MENISCUS AND MENISCAL INJURY

27 Sep MENISCUS AND MENISCAL INJURY

Anatomy

• Fibro-cartilaginous disc crescentic in shape
• Wedged cross section with tapered inner border
• Generates hoop stress
• Loading causes water to drive out of meniscus and unloading attracts water
• Peripheral 1/3 is vascular, whereas, inner border is avascular.

Macro- structure

• 3 layers
• Surface , superficial radial fibre and deep circumferential fibres

Micro-structure

• Extracellular has type 1 collagen 20%, elastin 10%, proteoglycans and water 65%
• Cellular – chondrocytes and fibroblasts
• Blood supply – medial and lateral inferior vehicular artery in outer 25% and 75% by synovial fluid diffusion. posterior horn by middle vehicular artery.

Medial meniscus

• Semilunar in shape
• Attached to deep MCL and coronary ligament and is vulnerable to tear
• Less mobile
• Covers 1/2 of tibial articular surface
• Absorbs 505 of medial load

Lateral meniscus

• Circular
• Covers 2/3 articular surface
• Absorbs 70% of lateral load
• More mobile

Function of meniscus

• Secondary stabiliser
• Distributes weight
• Shock absorber
• Joint lubricatiion
• Proprioreception

Symptoms

• Locked knee – pain and joint line tenderness and inability to extend knee.

Types of meniscal tear

• Longitudinal/vertical tear(bucket handle tear)

• Oblique tear(radial tear)
• Complex tear
• Horizontal tear
• Root tear

Investigation

• x-ray
• MRI – double pal sigh, double anterior horn sign

Treatment

• Meniscus debridement
• Total meniscectomy
• Meniscal repair
• Meniscal replacement