Knee injuries

 KNEE INJURIES  Prof.Dr.Sadeq A L-Mukhtar

A- Internal derangement
Traumatic synovitis &hemoarthrosis. Injuries of medial , lateral, &cruciate ligaments. Dislocation of the knee. Injury of the semilunar cartilage.

B- Injuries of the extensor mechanisms of the knee.

- Avulsion of quadriceps. -Fracture patella. - Avultion of ligamentum patellae. - Injuries of tibial tubercle. Dislocation of patella

Traumatic synovitis:

A strain or twist of knee may cause effusion Treatment: -The joint should be bound firmly with crepe bandage with immobilization by a back splint in full extension. -Weight bearing after few days, back slab is discarded after 10 days. - Quadriceps exercises start at once ( after the accident)

Traumatic Hemoarthrosis :

Severe blow or twist may tear the vessels of synovial membrane & cause hemoarthrosis. Also hemorrhage may be associated with fracture of tibial spine, patella or it may complicate tears of peripheral part of semilunar cartilage.

Traumatic Hemoarthrosis

The joint fills rapidly & is swollen within an hour while in traumatic synovitis, it takes 6-8 hours to reach its maximum. The joint contents feel firm & less fluid than in synovitis, pain is greater &there is a febril reaction(37.5 degree cent.).& the joint feels hot.

Treatment:

The joint should be aspirated &firmly bound with crepe bandage & back splint. Quadriceps exercises begin 10-14 days when the danger of hemoarthrosis is over

Ligament injury:

A- Medial ligament: It can be torn anywhere throughout its length but commonly at femoral or tibial attachments. Complete tear always include posteromedial capsule

A- Medial ligament

Mechanism: Abduction strain & by forced external rotation of tibia. Diagnosis ; History, together with swelling, ecchymosis & localized tenderness to the site of injury& pain in valgus stress test

Treatment

This depends on the degree of injury& if associated with capsule injury or not. - Minor injury needs crepe bandage. - A definite ligament tear requires treatment urgently. - If isolated ligament tear ; immobilization in pop in flexion 45 degrees for 8 weeks. - If associated with capsule (posterior) tear surgery is indicated for repair

B- Lateral ligament:

Stability of lateral side of knee is produced by lateral ligament, fascia lata , popliteus muscle & biceps muscle. Lateral structure tear is less common than medial & is caused by varus strain. When damage occur it usually involves not only the ligament & marked injury usually associated with one or both cruciate injury.

Treatment:

- If sprain: Crepe bandage with regular muscle exercise. - If complete tear: Surgical repair

C-Injury of cruciate ligament

1-Anterior cruciate ligament ACL. It is attached to the anterior part of the intercondylar area of the tibia & passed upward & backward to be attached to the lateral femoral condyle.This ligament is taut in full flexion & internal rotation of tibia & damaged by :

Mechanisms:

1-Isolated damage by forced full flexion with internal rotation. 2-Damage associated with rupture medial ligament.

On examination

1-Lachmans sign: if abnormal forward mobility of tibia in 10 degrees of knee flexion the ligament is ruptured & Lachman sign is positive. 2-Anterior draw sign usually combined damage of ACL & medial ligament

2-Posterior cruciate ligament PCL

It is attached to intercondylar surface of tibia behind the intercondylar eminences& passes upward &forward to be attached to the medial condyle of femur

Mechanisms

1-Isolated damage caused by blow on the front of a flexed knee (motorcycle injury). 2-Combined damage occurs with medial or lateral structure.

PCL-Sign:

Abnormal posterior mobility of tibia on femur detected when the knee is examined at flexion.

For both cruciate injury diagnosis

1-Proper history in details. 2-Physical examination. 3-Examination under anaesthesia. 4-X-ray if associated with fracture tibial spine 5-Arthroscopy .



Treatment:ACL&PCL
Partial tear: 1-Aspiration of blood of hemoarthrosis. 2-Ice packing. 3-Back splint & exercise.

ACL-PCL Treatment

Complete tear: 1-If there is avultion of tibial spine need fixation. 2-If torn, direct suturing neither enough nor useful, it needs reconstructive&reinforcement surgery.

D- Anterior Lateral Ligament Injury

ALL –Injury is a very common injury in practice

E- Medial patello-femoral Ligament

Weakness of this ligament lead to patellar dislocation.

Dislocation of the knee:

- Complete rupture of medial, lateral, or cruciate ligaments must be associated with knee joint dislocation. - Less frequently, direct trauma applied to proximal end of tibia. - Indirect twisting or hyperextension strain.

Types of dislocation

Anterior dislocation(common), posterior, lateral, medial, or rotatory dislocation.


Pathology of knee dislocation
In addition to ligament injury, the capsule is torn, the semilunar cartilage may be displaced & chip fracture of tibial spine, tuberosities or femoral condyles may occur

Clinical features: Swelling, bruising, deformity, check neurovascular status.

Treatment: 1- Urgent treatment is needed by MUA( Manipulation under anaesthesia), posterior slab. This conservative method carries a high risk of chronic instability. 2- Surgical treatment: Open reduction & repair of torn ligament fix fractured bones.

Injuries of semilunar cartilages:

Medial Meniscus injury: In association with medial ligament injury, in which abduction strain of the extended knee leads to rupture of MCL, BUT tear of meniscus needs the following:

MEDIAL MENISCUSMechanisms

1- Weight bearing stress of the flexed knee so the joint must be flexed. 2- Body weight must be carried through the at the moment of strain to give the grinding splitting force. 3- The tibia must be rotated laterally on the femur (or the femur rotates on the tibia medially if the tibia is flexed). 4- At the same time abduction to displace the medial meniscus between weight- bearing surfaces(footballer injury).

