Session 7 Flashcards
Describe the fusion of the three bones that make up the hip
At birth, the three primary bones are joined by hyaline cartilage.
In children they are incompletely ossified.
At puberty, the three bones are still separated by a Y-shaped Triradiate cartilage centred in the acetabulum, although the two parts of the ischiopubic rami fuse by the 9th year.
The bones begin to fuse between 15 and 17 yesrs of age; fusion is complete between 20 and 25 yesrs LV she.
What is the Obturator Foramen?
Large oval opening in the hip bone.
It is bounded by the pubis and ischium and their rami.
Except for a small passageway for the obturator nerve and vessels (the obturator canal), the obturator foramen is closed by the thin, strong obturator membrane.
The presence of the foramen minimises bony mass (weight) while its closure by the obturator membrane still provides extensive surface area on both sides for fleshy muscle attachment.
What is the pubic symphysis?
The pubic symphysis unites the two hip bones (specifically the bodies of the two opposing pubic parts of the hip bones) anteriorly in the midline.
What is Shenten’s line?
When studying a Hip X-Ray, Shenten’s line is formed by the medial edge of the femoral neck and the inferior edge of the superior pubic ramus.
Loss of contour of Shenten’s Line is a sign of a fractured neck of femur.
Important note: fractures of the femoral neck do not always cause loss of Shenten’s line.
Describe Fractures of the Hip Bone
Weak areas are the pubic rami, the acetabula (or the area immediately surrounding them), the region of the sacro-iliac joints and the alae of the ilium.
Fractures can result from direct trauma to the pelvic bones such as occurs during a car accident or can be caused by forces transmitted to these bones from the lower limb during falls on the feet.
Pelvic fractures may cause injury to soft pelvic tissues, blood vessels, nerves and organs.
Fractures in the pubo-obturator area are relatively common and are often complicated because of their relationship to the urinary bladder and urethra which may be ruptured or torn.
Describe fracture of the neck of femur
Most frequently fracture because it is the narrowest and weakest part of the bone and it lies at a marked angle to the line of weight-bearing (pull of gravity).
It becomes increasingly vulnerable with age, especially in females, secondary to osteoporosis.
Fractures are often intracapsular and realignment of the neck fragments require internal skeletal fixation.
Shortening and lateral/external rotation of the lower limb occurs and blood supply is often disrupted - the retinacular arteries of the medial circumflex femoral artery may be torn.
Describe fractures of the proximal femur
Can occur at several locations such as the middle of the neck and intertrochanteric.
Because of the angle of inclination, these fractures are inherently unstable and impact (overriding of fragments resulting in foreshortening of the limb) occurs.
Muscle spams also contribute to the shortening of the limb.
What do fractures of the great trochanter and femoral shaft usually result from?
Direct trauma and are most common during the more active years (during motor vehicle accidents and sports such as skiing and climbing).
In some cases, a spiral fracture of the femoral shaft occurs resulting in foreshortening as the fragments override or the fracture may be comminuted with the fragments displaced in various directions as a result of muscle pull and depending on the level of the fracture, union of this type of fracture may take up to a year.
How may fractures of the inferior or distal femur be complicated by?
By separation of the condyles, resulting in misalignment of the articular surfaces of the knee joint or by haemorrhage from the large popliteal artery that runs directly on the posterior surface of the bone. This fracture compromises the blood supply to the leg.
Describe Tibial Fractures
Tibial shaft is narrowest at the junction of its middle and inferior thirds which is the most frequent site of fracture.
This area of the bone also has the poorest blood supply. Because its anterior surface is subcutaneous, the tibial shaft is the most common site for a compound (open) fracture.
Compound fractures may also result from direct trauma e.g. When a car bumper strikes the leg.
Fracture of the tibia through the nutrient canal predisposes the patient to non-union of the bone fragments resulting from damage to the nutrient artery.
Describe Fibular Fractures
Commonly occur 2-6cm proximal to the distal end of the lateral malleolus and are often associated with fracture-dislocation of the ankle joint, which are combined with tibial fractures.
When a person slips and the foot is forced into an excessively inverted position, the ankle ligaments tear, forcibly tilting the talus against the lateral malleolus and may shear it off.
Fractures of the lateral and medial malleolus are relatively common in soccer and basketball players.
Fibular fractures can be less painful owing to disrupted muscle attachments. Walking is compromised because of the bone’s role in ankle stability.
Describe Calcaneal Fractures
A hard fall on the heel may fracture the calcaneous into several pieces, producing a comminuted fracture.
A calcaneal fracture is usually disabling because it disrupts the subtalar (talcalcaneal joint where the talus articulates with the calcaneus).
Describe how a Fracture of the Talar neck may occur
During severe dorsiflexion of the ankle e.g. When a person is pressing extremely hard on the brake pedal of a vehicle during a head-on collision.
In some cases the body of the talus dislocates posteriorly.
Describe Fractures of the Metatarsals
They occur when a heavy object falls on the foot of when it is run over by a heavy object such as a metal wheel.
Metatarsal fractures are also common in dancers - esp. Female ballet.
Fatigue fractures may result from prolonged walking -repeated stress on the metatarsals.
Describe an avulsion fracture of the tuberosity of the 5th metatarsal
When the foot is suddenly and violently inverted, the tuberosity of the 5th metatarsal may be torn away by the tendon of the fibularis brevis muscle.
It is common in basketball and tennis players.
The injury produces pain and oedema at the base of the 5th metatarsal and may be associated with a severe ankle sprain.
What is the Femoral Sheath?
Funnel shaped fascial tube, formed by an inferior prolongation of transversalis and iliopsoas fascia from the abdomen.
The femoral sheath does not enclose the femoral nerve because it passes through the muscular compartment.
The femoral sheath allows the femoral artery and vein to glide deep to the inguinal ligament during movements of the hip joint.
Describe how to palpate the Femoral Artery
Lay patient in supine position.
The femoral pulse may be palpated midway between the ASIS and the public symphysis: by placing the tip of the little finger on the ASIS and the thumb on the public tubercle, the femoral pulse can be palpated with the midpalm just inferior to the midpoint of the inguinal ligament by pressing firmly.
