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Normal anatomic variation: A never ending saga
CLINICAL IMAGING 1993;17:169
16:
EDITORIAL
NORMAL ANATOMIC VARIATION: A NEVER ENDING SAGA T.E. KEATS,
MD
I have spent a large portion of my professional life collecting and documenting normal anatomic variants, and I find the task endless. It seems that Mother Nature is boundless in the infinite variations in the way we are constructed. This variation pertains not only to us as differing individuals, but even in our own symmetry, side to side. It is this bounty that keeps it endlessly exciting. Two articles in this issue deal with variations in anatomic architecture that deserve some comment. I have long recognized that roentgen visualization of the psoas muscles as a diagnostic sign is fraught with hazard. Not only do the muscles arise from different structures in different individuals, but they may differ in their contour from side to side in the same individual. In some cases, we may not be able to visualize them at all. Some of these issues are related to anatomy, while others are due to technical issues such as positioning or exposure technique. In addition, oversize psoas muscles produce other misleading findings in their effects on the course of the ureters and adjacent structures. In light of all this, Goldfeld’s and Luberant’s observations concerning the “vanishing psoas” by CT comes as no surprise. My own feeling about the psoas
From the Department of Radiology, University of Virginia Health Sciences Center, Charlottesville, VA 22908. 0 1993 Else&-r Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0899-7071/93/$6.00
muscles is that they are great when they are there, but their roentgen absence is not very useful in diagnosis. Concerning the paper of Bloom, et al. concerning the ossicles anterior to the proximal tibia, it has long been recognized that ossification of the tibia1 tubercle from multiple centers is indeed a variation of normal. It is this pattern of ossification that makes the radiological diagnosis of Osgood-Schlatter disease hazardous by roentgen means alone. It remains largely a clinical diagnosis which is based upon the presence of swelling and pain over the tubercle to complete the diagnosis. The roentgen appearance of the tubercle contributes little. Soft tissue edema of the patellar tendon and infrapatellar fat pad have more specificity. It is also worth noting that when ossification centers fail to fuse properly they represent a normal variant that is less sturdy than the single fused ossification center. A tibia1 tubercle so constituted is more apt to be subjected to avulsive forces and become symptomatic and indeed become painful normal variants. Another good example of this phenomenon is seen at the distal extremity of the patella in “jumper’s kneel’ The interpretation of normal variants must always include proper incorporation with clinical history and physical findings or we may inadvertently give patients diseases which they do not have, and this is probably the worst mistake we can make in medicine.
16:
EDITORIAL
NORMAL ANATOMIC VARIATION: A NEVER ENDING SAGA T.E. KEATS,
MD
I have spent a large portion of my professional life collecting and documenting normal anatomic variants, and I find the task endless. It seems that Mother Nature is boundless in the infinite variations in the way we are constructed. This variation pertains not only to us as differing individuals, but even in our own symmetry, side to side. It is this bounty that keeps it endlessly exciting. Two articles in this issue deal with variations in anatomic architecture that deserve some comment. I have long recognized that roentgen visualization of the psoas muscles as a diagnostic sign is fraught with hazard. Not only do the muscles arise from different structures in different individuals, but they may differ in their contour from side to side in the same individual. In some cases, we may not be able to visualize them at all. Some of these issues are related to anatomy, while others are due to technical issues such as positioning or exposure technique. In addition, oversize psoas muscles produce other misleading findings in their effects on the course of the ureters and adjacent structures. In light of all this, Goldfeld’s and Luberant’s observations concerning the “vanishing psoas” by CT comes as no surprise. My own feeling about the psoas
From the Department of Radiology, University of Virginia Health Sciences Center, Charlottesville, VA 22908. 0 1993 Else&-r Science Publishing Co., Inc. 655 Avenue of the Americas, New York, NY 10010 0899-7071/93/$6.00
muscles is that they are great when they are there, but their roentgen absence is not very useful in diagnosis. Concerning the paper of Bloom, et al. concerning the ossicles anterior to the proximal tibia, it has long been recognized that ossification of the tibia1 tubercle from multiple centers is indeed a variation of normal. It is this pattern of ossification that makes the radiological diagnosis of Osgood-Schlatter disease hazardous by roentgen means alone. It remains largely a clinical diagnosis which is based upon the presence of swelling and pain over the tubercle to complete the diagnosis. The roentgen appearance of the tubercle contributes little. Soft tissue edema of the patellar tendon and infrapatellar fat pad have more specificity. It is also worth noting that when ossification centers fail to fuse properly they represent a normal variant that is less sturdy than the single fused ossification center. A tibia1 tubercle so constituted is more apt to be subjected to avulsive forces and become symptomatic and indeed become painful normal variants. Another good example of this phenomenon is seen at the distal extremity of the patella in “jumper’s kneel’ The interpretation of normal variants must always include proper incorporation with clinical history and physical findings or we may inadvertently give patients diseases which they do not have, and this is probably the worst mistake we can make in medicine.