Patellar Fractures

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Definition/Description

Patellar fractures are caused by direct trauma or indirectly as the result of quadriceps contractions or excessive stress to the extensor mechanism. Indirect injuries are commonly associated with tears of the retinaculum and vastus muscles. Patella fractures make up about 1% of all skeletal injuries.

The patella is very vulnerable to injury as a result of it's subcutaneous location,. Patellar frac-tures occur as a result of a compressive force, a sudden tensile force (as occurs with hyper flexion of the knee), or a combination of these two causes. These fractures can be caused by direct blows to the knee in sports injuries or accidents, or from indirect stresses caused by twisting actions or violent contractions in the muscles sur-rounding the knee.

Clinically relevant anatomy

The patella is a triangular bone situated on the anterior surface of the knee at the distal end of the femur. It is the largest sesamoïd bone in the body and makes part of the knee joint. Vastus medialis and lateralis, as part of the quadriceps group, control movement at the patella. See the page on the patella for more details.

extensor mechanism

Complications

• Injuries (sprain/rupture) to ligaments and tendons attached to the patella:
  • Long term complications include stiffness, extension weakness, and patellofemoral arthritis.

• Avascular necrosis
  

Characteristics/Clinical Presentation

Types of fractures

Patella fractures are classified as either displaced or non-displaced. Displaced fractures are unstable and can be further classified as:

• Comminuted: As a result of direct trauma (mostly due to blows or falls on flexed knee)
  • Can cause damage to the articular cartilage of patella and femoral condyles.
• Tansverse/stellate: As a result of muscle contraction/extensive stress on the extensor mechanism, e.g. explosive quadriceps contraction after jumping from height.
  • Most common type
  • Proximal blood supply may be compromised
• Marginal: As a result of a fall on the knee
• Vertical
• Lower/upper pole
• Osteochondral
• Sleeve (only in paediatric patients)

Differential Diagnosis

A doctor can diagnose a fracture of the patella by asking you about the details of your acci-dent and by examining you. He will inspect your knee, focusing on where it is tender, swol-len or misshapen. Then, he may also ask you to raise your leg or extend your knee, possibly after giving you a local anesthetic to eliminate pain. This helps the doctor to see if there are other injuries in and around your knee.
Most of the times the individual reports pain during this examination of the affected knee.
Common causes that the patients may report for this pain are: an accident, a fall from height or a direct blow to the knee.

The best way to exclude or include a patellar fracture is an X-ray, taken from several angles, to determine the extent of a fractured kneecap and to check for other injuries. If other inju-ries are suspected, a computer tomography (CT) or magnetic resonance imaging (MRI) scan may also be done.

Diagnostic procedures

A patellar fracture is suspected when there is a history of direct violence, when there are difficulties in standing or when there is a snapping sensation. In most cases there is straight leg raise inability and the inability to extend the knee.
Bruising and abrasion, the presence and site of tenderness, any palpable gap above or be-neath the patella as well as any obvious proximal displacement of the patella can indicate a patellar fracture.
Radiographs are necessary to clarify because there isn't some kind of specific test to identify a patellar fracture. Standard x-rays with special views of the patella are usually sufficient to diagnose a patellar fracture. However in more difficult cases where x-rays are not decisive, CT scan may be necessary. Associated injuries to nearby tendons and ligaments may need to be evaluated by MRI studies.

Physical examination

The clinical examination should include an inspection of the whole extremity. Clinical signs of a patellar fracture are swelling and pain in the knee joint. Wounds should be checked to con-firm whether the fracture is open or closed.
In displaced patellar fractures, a defect zone between the fragments may be palpable. Often there is a haemarthrosis of the knee. Flexion and extension in the knee joint is limited and painful. Active extension and lifting of the leg is usually impossible.
However, the ability to extend the knee does not rule out a patellar fracture, because the medial and lateral retinacula may be still intact.
Of course a check of the peripheral pulses, the compartments of the leg, and a neurological examination should always be performed. Special interest should be paid to potential ipsi-lateral concomitant injuries (e.g. acetabular fractures, femoral fractures or tibial fractures) which are signs of serious trauma.

Outcome measures

The outcome depends primarily on the quality of articular restoration. Any intra-articular incongruities lead to the development of posttraumatic arthritis.
The prognosis of the injury depends on the amount of chondral damage at the time of injury. Functional outcome depends on the ability to achieve pain-free and stabile range of motion in an early stage.
Manipulation under anesthesia or the arthroscopic releasing of adhesions is required when athrofibrosis occurs.
Future treatment options may include osteochondral allograft reconstructions of the patella, for posttraumatic arthritis. Currently, several fixation methods of patellar fractures includes modified tension band wiring, Circumferential cerculage wires, and screw fixation and re-cently bioabsorbable fixation which may reduce the frequency of hardware symptoms.

