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Flashcards in Patella Deck (17)
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1
Q

Patellar Fracture mechanism

A
  • direct blow to the patella: fall, MVC (dashboard)

* indirect trauma by sudden flexion of knee against contracted quadriceps

2
Q

Patellar Fracture clinical features

A
  • marked tenderness
  • inability to extend knee or straight leg raise
  • proximal displacement of patella
  • patellar deformity
  • ± effusion/hemarthrosis
3
Q

Patellar Fracture investigations

A

• X-rays: AP, lateral, skyline

do not confuse with bipartite patella: congenitally unfused ossification centres with smooth margins on X-ray at superolateral corner

4
Q

Patellar Fracture treatment

A

• non-operative
■ indication: non-displaced (step-off <2-3 mm and fracture gap <1-4 mm)
◆ straight leg immobilization 1-4 wk with hinged knee brace, weight bearing as tolerated
◆ progress in flexion after 2-3 wk
◆ physiotherapy: quadriceps strengthening when pain has subsided

• operative
■ indication displaced (>2 mm), comminuted, disrupted extensor mechanism
■ ORIF, if comminuted may require partial/complete patellectomy

• goal: restore extensor mechanism with maximal articular congruency

5
Q

Complications of patellar fracture

A
  • Symptomatic wiring
  • Loss of reduction
  • Osteonecrosis (proximal fragment)
  • Hardware failure
  • Knee stiffness
  • Nonunion
  • Infection
6
Q

Types of patellar fractures

A

undisplaced

vertical

lower/upper pole

comminuted displaced

transverse

osteochondral

7
Q

Patellar dislocation mechanism

A
  • usually a non-contact twisting injury
  • lateral displacement of patella after contraction of quadriceps at the start of knee flexion in an almost straight knee joint
  • direct blow, e.g. knee/helmet to knee collision
8
Q

Patellar dislocation risk factors

A
  • young, female
  • obesity
  • high-riding patella (patella alta)
  • genu valgus
  • Q-angle (quadriceps angle) ≥20°
  • shallow intercondylar groove
  • weak vastus medialis
  • tight lateral retinaculum
  • ligamentous laxity (Ehlers-Danlos)
9
Q

Patellar dislocation clinical features

A
  • knee catches or gives way with walking
  • severe pain, tenderness anteromedially from rupture of capsule
  • weak knee extension or inability to extend leg unless patella reduced

• positive patellar apprehension test
■ passive lateral translation results in guarding and patient apprehension

  • often recurrent, self-reducing
  • concomitant MCL injury
  • increased Q-angle
  • J-sign
10
Q

What is the Q angle

A

The angle between a vertical line through the patella and tibial tuberosity and a line from the ASIS to the middle patella; the larger the angle, the greater the amount of lateral force on the knee (normal <20°)

11
Q

Patellar dislocation treatment

A

• non-operative first
■ NSAIDs, activity modification, and physical therapy
■ short-term immobilization for comfort, then 6 wk controlled motion
■ progressive weight bearing and isometric quadriceps strengthening

• operative
■ indication: if recurrent or if loose bodies present
■ surgical tightening of medial capsule and release of lateral retinaculum, possible tibial tuberosity transfer, or proximal tibial osteotomy

12
Q

Patellofemoral syndrome (Chrondromalacia Patellae) description

A

syndrome of anterior knee pain associated with idiopathic articular changes of patella

13
Q

Patellofemoral syndrome (Chrondromalacia Patellae) risk factors

A
  • malalignment causing patellar maltracking (Q angle ≥20°, genu valgus)
  • post-trauma
  • deformity of patella or femoral groove
  • recurrent patellar dislocation, ligamentous laxity
  • excessive knee strain (athletes)
14
Q

Patellofemoral syndrome (Chrondromalacia Patellae) mechanism

A
  • softening, erosion, and fragmentation of articular cartilage, predominantly medial aspect of patella
  • commonly seen in active young females
15
Q

Patellofemoral syndrome (Chrondromalacia Patellae) clinical features

A

• deep, aching anterior knee pain
■ exacerbated by prolonged sitting (theatre sign), strenuous athletic activities, stair climbing, squatting, or kneeling

  • insidious onset and vague in nature
  • sensation of instability, pseudolocking
  • pain with extension against resistance through terminal 30-40°
  • pain with compression of patella with knee ROM or resisted knee extension
  • swelling rare, minimal if present
  • palpable crepitus

Pain with firm compression of patella into medial femoral groove is pathognomonic of patellofemoral syndrome

16
Q

Patellofemoral syndrome (Chrondromalacia Patellae) investigations

A
  • X-ray: AP, lateral, skyline – may find chondrosis, lateral patellar tilt, patella alta/baja, or shallow sulcus
  • CT-scan
  • MRI – best to assess articular cartilage
17
Q

Patellofemoral syndrome (Chrondromalacia Patellae) treatment

A

Treatment

• non-operative
■ continue non-impact activities; rest and rehabilitation
■ NSAIDs
■ physiotherapy: vastus medialis and core strengthening

• operative  
■ indication: failed non-operative treatment  
■ tibial tubercle elevation  
■ arthroscopic shaving/debridement  
■ lateral release of retinaculum