This document discusses acute knee ligament injuries, including their common causes, mechanisms of injury, classification, and management. The most common injury mechanism is abduction, flexion, and internal rotation of the femur, which typically injures the medial ligaments. Injuries are classified by degree of ligament disruption. Treatment options include nonoperative management, repair, and reconstruction, depending on the specific ligaments injured and degree of instability. Post-operative rehabilitation focuses on regaining range of motion and strengthening.

1. ACUTE KNEE LIGAMENT INJURIES
Dr Milind Merchant

2. INTRODUCTION
• Knee ligaments often are injured in athletic activities,
especially those involving contact, such as football, Skiing, ice
hockey, gymnastics which produce enough sudden stress to
disrupt knee ligaments.
• Motor vehicle accidents, especially those involving
motorcycles, are common causes of knee ligament
disruptions.
• Ligament disruption can occur without a fall or direct contact
when sudden, severe loading or tension is placed on the
ligaments, such as when a running athlete plants a foot to
suddenly decelerate or change directions.

3. MECHANISM -
• four mechanisms capable of disrupting the
ligamentous structures about the knee:
• (1) abduction, flexion, and internal rotation of the
femur on the tibia,
• (2) adduction, flexion, and external rotation of the
femur on the tibia,
• (3) hyperextension,
• (4) anteroposterior displacement

4. • most common mechanism is abduction, flexion, and
internal rotation of the femur on the tibia when the
weight-bearing leg of an athlete is struck from the lateral
aspect by an opponent.
• This mechanism results in an abduction and flexion force
on the knee, and the femur is rotated internally by the
shift of the body weight on the fixed tibia.
• This mechanism produces injury on the medial side of the
knee, the severity of which depends on the magnitude
and dissipation of the applied force.
• When abduction, flexion, and internal rotation of the
femur on the tibia occur, the medial supporting structures
—the tibial collateral ligament and the medial capsular
ligament—are the initial structures injured. If the force is
of sufficient magnitude, the anterior cruciate ligament
also can be torn.

5. • The medial meniscus may be trapped
between the condyles of the femur and the
tibia, and it may be torn at its periphery as the
medial structures tear, thus producing "the
unhappy triad" of O'Donoghue .

6. • Mechanisms reported as possibly able to
disrupt the anterior cruciate ligament with
minimal injury of other supporting
structures are hyperextension, marked
internal rotation of the tibia on the femur,
and pure deceleration.
• Isolated posterior cruciate disruption can
result from a direct blow to the front of the
tibia with the knee flexed.

7. CLASSIFICATION -
• Sprains are classified into three degrees of
severity.
• A first-degree sprain of a ligament is defined as a
tear of a minimal number of fibers of the ligament
with localized tenderness but no instability;
• a second-degree sprain as a disruption of more
ligamentous fibers with more loss of function and
more joint reaction with mild to moderate
instability;
• third-degree sprain as a complete disruption of
the ligament with resultant marked instability.
• These often are classified as mild, moderate, and
severe for first-, second-, and third-degree
sprains, respectively.

8. • Third-degree sprains, that is, those
demonstrating marked instability, can be
further graded depending on the degree of
instability demonstrated during stress
testing.
• With 1+ instability the joint surfaces
separate 5 mm or less;
• with 2+ instability they separate 5 to 10
mm; and
• with 3+ instability they separate 10 mm or
more

9. ACUTE ACL INJURY -
• The exact incidence of anterior cruciate ligament injuries
is unknown;
• The classic history of an anterior cruciate ligament injury
begins with a noncontact deceleration, jumping, or
cutting action. Obviously, other mechanisms of injury
include external forces applied to the knee.
• The patient often describes the knee as having been
hyperextended or popping out of joint and then reducing.
A pop is frequently heard or felt.
• The patient usually has fallen to the ground and is not
immediately able to get up. Resumption of activity usually
is not possible, and walking is often difficult. Within a few
hours, the knee swells, and aspiration of the joint reveals
hemarthrosis. In this scenario, the likelihood of an
anterior cruciate ligament injury is greater than 70%.

