The investigate whether the mechanism of meniscal tear were different between the fresh and old isolated anterior cruciate ligament tear or not the patterns and incidence of the meniscal tear in both ligament tear groups were compared. Seventy
knees of
old ligament tear and 26 knees of fresh ligament tear, treated between April, 1984 and December, 1992 were involved in this study. The tear patterns were divided according to the location and shape of tear in medial and lateral menisci. The
results
were
analyzed statistically with chi-square test and Fisher´s exact test. The incidence of meniscal tear was higher in old ligament tear group(45 out of 70, 64.3%) than in fresh ligament tear group(7 out of 26, 26.9%)(p=0.001). Among single meniscal
tears
the lateral menisci(4 knees) were more frequently torn than the medial menisci(2 knees) in fresh ligament tear group, whereas the reverse as true( 13 lateral and 21 medial menisci) in old ligament tear group. In fresh ligament tear group
longitudinal
meniscal tears were noted in 4 out of 7 knees(51.7%). In old ligament tear group the longitudinal meniscal tears including peripheral tears were noted in 19 out of 34 single meniscal tear(55.9%). In cases of both meniscal tear in old ligament
tear
group, the incidence of longitudinal tear of one of the both menisci was 9 out of 11 knees(81.8%). So the incidnece of longitudinal meniscal tear was 28 out of 45 knees(62.2%) in old ligament tear group. These findings suggested the higher
incidence of
longitudinal tear was expected not in fresh(p=0.857) but in old ligament tear group(p=0.020) and in total anterior cruciate ligament tears(p=0.019) compare to other patterns of meniscal tear. In cases of single meniscal tear in old ligament tear
group
the incidence of longitudinal tear of medial menisci(13 out of 21 knees, 61.9%) was not significantly higher than that of lateral meniscal tear(6 out of 13 knees, 46.1%)(p=0.369).
In summary, the incidence of meniscal tear in the fresh anterior cruciate ligament tear group was lower than in the old anterior cruciate ligament tear group, longitudinal tear and tear of both menisci were more frequently seen old ligament tear
group
than in fresh ligament tear group, suggesting different mechanism of meniscal tear.
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