Patellar Fractures

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Definition/Description

Patella fractures are caused by directly by trauma or a compressive force, 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.

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. The extensor mechanism as a whole plays a major role in patella fractures. This consists of the quadriceps, quadriceps tendon, retinaculum, patella tendon, tibial tubercle and patellofemoral and patellotibial ligaments, See the page on the patella for more details.

Epidemiology/Etiology

In a recent study, the average mortality rate at one year after patella fractures was 2.8%, increasing to 6.2% in the geriatric population. Patella fractures are not associated with an increased mortality rate, as the relative risk of death was 0.9.

Complications

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

• Avascular necrosis
• posttraumatic arthritis.
• Osteochondral damage to patella-femoral joint
• Stiffness
• Non-union
• Malunion
• 
  

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
  • Usually as a result of hyper flexion of the knee
• Marginal: As a result of a fall on the knee
• Vertical
• Lower/upper pole
• Osteochondral
• Sleeve (only in paediatric patients)

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.

Differential diagnosis

• Bipartite patella

Diagnosis

Interview

• Details regarding accident
• Mechanism of injury
• Pain at knee
• Complaints of difficulty standing or snapping sensation at knee

Physical examination

• Observation:
  • Whole extremity
  • Swollen, bruised knee
  • Deformity around knee
  • Possible wounds (open fracture)
• Palpation (often done after local anesthetics to eliminate pain):
  • Tenderness around patella
  • Palpable gap (for displaced fractures)
• Rule out concomitant injuries:
  • e.g. fractures of the acetabulum, femur and tibia
• Haemarthrosis
• Range of motion:
  • Acute:
    • Limited knee and painful knee flexion and extension
    • Often unable to do straight leg raise
  • Chronic:
    • Full knee flexion with extension lag

• Distal pulses
• Assess compartment of the leg
• Neurological assessment

Special investigations

• X-rays:
  • AP view:
    • May be difficult to see patella
  • Lateral view:
    • Undisplaced - < 2mm separation
    • Displaced - > 2mm separation
  • Sky view
  • Regular monitoring of healing process and any possible complications

• CT scan: Usually not needed
• MRI: Diagnosis of associated injuries to nearby tendons and ligaments
• Bone scans: To identify stress fractures

Outcome measures

• Knee injury and osteoarthritis outcome score
• Knee outcome survey
• Lower extrimity function scale
• McGill pain questionnaire

Medical management

In acute cases, local anesthetics can be given to eliminate pain. This helps to aid in the assessment and diagnosis of the patella fracture.

Conservative management

Indication: Undisplaced fracture (mostly vertical and horizontal fractures) with extensor mechanism in place

Management:

• Fracture immobilized with cast or splint (start off in full extension):
  • As healing takes place, knee flexion can gradually be increased
  • Must be worn until union (on X-rays) and clinical signs of healing (not tender on palpation) are present
• Crutch walking 6-8 weeks
• Rehabilitation

Surgical intervention

Indication: Significant displacement with extensor mechanism not intact.

Aim: Restore extensor function, align articular incongruities, and allow early motion

Management:

• Open reduction and internal fixation using tension band wire technique
  • Transverse fracture: Open reduction and internal fixation using tension band wire technique using pins and wires and 'a figure of eight' to press the pieces together
  • Comminuted fracture: Partial vs complete patellectomy:
    • Quadriceps muscles is is attached to the patellar ligament to ensure function of the extensor apparatus during a complete patellectomy
    • Patellectomy: Relatively old procedure, last treatment of choice
• Repair of bilateral vastus muscles
• Rehabilitation same as with conservative management
  

Later stages:

Manipulation under anesthesia or the arthroscopic releasing of adhesions is required when athrofibrosis occurs.

Physiotherapy management

Extensor mechanism in place

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

cons mx Crutches will be used during the 6 to 8 week healing process.

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.

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

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