THE PRINCIPLES OF MYODYNAMICS. I4I 



pressure of the surface of the femoral head on 

 the acetabular surface will equal 1,700 pounds. 



141. Some practical observations may be 

 made in this connection : — 



(i.) The myodynamic facts, as above ex- 

 plained, forbid us to treat the active conditions 

 of hip-joint disease by permitting the patient to 

 walk about— because walking about causes the 

 muscles of the hip, even under surgical appli- 

 ances, to contract — and we now know what 

 great pressure these muscles can make on the 

 surfaces of the hip joint. 



(2.) If we put the patient on the back, and 

 make extension of the lower limb on the af- 

 fected side, we accomplish two important results : 

 (a.) The side of the pelvis on the affected side 

 is tilted downward, and that shortens the lower 

 limb, when the measurement is made from the 

 pelvis. — (b.) And the lower limb is pulled more 

 in a line with the long axis of the glutei medius 

 and minimus : Thus diminishing pressure be- 

 tween the hip-joint surfaces by diminishi7tg the 

 size of retentive muscidar components. 



