Injuries of the Knee

1. Injuries of the Knee
Groups;
1. Fracture of the Femoral condyles
2. Fractures of the Tibial condyles
3. Fracture Patella
4. Injuries to the extensor mechanism
5. Internal Derangements of the knee (I.D.K.)
6. Dislocation of the knee
1. Fracture of the Femoral Condyles
 Can be fractured by
a. direct violence or
b. by sudden vulgus or varus strains on the knee joint.
 Unicondylar
- Involving the medial or lateral condyle only
 Bicondylar
- Extending in to the articular surface in a T or Y shaped manner.
- Hemarthrosis occurs always when the fracture line runs into the articular surface of the knee.
 Treatment: a. Accurate anatomical reduction
b. Early mobilization of the joint
c. Delayed weight bearing
 The displaced fragment is reduced by manipulation.
 If the fragment is large and reduction is not possible,
-Open reduction and internal fixation with dynamic condylar screw system will be necessary.

2. 2. Fracture of the Tibial Condyles
 Unicondylar
 Bicondylar
 Types are: i) Undisplaced crack fracture
ii) Displaced or depressed fractures with or without comminution.
 Mechanism and Clinical features
- A sudden vulgus strain of the knee due to direct injury on the lateral aspect of the knee when the
patient is standing, causes a depressed fracture of the lateral condyle of the tibia.
-Depending on the severity of the valgus violence, the medial collateral ligament and anterior cruciate
ligament may get damaged.
-May also be complicated by a fracture neck of the Fibula and injury to the lateral popliteal nerve.
-The patient presents with a swollen knee and evidence of local contusion on the lateral aspect and
hemarthrosis.
 Treatment: i) Unicondylar Fracture with minimal displacement
-The fragment may be restored by traction and direct compression. The leg is
immobilized in an above knee plaster slab.
ii) Cases with a marked depression of the condyle
-Surgical elevation to restore articular congruity and internal fixation with special T
shaped buttress plate and screws is done.
3. Fracture Patella
 The Biggest sesamoid bone in the body.
 Being incorporated in the quadriceps muscle, it improves the leverage for the action of its tendon by
altering favourably the line of insertion of the tendon.
 Mechanism
a. Muscular Violence
- A sudden contraction of the muscle to prevent a fall causes a transverse fracture of the

3. patella, along with a tear of the medial and lateral retinacula of the quadriceps expansion.
- The fracture may be across the middle of the patella or near the lower pole.
b. Direct Violence
- A direct injury on the patella due to a fall on the knee usually produces a stellate
fracture of the patella with a comminution of the bone.
- The quadriceps expansion is intact.
 Clinical Features
- A history of a feeling of something giving away in the knee, when attempting to avoid a fall
or a fall directly on the knee.
- Swollen knee and evidence of Hemarthrosis in the joint.
- Presence of bruises over the surface indicates direct violence.
- A transverse line of tenderness across the patella on palpating the bone.
- If the fragments are separated,a gap could be felt between the two fragments and there will
be inability to actively extend the knee.
 Radiographs
- Can distinguish which type is it
a. Transverse fracture
b. Fracture of the upper or lower pole
c. Comminuted fracture
 Treatment
i) Transverse Crack Fracture
- The hemarthrosis is aspirated and the knee immobilized in a tube plaster cast for
about 4 weeks.
ii) Transverse fracture with separation
- Always means that the quadriceps expansions are ruptured. Need operative
treatment to repair and restore the quadriceps mechanism.
- Patellar fragments are brought together and sutured with stainless steelwire in a
circumferential or in a figure 8 manner.
- The medial and lateral quadriceps expansions are carefully sutured.
iii) Comminuted fracture
- Here,the fracture with displacement, the articular surface is badly damaged.
Treatment is Patellectomy and repair of quadriceps mechanism.
iv) Fracture lower pole
- The small lower pole fragment is excised and the ligamentum patellae is attached to
the main fragment.

4. 4. Injuries of the Extensor Mechanism
 It consists of the; a. Quadriceps muscle
b. The patella
c. Ligamentum patellae
d. The medial retinacula
e. The lateral retinacula
 Injuries could be;
i) Rupture of the quadriceps muscle
ii) Fracture of the patella
iii) Avulsion of its insertion
 Rupture of the quadriceps muscle occurs due to sudden violent contraction.
 Usually occurs at the upper border of the patella.
 Rupture across the ligamentum patellae has the same effect.
 There is an inability to actively extend the knee.
 In both cases the surgical repair is indicated.
5. Dislocation of the Knee
 Traumatic dislocation of the knee is an uncommon injury.
 It is caused by road traffic accidents and sometimes in sports injury.
 According to the direction of the displacement of the tibia;
a. Anterior
b. Posterior
c. Lateral
d. Medial
6. Traumatic Dislocation of Patella
 A rare condition where the patella gets laterally dislocated due to sudden quadriceps contraction.
 Mostly it is easily reduced.
 It leaves the patient with a sense of knee giving way and an apprehension of instability.
 If patient presents with an acute dislocation of patella, it is reduced under generalanesthesia
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