Diseases affecting bone quality: beyond osteoporosis.
BACKGROUND
Bone quantity, quality, and turnover contribute to whole bone strength. Although bone mineral density, or bone quantity, is associated with increased fracture risk, less is known about bone quality. Various conditions, including disorders of mineral homeostasis, disorders in bone remodeling, collagen disorders, and drugs, affect bone quality.


OBJECTIVE
The objectives of this review are to (1) identify the conditions and diseases that could adversely affect bone quality besides osteoporosis, and (2) evaluate how these conditions influence bone quality.


METHODS
We searched PubMed using the keywords "causes" combined with "secondary osteoporosis" or "fragility fracture." After identifying 20 disorders/conditions, we subsequently searched each condition to evaluate its effect on bone quality.


RESULTS
Many disorders or conditions have an effect on bone metabolism, leading to fragility fractures. These disorders include abnormalities that disrupt mineral homeostasis, lead to an alteration of the mineralization process, and ultimately reduce bone strength. The balance between bone formation and resorption is also essential to prevent microdamage accumulation and maintain proper material and structural integrity of the bone. As a result, diseases that alter the bone turnover process lead to a reduction of bone strength. Because Type I collagen is the most abundant protein found in bone, defects in Type I collagen can result in alterations of material property, ultimately leading to fragility fractures. Additionally, some medications can adversely affect bone.


CONCLUSIONS
Recognizing these conditions and diseases and understanding their etiology and pathogenesis is crucial for patient care and maintaining overall bone health.
Department of Orthopaedic Surgery, Hospital for Special Surgery, and Weill Cornell Medical College, Cornell University, 535 East 70th Street, New York, NY 10021, USA. uaasis@yahoo.com
Aasis
A
Unnanuntana
Brian J
BJ
Rebolledo
M Michael
MM
Khair
Edward F
EF
DiCarlo
Joseph M
JM
Lane
D018501:Antirheumatic Agents / Q000627:therapeutic use; D015519:Bone Density; D001847:Bone Diseases / Q000378:metabolism / Q000503:physiopathology*; D001862:Bone Resorption / Q000503:physiopathology; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D003095:Collagen Diseases / Q000503:physiopathology; D050723:Fractures, Bone / Q000503:physiopathology; D005938:Glucocorticoids / Q000627:therapeutic use; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006961:Hyperparathyroidism / Q000503:physiopathology; D010022:Osteopetrosis / Q000503:physiopathology; D010024:Osteoporosis / Q000503:physiopathology*
D018501:Antirheumatic Agents; D005938:Glucocorticoids