Question

Describe the engineering explanation behind the following structural/anatomical

features as related to bone, articular cartilage, tendons and ligaments. Please use

precise and concise answers.

Bone

1. The cement line is the weakest part of the osteon’s microstructure in bone

2. Cortical bone typically always surrounds cancellous bone

3. Bone with denatured collagen is highly susceptible to failure

4. In addition to the amount of load and number of cycles, the frequency of

loading is critical to bone failure in fatigue

5. Torsional tibial fractures commonly occur distally

Answer 1

1.Cement line is the weakest part of osteons microstructure in bone

Osteon is the fundamental structural unit of bone.The periphery of each osteon has a cement line,a narrow area of cement like substances made up of polysaccharides glycosaminoglycans.The collagen fibers in bone matrix interconnects from one lamella to another within an osteon not crossing the cement line,this increases the bones resistance to mechanical stress.This is why cement line is weakest part of osteons microstructure.

2. Cortical bone is stiffer than cancellous bone,withstanding greater stress .cortical bones fracture when strain exceeds. cancellous bone has more pores and has a large capacity of energy storage.

3.collagen fibers cross link to give strength to the tissues and allows tissues to function under mechanical stress.The collagen cross link gets denatured by heat and reduces the number and has high susceptible to failure.

4.Bone is a viscoelastic material and is stiffer and sustains higher load to failure.Failure of tensile load proceeds rapidly to complete fractures and in compressive load it proceeds more slowly.

5.under torsional loading ,maximum stress acts on planes parallel and perpendicular to the neutral axis of tibia and the fracture ocuurs in the neutral axis of tibia.