Dislocation of the hip
It is of three main types : 1- posterior type . 2- anterior type . 3- central type . four out of five traumatic dislocation of the hip is of posterior type .Posterior hip dislocation
It is the commonest type of hip dislocation Mechanism of injury :It is occur in road traffic accident when some one seated in truck or car is thrown foreword striking the knee against the dashboard . The femur is thrust backward and the femoral head is forced out of its socket . Often a piece of bone of the acetabulum is sheared off making it a fracture – dislocationDashboard injury
Clinically : On examination the leg is short lies adducted , internally rotated and slightly flexed . This injury is easily to be missed when associated with fracture femur . The lower limb should be examined for sciatic nerve injury . X-ray : a-p view : the femoral head is seen out of its socket and above the acetabulum . There may be associated fracture in the femoral head or in the rim of the acetabulum .Treatment : Dislocation must be reduced as soon as possible under general anesthesia . The assistant steadies the pelvis , the surgeon start by applying traction in the line of the femur 90% flexion of both hip and knee , then a clunk terminate the maneuver . Followed by x-ray checking ; then put the injured limb in rest by applying skin or more beneficial skeletal traction for 3-6 weeks , the patient is allowed to walk by crutches ; if there is fracture rim of the acetabulum and the piece is large the internal fixation is mandatory .
Reduction of posterior dislocation of the hip
Complication : Early : 1- sciatic nerve injury : it is occur in 10-20 % of the cases but fortunately it is usually recovered , if not , then nerve exploration . 2- vascular injury : superior gluteal artery . 3- associated fractures : acetabular , femoral head , femoral neck and femoral shaft and here the dislocation may be missed .
Late : 1- avascular necrosis of the femoral head : in any dislocation the vascularity is impaired about10% , if the reduction is delayed it may reached up to 40% . Avascular necrosis appear in the x-ray as an increase in density of the femoral head , but it is not seen before 6 weeks and some time up to 2 years . In early weeks , bone scan and MRI will be helpful in the diagnosis of ischemia .
Treatment of avascular necrosis : younger patient treated either by femoral head replacement or realignment osteotomy if it is partial or by arthrodesis of the hip . In older patient with acetabular changes then total hip replacement . 2- myositis ossificans . 3- unreduced dislocation : if after few weeks the dislocation is missed and not reduced , open reduction is mandatory 4- secondary osteoarthritis : and this due to : a- cartilage damage . B- retained fragment . C- ischaemic necrosis.
Anterior dislocation of the hip
it is rare . Clinically : the leg is externally rotated , abducted and slightly flexed , not short . some time the lower limb is abducted to right angle . X-ray : a-p view , the dislocation is obvious , any doubt is resolved by lateral view .Central dislocation of the hip
fall on the side or blow over the greater trochanter may force the femoral head medially through the floor of the acetabulum . Although it is called central dislocation of the hip , it is really a fracture of the floor of the acetabulum.Fractures of the femoral neck
Neck of the femur is a commonest site of fracture in elderly . Risk factors : 1- osteoporosis . 2- osteomalascia . 3- diabetes mellitus . 4- stroke (disuse) . 5- weak muscles and poor balance . 6- alcoholism . 7- debilitating diseases .Generally fracture neck femur is classified in to :A – intra capsular fracture neck of femur .B - extra capsular fracture neck of femur .A- intracapsular fracture neck of femur :Mechanism of injury :This fracture usually result from a fall directly on to the greater trochanter . In very osteoporotic patient less forced is required . Some time no more than catching a toe in the carpet and twisting the hip into external rotation .In young people the cause is mainly car accident or fall from height .
Classification : the most useful classification intracapsular fracture neck of femur is that of (Garden classification) which based on the degree of displacement . Stage one : is incomplete impacted fracture . Stage two : is complete undisplaced fracture . Stage three : complete fracture with moderate displacement . Stage four : is severely displaced fracture .
The blood supply of the head of the femur : 1- intramedullary (metaphyseal) vessels in the femoral neck. 2- capsular vessels ; in the capsule of the joint . 3- the vessel in the ligamentum teres . The first two vessels are interrupted by the fracture and the third is present in only 20% of the population.
Blood supply of the femoral head
Intracapsular fracture neck of femurClinical feature : History of fall followed by pain in the hip . If the fracture is displaced , the limb will be externally rotated ,and short . Treatment : The first measure is to apply skin traction to splint the fracture and to control the pain , and give analgesic for pain relieve . Operative treatment is always mandatory . Displaced fracture will not unite without internal fixation . Old people should be got up and active without delay to avoid pulmonary complication ,bed sore ,DVT and other bed ridden complications .
Limb short and externaly rotated in fracture neck of femur
Impacted fracture can be treated conservatively with traction to avoid displacement . But internal fixation is safer .The operation should be done as early as possible to avoid risk of complications .The principle is perfect reduction , secure rigid fixation and early mobilization .the fixation should be done by internal fixators like compression screws , plate and screws , dynamic hip screw ……etc .In patient above 60 with displaced fracture , partial hip replacement is indicated ; total hip replacement is indicated if the treatment is delayed or in metastatic disease .Dynamic hip screw
Complications : General complication : Most of these patients are elderly , and they are prone to general complication such as : 1- deep vein thrombosis . 2- pulmonary embolism . 3- pneumonia . 4- bed sore .Local complication : 1- a vascular necrosis of the femoral head . It is occur in 30% of the displaced fracture , and in 10% of the undisplaced fracture . There is no way to diagnose avascular necrosis of femoral head immediately , but few weeks later we can diagnose it by bone scan MRI and later by x-ray . X-ray changes may not show it self for months or even years . whether the fracture unite or not there will be collapse of the femoral head and this will lead to pain , shortening of the limb and progressive loss of function .