Knee injuries by Dr.Karen D’sa .
Introduction to Knee injuries.
 Biomechanics of knee.
 Anatomy of Meniscus.
 Anatomy of Cruciate ligaments.
 Function of meniscus.
 Tests for ACL , PCL.

Knee injuries

Complex joint :
ginglymus
trochoid

Prone to injuries

Incidence has
increased
…where?
Biomechanics
SCREWING HOME MOVEMENT

Differences in radii for femoral condyles
 lateral condyle longer and flatter than the medial
side.

The articular surface of the medial condyle is
prolonged anteriorly, and as the knee comes into
the fully extended position, the femur internally
rotates during last 10 – 20 deg extension.

Greatly influenced by the Posterior Cruciate
Ligament.
Biomechanics

Locking occurs by internal rotation of femur
on fixed tibia or external rotation of tibia on
fixed femur, both occurring at terminal part of
knee extension.

Unlocking occurs in early part of flexion

Popliteus is unlocking muscle

Locking by ITB and Biceps femoris
Biomechanics
Normal range of movements :

Flexion 0-140 degrees

Hyperextension 5-10 degrees

Rotations 5-25 degrees

Mechanism of injury

1.Direct valgus force.
2.Rotational or twisting force:

abd+FIR

Meniscal injuries

Anatomy:
 Crescent shaped
 Composed of dense,
tightly woven collagen
fibres
 Predominantly
circumferential fibres
and a few radial and
perforating fibres
Anatomy

Medial meniscus:
 Semicircular
 Attached to MCL
 Less mobile
 More prone to injury

Lateral meniscus:
 Circular
 More mobile
 Less prone to injury
Blood supply to Meniscus
•
Blood supply:
lateral, medial and
middle genicular vessels
• Only the periphery is
vascularized
• Three zones
1.
2.
3.
Red – red
Red – White
White – white
Functions of the Meniscus
1. Improves articular
2.
3.
4.
5.
congruency
Increases stability
Distributes load
Acts as a shock
absorber
Controls the
complex rolling and
gliding actions of
knee joint
6. Prevents impingement of synovial
membrane and capsule
7. Helps in the locking mechanism
8. Assists in nutrition of the articular cartilage
Mechanism of Injury

Mechanism of injury:
1.
Traumatic:
○
○
○
2.
Young
Rotational grinding
force
Flexed +twisting
strain
Degenerative:
○
○
○
Middle aged
Fibrosed, less
mobile
Arthritis,
chondrocalcinosis
Meniscal tears

Types of tears:
 Longitudinal tears
(vertical splits) 75%
 Bucket handle tear
 Horizontal tears
(degenerative)
flap tear
 Radial tears
Longitudinal tears are
most common
Mechanism of meniscal tear

Meniscus is torn by a rotational force incurred
while the joint is partially flexed

If the longitudinal tear extends anteriorly :
“BUCKET HANDLE TEAR”

Clinical Features of Meniscal
Injury
1. History of trauma- twisting injury to the
2.
3.
4.
5.
knee
Pain – mechanical pain
Swelling – recurrent
Locking or giving way episodes
Clicks
Diagnostic tests
1.
2.
3.
4.
Joint line
tenderness
McMurray’s test
Apley’s grinding test
Painful restriction of
terminal extension
Differential Diagnosis





Loose bodies
Recurrent
dislocation of
patella
MCL or ACL tear
Fracture of tibial
spine
“FALSE LOCKING”
Investigations
1.
2.
3.
X-rays – usually
normal
MRI – most reliable
method
Arthroscopy –
advantage of being
a therapeutic
procedure
Management of Meniscal injuries
 Conservative treatment:
○ If joint is not locked and no added ACL injury
○ Brace for 3-6 weeks-small tears
○ Non-weight bearing, physio
Operative:
1. If joint cannot be unlocked
2. Recurrent symptoms
Management of Meniscal injuries
“ARTHROSCOPIC
REPAIR”
Indications:
1.Acute tears
2. Longitudinal tears in peripheral
red-red zone
3.Unstable more than 3 mm of
excursion




Technique :
1. Inside to outside repair
2. Outside to inside repair
3. All inside technique
Cruciate ligament injuries

Anatomy:
 Intracapsular but




extrasynovial
Layered structure,
distinct bundles
Highly organized
collagen
Blood supply –middle
and inferior genicular
arteries
Nerve supply – tibial
nerve
Anatomy

ACL –
 Medial surface of lateral
femoral condyle and anterior
part of tibial plateau
 Runs in postero-superior to
antero-inferior direction

PCL –
 Lateral surface of medial
femoral condyle to posterior
aspect of tibial plateau
 Runs in antero-superior to
postero-inferior direction
Biomechanics of ACL
1. Primarily antero-posterior stability
○ ACL prevents anterior translation of tibia on
femur
○ PCL prevents posterior translation of tibia
on femur
2. Secondary restraint to varus-valgus and
rotational stresses
3. Proprioception
Mechanism of injury
1. Abduction, flexion
and internal rotation
○
○
○
Commonest
mechanism
Football tackle
Unhappy triad
2. Antero-posterior
displacement
○
Dashboard injury
Clinical Features of ACL injury
 Symptoms:
○ History of twisting injury
○ “Popping out of the joint ”
○ Pain
○ Immediate swelling –
hemarthrosis
○ Inability to bear weight /
continue playing
○ Giving way
○ Difficulty in stair climbing and
walking on uneven surfaces
Diagnostic tests

Signs:
 Anterior drawer test
 Lachman test
 Pivot shift test
PCL

Signs:
 Posterior drawer test
 Posterior sag sign
 “DOOR STOP
PHENOMENON”
Investigations
 X-rays: “SEGOND”
fracture
 MRI –most reliable
 Arthroscopy
Treatment of ACL injury
 Conservative:





Indications :
1. Age >40 years
2.Instability
3.Associated meniscal injury
4.Lifestyle.
ACL

Operative treatment:

Arthroscopic
reconstruction –
 Autologous graft
 Patellar tendon or
hamstring tendons
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