Lecture on Anterior Cruciate Ligament (ACL) Injuries and their management by Dr Muhammad Abdelghani

1. Muhammad Abdelghani
ANTERIOR CRUCIATE
LIGAMENT INJURIES

2. Functions of the ACL
 Primary restraint to anterior tibial
displacement, accounting for ~ 85% of the
resistance to anterior drawer test when the
knee is at 90° of flexion and neutral rotation.
 Secondary restraint to tibial rotation and
varus-valgus angulation at full extension.
 Proprioceptive function: evidenced by
presence of mechanoreceptors in the
ligament.

3. Mechanism of injury
 The classic history of an
ACL injury begins with a
noncontact deceleration,
jumping, or cutting action.
 Other mechanisms of injury
include external forces
applied to the knee.

4. Symptoms
 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
(haemarthrosis).

5. Symptoms
There are no pain receptors in the ACL,
therefore pain is not an immediate feature in
isolated ACL tears, but develops with
hemarthrosis.
70% of acute knee hemarthrosis are associated
with ACL tears.
Locking in ACL-deficient knees denotes
associated meniscal tears either from the
original injury, or from repeated giving way .

6. Signs
 Aspiration of the joint reveals hemarthrosis.
In this scenario, the likelihood of an ACL
injury is >70%.
Before the development of a hemarthrosis, the
physical examination is easier and more
revealing; conversely, the examination is more
difficult once pain and muscle guarding appear.

7. Signs
• Lachman test is the most sensitive test for
anterior tibial displacement (95% sensitivity).
• The patient’s knee is flexed 20°; with one hand
grasping the lower thigh and the other the upper
part of the leg, the joint surfaces are shifted
backwards and forwards upon each other.
• If the knee is stable, there should be no gliding.
• The test is difficult if the patient has big thighs (or
the examiner has small hands).

8. Signs
Anterior drawer test:
 Have the patient lie supine on the examination table with
his knees flexed to 90°and his feet flat on the table.
 Position yourself on the edge of the table so that you can
stabilize his foot by sitting on it.
 Cup your hands around the patient’s knee, with your
fingers on the area of insertion of medial & lateral
hamstrings and your thumbs on the medial & lateral joint
lines.
 Draw the tibia toward you; if it slides forward from under
the femur (+ve anterior drawer test), the ACL may be torn.

9. Signs
In both the drawer and Lachman test,
note whether the end-point of
abnormal movement is ‘soft’ or
‘hard’.

10. Signs
• Pivot shift test requires a relaxed patient
and an intact MCL.
• When the result is positive, this test reproduces
the pathological motion in an ACL–deficient knee
and is easier to elicit in a chronic ACL disruption
or in an anesthetized patient with an acute ACL
injury.

11. Radiographic evaluation
Plain x-ray
 Plain radiographs often are
normal; however, a tibial
eminence fracture indicates
an avulsion of the tibial
attachment of ACL.
 Segond fracture (avulsion
fracture of the lateral
capsule), is pathognomonic
of an ACL tear.

12. Radiographic evaluation
MRI
 MRI is the most helpful diagnostic
radiographic technique.

13. Radiographic evaluation
MRI
Primary signs:
 Absent ACL
 Fuzzy ACL
 Bony avulsion

14. Radiographic evaluation
MRI
Secondary signs:
 Those alert attention to ACL tear
Lateral femoral condyle contusion
Anterior translation of the tibia
Sigond fracture
Lateral femoral condyle impression fracture
Contusion of the posteromedial corner of tibia
Sigmoid PCL

15. Lateral femoral condyle
contusion

16. Anterior translation of the tibia

17. Sigond fracture

18. Lateral femoral condyle
impression fracture

19. Contusion of the posteromedial
corner of tibia

20. Sigmoid PCL

21. Natural history
 As a result of abnormal loading and shear
stresses in the ACL–deficient knee, the risk of
late meniscal injury is high and appears to
increase with time from the initial injury.
Most late meniscal tears occur in the medial
meniscus because of its firm attachment to the
capsule.
 Osteochondral damage also influences
prognosis and may be precursors of
osteoarthritis.

22. Treatment
 Treatment options available include
1. Nonoperative management
2. Repair of the ACL (± augmentation)
3. Reconstruction with either autograft or allograft
tissues or synthetics.

23. Non-operative Treatment
 Non-operative treatment is a viable option for a
patient who is willing to make lifestyle changes
and avoid the activities that cause recurrent
instability.
 If a nonoperative approach is chosen, it should
include an aggressive rehabilitation program
and counseling about activity level.

24. Non-operative Treatment
 The use of a functional
knee brace is controversial
and has not been shown to
reduce the incidence of re-
injury significantly if a
patient returns to high-level
sports.

