Injuries of the knee

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عادل الهنداوي . دInjuries of the knee &leg

Acute knee ligament injuries : common in sports &RTA.
Knee stability depends on joint capsule, intra -&extra -articular
ligaments &muscles rather than on bony structures.
MOI: Valgus force→ MCL tear; Valg us +rotation→ MCL+ ACL tear;
Valgus +rotation+weight bearing→ MCL+ACL+ medial meniscus tear;
Varus force→ LCL tear; Varus + rotation→ LCL + ACL tear;
Dashboard injury→ PCL tear.
CF: history of twisting injury→ immediate painful doughy swelling (hemarthrosis)
while in meniscus injury the swelling is late & fluctuant (synovial effusion).
Look for site of maximum tenderness, bruises &abrasion.
Test for ligament tear :
Partial tear is pa inful with no abnormal movement, if in doubt→ stress view .
Complete tear → painles s abnormal movement :
If the knee open with valgus or varus stress in 30°flexion→ only collateral tear;
If open in extension→ capsule + collateral + cruciate tear ;
Anteroposterior stability: posterior sag→ PCL tear;
anterior drawer test→ ACL; Lachman tes t→ ACL.

Imaging: X -ray: may show avulsion fracture e.g. ACL may avulse tibial spine.

MRI: to differentiate partial from complete tear.
Arthroscopy: is not indicated in acute complete tear.
Treatment:
Partial tear : aspirate hemarthrosis→ 6weeks functiona l
brace or crepe bandage with early exercise.
Complete tear : MCL or LCL tear: 6weeks cast -brace→ exercise.
ACL or PCL tear : 6we eks cast -brace→ exercise; later if instability persists→
ligament reconstruction.
Combined collateral + ACL or PCL : 6wee ks cast -brace → exercise→ later
reconstruction.
Complications: 1-adhesion: occurs with partial tear because torn fibers
stick to surrounding structures; CF: attacks of pain &giving way; MRI differentiate
it from menis cus tear; Ŗ: physiotherapy.
2-instability: the knee continue to give way→ OA.

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Fractured tibial spine:

is the adolescent variant of ACL tear.
MOI: ACL traction by severe twisting or varus/valgus force.
CF: swollen tender knee with doughy feel.
X -ray: the # may be missed; the spine(inter condylar eminence)
may be: І-undisplaced; П -hinged; Ш -completely displaced.
Treatment: UGA the joint is aspirated→ 6weeks plaster cylinder in full
extension. If there is block to full extension or the fragment is significantly
displaced→ ORIF.

Disloca tion of the knee:

MOI: severe inj ury may tear cruciate &collateral lig. → knee ≠.
CF: severe knee swelling, bruising &deformity. The popliteal artery
may be torn or obstructed. Peroneal &/or tibial nerve may be injured.
X -ray: the ≠ can be in any direct ion; tibial spine may be avulsed .

Treatment: Urgent CR UGA→ back -splint in 15°flexion -check

circulation in the1 st week - when swelling subsided→ 12weeks cast.
If 1-CR fails, 2 -vascular injury or 3 -open ≠→ open reduction with
ligament repair. Complicat ion: 1-knee instability & 2 -knee stiffness.

Fractured patella:

Anatomy: the patella is a sesamoid bone in the quadriceps tendon;
the vastus medialis &lateralis also inserted into medial &lateral sides
of the patella; the medial &lateral exten sor retinacula are expansion
of quadriceps by passing the patella & inserting to the upper tibia.
MOI: either
D irect injury like dashboard blow or fall onto the knee→ either undisplaced
crack or comminuted(stellate) # with no tear of the extensor expansion.
Indirect injury by resisted quadriceps contraction→ transverse # with
gap due to tear of extensor expansion.
CF: swolle n bruised knee; with direct injury the patient can lift his leg &no gap
can be felt in contrast to indirect injury. Aspiration→ blood with fat droplets.
X -ray: bi -, tri - or multi -partite patella( with smooth oblique line at supero -
lateral angle ) sh ould not be mistaken for #.
Treatment:
Undisplaced #→ aspirate hemarthrosis→ 3 -6weeks cast with quadriceps exercise.

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Comminuted #: if undisplaced → the same Ŗ.

If displaced → immediate or late patellectomy(to avoid patellofemoral OA).
Transverse # with ga p→ ORIF(2K -wires with tension band wiring) + repair of torn
extensor expansion.
Complication : patellofemoral OA.

Dislocation of the patella:

Is almost always a lateral ≠ with tear of medial retinaculum.
MOI: direct force is rare; often the ≠ is due to in direct (sport) injury:
quadriceps contraction while the knee in valgus &external rotation.
Risk factors: genu valgum, tibial torsion, patella alta, shallow
intercondylar groove, ligament laxity &muscle weakness.
CF: the patient fall to the ground; the p atella can be felt on lateral side
of the knee; knee movement is impossible; bruises on medial side.
X -ray: the patella is displaced laterally &there may be osteocho ndral #.
Treatment: push the patella back into it's place→ 3weeks cast→ 3months
quadriceps exercise. Some prefer operative repair of medial ligaments to
prevent recurrent ≠ especially in severe injury. Complication: recurrent ≠ (20%) .

