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Patellar Fracture
Dr Mohd Syafiq Bin Shahbudin
MB BCh (Alex)
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Introduction
Patella is a thick, circular-triangular bone which
articulates with the femur (thigh bone) and
covers and protects the anterior articular
surface of the knee joint
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Anterior surface
Posterior surface
Course ,flattened
and rough.
(For quadriceps
tendon attachment)
Distal apex
Origin of patella
ligament
Medial
facet
Lateral facet
Numerous
vascularcanaliculi
Vascular canaliculi
filled by fatty tissue
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Incidence
• 1% of all fractures
• common: 20 to 50 years old.
• Men > women
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Type of patella fracture
• Non displaced
- Tranverse
- Stellate
- Vertical
•Displaced-Tranverse
-Stellate-Multifragmented
-Polar
-Proximal
-Distal
-Osteochondral
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Non Displaced fracture
Transverse pattern (50 – 80% of cases)
• 80% occur -> middle to lower 3rd of patella
• >35% injuries are non displaced
• Usually minimal damage -> extensormechanism remains intact.
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• Stellate fracture
- From a direct compressive blow
- Account 30% - 35% of patella fracture
- > 50% of these fracture are nondisplaced
- Due to it injury mechanism, damage to
femoral and patellar articular surfaces can
occur
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• Longitudinal / marginal vertical
- 12 to 17% of patella fractures
- Marginal -> from direct trauma and involve
lateral facet
- The fracture not seen in standard x-ray view.
axial views are necessary
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Displaced fracture
Fracture fragment separation more than 3mmor an articular incongruity of 2mm or more.
Extensor mechanism disruption with displaced
fracture -> indication for operative repair
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• 52% displaced tranverse -> non comminuted
• Some patient may demonstrate displaced
fracture fragments but maintain active
extension of the leg
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Comminuted fracture
Unstable fracture.
The bone shatters into pieces
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Open fracture
The skin has been broken and exposes the bone.
Involve much more damage to the surrounding
muscles, tendons, and ligaments.
Higher risk of complication and late healing.
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Cause
• Patellar fractures are most commonly caused
by a direct blow.
• The patella can also be fractured indirectly.
Eg: Quadriceps muscle is contracting but the
knee joint is straightening.(Eccentric contraction)
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Investigations
• History taking
• c/o by the patient
•
Test: Straight leg raise test
- To test the function of the the quadriceps
muscle and its attachment to tibia.- Disruption of quadriceps, patella tendon or
patella itself lead to inability to perform test.
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• X-ray
- Differentiate other abnormalities such as
bipartite patella.
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Bipartite patella
- A congenital fragmentation or synchondrosis
of the patella as the result of developmentallack of assimilation of the bone during growth.
- Occurs in approximately 1 % of population.
Characteristic x-ray
features:
- Rounded
- Sclerotic lines ratherthan the sharp edges of
a fracture.
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Treatment
• Non surgical treatment –
Indications:
- For undisplaced fractures with intact articular surface.- Preserved extensor mechanism with maintained active
extension against gravity.
- Retinacula on either side of patella should not be torn.
- There should be minimal displacement of fragments (2-3mm)
- Minimal disruption of the articular surface (2-3mm)
- Tranverse undisplaced fracture of the patella is anavulsion fracture
- Should aspirate with occurrence of tense hemoarthrosis.
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Management:
• Intact extensor function:
-knee immobilizer, rest, ice, analgesia
• Diminished extensor function:
- Immobilize, rest, ice, analgesia, Non weight
bearing and proceed with ORIF
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• Surgical treatment –
Indications:
- Extensor mechanism involvement
- Displaced transverse fracture, either simple or comminuted,with associated disruption of quadriceps retinacula.
- Patella fractures with compromised overlying skin shouldundergo delayed fixation.
Disruption of
quadriceps
retinacula
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Cerclage wiring
Indicated in:
- Displaced fracture
- Impaired extensor function.
• Cerclage wiring may be used alone or
combination with lag screw.
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• cerclage wire plaster/ thermoplastic/
cylinder treatment of the leg/ removablesplintage as support
Contraindication:• Polytrauma patient in extremis
• Medically unfit for surgery
• Local soft-tissue compromise
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Advantages
•Restoration of extensor function
•Early mobilization of knee joint
•No plaster, or prolonged splintage
Disadvantages
•Caution with knee mobilization is needed, if asingle cerclage wire is used
•Secondary displacement
•Prominent metalwork after fixation•articular malunion
•Risks of open operation
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Tension band wiring
• Commonly indicated in transverse displaced
patella fracture and also comminuted fracture
of patella.
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Technique:
- Reduction of fracture with reduction of clamp
- K-wire is inserted perpendicular to the
fracture- Figure of 8 tension band wire is applied for
compression of the fracture
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• These tension band wires convert anterior
distractive forces to compressive forces at the
articular surface
• (More flexion of the knee will give more
compression to the articular surface)
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Wound Closure:
- Following implant insertion, the extensor
retinaculum is repaired
- The superficial retinaculum must be closed
properly in order to maximize coverage over
the implant.
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• Post Operative Care:
- Patient is immobilized for 2-3 weeks
- begin prone hang exercises at 2-3 weeks
- crutches are discontinued after 6 weeks
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Claw plate
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Patellectomy
Partial Patellectomy
Involve distal pole of patella
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• Smaller fragments are excised
• The patella tendon is reattached anteriorly
with sutures
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• Complications: Suture pull out.
Signs:
- Look for proximal migration of upper patellar
pole on radiography or by absence of palpable
quad tendon repair to inferior pole fragment
- Absence or weakness of quadriceps function
- Inability to palpate the patellar ligament or
detection of gap between ligament and pole.
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Total Patellectomy
Total patellectomy is reserved for severe
multifragmentary fractures (comminuted and
displaced) of the patella, which may be
combined with significant osteochondral
damage to the patellofemoral joint
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• Bone fragments are excise before
reattachment to patella tendon
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Complication of patella fracture
• Infection
• Loss of reduction
• Failure of internal fixation
• Malunion
• Quadriceps weakness
•Extensor lag
• Traumatic arthritis of patellofemoral joint
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