TO THE EDITOR:
The article "Anomalous Insertion of the Medial Meniscus of the Knee. A Case Report" (77-A: 1894—1896, Dec. 1995), by Shea et al., describes what they believe is an anomalous insertion of the medial meniscus of the knee.
I have on several occasions witnessed the same arthroscopic view as was shown in their Figure 1-A. The first time that I saw this, I too believed that there was some sort of anomalous insertion of the anterior horn of the medial meniscus. After I adjusted the lateral portal to a more proximal position, this anomalous insertion seemed to go away. I believe that the arthroscopic view of the knee shown in Figure 1-A is simply a matter of the lateral portal being in a too inferior position—inferior to the intermeniscal ligament—so that the ligament was levered up on the anterior horn of the medial meniscus. Adjustment of the portal to a more proximal location normalizes this so-called anomalous insertion. One of my own arthroscopic images (Fig. 1) is similar to Figure 1-A of Shea et al. However, I assure you that the meniscus seen on this image was not anomalous.
Furthermore, I do not have a clear understanding of what Figure 2-A represents even though the diagram in Figure 2-B explains it. I do not understand what it means to have this meniscus attached to the intercondylar notch. Does it attach to the roof of the notch, the lateral wall of the notch, or the medial wall of the notch? Certainly, it does not attach to the tibia if it is attached to the notch, since the notch is part of the femur.
In summary, I think that the so-called anomalous insertion of the anterior horn of the medial meniscus is secondary to an inferiorly placed lateral portal that was inadvertently placed distal to the level of the intermeniscal ligament or the anterior horn of the medial meniscus, or both, thereby giving the illusion of an anomalous insertion.
Scott E. Cameron, M.D.: Marshfield Clinic, 1000 North Oak Avenue, Marshfield, Wisconsin 54449
Dr. Shea, Dr. Westin, and Mr. West reply:
We agree with Dr. Cameron's observation that use of the lateral arthroscopic portal can result in the image shown in Figure 1-A. Our first portal view during the procedure showed the abnormal meniscus. We suspected that our lateral portal view was too distal and that we had placed the arthroscope inferior to the intermeniscal ligament. When we redirected the arthroscope in a more proximal direction through the lateral portal, the meniscal anomaly was still present. The arthroscope was then moved to the medial portal. The view from the medial portal also demonstrated the meniscal anomaly, as shown in Figure 2-A. Complete exploration of the medial meniscus verified that it was clearly attached to the roof of the intercondylar notch of the femur, just anterior to the anterior cruciate ligament.
We appreciate Dr. Cameron's comments and agree that the lateral portal can yield this view if the arthroscope enters the joint inferior to the intermeniscal ligament. However, in the case of our patient, this clearly was not the reason for this appearance.
Kevin G. Shea, M.D.; John West: Department of Orthopaedic Surgery, University of Utah School of Medicine, 50 North Medical Drive, Salt Lake City, Utah 84132
Craig Westin, M.D.: 9844 South 1300 East, Suite 100, Sandy, Utah 84094