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Knee Injury
Pain in knee PLUS
Ottawa Knee
Rules
>55 years
tender head of fibula / patella
active knee flexion <90°
inability to weight bear 4 steps immediately and at time of assessment
Nearly 100% sensitive for significant fracture; 50% specific;  XR use by 25%;  waiting times and cost;
also can be used in children
X-rays
Oblique views for tibial condyles; tunnel view for
intercondyle; skyline patellar for vertical patella
fracture; significant fracture in 6%, insignificant
fracture in 0.5%
Secondary ossification centre of patella is at
superior pole (begins at 3yrs, closes at 15yrs);
fabella/sesamoid in lateral head gastrocnemius
AP: <5mm of tibial condyle should be seen lateral
to line from lateral femoral condyle to medial
proximal fibular shaft
CT: helpful if fracture of articular surface
MRI: for STI (80% sensitive for ACL; 95% sensitive
for all types of injury)
Lipohaemarthosis: 10% have osteochondral
fracture (60% in adolescents); if no #, 70% have
ACL injury; 20% have MCL/LCL injury; 9% have PCL
injury; in adolescents, 50% have intra-articular FB,
50% have meniscal tear
Knee Dislocation
Epidemiology: requires much force; can be
Anterior: most common, 40%; tibia anterior
Posterior: 33%
Medial: 4%
Lateral: 18%
Rotatory
Usually med and lat quads remain intact;
reduction occurs spontaneously prehospital in 65% (but still need to evaluate
for vascular injury)
Angiography if:  distal pulses, abnormal ABI (if abnormal examination, 40% have a vascular injury)
Management: reduction via longitudinal traction  splint in 20° flexion and admit
Complications: 20-30% are open; single cruciate injury in 85%, both in 70%, med / lat collateral in
40-60%; intra-articular fracture in 25%; popliteal vessel in 35-40% (presence of distal pulses
doesn’t exclude injury; ?do arteriogram in all patients; if normal pulse before and after and normal
ABI, can just do serial exams); high risk of compartment syndrome (may be delayed after
reduction); peroneal nerve injiry in 25-35% ( foot drop, altered sensation lateral foot); 80% risk
of amputation if reduction delayed >8hrs
Patella
Dislocation
Patella Fracture
MOI: twisting on extended knee or direct blow; often due to patellofemoral
dysplasia, hypoplastic vastis medialis, shallow trochlear groove, genu
valgum; 30% have recurrent, 50% ongoing patellofemoral symptoms
Examination: 60% have abnormal extensor mechanism, high riding patellar;
usually dislocates laterally; patellar apprehension sign (knee flexed at
30°, firm lateral pressure to patella)
Complication: torn medial joint capsule
Management: push medially on patella while extending knee using element
of surprise  cast or zimmer splint 2-4/52 (minimal immobilisation if
recurrent)
MOI: direct blow, fall on flexed knee, forceful
contraction of quads
Transverse: 80%; more likely to be displaced and
associated with disrupted extensor mechanism
Examination: loss of SLR
Management: if undisplaced, POP or Zimmer splint
6/52; if >3mm displaced, ORIF
ACL Injury
Lateral condyle of femur  anterior intercondylar eminence of tibia (may be associated with
avulsion # here = Segond # (see X-ray above))
Prevents: anterior movement of tibia on femur; stabilises knee in extension
Test: Lachman (85-95% sensitivity, 100% specificity; >5mm positive)
Anterior drawer (60% sensitivity, 65% specificity; >6mm positive)
lateral pivot shift (40-70% senstivity)
knee arthrometer (95% sensitivity)
Epidemiology: most commonly injured ligament; accounts for 70% haemarthroses; associated with
MCL/LCL/meniscal injury in 50%
MOI: rotational, hyperextension, deceleration  snap/pop
Complication: medial meniscal tear
Mng: OT
PCL Injury
Medial condyle of femur  posterior intercondylar eminence of tibia (may be associated with
avulsion fracture here)
Prevents: posterior movement of tibia on femur; stabilises knee in flexion
Test: Godfrey’s sign
posterior drawer (55-85% sensitivity)
Epidemiology: rarely isolated; associated with hip injury, femoral and tibial fracture
MOI: blow to leg with flexed knee
Mng: may be conservative if isolated injury
MCL Injury
Medial epicondyle of femur  medial proximal tibia (7cm from joint) (also attached to medial
meniscus)
Epidemiology: most common isolated ligament injury; may be associated with ACL injury
MOI: abduction, flexion, internal rotation; rupture if >1cm laxity without endpoint
Mng: conservative, unless other ligament involved
LCL Injury
Lateral epicondyle of femur  lateral fibula? (separated from lat meniscus by popliteus tendon)
MOI: adduction, flexion, external rotation; rupture if >1cm laxity without endpoint
Complication: peroneal nerve inj
Mng: conservative, unless other ligament involved
Meniscal Injury
Baker’s Cyst
Medial mensicus 2x more common; most are posterior aspect of meniscus
Test: Bragard’s sign (medial)
McMurray’s test (50% sensitvitiy)
Apley compression / Grind test (50% sensitivity)
Protrusion of synovium and synovial fluid into semimembranous bursa; popliteal fossa ache;
palpable bulge; do USS; symptomatic treatment