 David, 21, apprentice
plumber
 R leg injury during rugby game (last pm)
 Hit from R side during tackle
 Impact on upper outside 1/3 of leg (foot
planted on ground)
 No previous Hx of knee injuries
 No PMH of note
Condyle
Tubercle
Epicondyle
Condyle
Articulation
Articulation
Condyle
Tubercle
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Patellar ligament:
makes up the joint capsule on either side of the patella; maintains
patella alignment
Collateral ligaments:
contribute to stability when standing (this is when they are taut) 
are also ‘check’ ligaments for flexed rotation (permit but limit
rotation)
Oblique popliteal ligament:
reinforces the joint capsule posteriorly
Arcuate popliteal ligament:
strengthens the joint capsule posterolaterally
Anterior cruciate ligament:
limits posterior rolling of the femoral condyles on the tibial
plateau during flexion; prevents posterior displacement of the
femur on the tibia and hyperextension of the knee joint
Posterior cruciate ligament:
limits anterior rolling of the femur on the tibial plateau during
extension; also prevents anterior displacement of the femur on the
tibia and helps prevent hyperflexion of the knee joint.
 ACL
 Medial
collateral ligament tear
 ACL:
 Non-contact
change of direction;
hyperextension on landing from a jump or;
direct valgus force
 PCL:
 Contact injury to the ground or; clash of
knees
 MCL:
 Contact valgus injury
 Meniscal tears:
 Twisting on a planted foot
 Positive
swipe test
 Tenderness along the subcutaneous
border of the fibula (around the area he
identifies as the impact site)
 Grade 3 laxity with valgus stress
 Lachman’s Test and anterior draw are
inhibited by pain from David
 Tell
David he has injured a major knee
ligament and that the pain is from local
bruising
 Knee splint + crutches
 Refer for physiotherapy  rehab and
advice on weight bearing/return to
work+sport
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Look:
• Swelling, wasting, spasm, scars, erythema, deformities
• Posture (leg length, foot posture)
• Gait (walk 10 steps, in/out of chair, socks on/off)
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Feel:
• Skin: temperature
• Quadriceps bulk (loss of tone/bulk, spasm, tenderness, loss of
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continuity in extension)
patella (tenderness, thickened ligament, gaps, creptius,
articular surface, suprapatellar bursa, prepatellar bursa)
Medial/lateral femoral condyles and epicondyles
Medial and lateral colateral ligaments
Medial and lateral joint lines
Popliteal fossa (masses, pulse)
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Knee effusion: is the swelling within joint or
extrinsic to joint?
• Patella tap: slide hand down thigh towards knee; push
down gently on patella
• Swipe/bulge test: stroke medial side upwards; empty
suprapatellar pouch; stroke lateral side downwards
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Move:
• Flexion: 135⁰; extension: 0-10⁰
• Observe patellar tracking
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Special tests
• Patella apprehension: patella dislocation (knee flexed
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30⁰; thumbs on medial border; lateral force)
MCL/LCL stress test: MCL/LCL tear (knee flexed 15-30⁰;
varus/valgus force to distal tibia; repeat in full extension)
Anterior draw test: ACL tear (knee flexed; sit on foot;
gently pull upper tibia forwards)
Lachman’s test: ACL tear (knee slightly flexed; stabilise
femur with hand; apply pressure to posterior proximal
tibia to move it anteriorly)
McMurray’s test: medial/lateral meniscal tear (full flexion;
externally rotate foot + varus force Vs internally rotate
foot + valgus force; extend knee
 Source: Angus Hann
 With Ligament testing
you assess symptom
response ( pain), laxity and end feel. Acute
spasm will guard the joint and give u a false
negative on Ligament testing.
 Inhibition affects strength. May be unable to
straight leg raise. Pain causes reflexive
inhibition and may cause knee to give way.
Need to encourage patient to relax when
testing. Acute knee difficult.
 3.
What could be done to improve your
confidence in the Lachman's and anterior
draw test in this case?
• Tell the patient to relax and practice more
• UptoDate: The stability of the knee is assessed by
varus and valgus stress testing, the Lachman's test,
and the anterior and posterior drawer signs. The
usefulness of these tests is limited if the patient's
muscles are not relaxed, as quadriceps contraction
masks signs of instability
• To improve confidence – be Angus or Pete
 Rupture
– patella loses its anchor  patella
moves inferiorly (towards foot)  unable to
straighten knee
• A large sudden load may cause the entire insertion
to be compromised, leading to complete rupture.
Repetitive loading, particularly eccentric loads,
causes microfailure, usually at the muscle tendon
junction. This microfailure can result in partial tears
 Strain
– due to repetitive functional
overload, knees subjected to high levels of
repeated loading of extensor mechanism
The following week you are surprised to see David represent
with a letter from the physio agreeing with your diagnosis about
the knee injury, but expressing concern about the cause of the
ongoing leg pain.
Repeat clinical examination shows a large effusion and there is
laxity with Lachman's test.
You refer David for an x-ray which is shown below.
Fibula
Head
Neck
Body
Femortibial
joint space
hyper-extension lateral view
allows assessment of slope of
intercondylar roof in relation to
the tibial plateau;
 Plain radiographs cannot be used
to diagnose ACL tears. In some
cases, an avulsion fracture of the
anterolateral tibial plateau (ie,
Segond fracture) is identified at
the site of attachment of the lateral
capsular ligament.
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3. Review the mechanism of injury and describe the
sequence of events that occurred to his knee.
The impact was on the upper outside one third of
the leg while his foot was planted on the ground.
running
landing from a jump
1.
What is the common mechanism for ACL rupture?
A blow to the side of the knee, which can occur during a football tackle, may
result in an ACL tear.
Coming to a quick stop, combined with a direction change while running,
pivoting, landing from a jump, or overextending the knee joint (called
hyperextended knee), also can cause injury to the ACL.
Basketball, football, soccer, and skiing are common causes of ACL tears
2. ACL ruptures in children are uncommon - why? What injury might a child sustain instead?
The ACL infrequently ruptures in children. Rather the
bone on either end comes off.
3. What are the indications for imaging knee
injuries?
4. What are the potential long term sequelae
to an ACL rupture which is not operated on in
this age group?
Depends on activity level of patient
Long term sequelae include instability,
particularly with pivoting type sports, but even
walking
Instability causes damage to the menisci and
the other ligaments