A radial tear of the meniscus cuts across the main fibres of the meniscus, from the inner rim to the outer rim.
A radial tear of the meniscus cuts across the main fibre bundles, and there is poor healing.
A cross-section of a meniscus, showing the fibres and the blood supply.
Why radial tears heal poorly
With each step the radial tear can open up. Also the cutting of the fibres interrupts the hoop forces that normally displace the pressures to the outer edge of the meniscus.
Associated tears of the lateral meniscus in anterior cruciate ligament injuries: risk factors for different tear patterns. Feucht MJ, Bigdon S, Bode G, Salzmann GM, Dovi-Akue D, Südkamp NP and Niemeyer P. J Orthop Surg Res. 2015; 10: 34.