25. Primary repair (±Augmentation)
 Primary repair of the ACL is no longer
practised; reconstruction several weeks after
the acute injury is the preferred choice.
 Acute repair is appropriate when a bony
avulsion occurs with the ACL attached.
 The avulsed bone fragment often can be replaced
and fixed with sutures or passed through
transosseous drill holes or screws placed through
the fragment into the bed.
 ACL avulsions usually occur from the tibial
insertion.

26. Primary repair
Repair of acute tear with avulsed bone
fragment is rarely satisfactory (poor healing
potential, interrupted blood supply, complex
geometry of ACL), therefore, its better to go
directly into primary reconstruction.

27. ACL Reconstruction
• As evidence mounted that primary repair of
midsubstance ACL tears routinely failed,
interest turned to reconstruction of the
ligament.
• The advances made in arthroscopy have led
to the development of arthroscopic
techniques for ACL reconstruction.

28. Proper selection of patients.
Appropriate graft.
Meticulous technique.
Adequate rehabilitation.
Pre-requisites for successful
reconstruction

29. Graft selection
Autograft tissues
 Autograft tissue is used most commonly.
 Advantages:
○ Low risk of adverse inflammatory reaction
○ No risk of disease transmission.
 As a biological graft, an autograft undergoes
revascularization and recollagenization, but
initially a 50% loss of graft strength occurs after
implantation.
○ Therefore, it is desirable to begin with a graft
stronger than the tissue to be replaced.

30. Graft selection
Autograft tissues
The most common current graft choices
are:
 Bone–patellar tendon–bone graft
 Quadrupled hamstring tendon graft.

31. Graft selection
Autograft tissues
Bone–patellar tendon–bone (BPTB) graft
 Taken from the central third of patellar tendon,
with its adjacent patella and tibial bone blocks.

32. Graft selection
Autograft tissues
Hamstring tendon graft
 The use of hamstring tendon graft has increased in
recent years because of its relatively low donor site
morbidity.
• Use of a single strand of the semitendinosus or
gracilis tendon is inadequate because the
semitendinosus tendon has only 75% and the
gracilis tendon only 49% the strength of the ACL.
• Now, surgeons are using either a triple- or
quadruple-stranded semitendinosus graft or a
quadruple-stranded semitendinosus-gracilis tendon
graft with both ends folded in half and combined.

33. Graft selection
Autograft tissues
Quadriceps tendon graft
• The quadriceps tendon graft also has attracted
interest recently.
• It can be harvested with a portion of patellar bone
or entirely as a soft-tissue graft.
• This has become an alternative replacement graft,
especially for revision ACL surgeries and for knees
with multiple ligament injuries

34. Graft selection
Allograft ligament replacement
 Although autogenous tissues currently are
the most commonly used grafts for ACL
reconstruction, these transfers sacrifice a
normal musculotendinous structure in an
already deficient knee, adding to the
functional disturbance.
 Extensive surgical exposure, long tourniquet
times, and prolonged rehabilitation are other
disadvantages of these techniques.

35. Graft selection
Allograft ligament replacement
 Because collagen allografts appear capable
of fulfilling many of the requirements for an
ideal ligament substitute, free allografts for
ligament reconstruction have received
growing attention during the past 15 years.

36. Graft selection
Allograft ligament replacement
 Bone-patellar tendon-bone
 Achilles’ tendon
 Hamstrings
 Quadriceps tendon
 Fascia lata

37. Graft selection
Autograft vs. allograft
 Viral disease transmission (1:1million)
 Graft incorporation & remodeling is faster
with autografts.
 Donor site morbidity with autografts

38. Graft selection
Synthetic materials for ligament reconstruction
 Theoretical advantages compared with
autogenous tissues
 No autogenous tissues are sacrificed
 Avoidance of the increased morbidity associated
with the harvest of autogenous tissues.
 However, many materials have failed,
because they do not have the functional,
physiological, and biomechanical
characteristics of the normal ACL.

39. Graft selection
Synthetic materials for ligament reconstruction
 The artificial ligaments are subjected to
tension, bending, and abrasion against bony
structures and to interfiber friction.
 With time, these stresses can result in ligament
wear, fiber failure, and generation of artificial
ligament wear particles.

40. Graft selection
Synthetic materials for ligament reconstruction
 Artificial ligaments that serve as
augmentation devices to biological grafts
may provide temporary protection for
autogenous tissues, allowing earlier motion
of the joint during the necrosis-
revascularization-remodeling of the graft.
 Ligament loading is shared by the graft tissue
and the artificial device, allowing the autogenous
tissue graft to remodel.

