patellar fractures

7/30/2019 Patellar Fractures

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The patella is the largest sesamoid bone inthe body.

Fractures to this bone makes upapproximately 1% of all skeletal fractures.

Fractures of the patella are more common inmales between the age of 20 to 50 years


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Largest sesamoid bone in body and lies w/nthe quadriceps tendon;

Triangular with apex directed distally

Posterior cartilaginous surface is divided by a

rounded vertical ridge into a lateral andmedial portion for articulation with lateraland medial femoral condyles resp.

Articular surface of patella is divided into 7

facets by longitudinal ridge into medial andlateral 1/3 and 7th being the most medialportion called the odd facet


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Blood supply to patella originates from asmany as 12 nutrient arteries at the inferiorpole, which run upward on the anteriorsurface of the bone in a series of furrows

originating from the superior, medial andinferior genicular arteries.


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The functions of the patella includesincreasing the mechanical advantage of thequadriceps tendon by transmitting forcesacross knee at greater distance (moment)

from axis of rotation. It also increases functional lever arm of quads

as well as changing direction of pull of quadmechanism.

It aids in the nourishment of the articularsurface of the femur and protects the femoralcondyles from direct injury.


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The area of contact between the patella andfemur varies according to the position of theknee; extension vs flexion.

Articulation between the inferior margin ofthe patella and the femur begins at approx10 20 degrees of knee flexion.

Contact area increases from 0.8 cm2 at full

extension to 4cm2

at 90 degrees flexion.


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Can be indirect and direct Indirect occurs when intrinsic strength exceeds the

pull of musculotendinous attachments.

Most commonly results in a transverse # with

comminution. Direct occurs with striking a solid object e.g

dashboard

Results in incomplete or undisplaced, stellate or

communited.


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History of direct injury or indirect injuryfollowed by painful swelling and weakness toknee.

Physical Examination: Pain with manipulation, point of maximal

tenderness palpated and defect or separation canusually be felt.

There is usually compromised ant skin andsubcutaneous tissue.

N.B The ability to extend the knee must be fullyassessed (under LA) to estimate continuity ofextensor mechanism.

Hemarthrosis normally results and there will be

tissue tension w/n knee with severe pain.


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Antero-Posterior view Can detect stellate, transverse and distal pole # peripheral fractures (osteochondral frx) may be

confused w/ bipartite patella.

radiographs of contralateral knee can help in thisdifferentiation because bipartite patella rarelyoccurs unilaterally

Lateral view Profiles patella and shows fragment displacement

Sunrise view Rules out vertical marginal # which are usually

missed.


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Radiograph of a displaced transverse fracture ofthe patella.


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Radiograph of a nondisplaced transverse fracture of thepatella


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Stellate patellar fracture


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Comminuted fracture


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Longitudinal Patella Fracture


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Distal pole fracture of patella


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Osteochondral patellar fracture


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Non Operative Non displaced # with preserved extensor

mechanism

If hematoma is present, aspirate

Cylinder or long leg cast with partial or full weightbearing with crutches for support

Quadriceps exercises with straight leg raising 1-2days after injury

Removal of cast in 4-6 weeks


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Indications: extensor mechanism is avulsed from the patella;

displaced transverse fracture, either simple orcomminuted, w/ associated disruption of

quadriceps retinacula. patellar frxs w/ compromised overlying skin should

undergo delayed fixation;


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Tension band wiring Partial Patellectomy

Total Patellectomy

Screw fixation
http://www.wheelessonline.com/image3/i1/patel1.jpghttp://www.wheelessonline.com/image3/pate52.jpg


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infection : communicates with the kneejoint loss of reduction failure of internal fixation

avascular necrosis Chondromalacia traumatic arthritis of the patellofemoraljoint

quadriceps weakness extensor lag arthrofibrosis of the knee joint; Non union, mal union or delayed union

patellar fractures

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