These outcomes can be measured by the following measures:

- Knee injury and osteoarthritis outcome score

- Knee outcome survey

- Lower extrimity function scale

-McGill pain questionnaire

Medical management

Surgical treatment is usually performed in patients with a displaced fracture and is carried out on an emergency basis if the fracture is open or if an associated traumatic arthrotomy is present.Sometimes surgery is necessary because the strong M. Quadriceps can pull the broken pieces out of place and apart from each other so callus cannot form. When this occurs, healing with ossification is im-possible.

The therapy procedure variates with the characteristics of the patella fracture. If you have a transverse fracture If the fracture is transverse, the most common procedure is to use pins and wires and 'a figure of eight' to press the pieces together (AO tension band wiring). A comminuted fracture is usually associated with a blow or a fall on a flexed knee, and causes the patella to break in several pieces. In this case, the small crushed pieces of the patella will be re-moved.(partial patellectomy). In addition, there is also a procedure called ‘complete pallac-tomy’. In this case the whole patella is removed and the tendon of the M. Quadriceps is at-tached to the ligamentum patellae, to ensure the function of the extensor apparatus. But, this is a relatively old procedure and its effects are controversial. (Günal L. et al )
A break in the center of the kneecap can be fixed using wires and screws. Note that a patellec-tomy is the last treatment for a comminuted fracture.
Operative treatment aims to restore extensor function, align articular incongruities, and al-low early motion (Fourati M.K. Level 2b: levels of evidence, Mehling, I. et al, Scolaro, J. et al. level of evidence 5, Zhongguo Gu Shang et al. level 2b: levels of evidence, Strauss J. MD Lev-el 5 :levels of evidence)

Significant displacement, extensor mechanism not intact. ORIF tension band wire technique. Repari or bilater. vastus. same rehab as with no-operative-SPORT

Nonsurgical treatment (Orthopeadic) is indicated when the broken pieces of the patella aren't displaced. The patient needs a casts or splints to immobilize the fractured pieces, this is done in vertical and horizontal fractures. In horizontal fractures, radiographs are taken at weekly intervals to exclude late separation of the pieces. so callus formation can take place. In this way the callus can form. Crutches will be used during the 6 to 8 week healing process.
Once radiographic evidence indicates union and clinical signs of healing (nontender to palpa-tion) are present, the patient is changed to a removable brace.( Mehling, I. et al )

Extensor mechanism in place

Extension splint. as fracture heals, gradulally increase knee flexion. quads strengthening in inner ranges. -SPORT

New technique to treat a patellar fracture: El-Sayed and Ragab reported on arthroscopic-assisted reduction and fixation of displaced transverse fractures of the patella in 14 patients with displaced transverse fractures of the patella. Patients were treated by means of arthro-scopic-assisted closed reduction of the fracture with percutaneous screw fixation. Patella fractures were found to unite in a mean of 7 weeks. All 14 patients regained full extension of the knee, and full range of motion was achieved in 12 patients, with 2 patients experiencing a 10º loss of flexion.

Physical Therapy Management

Treatment with cold can be used to control pain and oedema. During the immobilization of the knee the patient is encouraged to train other leg muscles. After removing the cast or splint, and the fracture is considered healed, the therapy to regain range of motion starts.
There are instructions to prevent loss of motion and strength in adjacent joints. Ankle exer-cises are taught to promote circulation.
The range of motion, strengthening, and proprioceptive exercises of the involved joint should be initiated and progressed as indicated and tolerated by the individual.

Treatment procedure Post-Operative :

Phase
 I:
0­-2 
Weeks
Knee
Immobilizer:
Worn
at
all
times
(taken
off
only
for
physical
therapy
sessions
converted
to
hinged
knee)
brace is worn
at
first
post‐op
visit

• Weight bearing: with
the
knee
locked
in
extension
• Range
 of 
Motion:
 0‐30
degrees
• Therapeutic 
Exercises:


• 
Isometric
quadriceps/hamstring/adductor/abductor
strengthening,

• Ankle
theraband exercises

Phase
 II:
2-­6
 Weeks
Knee 
Brace:
 Worn
 with 
weight bearing
 activities 
still 
locked 
in 
full 
extension,
may
be
 removed 
at 
night

• Weightbearing:
• Range
of
Motion:

 add
15
degrees
of
flexion
each
week
–

• Goal
is
90
degrees
by
post‐op
week
6

• Therapeutic
Exercises:


• Isometric
quadriceps/hamstring/adductor/abductor
strengthening,

• Ankle
theraband
exercises,

• Initiate
straight
leg
raises

Phase
 III:
 6-­10 
Weeks
Knee
 Brace:
Unlocked,
worn 
with 
weight bearing
 activities

• Weightbearing:
Full
• Range
of
Motion:
 progress
to
full
ROM
by
post‐operative
week
10
• Therapeutic
Exercises:
Isometric
quadriceps/hamstring/adductor/abductor
 strengthening,
Ankle
theraband
exercises,
Initiate
straight
leg
raises

Phase
 IV:
10­-12 
Weeks
Knee
Brace:
Discontinue

• Weightbearing:
Full
• Range
of
Motion:
Full
• Therapeutic
 Exercises:
Isometric
 quadriceps/hamstring/adductor/abductor
 strengthening, Ankle 
theraband
exercises,
Initiate
 straight
leg
raises,
Start
 stationary 
bicycle

Phase
V:
3­6
 Months: return 
to 
full 
activities
 as
 tolerated

(Strauss J. (MD)(level of evidence : 5), Elizabeth Arendt(MD) ( level of evidence: 5) )

Treatment procedure Non-Operative :

Phase
 I:
0-­6 
Weeks
• Knee
Brace:
 Brace locked in extension 2-3 weeks, controlled motion brace at 2-3 weeks
o Weightbearing:
• PWB in brace and on crutches.
• May stand tandem.
• Duration of crutches as per surgeon
o Range
of
Motion:

 ROM as per surgeon
o Therapeutic
Exercises:

• Start open kinetic chain strengthening and ROM of knee at 3-4 weeks or per surgeon order.
• Quadriceps
• Hamstring
• Glutei sets
• SLR
Open and close kinetic chains hip strengthening exercises.
• Patellar mobilization

Examples of a knee braces after a patellar fracture:

Open kinetic chain strengthening and ROM of knee:

Phase II: 6-12 Weeks
• Knee Brace: Discharge per surgeon order
o Range of Motion: Progress toward full knee flexion, extension
o Therapeutic Exercises:
▪ Stationary biking with seat elevated and no resistance for ROM
▪ Progress close kinetic chain exercise: mini squats, step up, retro step, etc
▪ Progress resistance on hip exercise.
▪ Advance proprioceptive exercise
▪ Begin lunges 8-10 weeks

(Strauss J. (MD)(level of evidence : 5), Elizabeth Arendt(MD) ( level of evidence: 5), Kathryn E. Cramer, MD et al (level of evidence 5 )

Examples of exercices:

Quadriceps: The patient sits on the floor with his injured leg straight and his other leg bent. He presses the back of the knee of his injured leg against the floor by tightening the muscles on the top of his thigh. He has to hold this position 10 seconds and then re-lax, the patient does 2 sets of 15seconds. (Bhave A et al. (Level of evidence :5), Creighton AR et al. (level of evidence : 5))

SLR : The patient has to lie on his back with his legs straight. Then he has to bend the knee on his uninjured side and place his foot flat on the floor. Once this is done, he has to tighten the thigh muscle on his injured side and lift his leg about 8 inches off the floor. The patient keeps his leg straight and his thigh muscle tight and then he brings his leg slowly back down to the floor. This exercise is also done in 2 sets of 15 seconds. Bhave A et al. (Level of evidence :5), Creighton AR et al. (level of evidence : 5)

Patellar mobilisation :

o Patient sits with his injured leg in front of him. His leg should be completely straight and relaxed. Patient has to use his hands to move the patella sideways toward the inside of his leg. Then he has to move it sideways toward the inside of his leg. Each position has to be hold for 15 to 30 seconds.
Fourati M.K. (level of evidence:2b), Elizabeth Arendt(MD) (level of evidence: 5),Bhave A et al. (Level of evidence :5), Creighton AR et al. (level of evidence : 5)

o Patient has to use his hands to move his patella toward him and then away from him for 15 to 30 seconds in each direction. Then he has to compare the movement of the injur
ed patellla with the movement of the uninjured patella. The main goal is to have the same amount of movement for bouth kneekaps.

Resources

http://www.physioroom.com/injuries/knee/patella_fracture_full.php
http://www.summitmedicalgroup.com/library/adult_health/smapatellarfractureexecises_references/
http://www.mdguidelines.com/fracture-patella
http://www.ncbi.nlm.nih.gov/pubmed/?term=patellar%20fracture
http://www.healthline.com/human-body-maps/knee