41. Graft placement
 Although both tibial and femoral attachment
sites are important, errors in the femoral site
are more critical because of the proximity to
the center of axis of knee motion.

42. Graft placement
 A femoral tunnel that is too anterior will
result in lengthening of the intraarticular
distance between tunnels with knee flexion.
 The practical implications of this anterior location
are “capturing” of the knee and loss of flexion or
stretching and perhaps clinical failure of the graft
as flexion is achieved.

43. Graft placement
 Posterior placement of the femoral tunnel or placement of
the graft over the top of lateral femoral condyle produces a
graft that is taut in extension but loosens with flexion.
 This location produces an acceptable result, since the
instability from an ACL deficiency occurs near terminal
extension.
○ Clinical examination yields a negative Lachman test result and
a 1+ posterior drawer.
 If this location is chosen, secure the graft with the knee in
extension, since securing the posteriorly located graft with
the knee in flexion may result in loss of extension.
 If an over-the-top position is chosen, the route may be
deeply grooved to approximate the “isometric” femoral
position.

44. Graft placement
 The preferred location has been isometric
placement of the graft that limits changes in graft
length and tension during knee flexion and
extension, which possibly may lead to
overstretching or failure of the graft.
 Now, however, the concept of isometry is
considered oversimplified, since it has been shown
that the normal ACL is not isometric.
 ACL bundles are under variable stress during knee
motion.
○ Anteromedial bundle: higher stress during flexion.
○ Posterolateral bundle: higher stress during extension.

45. Graft placement
 Currently, most surgeons advocate
placement of the graft at the posterior
portion of the ACL tibial insertion site near
the posterolateral bundle position for best
reproduction of the function of the intact
ACL.
 This location also decreases graft
impingement against the roof of the
intercondylar notch with knee extension that
can occur with anterior placement.

46. Graft placement
 Various tools have been developed to assist
the surgeon with placement of the tunnels.
 These include devices in which the key point
of reference is the over-the-top position, the
roof of the intercondylar notch, or the
anterior surface of the PCL.

47. Tibial drill guide for ACL
referencing off PCL. ACL femoral guide.

48. Graft placement
 Earlier techniques often included widening
of the intercondylar notch or notchplasty to
prevent impingement, which is more likely
with anterior placement of the graft.
 The posterior tibial location requires a
minimal notchplasty, if at all, unless the ACL
deficiency is chronic and the intercondylar
notch has become stenotic with
osteophytes.

49. Graft placement
 On occasion, the surgeon encounters a
narrow intercondylar notch, which has been
shown to contribute to ACL injury, and
notchplasty will protect the graft.

50. Graft placement
 A vertical tunnel position high in the intercondylar
notch near the 12-o'clock position has been shown
to provide stability in the anteroposterior plane but
does not restore stability in the rotational direction.
 With this tunnel placement, the Lachman test result
is normal but the pivot shift test result is positive.
 Consequently, surgeons are beginning to place the
femoral tunnel lower on the lateral wall toward the
10:30- or 1:30-o'clock position, which more
accurately reproduces the femoral attachment site
of ACL and provides rotational stability.

51. Graft tension
 The application of tension to the graft at the
time of initial fixation can significantly alter
joint kinematics and in situ forces in the graft
during knee motion.
 Theoretically, the desired tension in the graft
should be sufficient to obliterate the instability
(Lachman test).

52. Graft tension
 Too much tension may:
 “Capture” the joint, resulting in difficulty in
regaining motion, or
 lead to articular degeneration from altered joint
kinematics.

53. Graft fixation
 In the early weeks after surgery, the
weakest links in reconstruction are
the fixation sites, not graft tissue
itself.
 Fixation of replacement grafts can be
classified into direct and indirect
methods.

54. Graft fixation
 Direct fixation devices
include
 Interference screws
○ Bioabsorbable screws
have been introduced as
an alternative to metal
screws
 Staples
 Washers
 Cross pins

55. Graft fixation
 Indirect fixation devices include
 Polyester tape–titanium button
 Suture-post.

56. Two bundles vs one Bundle
 The single-bundle technique traditionally
used recreates the anteromedial bundle and
ignores the posterolateral bundle.
 Considering the two-bundle anatomy of the
native ACL, some investigators are
experimenting with a two-tunnel ACL
reconstruction.
 The technique usually involves making 2 femoral
tunnels with one tibial tunnel, but some are also
using 2 tibial tunnels.

