The joint is the area where the two or more bones are connected in our body structure. Most of the joints are synovial joints, where bones are held together with the ligaments and are lubricated by a fluid called as synovial fluid, secreted by the joint lining. Example, the knee joint is a type of synovial joint and it consists of the following structures: (Figure 7 & 8)
If we know the constituents of bone we can ourself assess, what is required for the development and growth of bones and joints. Basically, the bone is made up of osseous tissue formed by organic material 25% and inorganic material 65% along with water (10%) (Figure 9)6
The inorganic constituents of bone contains the bulk of the calcium and phosphate. Magnesium, sodium and potassium minerals are although required in minor quantity, but are equally essential for bone growth and development.Theorganic constituents contains collagen and other polysaccharides (mucoproteins and glycoproteins) and lipids (including phospholipids). There are number of other hormones which helps in the maintenance and growth of bone. It can be of protein in nature like growth
hormones, thyroid, parathyroid, calcitonin and other steroidal hormones like estrogen and testosterone which requires cholesterol i.e fats as the precursor for its synthesis. Although the list is simple but all these compositions are interlinked with number of biochemical reactions which requires many other minerals and micronutrients for the enzymatic reactions. All the above constitution and reactions itself explains, what are the basic requirements for the development and maintenance of the bone growth.
The joints have the similar composition, as these are made up of ligaments as well as bones. The main part of the bone involved in joint is the cartilage. For example in the synovial joints, the cartilage present is the articular cartilage. The articular cartilage is devoid of blood vessels, lymphatics, and nerves and is
generally subjected to a harsh bio-mechanical environment, moreover it has a limited capacity for intrinsic (self /inner) healing and repair. Therefore, the preservation and health of articular cartilage is very important for joint health. Articular cartilage is the highly specialized connective tissue with cells (chondrocytes) and dense extracellular matrix (ECM) (Figure 10), basically composed of water, collagen,proteoglycans, non-collagenous proteins and glycoproteins and functions as a wear-resistant, load-bearing, smooth and frictionless surface. Collagen is one of the two major load-bearing macromolecules present in cartilage. Proteoglycans and glycosaminoglycans are synthesised by one of the endogenous amino-mono- saccharide, Glucosamine, which is inturned synthesized from glucose.
Basically, the joint is an organ whose main purpose is articulation that is, the movement of this bony frame of our body. These are also the load-bearing structures.Thus, joints helps in the mobility, flexibility and the stability of the body's skeleton. It is remarkable that under such potentially punishing mechanical conditions, most joints functions throughout the life of the individual without evidence of destruction of their major load-bearing areas.
2. Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000.,Chapter 1 section 4; Available from: https://www.ncbi.nlm.nih.gov/books/NBK9974/
3. LARSEN'S HUMAN EMBRYOLOGY, 5TH EDITION; © 2015, 2009 by Churchill Livingstone, an imprint of Elsevier Inc. Chapter 8 Pg. 189
4. Robert J. Peshek, Clinical Nutrition Using the Seven Lines of Defense Against Disease.
5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings.
6. Essential Orthopaedics By J Maheshwari; chapter 37; pg 297