Recallab › Question bank › Anatomy › Histology › #50104
Fibrocartilage: meniscal healing
A 24-year-old footballer has a tear of the medial meniscus confined to its inner third. The surgeon explains that this part of the meniscus heals poorly and is likely to need excision rather than repair. What is the reason?
- A. The inner third is hyaline rather than fibrocartilage
- correctB. The inner third is avascular and receives nutrition only by diffusion
- C. The inner third bears no load during walking
- D. The inner third contains no collagen
Explanation
Key fact
The meniscus is vascular only at its periphery. Tears in the outer red-red zone can be repaired; those in the inner white-white zone cannot heal.
The inner third is avascular. Without a blood supply there is no inflammatory response and no healing.
Why
The meniscus is fibrocartilage - type I collagen in dense bundles.
Its blood supply enters from the capsule at the periphery only.
That gives three zones: red-red outer, red-white middle, white-white inner.
The inner third is nourished by diffusion from synovial fluid.
Repair needs cells and blood vessels, and neither reaches the inner third.
The three meniscal zones
| Zone | Position | Blood supply | Tear management |
|---|---|---|---|
| Red-red | Outer third | Good | Repair |
| Red-white | Middle third | Partial | Repair may be attempted |
| White-white | Inner third | None | Partial meniscectomy |
Blood reaches the outer third only, and repair needs blood
Why not the others
- A. The inner third is hyaline rather than fibrocartilage — is wrong. The whole meniscus is fibrocartilage; the zones differ in vascularity, not in tissue type.
- C. The inner third bears no load during walking — is wrong and backwards. The meniscus transmits a large share of the load across the knee, which is why removing it accelerates osteoarthritis.
- D. The inner third contains no collagen — is wrong. Type I collagen is the bulk of the meniscus throughout, and it is what gives it tensile strength.
Remember
Red heals, white does not. Preserve as much meniscus as possible - every millimetre removed raises the contact pressure on the articular cartilage.
Go deeper
Articular (hyaline) cartilage has no perichondrium and no blood supply either, which is why full-thickness defects also fail to heal.
Hyaline cartilage is type II collagen and is the most abundant type; fibrocartilage is type I and is found in menisci, intervertebral discs, the pubic symphysis and the glenoid and acetabular labra.
Elastic cartilage, with elastin as well as type II collagen, is in the pinna, epiglottis and auditory tube.
Gray's Anatomy for Students, 5th ed. (Elsevier, 2023); Apley & Solomon's System of Orthopaedics and Trauma, 10th ed. (CRC Press, 2018).