57. Two bundles vs one Bundle
 Disadvantage of 2 Bundles:
Numbers of femoral tunnels
Operative time
Femoral condyle osteonecrosis, chondrolysis
More technically demanding

58. Present recommendationPresent recommendation
for 2 bundlesfor 2 bundles
 Only for hands of the most experienced ACL
surgeon
 Standard for patients who performs
demanding pivoting sports

59. Rehabilitation after ACL Reconstruction
 Goal of rehabilitation after ACL surgery:
to restore normal joint motion and strength
while protecting the ligament graft.

60. Rehabilitation after ACL Reconstruction
 Appropriate rehabilitation is crucial to the
success of ACL reconstruction.
 Some stress to the graft is desirable for
healing and remodeling but should not be
excessive and disruptive.
 Current evidence indicates that intensive
rehabilitation can help prevent early
arthrofibrosis and restore strength and
function earlier.

61. Rehabilitation after ACL Reconstruction
 Perhaps the most important step is the earlyPerhaps the most important step is the early
restoration of full extension.restoration of full extension.
 Knee immobilization in a fully extendedKnee immobilization in a fully extended
brace is started immediately after surgery tobrace is started immediately after surgery to
prevent development of a flexionprevent development of a flexion
contracture.contracture.

62. Rehabilitation after ACL Reconstruction
• After surgery, the thigh muscles atrophyAfter surgery, the thigh muscles atrophy
quickly.quickly.
• Early quadriceps strengthening concentratesEarly quadriceps strengthening concentrates
on quadriceps sets and straight leg raises.on quadriceps sets and straight leg raises.

63. Rehabilitation after ACL Reconstruction
 After isolated ACL reconstruction, partialAfter isolated ACL reconstruction, partial
weight bearing with crutches is allowedweight bearing with crutches is allowed
immediately.immediately.
 A straight-leg brace is worn to support theA straight-leg brace is worn to support the
weakened quadriceps.weakened quadriceps.
 Certain types of concurrent meniscal repairsCertain types of concurrent meniscal repairs
or articular cartilage procedures may dictateor articular cartilage procedures may dictate
a different weight bearing status.a different weight bearing status.
 Crutches usually are discontinued by 3-4Crutches usually are discontinued by 3-4
weeks postoperativelyweeks postoperatively

64. Rehabilitation after ACL Reconstruction
 Proprioceptive training also is instituted inProprioceptive training also is instituted in
the first 2 weeks.the first 2 weeks.
 Return to sports should be delayed for atReturn to sports should be delayed for at
least 6 months after surgery to allowleast 6 months after surgery to allow
maturation of the graftmaturation of the graft

65. Results of ACL Reconstruction
 The results reported with use of patellarThe results reported with use of patellar
tendon and hamstring tendons aretendon and hamstring tendons are
comparablecomparable.

66. Complications of ACL Surgery
Intraoperative
 Patellar fracture
 Inadequate graft length
 Mismatch between bone plug & tunnel sizes
 Graft fracture
 Suture laceration
 Violation of posterior femoral cortex
 Incorrect femoral or tibial tunnel placement

67. Complications of ACL Surgery
Postoperative
Motion (primarily extension) deficit
 This can result from
 Preoperative factors: incl. preoperative effusion,
limited ROM, & concomitant knee ligament injuries.
Those make poor postoperative motion more likely.
 Intraoperative factors: incl. incorrect tunnel position
and inadequate notchplasty, which can result in
overtightening or impingement of the graft, leading to
loss of extension.
 Postoperative factors: incl. prolonged immobilization
and inadequate or inappropriate rehabilitation.

68. Complications of ACL Surgery
Postoperative
Persistent anterior knee pain
 Anterior knee pain probably is the most
common and most persistent complication
after ACL reconstruction.
 Several studies have suggested a
relationship between patellofemoral pain and
persistent flexion contracture or quadriceps
weakness .

69. Failure of ACL Reconstruction
Factors potentially involved in the failure of ACL
reconstruction include
 surgical technique,
 selection of graft material,
 problems with graft incorporation,
 integrity of the secondary restraints,
 condition of articular & meniscal cartilage,
 postoperative rehabilitation,
 motivation and expectations of the patient.

70. Failure of ACL Reconstruction
 Selection of patients and timing of surgery
are crucial aspects of the preoperative plan.

71. Failure of ACL Reconstruction
 Early failure, usually within the first 6
months, most often is the result of
 Technical errors: This is the most avoidable and
most common cause. Errors in surgical technique
can include improper tunnel placement,
inadequate notchplasty, and errors in graft
selection, size, physiometry, or tensioning.
 Incorrect or overly aggressive rehabilitation
 Premature return to sport
 Failure of graft incorporation.

72. Failure of ACL Reconstruction
 Later failure, usually after 1 year, more
typically is caused by recurrent injury.