Amit Sahasrabudhe 2013-10-25 12:07:35
What Came First, The Meniscus Tear Or The Arthritis? I am oft en asked to opine whether surgical intervention for a meniscus tear is causally related to an industrial or personal injury. The answer ... it depends. BRIEF OVERVIEW OF ANATOMY / FUNCTION The knee joint is made up of 4 bones – patella (kneecap), femur (thigh bone), tibia and fibula (shin bones). Articular cartilage lines the surfaces of these bones. The medial and lateral menisci are cushion pads, sitting on top of the tibia. They serve as shock absorbers, allowing for dissipation and distribution of stress and force across a wider area, so as to decrease strain on the cartilage. When cartilage gets damaged, it unfortunately does not have the capacity to heal or grow back, thus leading to arthritis. NATURAL HISTORY OF A MENISCUS TEAR When one sustains a meniscus tear, arthroscopic surgery is oft en done to “eliminate” the tear. The tear is not oft en repaired since the meniscus has limited healing capacity; rather the tear is typically “trimmed.” In the process, one ends up with less of a shock absorber pad in the knee. The forces transmitted to and through the cartilage are thus increased considerably. Normally the meniscus transmits up to 70 percent of joint loads. Partial meniscectomy (trimming) can increase peak loads up to 65 percent, while complete meniscectomy may increase peak loads up to 235 percent! Thus a meniscus tear and subsequent surgery oft en leads to development of arthritis. FAIRBANKS SIGNS Fairbanks signs are characteristic X-ray findings, indicative of arthritis. Specifically these are joint space narrowing, squaring of the condyles, and ridge formation (bone spurs). The findings do not occur overnight; rather they are the result of long-standing wear and tear. An acute injury will not cause the immediate formation of arthritis. It should be noted that when one sees Fairbanks signs on an X-ray, it is highly likely that an MRI will show some degenerative meniscus tearing, again typically related to the arthritis, rather than an acute injury. CASE STUDY Fifty-two-year-old male complains of increased left knee pain while on the job. He twisted his knee and felt immediate pain on the inside of his knee. His past surgical history is notable for a left knee medial meniscus “trimming” in 2003. He denies having any problems with the knee aft er that surgery. On physical examination, he has a small effusion, obvious spurring and medial joint line tenderness. X-rays show Fairbanks signs. An MRI shows arthritis and a medial meniscus tear. In this case, the twisting injury likely aggravated a pre-existing degenerative meniscus tear, warranting further treatment, including the possibility of arthroscopic surgery, related to his work injury. However, the presence of Fairbanks signs indicates that the arthritis was long-standing in nature. An acute twisting injury would not cause arthritis to form immediately. He is likely to benefit from a knee replacement in the future, however this would not be related to the industrial injury. He was pre-disposed to developing arthritis from his original meniscus surgery and in fact already had it on X-rays and MRI at the time of the industrial injury. If this case had involved simple repetitive activity, such as walking at work, without twisting injury or fall, it is likely that it would have been a temporary exacerbation of pre-existing degenerative changes, including arthritis and a meniscus tear. This would require treatment in the form of a cortisone injection and perhaps physical therapy, but not surgery. The X-rays oft en give us the answer. Dr. Amit Sahasrabudhe is a board certified orthopedic surgeon specializing in sports medicine surgery and fracture care at the Arizona Sports Medicine Center (www.asmcmd.com). Dr. Amit is one of the team physicians for the Arizona Cardinals, Phoenix Coyotes, Colorado Rockies, and Chicago Cubs. He also takes care of several local area high schools. In addition to taking care of athletes and their families, his practice focuses on independent medical examinations for workers’ compensation cases as well as personal injury. He currently holds active medical licenses in Arizona and New Mexico. For more information or to get in touch with Dr. Sahasrabudhe, please feel free to call ExamWorks at (866) 800-4637.
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