10. Investigations
• Plain Xrays often are normal; however, a tibial eminence
fracture indicates an avulsion of the tibial attachment of
the anterior cruciate ligament.
• The Segond fracture, or avulsion fracture of the lateral
capsule, is pathognomonic of an anterior cruciate
ligament tear .
• MRI - diagnostic technique. The reported accuracy for
detecting tears of the anterior cruciate ligament has
ranged from 70% to 100%. Because the anterior cruciate
ligament crosses the knee joint at a slightly oblique angle,
the complete ligament rarely is captured in its entirety by
a single MRI scan in the true sagittal plane.
• More recent investigators reported that the accuracy for
MRI in evaluating injuries to the anterior cruciate ligament
approaches 95% to 100%. With the availability and
accuracy of MRI.

12. Management-
• The treatment options available include
nonoperative management,
• repair of the anterior cruciate ligament, either
isolated or with augmentation,
• reconstruction with either autograft or allograft
tissues or synthetics .

13. Repair of Bony Tibial Avulsions of ACL
• AFTERTREATMENT.
• At 3 weeks, flexion from 0
to 90 degrees is allowed in
the brace, and isometric
quadriceps and hamstring
exercises are begun.
• Crutches are discontinued
at 6 weeks, and full active
and passive range of
motion should be obtained
by 8 weeks.
• Progressive resistance
exercises are continued for
at least 3 months

14. ACUTE PCL INJURY -
• As with the anterior cruciate ligament, "isolated" tears of the
posterior cruciate ligament are relatively rare; as a rule, ruptures of
this ligament are associated with medial or lateral compartment
disruptions, especially the latter.
• Clinically, however, isolated tears of the posterior cruciate ligament
can be caused by a fall on the flexed knee or striking of the flexed
tibia on the dashboard in a motor vehicle accident.
• Such a mechanism (the upper tibia driven posteriorly with the knee
flexed) may produce posterior cruciate ligament disruption as the
only clinically detectable instability.
• These "isolated" posterior cruciate ligament disruptions can be
difficult to diagnose acutely unless a fragment of bone is avulsed
from the posterior tibial insertion and is noted on roentgenograms .

15. Rx -
• The commonly quoted criteria for nonoperative
treatment include
• (1) a posterior drawer of less than 10 mm with
the tibia in neutral rotation (posterior drawer
excursion decreases with internal rotation of the
tibia on the femur),
• (2) less than 5 degrees of abnormal rotary laxity
(specifically, abnormal external rotation of the
tibia with the knee flexed 30 degrees, indicating
posterolateral instability), and
• (3) no significant valgus-varus abnormal laxity (no
associated significant ligamentous injury).

18. MCL REPAIR -
• If surgical repair of the torn medial support of the knee is
planned, arthroscopic examination of the knee to rule out
other intraarticular pathological conditions is done before
open surgical exploration .
• The surgeon must be aware of the capsular disruption
that may allow significant extravasation of irrigation fluid
during arthroscopy of an acutely unstable knee.
• Ordinarily a synovial or capsular rent will seal sufficiently
to prevent dangerous extravasation of irrigation fluid if
the arthroscopic examination is delayed for 5 to 7 days
and the surgeon is skilled and expedites the examination.
A lengthy examination of an acutely injured knee is not
justified, and massive extravasation of irrigation fluid may
occur in such instances.

19. MCL REPAIR -

20. POPLITEUS REPAIR -

21. LCL REPAIR -

22. AFTER Rx -
• The repair can be protected by applying a
long leg cast with the knee flexed 30 degrees,
but we prefer to allow immediate protected
motion by placing the knee in a controlled
motion brace, which initially is locked in full
extension.
• The leg is removed from the brace several
times each day for range-of-motion exercises.