Which of the following is classified as peripheral sites of the skeleton?

• A. Femur and pelvis
• B. Calcaneus and tibia
• C. Thoracic spine and femoral neck
• D. Spine and proximal femur

Answer: (B)

Peripheral sites of the skeleton refer to areas that are not central or axial components. These peripheral sites are typically assessed in bone densitometry because they provide insight into the bone density that may be indicative of overall skeletal health, yet they are located at the extremities of the body rather than the central axis.

The calcaneus (heel bone) and tibia (shinbone) are considered peripheral bones. The calcaneus is particularly relevant because it is a weight-bearing bone and its density can reflect changes in bone strength. Furthermore, the tibia is a long bone in the lower leg, also capable of holding weight and thus is a relevant site for assessing bone density changes. This choice aligns directly with the understanding of peripheral sites in the context of bone densitometry.

In contrast, the other choices involve central skeletal elements. The femur and pelvis, the thoracic spine and femoral neck, and the spine and proximal femur are all areas more commonly associated with central skeletal assessments and are not classified as peripheral sites. These include larger structural components that contribute to the overall posture and support of the torso and play significant roles in weight distribution. Understanding these distinctions is crucial in bone health assessments and diagnostics in the field of densitometry.