Wolff's law
Encyclopedia
Wolff's law is a theory developed by the German Anatomist/Surgeon Julius Wolff
Julius Wolff
Julius Wolff was a German surgeon.-Biography:Julius Wolff was born on March 21, 1836, and received his doctorate in 1860 in the field of surgery for Bernhard von Langenbeck at the Friedrich-Wilhelms University to Berlin. In 1861 he settled down after the state examination as a general...

 (1836–1902) in the 19th century that states that bone in a healthy person or animal will adapt to the loads it is placed under. If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading. The internal architecture of the trabeculae
Trabecula
A trabecula is a small, often microscopic, tissue element in the form of a small beam, strut or rod, generally having a mechanical function, and usually composed of dense collagenous tissue They can be composed of other materials; in the heart, for example, muscles such as trabeculae carneae...

 undergoes adaptive changes, followed by secondary changes to the external cortical portion of the bone, perhaps becoming thicker as a result. The converse is true as well: if the loading on a bone decreases, the bone will become weaker due to turnover, it is less metabolically costly to maintain and there is no stimulus for continued remodeling
Bone remodeling
Bone remodeling is a lifelong process where mature bone tissue is removed from the skeleton and new bone tissue is formed...

 that is required to maintain bone mass.

Associated laws

  • In relation to soft tissue, Davis's Law
    Davis's Law
    Davis's law is used in anatomy to describe how soft tissue models along imposed demands. It is the corollary to Wolff's law. It is used in part to describe muscle-length relationships and to predict rehabilitation and postural distortion treatments as far as muscle length is concerned.This is not...

     explains how soft tissue remolds itself according to imposed demands.
  • Refinement of Wolff's Law: Utah-Paradigm of Bone physiology (Mechanostat
    Mechanostat
    The Mechanostat is a model describing bone growth and bone loss. It was promoted by Harold Frost and described extensively in the Utah Paradigm of Skeletal Physiology in the 1960’s...

     Theorem) by Harold Frost
    Harold Frost
    Harold M. Frost was an US-American orthopedist and surgeon considered to be one of the most important researchers and theorists in the field of bone biology and bone medicine of his time...

    .

Examples

  • The racquet
    Racquet
    A racquet or racket is a sports implement consisting of a handled frame with an open hoop across which a network of cord is stretched tightly. It is used for striking a ball in such games as squash, tennis, racquetball, and badminton...

    -holding arm bones of tennis
    Tennis
    Tennis is a sport usually played between two players or between two teams of two players each . Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Tennis is an Olympic sport and is played at all levels of society at all...

     players become much stronger than those of the other arm. Their bodies have strengthened the bones in their racquet-holding arm since it is routinely placed under higher than normal stresses.
  • Surfers
    Surfing
    Surfing' is a surface water sport in which the surfer rides a surfboard on the crest and face of a wave which is carrying the surfer towards the shore...

     who knee-paddle frequently will develop bone bumps, aka exostoses, on the tibial eminence and the dorsal part of the navicular tarsal bone from the pressure of the surfboard's surface. These are often called "surf knots."
  • Astronaut
    Astronaut
    An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....

    s who spend a long time in space will often return to Earth with weaker bones, since gravity hasn't been exerting a load on their bones. Their bodies have reabsorbed much of the mineral that was previously in their bones.
  • Weightlifters often display increases in bone density
    Bone density
    Bone density is a medical term normally referring to the amount of mineral matter per square centimeter of bones. Bone density is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk.This medical bone density is not the true physical "density" of the bone, which...

     in response to their training.
  • Martial artists who strike objects with increasing intensity (or of increasing hardnesses), display increases in bone density in the striking area. This process is termed cortical remodeling.

External links

  • Julius Wolff Institut, Charité - Universitätsmedizin Berlin, main research areas are the regeneration and biomechanics of the musculoskeletal system and the improvement of joint replacement.
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