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Microvascular Anatomy and Intrinsic Gene Expression of Menisci From Young Adults
Matthew D Crawford1, Justin E Hellwinkel2, Zachary Aman3
1Orthopedic Associates of Central Texas, Round Rock, Texas, USA.
Background:
Meniscal vascular supply is an important determinant of its healing potential. It has been reported that only the peripheral 30% of the meniscus is vascularized in cadavers aged 53 to 94 years; however, the vascularity in young patients, in whom meniscal repair is more often performed, is unknown.
Purpose:
The primary objective was to analyze and measure the microvascular anatomy of the meniscus in adult cadaveric specimens <35 years old. The secondary objective was to assess angiogenic potential by quantifying regional gene expression in a meniscal allograft cohort <45 years old.
Study Design:
Descriptive laboratory study.
Methods:
In part 1 of this study, 13 fresh-frozen cadaveric knees (age range, 22-34 years; mean, 28.5 years) underwent popliteal artery India ink injection and tissue clearing using a Spalteholz technique, followed by microvascular vascular measurement. In part 2, mRNA was isolated from 13 meniscal allografts (age range, 17-43 years; mean, 27.2 years), and expression of angiogenic genes, vascular endothelial growth factor (VEGF), and vascular endothelial growth factor receptor 1 (FLT1) was quantified using real-time polymerase chain reaction.
Results:
The maximal depth of vascular penetration into the periphery of the medial and lateral menisci ranged from 0% to 42% and 0% to 48%, respectively. There was variation in the degree of vascular penetration within the medial meniscus, with the posterior horn having a significantly smaller depth of penetration (median, 8.7%) than that of the anterior horn (median, 17.4%; P < .0001) or midbody (median, 17.5%; P = .0003). There were no differences in angiogenesis gene expression (VEGF/FLT1) based on circumferential or radial meniscal locations.
Conclusion:
The vascular supply of the medial and lateral menisci in specimens from adults <35 years of age extended farther than what was reported in specimens from older individuals; however, median values remained consistent. Gene expression of the angiogenic marker VEGF was low throughout all regions of uninjured menisci from young adults, which is consistent with reports in older specimens.
Clinical Relevance:
Improved understanding of meniscal vascular supply in young adults is critical to informing clinical treatment decisions.
Insights
Meniscal vascularity in young adults extends farther than in older individuals, but healing potential remains limited. Angiogenic gene expression is low, suggesting intrinsic healing limitations in the meniscus.
Area of Science:
- Orthopedic research
- Vascular anatomy
- Regenerative medicine
Background:
- Meniscal vascular supply significantly influences healing potential.
- Previous studies indicate limited vascularization (approx. 30%) in older cadavers (53-94 years).
- Vascularity in younger populations, crucial for meniscal repair, remains largely uncharacterized.
Purpose of the Study:
- To precisely measure and analyze the microvascular anatomy of the meniscus in adult cadavers under 35 years old.
- To evaluate the angiogenic potential by quantifying gene expression in a meniscal allograft cohort under 45 years old.
Main Methods:
- Part 1: India ink injection and Spalteholz tissue clearing in 13 cadaveric knees (22-34 years) to measure microvascularization.
- Part 2: mRNA isolation from 13 meniscal allografts (17-43 years) for quantitative real-time PCR of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 1 (FLT1) gene expression.
Main Results:
- Vascular penetration depth varied (0-42% medial, 0-48% lateral meniscus).
- The posterior horn of the medial meniscus showed significantly less vascular penetration (median 8.7%) compared to the anterior horn (17.4%) and midbody (17.5%).
- No significant differences in VEGF/FLT1 gene expression were found across meniscal regions.
Conclusions:
- Meniscal vascular supply in adults <35 extends further than in older individuals, though median penetration depths are consistent.
- Low gene expression of VEGF in young adults' menisci suggests limited intrinsic angiogenic potential, similar to older specimens.
