The investigation shown here is:
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Arthroscopy
Arthrotomography
Arthrography Correct, This is an arthrogram, showing a thickened, discoid, meniscus. The
investigation consists of injecting a small quantity of radiopaque contrast medium which
adheres to the surfaces of the joint and therefore outlines them. If air is also added a double
contrast arthrogram is produced. If, in addition to the dye injection, tomograms are taken this
becomes an arthrotomography. These are not tomographic x-rays.
Myelography
Arthrotomy
The brace worn by this man is used to:
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Treat fractures on the upper tibia
Treat fractures of the patella
Help to build up the quadriceps muscle by a dynamic loading effect
Control knee instability Correct, This is a 'Lennox-Hill' knee brace designed to control
ligamentous, rotary, instability. It does not affect the patella significantly. A fracture of the upper
tibia cannot be controlled by such a device. Either a full leg plaster or a cast brace would be
needed. No form of bracing or immobilisation helps to build up muscle power, except perhaps
through an indirect effect. If people have recurrent instability then the injuries they sustain may
impede their muscle rehabilitation. Menisci do not heal and braces do not help the process.
Allow healing of meniscal tears
Which of the following disorders is most likely to have caused the arthropathy in the knees of this boy?
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Down's syndrome
Osgood-schlatters disorder
Haemophilia Correct, The presence of unobliterated growth plates indicates that this x-ray is of a
child. There is an effusion into the joint, marked irregularity of the articular surfaces and
osteoporosis. This suggests both acute and chronic features simultaneously. Recurrent bleeding
into the joint causes destruction of cartilage, intra-articular adhesions and a growth disturbance.
None of the other disorders causes arthropathy at such an early age. Down's syndrome does
have an incidence of premature degenerative arthropathy in adult life. Neurological disorders can
cause major joint problems, with contractures and pathological dislocations featuring
prominently. Often there is abnormal development of the articulating bone ends. However,
effusions are not a specific feature, nor is irregularity of the articular surfaces.
Hypothyroid infantilism
Spina bifida
The test being shown is used to demonstrate:
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Antero-posterior instability
Antero-posterior laxity Correct, The test is demonstrating laxity of the knee, in the anteroposterior plane, with the knee at right angles. It is the so called 'antero-posterior' draw test.
Instability is the subluxation or dislocation of the knee during use and therefore cannot be
demonstrated passively.
Rotary instability
Rotary laxity
A meniscal tear
This radiograph demonstrates:
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Normal appearance for an oblique radiograph of the knee
Congenital dislocation of patella
Acute traumatic dislocation of the patella Correct, This x-ray demonstrates a lateral dislocation of
the patella assocated with a fragment of bone which is lying on the medial aspect of the patella.
This fragment of bone may have come from the patella itself, or from the lateral femoral condyle
as the patella dislocated. It is therefore an example of an acute traumatic dislocation of the
patella. A bipartite patella is a congenital variation in which the superolateral pole of the patella
appears to be separated from the rest of the patella. The superior pole has a cortical rim which
differentiates it from a fracture.
Habitual patellar dislocation
Bipartite patella
The test that is being performed is an attempt at demonstrating:
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Antero-posterior laxity
Rotary subluxation of the tibia Correct, The test being performed is a test for rotary subluxation
of the tibia. This particular test is known as the pivot shift test. A positive test is an indication of
a deficient anterior cruciate ligament.
A tear of the medial mensicus
Collateral laxity
A femoral nerve stretch test
This slide demonstrates a torn meniscus. Which of the following is NOT a function of the meniscus:
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Aid in joint lubrication
Directly involved in load transmission
Static stabiliser of joint
Production of synovial fluid Correct, The meniscus is an important part of the knee joint. It does
aid in lubrication in that it helps spread synovial fluid around the joint. It is also shown to be
directly involved in load transmission of up to 40-60% of the transmitted pressure of load across
the joint. It is obviously a static stabiliser of the joint and is important in the screw-home
mechanism following full extension of the knee. However, it has no capacity to produce synovial
fluid.
Allow the screw-home mechanism to operate properly
This patient is probably suffering from:
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Rupture of the posterior cruciate Correct, This patient is suffering from rupture of the posterior
cruciate. Bruising and superficial laceration, at the upper end of the tibia, is a classical sign of a
dashboard impaction injury. A patient sitting with his knees bent 90% is involved in a motor
vehicle accident. The dashboard is driven inward and hits the tibia and drives it backwards
rupturing the posterior cruciate. It is an important sign to note, because with the knees swelling,
posterior subluxation of the tibia is often missed. If the cruciate is avulsed with a fragment of
bone it is a relatively simple matter to reattach it with a screw. Function of the knees
subsequently is significantly improved by this manoeuvre.
Avulsion of the patellar tendon
Rupture of the anterior cruciate
A lateral popliteal nerve injury
This deformity is called:
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Flexion deformity
Volkmanns extension contracture
Anterior tibial subluxation
Dislocation of the knee
Genu recurvatum Correct, This knee shows hyperextension. It is not severe enough to qualify for
a subluxation. It is a normal variant. It can be associated with generalised joint laxity. It also
occurs in conditions in which the quadriceps are paralysed. The patients need to stabilise their
knees by forced hyperextension when walking. Genu recurvatum has also been called the
'vulnerable knee' by some authorities because it is thought to predispose to a wide range of
internal derangements, including meniscal tears and osteochondritis dissecans.
Regarding this patients knee, the most appropriate management plan is:
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Elevation in a Thomas splint and analgesia
Plaster cylinder, elevation and analgesia
Knee splint, crutches and send the patient to out-patient physiotherapy
Organise an emergency operating theatre Correct, This radiograph demonstrates a posterior dislocation
of the knee joint. This is a high velocity injury, is associated with gross ligamentous disruption and has a
40% incidence of damage to the poplital artery, which is usually in the form of an intimal tear. The most
appropriate treatment therefore is clinical assessment of the circulation followed by an emergency
reduction of the knee joint and assessment again of the status of the circulation and arteriogram if there
is any doubt as to the adequacy of the arterial supply.
List the patient for your next routine operating session
This radiograph shows which of the following disorders?
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Avulsion of the lateral ligament Correct, There is a bone fragment lying lateral to the joint and
there is a defect in the lateral tibial plateau which is obviously the origin of the fragment. In
addition, the leg is in varus and there is opening of the lateral joint space. This all adds up to an
avulsion fracture of the lateral ligament. The patella is in its normal position and therefore neither
dislocated laterally, nor proximally. Rupture of the anterior cruciate alone does not cause varus
laxity though a combination of collateral ligament tear and cruciate rupture does give rise to
gross laxity. When an anterior cruciate is avulsed it can produce an avulsion fragment but this is
found in the intercondylar notch. Meniscal tears do not show up on plain radiographs, except in
the long term through the secondary effects that are generated.
Avulsion of the infra-patellar ligament
Lateral dislocation of the patella
Rupture of the anterior cruciate
Tearing of the lateral meniscus