Background/Purpose:

Meniscal pathology is highly prevalent in knee Osteoarthritis (OA).  However, details regarding the distribution of pathology within the meniscus has yet to be described in patients with and without radiographic signs of OA.  Cross-sectional distribution of medial meniscal pathology as it relates to the anterior horn, body, and posterior horn may be informative of the role of the meniscus in the natural history of OA 

Methods:

We studied participants in the Osteoarthritis Initiative (OAI) progression subcohort who had the OAI core set of magnetic resonance (MR) images at the 24-month OAI visit and consented to participate in the Bone ancillary project. By definition, members of the progression subcohort had at least one symptomatic knee with radiographic evidence of OA. .  The right knee was selected as the index knee for investigation among these participants unless there was a contraindication for MR imaging; therefore, the index knee did not have OA as a pre-requisite. A single experienced fellowship trained musculoskeletal radiologist reviewed the MR images  for meniscal pathology  by location (e.g. anterior, body, and posterior horn) within the medial menisci using a modified International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine (ISAKOS) meniscal tear classification system.  We presented the prevalence of meniscal pathology within the medial meniscus among this sample both with and without knee OA.  PA standing radiographs were obtained of the same knees and read for Kellgren-Lawrence grade. 

Results:

464 knees were included in the analysis; 454 were right knees; 244 (53%) men, with a mean age of 63 years (SD). 135 (29.4%) knees had no radiographic evidence of knee OA (Kellgren-Lawrence Grade = 0 or 1).  114 (24.6%) had normal medial menisci, leaving 350 (75.4%) with some pathology in at least one region of the medial menisus.  117 (25.2%) knees had pathologic anterior medial menisci and among those 98.3% had concurrent findings in the body or posterior horn. 272 (58.6%) medial menisci have pathologic findings in the meniscal body and among those 97.4% had concurrent findings in the anterior or posterior meniscal horn. 336 (72.4%) medial menisci had pathologic findings in the posterior meniscus and among those 263 (78.3%) had concurrent findings in the body or anterior regions. Finally, 107 (23.1%) had pathologic findings in all three regions (regardless of type of finding). 

Conclusion: Medial meniscal pathology is highly prevalent.  In our sample, of those with medial menisci pathology some damage was also almost universally found in the posterior horn.  Those with posterior horn damage also very commonly had concurrent pathology in the body and anterior horn.  Isolated involvement of the anterior horn and body of the medial meniscus are rare.  Though this is a cross-sectional study, these findings suggest that medial meniscal pathology may initiate in the posterior horn.  Longitudinal studies are needed to confirm this possibility.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/degenerative-medial-meniscal-pathology-may-initiate-in-the-posterior-horn-data-from-the-osteoarthritis-initiative/