Dr. Ali Abd El-Monsif Thabet Ligamentous injury Dr. Ali Abd El-Monsif Thabet

Anatomy and Structure The word 'ligament' is derived from a Latin word 'ligare' which means 'binding' Ligaments are white, shiny, band-like structures that connect bones to each other. They are composed of abundant collagen fibers that are nearly parallel with the long axis of the ligament. Under polarized light microscopy, these fibrils have a sinusoidal wave pattern or crimp

Ligaments are composed of dense connective tissue arranged in parallel bundles of collagen composed of rows of fibroblasts(Along the fibers are some scattered, long, thin fibroblasts that produce and maintain the surrounding matrix).

Function The major functions of skeletal ligaments include : 1- Attachment of articulating bones to one another across a joint 2- To provide stability to a joint 3- Guidance of joint movements 4- Maintenance of joint congruency 5- Action as position sensors for joints

Composition Fibroblasts Extracellular Matrix Collagen=25% Proteoglycans=1% Elastin<5% Water=70%

Collagen Structure Triple helix collagen molecule

ELASTIN Elastin is fibrous protein characterized by a high degree of reversible extensibility with small forces Elastin, however, produces highly elastic tissues that assist in recovery from deformation.

Proteoglycans Protein core with glycosaminoglycans chains that are polysaccharides of repeating disaccharide units Regulate collagen fiber formation and improve tensile properties of collagen Proteoglycans resist compressive loading

Strain (%) (B) ( A) Elongation (mm) A Structural properties of the bone-ligament-bone complex during uniaxial tensile test. 1 Nonlinear region referred to as the toe region, 2 stiffness, 3 ultimate tensile load, 4 energy absorbed to failure, B Mechanical properties of ligament substance during uniaxial tensile test. The stress-strain curve delineates parameters of the ligament substance such as 5 modulus, 6 tensile strength, 7 ultimate strain, and 8 the strain energy density.

LIGAMENT SPRAINS A sprain involves damage to a ligament that provides support to a joint. If stress is applied to a joint that forces motion beyond its normal limits or planes of movement, injury to the ligament is likely (Figure 3).

Figure 3 Example of a ligament sprain in the knee joint.

The mechanisms of injury can be classified into the following categories: Contact or direct trauma Dynamic loading Repetitive overuse Poor flexibility Muscle imbalance

The severity of damage to the ligament is classified in many different ways. The most commonly used system involves three grades (degrees) of ligamentous sprain: Grade 1 sprain Grade 2 sprain Grade 3 sprain

Thank you