Histology of the Torn Meniscus: A Comparison of Histologic Differences in Meniscal Tissue between Tears in Anterior Cruciate LigamentIntact and Anterior Cruciate LigamentDeficient Knees

Abstract

Purpose The purpose of this case control study was to evaluate possible preexisting structural differences between torn menisci in anterior cruciate ligament–intact and anterior cruciate ligament–deficient knees. Materials and Methods Subjects were prospectively enrolled into the study from new patient referrals to the orthopaedic clinic. Forty-four meniscal specimens were retrieved during routine arthroscopy. The anterior cruciate ligament–deficient group included 24 patients (15 men and 9 women, average age of 26.5 years, SD = 9.5) with 24 acute, displaced, longitudinal, bucket-handle tears of the medial meniscus in unstable, anterior cruciate ligament–deficient knees. The anterior cruciate ligament–intact group included 20 patients (14 men and 6 women, average age of 30.4 years, SD = 13.4) with similar tears in anterior cruciate ligament–intact knees. Longitudinal and transverse section specimens were stained with hematoxylin and eosin and safranin O, divided into zones based on proximity to the tear, and graded on safranin O uptake or tissue composition. Results Descriptive statistics and χ2 analyses were used to assess differences between groups within each zone. Significant differences (P < .05) were observed between anterior cruciate ligament–deficient and anterior cruciate ligament–intact specimens stained with hematoxylin and eosin in zone 3 for both transverse and longitudinal cuts. Significant differences were not found between anterior cruciate ligament–deficient and anterior cruciate ligament–intact specimens stained with safranin O. Conclusion Longitudinal meniscal tears occurring in anterior cruciate ligament–intact knees may result from early degenerative disease processes. Attempted repair of this diseased tissue may fail to have a positive effect on long-term preservation of the meniscus.