ABSTRACT
The hip joint reaction force is calculated by resolving the vector triangle shown in Figure 19.2.
Introduction 164 Total hip arthroplasty 166
Viva questions 168 Further reading 169
The major determinant of joint pathology is the joint reaction force, which is the resultant of the abductor force Fab and 5/6 body weight Fbw. Of these two factors, the abductor force predominates, but a reduction in either will reduce the joint reaction force and, thus, symptoms at the hip joint. In osteoarthritis, the near-frictionless articular cartilage is worn away and the resultant increased frictional forces exert a resistant moment. To overcome this, an increased abductor force is required.
