ABSTRACT
The workings of the musculoskeletal system, although complex, can be understood using basic laws of mechanics. A working knowledge of biomechanics is essential for the orthopaedic surgeon. Biomechanics is the branch of science dealing with the action and effects of internal and external forces on living biological systems using the principles and techniques of engineering and mechanics. In essence, the musculoskeletal system is a collection of lever systems linked together. From Newton's first law (inertia), an object is in static equilibrium if the sum of all the forces acting on it is balanced and all the moments acting on it are balanced separately from the forces. Static analysis by free-body diagram is a method of determining the forces and moments acting on a body by isolating that body part and ensuring that it is in static equilibrium.
