Which morphological change is associated with immobilization of connective tissue?

• A. GAGs increase dramatically.
• B. Increased collagen cross-linking.
• C. Formation of fibrofatty infiltrates.
• D. Adipose tissue is completely replaced by bone.

Answer: (C)

Immobilization removes the normal mechanical cues that keep connective tissue healthy, so the tissue undergoes disuse remodeling. The hallmark change you’ll see histologically is fibrofatty infiltration, where fibrous tissue and adipose tissue gradually replace the normal parenchyma within the connective tissue and surrounding muscle. This reflects a maladaptive repair process after disuse, with fat cells interspersed among fibrous bands contributing to decreased elasticity and increased stiffness.

GAGs don’t typically rise dramatically with immobilization; in fact, proteoglycan and ground-substance turnover can be reduced, so a large increase in GAGs isn’t expected. Adipose tissue completely replacing bone isn’t a recognized consequence of immobilization. Collagen cross-linking can increase with aging or fibrosis, but the distinctive histologic pattern associated with immobilization is the formation of fibrofatty infiltrates, which is why this option best fits the scenario.