Types: Medical meniscus

1- Longitudinal split( bucket- handle). 2- Peripheral capsular splitting so that the whole meniscus is displaced.

3- Localized posterior partial tear. 4- Localized split of central free margin

Lateral meniscus injury:

It tends to displace towards the middle of the joint by the opposite strain (internal rotation and adduction of the tibia on femur). The frequency of injuries of the lateral meniscus in 6-8 times less than medial meniscus because: The mechanism of injury is less common. The mobility of medial meniscus is more restricted normally


Clinical features of medial meniscus injury:
1-Bucket-handle: Classical history; there is immediate severe pain over the medial aspect of joint , often feeling of tearing sensation. The joint is locked in semiflexed position and extension of the joint is limited because of elastic resistance. Within few hours the joint swells and after several days the range of movement increases but the terminal degree of extension remains limited. After 3-4 weeks the joint seems to be normal. Recurrent attacks after repeated stresses always occur, after that locking and unlocking without interference. Such history with pain infront of medial ligament gives the diagnosis of medial meniscus tear

2-Posterior horn tear

There is no history of locking and unlocking but the patient feels that the joint about to lock but never does so . The patient reports that the joint feels unstable and gives a history of giving way. The site of pain is vague.

MacMurry sign

is of great value; The surgeon stands on the side of the affected knee, place fingers of one hand over the knee and with the other hand grasps the foot, flex the knee, the foot is then rotated inward and outwards on the femur and is moved sideways from adduction to abduction position and back again , as the torn cartilage gets caught dur[ng this manoeuvre, the patient will experience pain or click may be heard or felt. The angle at which these symptoms occurs indicate the position of the tear, the more posterior the tear, the more flexed position of the knee is when the sign becomes positive..

Apleys grinding test

The patient lies prone on the couch,the surgeon places one hand on the back of the thigh, and with the other hand flexes the knee to 90 angle, the surgeon applies compression along the axis of the tibia while rotating it on the femur( grinding movement). Pain during this movement indicates a meniscal tear, pain on lateral rotation indicates a medial meniscal tear.

Arthroscopy

Done under general or spinal anaesthesia through a stab incision just lateral and medial to the patellar ligament at the level of the knee joint . A good view of interior of the joint is obtained

indications- Arthroscopy

Treatment: MENISCUS INJURY
Notes: 1-Peripheral attachment of a cartilage to the capsule is vascular so that any tear here can unite. 2-A tear of avascular cartilage itself is seldom united. 3-No harm comes from allowing time for the reaction to settle and for diagnosis to be more certain.

MENISCUS INJURYTREATMENT

- So after first injury immobilize the knee with a pressure bandage or in a plaster cylinder for 3-4 weeks. Healing may occur in peripheral type or if the cause of the condition is traumatic synovitis. - Operative treatment is advised only when recurrent lovking occur and the diagnosis is proved. Notes: If torn meniscus is removed the recurrent trauma of repeated displacement lead ultimately to osteoarthritis of the joint.

Fracture Patella

Fracture of patella is not uncommon and often result in patellofemoral arthritis. arthralgia - quadriceps weakness- restricted knee motion and degenerative changes

Mechanism:Fracture patella

1-Direct force may lead to fracture but the extensor expansion is preserved so usually the fragment are not widely displaced. Here, abrasion or lacerations of skin may be seen. 2-Indirct force: Unexpected fall can generate violent contraction of quadriceps muscles and can lead to fracture or contraction of quadriceps against resistance leads to transverse fracture with displacement due to rupture of extensor expansion.

Clinical features: Fracture patella

Swollen knee, tender, haemoarthrosis, sometimes gap can be felt between the bony fragments. Treatment: 1-Crack: aspiration of haemoarthrosis, POP cylinder then physiotherapy. 2-Comminuted fracture; Young adult ;pop for 4-6 weeks Elderly; patellectomy. 3-Transverse fracture; Tension band wiring, pop cylinder followed by physiotherapy.

Dislocation of patella:

The relation between the axes of quadriceps muscle and ligamentum patellae predisposes to outward displacement of patella. The muscle passes downwards inwards but the ligament lies vertically and the patella is situated at the angle between the two. When the muscle contracts it tends to form a straight line between origin and insertion so that the angle is obliterated and the patella is displaced outwards.This normally corrected by lower most fibers of vastus medialis muscle as it pulls the patella inwards.

Predisposing factors Dislocation of patella

1-Laxity of capsule 50%. 2-Poor development of lateral femoral condyle so that the patellar groove is shallow. 3-Lateral rotation. deformity of tibia

Mechanism: Dislocation of patella

Direct lateral violence is applied on the patella when the knee is flexed and relaxed. Types: 1-Temporary: The patella over-rides the lateral femoral condyle

Mechanism

2-Permanent: When the patella rotates through 90 degrees and its articular surfaces lies in contact with the outer side of the lateral femoral condyle. The dislocation is often reduced spontaneously As the joint is extended.

On examination :Dislocation of patella

History of trauma, swollen knee and haemoarthrosis. In most cases the patient reaches the hospital after spontaneous reduction and we find only tenderness over the medial patellar margin.

Treatment: Dislocation of patella

1-If the patient reaches the hospital with dislocation, under general anaesthesia, the patella is forced medially with gradual extension of the knee. 2- Sometimes aspiration of haemoarthrosis is required. 3-Then the knee is immobilized by posterior slab for 3-4 weeks followed by physiotherapy.

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