Tibial plateau fracture s: adults(50 -60 ).

MOI: varus or vagus force + axial loading like
car striking a pedestrian(bumper #) or FFH.
Schatzker's classification:
Type 1 - lateral split #.
Type 2 - lateral # that is split and depressed .
Type 3 - lateral depressed fractur e
Type 4 - medial #(split or depressed), LCL?
Typ e 5 - bicondylar
Type 6 – condyle +subcondylar fracture.
CF: swollen, deformed &bruised knee
with doughy feel; examine for ligament
tear &neurovascular injury.
X -ray: AP, lateral &oblique views; CT &3D CT.
Treatment:
Conservative: aspirate the haemarthrosis & apply crepe
bandage→ 10days continuous passive motion(CPM) machine
3weeks hinged cast -brace→ 4weeks PWB→ FWB.

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Operative: ORIF using lag screws or buttress pl ate +

elevation of any depression &support with bone graft.
Type І&ІV: if undisplaced → conservative
If displaced → ORIF .
Type П&Ш: If depression >5mm &young→ ORIF.
if <5mm or elderly→ conservative.
Type V &VІ: if severe, there is a risk of compartment sy ndrome.
If undisplaced or slightly displaced in elderly→ conservative.
If displaced→ ORIF or circular -frame external fixation or
6weeks skeletal traction→ 6weeks PWB.
Complications:
Early: compartment syndrome: in closed type 5&6 due to excessive bleed ing.
Late: joint stiffness, varus or valgus deformity &OA( after 5-10yrs ).

Fractures of proximal end of fibula:

MOI: either direct or indirect twisting injury.
The isolated # is rare &needs no Ŗ but look for associated injuries:
1-ankle # or ligament tear (Maisonneuve #); always x -ray the ankle .
2-knee collateral ligament injury.
3-peroneal nerve injury.
late complication : peroneal nerve entrapment.

Fractures of the tibia &fibula: is a common injury &

many times it is open because of it's subcutaneous position.
MOI: twisting force→ spiral # at different level s.
A ngulation force→ transverse or oblique # at the same level.
Direct injury may crush or split the overlying skin.
Pathological anatomy: # healing depends on:
1-the severity of soft tissue injury: Tscherne's classification of skin damage in
closed # → 1-no skin injury; 2-contusion; 3-localized degloving; 4-extensive
degloving; 5-necrosis from degloving. For open # → Gustilo's classificat ion.
2-the severity of the # : high energy injury (direct force )→ comminuted &open(G
ШB or ШC). Low energy injury(indirect force)→ spiral &closed or open(GІ or П).
3-the stability of the #: transverse, spiral, butterfly or comminuted.
CF: swollen deformed leg &externally rotated foot.
Look for: open wound; skin bruisi ng, crushing & tenting; circulatory changes ,
nerve injury & compartment syndrome.
X -ray: the entire leg with knee &ankle should be seen.

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Low energy #→ uncomminuted spiral #.

High energy #→ displ aced transverse, short oblique or comminuted #.
Management:
Aim of treatment: 1-limit soft tissue damage &preserve the skin;
2-prevent compartment syndrome;
3-reduce &hold the #;
4-start early weight bearing;
5-early joint movement.
Conservative: full length cast(from upper thigh to metatarsal necks) &elevation
for 2weeks→ checking x -ray &change the cast as swelling↓→ 8-12weeks PWB. If
skin viability is doubtful→ 2weeks skeletal traction then casting.
Indications: 1-undisplaced &slightly displaced #; & 2 -displaced # that can be
reduced(&remain stable) by manipulat ion.
Operative: indications: 1 -failure of closed reduction; & 2 -displaced high energy #
that are comminuted &unstable. Types of fixations : closed intramedullary
nailing with locking screws (for closed diaphyse al # , plate fixation (for
metaphyseal #) & extern al fixation (for open# -&closed comminuted #).
Complications:
Early: 1-vascular injury: proximal 1/3 # may injure the popliteal artery→ repair.
2-compartment syndrome(proximal #)→ fasciotomy→ external fixation.
3-infection: the incidence is 1% for G І &30% f or G ШC.
Late: 1-malunion : 1.5cm shortening &7˚angulation are acceptable, if more or mal -
rotation→ tibial osteotomy.
2-delayed union & nonunion : especially in high energy #, infection or bone loss →
stable fixation &bone graft.
3-joint stiffness: of ankle ma y lasts 12months.

Fracture of the fibula alone :

MOI: 1 -indirect→ spiral # as a part of ankle injury .
2-direct blow→ transverse #; CF: local tenderness,ankle &knee movements are
free; Ŗ: analgesia,elastic bandage or below -knee walking cast .

Fracture of the tibia alone :

MOI: direct blow→ transverse #(adults ;)Indirect twisting i njury→ spiral
#(children -toddle.
Treatment: CR +above -knee cast(12wk in adult &6wk in children .
Complication: nonunion(lower 1/3 #), Ŗ→ ORIF+2.5cm excision of fibula .

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