The Hip Joint. 319 



Pain. With ordinary passive motion, there is very 

 little pain, in the early stages, in those cases in which the 

 tubercular processes have started in the bone, although 

 pain can be elicited by forced passive movements. The 

 pain, when present, would be due to the action of the ilio- 

 femoral ligament, which, acting as a fulcrum when the 

 limb is over-extended or over-abducted, would tilt the 

 head of the femur up against the upper part of the ace- 

 tabulum and thus induce pain. To prevent this pain on 

 forced passive movement the limb is instinctively brought 

 into a more or less spastic condition by the patient, espe- 

 cially when the surgeon attempts to over-extend it. This 

 spastic condition is termed "reflex spasm," and is one of 

 the diagnostic features of the early stage of hip joint dis- 

 ease, especially when the primary disease is situated in the 

 bones. When, however, the disease starts in, or early in- 

 volves the synovial membrane, any movement at the joint 

 is resisted, since such movement would result in friction 

 of the diseased surfaces and consequent pain. Pain may 

 be felt in children, old enough to localize it, either in the 

 neighborhood of the joint, such as near the apex of Scar- 

 pa's triangle, or over the ilium above the great trochanter, 

 or, more often, at the knee. The explanation of the loca- 

 tion of pain at this latter situation, i.e., the knee, is vague. 

 Bell, quoted by Senn, believed it due to a reference of the 

 pain to the cutaneous branches of the obturator nerve, 

 and Cbulson explains those cases, in which the pain is felt 

 at points other than the distribution of the branches of the 

 obturator, as being due to inflammation of the fascia of 

 the rectus femoris, which muscle is, at its origin, connect- 

 ed with the capsule of the hip joint, and that the pain is, 

 therefore, conveyed down along this muscle towards the 

 knee. In all probability, however, the reference of the 

 pain to the knee is dependent on the fact, that the nerves 



