Test on Bone Biology and Regeneration

Question 1: The consolidation stage of distraction osteogenesis immediately precedes the latency stage.

A. Yes

B. No

Explanation: The study materials state that distraction osteogenesis requires three main stages: latency, activation, and consolidation. Latency is the first stage, followed by activation, and then consolidation is the third and final stage. Therefore, consolidation does not precede latency.

Question 2: Which of the following histological characteristics are observed during successful distraction osteogenesis?

A. Formation of a cartilaginous intermediate prior to ossification

B. Appearance of multipotent precursor cells and type I collagen matrix expression in the distraction zone

C. Mineralization starting at the osteotomy fronts and proceeding centrally

D. Predominantly endochondral ossification throughout the process

Explanation: Successful distraction osteogenesis results from membranous ossification, not endochondral ossification or the formation of a cartilaginous intermediate. In the early phases, multipotent precursor cells and type I collagen matrix expression are characteristic. Mineralization by active mature osteoblasts starts 10–14 days after the onset of distraction, beginning at the osteotomy fronts and proceeding centrally.

Question 3: The risk of disease transmission from processed bone allografts remains substantial despite advanced donor screening and the removal of blood products.

A. Yes

B. No

Explanation: The study materials indicate that the risk of disease transmission from processed allografts is minimal due to extensive donor screening and testing, and that this risk appears to decrease to virtually zero with newer screening techniques and by removing blood and blood products from the graft.

Question 4: Which of the following is a critical consideration for handling bone grafts to optimize their survival?

A. Grafts should be stored at temperatures above 42°C to prevent bacterial growth.

B. Antibiotic washes should be used liberally to ensure sterility, regardless of cellular impact.

C. Exposure time of the graft to air at room temperature should ideally be less than 1 hour.

D. The cancellous portion of the graft should be placed facing away from the cancellous bone in the recipient bed.

Explanation: To optimize the chances of bone graft survival, graft exposure time to air at room temperature should be minimized, ideally to less than 1 hour. Grafts should be kept cool, as temperatures over 42°C may cause cell death. Antibiotic washes are cellucidal and should be used with caution. The cancellous portion of the graft should be placed in contact with the cancellous bone in the bed.

Question 5: The greater trochanter is a potential site for harvesting cancellous bone.

A. Yes

B. No

Explanation: The study materials explicitly state, 'The greater trochanter and the olecranon are potential sites of cancellous bone harvest, specifically when small amounts are needed.'