DISLOCATION OF THE HIP
Dr. Jamal Al-Saidy
M.B.Ch.B. .F.I.C.M.S
Because of the well-contained of the hip joint by bony and soft-tissue anatomy, the
magnitude of force needed to dislocate the hip is so great that the dislocation is
often associated with fractures – either around the joint or elsewhere in the same
limb.
Small fragments of bone are often chipped off, usually from the femoral head or
from the wall of the acetabulum.
If there is a major fragment, the injury is regarded as a Fracture-dislocation.
Hip dislocations are classified according to the direction of the femoral head
displacement: - posterior (commonest) 75%
- anterior
- central
POSTERIOR DISLOCATION
Mechanism of injury:-
In road accident the dashboard striking the knee and so the femur is thrust upwards
and the femoral head is forced out of its socket.
Clinical features:-
In a straightforward case the diagnosis is easy; the leg is short and lies adducted, internally
rotated and slightly flexed. However, if one of the long bones is fractured usually the femur,
the injury can easily be missed as the limb can adopt almost any position. The golden rule is
to x-ray the pelvis. The lower limb should be examined for signs of sciatic nerve injury.
X-ray:-
In the anteroposterior film the femoral head is seen out of its socket and above the
acetabulum. May be associated with fracture and an oblique films are useful in
demonstrating the size of the fragment, so a CT scan is the best way of demonstrating an
acetabular fracture (or any bony fragment).
Classification of hip dislocation (Thompson and Epstein -1951) .
I
Dislocation with no more than minor chip fractures
II Dislocation with single large fragment of posterior acetabular wall
III Dislocation with comminuted fragments of posterior acetabular wall
IV Dislocation with fracture through acetabular floor
V Dislocation with fracture through acetabular floor and femoral head
Treatment
The dislocation must be reduced as soon as possible under general anaesthesia.
In the vast majority of cases this is performed closed, but if this is not achieved after
two or three attempts an open reduction is required.
Manoeuvre:- An assistant steadies the pelvis; the surgeon starts by applying traction in
the line of the femur as it lies (usually in adduction and internal rotation), and then
gradually flexes the patient’s hip and knee to 90 degrees, maintaining traction
throughout. At 90 degrees of hip flexion, traction is steadily increased and sometimes a
little rotation (either internal or external) is required to accomplish reduction.
A satisfying ‘clunk’ terminates the manoeuvre .
Reduction is usually stable in type I injuries, but the hip has been severely injured and
needs to be rested.The simplest way is to apply traction and maintain it for 3 weeks.
Movement and exercises are begun as soon as pain allows; continuous passive
movement machines are helpful.
The terminal ranges of hip movements are avoided to allow healing of the capsule and
ligaments.
The patient is allowed to walk with crutches but without taking weight on the affected
side for at least 3 weeks.
Progression of weight bearing should be graduated and the hip joint monitored by x-
ray.
The indications for surgery: - 1.Unreduced 2.instability 3.retained fragments 4.joint
incongruity 5.type II.
Pipkin classification of femoral head fractures:-
Type I: - The fracture line is inferior to the fovea centrals.
Type II: - The fracture fragment includes the fovea
Type III: - As with types I and II but with an associated femoral neck fracture
Type IV: - Any pattern of femoral head fracture and an acetabular fracture
(coincides with Thompson and Epstein’s type V)
Complications
EARLY
Sciatic nerve injury: The sciatic nerve is damaged in (10–20 %) of cases but it usually
recovers. Nerve function must be tested and documented before reduction is attempted. If,
after reducing the dislocation, a sciatic nerve lesion is diagnosed, the nerve should be
explored to ensure it is not trapped by the reduction manoeuvre.
Vascular injury: Occasionally the superior gluteal artery is torn and bleeding may be
profuse.
Associated fractured femoral shaft: When this occurs at the same time as the hip
dislocation, the dislocation is often missed. It should be a rule that with every femoral shaft
fracture, the buttock and trochanter are palpated, and the hip clearly seen on x-ray. Closed
reduction of the dislocation will be much more difficult. A prompt open reduction of the hip
followed by internal fixation of the shaft fracture should be undertaken.
LATE
Avascular necrosis: (10 %), but if reduction is delayed by more than 12 hours, the figure
rises to over (40%). Changes are seen first on MRI or isotope bone scans. X-ray features
such as increased density of the femoral head may not be seen for at least 6 weeks, and
sometimes very much later (up to 2 years), depending on the rate of bone repair.
Ischaemia is due to interruption of femoral head blood supply (compression, traction and
arterial spasm).
Myositis ossificans: This is an uncommon complication, probably related to the severity of
the injury. During recovery, movements should never be forced. Small areas of ossification
Seen on x-ray usually bear no clinical significance.
Unreduced dislocation: After a few weeks an untreated dislocation can seldom be reduced
by closed manipulation and open reduction is needed. The incidence of stiffness or
avascular necrosis is considerably increased and the patient may later need reconstructive
surgery.
Osteoarthritis: Secondary osteoarthritis is not uncommon and is due to
(1) Cartilage damage at the time of the dislocation.
(2) The presence of retained fragments in the joint.
(3) Ischaemic necrosis of the femoral head.
In young patients treatment presents a difficult problem.
Joint instability: Recurrent dislocation
ANTERIOR DISLOCATION
It is rare
The usual cause is a road accident or air crash
The femoral head will then lie superiorly (type I - pubic) or inferiorly (type II -
obturator).
The leg lies externally rotated, abducted, slightly flexed and not short.
Occasionally the leg is abducted almost to a right angle.
Seen from the side, the anterior bulge of the dislocated head is unmistakable,
especially when the head has moved anteriorly and superiorly.
The prominent head is easy to feel, either anteriorly (superior type) or in the groin
(inferior type).
Hip movements are impossible.
On X-ray: in the anteroposterior view the dislocation is usually
Obvious, but any doubt is resolved by a lateral film.
CENTRAL DISLOCATION
A fall on the side, or a blow over the greater trochanter, may force the
femoral head medially through the floor of the acetabulum.
Although this is called ‘central dislocation’, it is really a fracture of the
acetabulum.
THANK YOU
Dr. Jamal Al-Saidy
M.B.Ch.B. .F.I.C.M.S