Anatomy, Physiology And Pathophysiology of the Human Pelvis and Femoral Bones in Relation to Femoral Fractures.

The human pelvis is a closed bony ring that is strong and massively constructed. It is the foundation for the torso and support for lower limb attachment and locomotion. It is shaped so that the ischial tuberosity forms a platform for sitting in an upright position. This occurs because the ischial tuberosity is the most distal part of the pelvis. When the legs are flexed anteriorly, all the weight of the body can be rested unencumbered on the ischial tuberosities.


Each tuberosity is medial to the shaft of the femur and is located half the distance between the midline symphysis pubis and the femoral shaft. They form the baseline of the uro-genital triangle which slopes anterior and cephelad. The external genitalia in both sexes are attached at the apex of the uro-genital triangle, and because of this both sexes can sit straddling bicycle seats, fences and saddles without discomfort or injury.

The largest muscle mass in the human body is located surrounding the length of the femur. When fracture of the femur occurs it can result in:

  • Laceration of arteries, veins and nerves at the site of the fracture.
  • Bone fragment overriding, deformity and shortening of the limb due to severe muscle spasm.
  • Decreased tissue pressure – resulting in further bleeding, shock, and severe pain.
  • Additionally, spasm of the psoas and piriformis muscles acting on the proximal fragment of the femur may cause a flexion, abduction and external rotation deformity.

Application of Traction

Application of traction breaks the spasm and eliminates much of the pain. It also causes alignment of the bone fragments and subsequent increase tissue pressure. This reduces and controls bleeding and shock, and prevents further nerve, vascular and tissue damage. World War I studies indicate that properly applied traction and immobilization of a fractured femur helps control shock and reduces morbidity and mortality.1


The traction needed to break the spasm of muscles associated with a fractured femur is a product of the traction force and the length of time it is applied. A very large traction force only needs to be applied a short while for muscle fatigue and dissolution of the spasm to occur. Large traction forces, generally in excess of thirty (30) to fifty (50) pounds can in some cases control spasm in a few seconds. However, there is a risk with this mode of traction – it may result in nerve, vascular, muscle and soft tissue injury, as well as over-extension of the bone fragments. Gentle traction – “…the amount of pull required to accomplish this (traction) will vary but rarely will exceed 15 pounds. This is gentle traction, and the least amount of force necessary is the amount that should be employed”.2 Application of traction should also avoid the pitfall of static traction as provided by a drum and crank arrangement. This type of traction is not quantifiable. Moreover, proper traction can be completely lost if leg spasm stops and the limb lengthens. Drum and Crank traction force exists only for a set length between points of traction and countertraction. It also necessitates constant monitoring and resetting of traction, which can lead to further distraction of bone elements and/or needless increase in pain. In addition, uneven forces in lifting and carrying, or simply moving a patient can double or triple the forces against the injured limb. This drawback is commonly associated with most Ischial Pad splints that promote the use of static traction arrangements.

1 Cannon, Walter B, Traumatic Shock, 1922.

2 American Academy of Orthopedic Surgeons, Emergency Care and Transport of the Sick and Injured, Third Edition, George Banta Co. Inc., 1981, San Antonio, TX, pg: 142

Safe Traction

Safe traction for field use should be traction in a known amount prescribed by protocol or a Medical Consultant. It should also be traction that is dynamic in nature using a resilient member that permits graded reduction of the traction force as the muscle spasm decreases and the leg length increases. It should avoid the pitfalls of rope, weight and pulley traction. This type of traction is a constant and unrelenting force that can result in over-extension of the bone elements and should only be available in a Hospital setting under the care of an Orthopedic Surgeon or other designated Medical Consultant.