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Flashcards in Knee and sport Deck (37):

Mechanism of ACL injury

non-contact pivoting injury


Common associated injury in ACL tear

Lateral meniscus injured in 54%


Concomitant pathology in Chronic ACL tear (3)

1. OCD
2. Complex meniscal tear
3. Arthritis (controversial)


1. gender predisposition

2. Reason / details

1. F:M = 4.5:1

2.a. landing biomechanics and neuromuscular activation patterns (quadriceps dominant) play the biggest role

- females get ACL injury at younger age
- females get more ACL injuries on the supporting leg / males get more ACL injuries on the kicking leg


ACL Function
i. _______% responsible for prevention Ant. Translation of Tibia

ii. Secondary restraint to what other tibial motion

i. 85%

ii. Tibial rotation and varus/valgus rotation


ACL Anatomy
i. Length

ii. Width

i. 32mm

ii. 7-12mm


ACL Anatomy
Anteromedial bundle is:

i.more or less isometric?

ii. Tight throughout ROM but tightest in ____________

iii. Primarily stops _________
and is tested best by ________ test

i. More

ii. Flexion

iii. Primarily stops ANT. TIBIAL TRANSLATION and is tested by ANTERIOR DRAW TEST


ACL Anatomy:
Posterolateral bundle is:

i. more OR less isometric

ii. Tightest in _________ and slack in ___________

iii. Primarily responsible for ___________ stability (test:

i. LESS (ie. greater length changes with ROM)

ii. Tightest in EXTENSION and slack in MID-FLEXION

iii. primarily responsible for ROTATIONAL STABILITY (test: PIVOT SHIFT)


ACL Anatomy

i. Femoral attachment - anterior border ?

ii. Femoral attachment: Bony landmark separating AM/PL bundle

iii. The tibial attachment is anterior tibia between the __(a)___ just medial to anterior horn of __(b)___ meniscus

i. Lateral intercondylar ridge

ii. Bifurcate ridge




ACL Anatomy:
i. Blood supply

ii. Innervation

iii. Composition = 90% Type (a) and 10% Type (b) collagen

iv. Strength: ____ N (anterior)

i. middle geniculate artery

ii. posterior articular nerve (branch of tibial)

iii. a=type 1 ; b=type 3

iv. 2200


ACL Clinical:
i. Most sensitive test (physical exam) for ACL rupture ?

ii. Grading test
(a) A = ____ endpoint / B= ____ endpoint
(b) Grade 1: _____mm translation / Grade 2 ____mm / Grade 3 _____mm

iii. False test may occur with ________

i. Lachman's

ii. (a) A= firm ; B= no

(b) Grd 1 = 3-5mm / Grd 2 =5-10mm / Grd 3 = >10mm

iii. PCL tear


ACL Clinical
i. What is pivot shift ?

ii. Must have an intact ______ for this to work

i. Knee moved from ext to flex and joint reduces/"clunks" at 20-30° of flexion

ii. MCL


Imaging ACL: Segond fracture
i. What is a Segond fracture

ii. Segond represents a bony avulsion of the _____

iii. Assoc. with ACL in ____% of cases

i. Avulsion of prox lateral tibia

ii. Anterolateral ligament

iii. 75-100%


Imaging ACL: XRay

i. Apart from Segond # what other XR sign is assoc with ACL tear ?

ii. What causes this sign?

i. Deep sulcus (terminalis) sign
OR "sulcus sign"

ii. Depression on the lateral femoral condyle at the terminal sulcus


Imaging ACL: MRI

i. sagittal view findings of ACL
(a) ___________

(b) ___________

(c) ___________

(a) discontinuity of fibres on T2

(b) abnormal orientation (flat compared to blumensaat line /intercondylar roof)
** can occur in chronic cases - ACL stick to PCL

(c) no ACL seen


imaging ACL: mri
i. bone bruising seen in > __%

ii. most common locations
(a) , (b) , (c)

i. >50%

(a) middle third of lfc (sulcus terminalis)

(b) Post. third of LTP

(c) Subchondral change persisting years in some cases


imaging : mri
finding on coronal view:
i.what is the "empty notch sign"?

