of damage to articular cartilage in the process of operative decision-making.
Scott F. Dye, M.D.: 45 Castro Street, Suite 117, San Francisco, California 94941
Alan C. Merchant, M.D.: 2500 Hospital Drive, Building 7, Mountain View, California 94040
Dr. Potter, Dr. Linklater, Dr. Allen, Dr. Hannafin, and Dr. Haas reply:
We read with interest the comments made by Dr. Dye and Dr. Merchant regarding the clinical utility of magnetic resonance imaging in the assessment of injuries of articular cartilage. We agree that a decision regarding operative treatment should not be based solely on an imaging test. In fact, at no point in our article did we state that the purpose of our study was to provide images that obviated the need for a comprehensive history and physical examination or appropriately made weight-bearing radiographs. We fear that Dr. Dye and Dr. Merchant have not gleaned the message of our study, which was to validate appropriately performed magnetic resonance imaging as a noninvasive tool with which to diagnose and monitor lesions of the articular cartilage of the knee. The development of numerous techniques, including perichondral grafting, implantation of autologous cartilage, and mosaicplasty, has clearly stimulated new interest in the diagnosis and treatment of chondral injuries. We submit that our magnetic resonance imaging pulse sequence is an accurate, noninvasive test that may be utilized as an objective measure of treatment outcome. At no point in our manuscript did we comment on the clinical symptoms of the individual patients or attempt to correlate the severity of chondral lesions with the severity of subjective clinical symptoms.
As noted by Dr. Dye and Dr. Merchant, several studies have demonstrated a relatively high prevalence of abnormal findings on magnetic resonance images of the shoulder5, knee2,3, and spine4,6 in asymptomatic patients, particularly those of advanced age. However, the finding of a relatively high prevalence of abnormal findings on magnetic resonance imaging in an asymptomatic population does not invalidate the utility of that same imaging modality in a symptomatic population. The utility of magnetic resonance imaging is found in its ability to diagnose meniscal, ligamentous, and chondral abnormalities noninvasively. It is but one part of a comprehensive patient evaluation, which should include a careful history, plain radiographs, and an extensive physical examination. Fellows and residents at our institution are constantly reminded to treat the patient and not the magnetic resonance image. At no point in our article did we state that providing an accurate imaging test in the assessment of chondral lesions would necessarily "lead to increased numbers of potentially deleterious chondroplasties" as suggested by Dr. Dye and Dr. Merchant. We fear that they have overlooked the purpose of our paper, which was, as noted in our introduction, "to assess the accuracy of magnetic resonance imaging in the detection, grading, and localization of chondral lesions in the knee and to compare the findings with those of direct arthroscopic inspection."
Hollis G. Potter, M.D.; James M. Linklater, M.D.; Answorth A. Allen, M.D.; Jo A. Hannafin, M.D., Ph.D.; Steven B. Haas, M.D., M.P.H.: Departments of Radiology (H. G. P. and J. M. L.) and Orthopaedics (A. A. A., J. A. H., and S. B. H.), The Hospital for Special Surgery, 535 East 70th Street, New York, N.Y. 10021