Sign of ACL rupture -> caused by fluid against the lateral wall


Treatment ACL: Non-op

i. non-op treatment: indications

ii. factors linked to cartilage/meniscal damage in ACL deficiency (3)

i. low demand and decreased laxity

(1) Loss meniscal integrity

(2) Frequency of "buckling" episodes/instability

(3) Level I/II activity (jumping, cutting, side-to-side sport, manual labour)


Treatment ACL: Operative
i. indications (4)

- younger, more active

- children (strongly consider operative as activity limitation is not realistic)

- older active patients (age >40 is not a contraindication if high demand athlete)

- prior ACL reconstruction failure


ACL: Treating assoc. injury

i. MCL injury: How to Rx?

ii. Meniscal tear: How to Rx?

iii. posterolateral corner injury: How to Rx?

i. allow MCL to heal (varus/valgus stability) and then perform ACL

*** Note: varus/valgus instability can jeopardize graft***

ii. meniscal repair at the same time as ACL
*** Note: increased meniscal healing rate when repaired at the same time as ACL

iii. recon PLC at the same time as ACL or as 1st stage of 2 stage recon


ACL: Return to sport

i. What determines time to return to sport ? (3)

1) Psychological

2) Functional

3) Demographics


ACL Repair: what is BEAR procedure ?

Arthroscopic Bridge-Enhanced ACL Repair (BEAR) (note: trial with a bridging scaffold is ongoing)

**** addit: repair traditionally high failure rate


ACL Recon Technique: Femoral tunnel

i. Correct placement
(a) Sagittal placement

(b) Coronal placement

i(a). 1-2 mm rim of bone between the tunnel and posterior cortex of the femur

i(b). Lateral wall @ 9-10 o'clock position to create a more horizontal graft


ACL Recon Technique: Tibial tunnel

i. Correct placement
(a) Sagittal placement

(b) Coronal placement

i (a).
center of tunnel should be 10-11mm in front of the anterior border of PCL insertion

i (b). tunnel trajectory of < 75° from horizontal

*** obtain by moving tibial starting point halfway between tibial tubercle and a posterior medial edge of the tibia.


ACL Recon Technique: Graft Placement

i. Graft preconditioning can reduce ____ by up to 50%

ii. Graft tension

iii. position of knee during graft tension ?

i. stress relaxation up to 50%

ii. controversial
- 20N or 40N had no clinical outcome effects in a level 1 study
- DONT overtension

iii. 20-30° of flexion


Principles for revision ACL

i. technique (4)

ii. post-op (1)

i. (1) high-strength grafts (quads , hamstring, allograft)
(2) use dual fixation
(3) bone grafting (tunnel dilation, poor bone stock, staged)
(4) re-harvesting BTB is contraindicated

ii. conservative rehab


ACL Technique: Graft Selection

i. Bone-Tendon-Bone
(a) Pros (4)
(b) Cons (1)
(c) Complications (2)

ia. (1) longest data/Hx "gold-standard"
(2) bone-to-bone healing
(3) can rigidly fix joint line (screws)
(4) Strong @ 2600N

ib. (1) High incidence ant knee pain (up to 10-30%)

ic. (1) patella # (during rehab)
(2) rerupture (assoc w <20yo & graft size <8mm)


ACL Technique: Graft Selection

i. Quadruple hamstring autograft
(a) Pros (4)
(b) Cons (3)
(c) Complications (2)

ia. (1) less perioop pain; (2) less ant knee pain; (3) small incision (4) load to failure 4000N

(1) fixation strength may be < than BTB; (2) decreased peak flexion strength at 3 years vs. BTB; (3) concern re: hamstring weakness in female athletes --> increased risk of re-rupture

ic. (1) "windshield wiper" effect (ie. suspensory fix. causes tunnel abrasion & expansion with rpt knee ROM)
(2) residual hamstring weakness


ACL Allograft
i. pros

ii. cons

iii. processing
(a) Problem with processing allograft with supercritical CO2 and/or radition?

(b) Deep freezing and 4% Chlorhex cause __(1)__ but dont effect __(2)___

i. revision / no donor site morbidity

ii. (1) disease transmission (HIV <1.1 million / Hep even less); (2) slow integration; (3) re-rupture 4.3X higher in pt <20

iiia. both pre-Rx cause decreased strucutral and mech properties

iiib. (1) cell death; (2) strucutral and mech properties


ACL: Paediatric Considerations

Treatment in open physis
i. Non-op
(a) indications

ii. Operative
(a) indications

ia. (1) compliant, low demand pt with no additional intra-articular pathologies
(2) partial ACL tear (60% of adolescents) with near normal Lachman and pivot shift

iia. (1) complete tear


ACL: Paediatric Considerations

i. Technique:
(a) intra-articular (3)

(b) Combined intra-/Extra- articular - what age ?

(c) Adult type - what age ?

ia. (1) Physis sparing (intra-epiphyseal);
(2) Transphyseal (M<13-16; F<12-14);
(3) Partial transphyseal

ib. M<12; F <11

ic. M>16 ; F >14


ACL: Paediatric Considerations

i. (a) what graft? (b) why?

i. (a) soft tissue; (b) rarely cause growth arrest



ACL: Paediatric Considerations

i. Factors found to increase physeal injury include:

a) Tunnel diameter >____mm
b) ________ tunnel position
c) with OR without interference screw ?
d) ________ reaming
e) Others (3)

a) >12mm
(note: 8mm=3% of physis cross-sectional area / 12mm >7-9%)

b) Oblique

c) with = higher risk

d) high speed

e) (1) suturing close to tib tub; (2) lateral extra-art tenodesis; (3) dissection near ring of LaCroix


ACL Rehabilitation
i. immediate
a) Ice Y/N ?
b) Weight-bearing - Y/N?
c) Early passive full extension esp in what group?

a) Yes
b) Yes. Evidence for reductino in PFJ pain
c) Especially in assoc MCL injury OR patella dislocation


ACL Rehabilitation
i. Early
a) Eccentric strength in first __(1)__ weeks has shown __(2)__

b) ________ hamstrings/quads contraction

c) active knee motion ____ to _____ degrees

d) emphasize ______ chain exercise

e) Avoid ? (2)

ia. (1) 3 weeks; (2) incr quads volume and strength

ib. Isometric

ic. 35-90 degrees

id. closed chain (exs with foot planted)

ie. (1) Isokinetic quad strength (15-30°)
(2) open chain quad strength


ACL Surgery: Complications

Tunnel Malposition
i. Causes failure in ____%

ii. Femoral
(a) coronal
(b) Sagital

iii. Tibial
(a) coronal
(b) Sagital

i. 70% (most common cause of failure)

iia. vertical femoral tunnel placement = continued rotational instab

- ant placement = knee too tight in flexion and loose in extension; posterior misplacement (opposite previous)

iiia. ant placement = knee tight in flex + impingement in ext;
iiib. post. placement = ACL will impinge with the PCL


ACL Surgery: Complications

Other causes of failure (14)

1. inadequate graft fixation (graft-screw divergence >30 degrees)
2. missed diagnosis other injuries
3. overaggressive rehab
4. Infection
- coag -ve Staph most common; S. epi > s. aureus
-often can retain graft with multiple I&Ds and antibiotics (6 weeks minimum)
5. Loss of motion & arthrofibrosis (preoperative prevention; regain full ROM during pre-hab; higher risk in acute phase; Rx: <12/52= Rx with aggressive PT and serial splinting / > 12/52 Rx with lysis of adhesions/MUA
6. Infrapatellar contracture syndrome (decreased patellar translation on exam)
7. PT Rupture
8. Patella fracture (most fx occur 8-12/52 postop)
9 Hardware failure
10 Tunnel osteolysis (Rx with observation)
11. Late arthritis (related to meniscal integrity)
12. Local nerve irritation (saph.nerve)
13 Cyclops lesion (fibroproliferative tissue blocks ext; "click" heard at terminal extension)