Chapter 121 - Extensor Mechanism Injuries

Question 1

Insall salvati ratio

Answer 1

ratio of A:B

A is the length of the posterior surface of the patellar tendon from the inferior pole of the patella to the tibial tuberosity

B: greatest diagonal length of the patella

Normal = 1.0 +/- 0.2

Question 2

Caton-Deschamps ratio

Answer 2

Ratio of A:B

A: distance from the inferior articular margin of the patella to the upper edge of the tibial plateau

B: length of the patella articular surface

normal = 0.08 - 1.3

Question 3

which measurement of patellar height better characterizes patellar alta

Answer 3

caton-deschamps ratio bc it references the plateau

Question 4

what measurement of tttg suggests a medializing tibial tuberosity osteotomy needs to be performed

Answer 4

20mm

Question 5

how to manage patella dislocation

Answer 5

1st time dislocators: pt and bracing unless osteochondral loose body

recurrent dislocators: mpfl recon

Question 6

risk factors for patellar dislocation and the appropriate surgical adjuncts

Answer 6

patella alta: distalizing tibial tuberosity transfer

lateral tubercle (TTTG >20): medializing tuberosity transfer

severe trochlear dysplasia: trochleoplasty

excessive LIMB rotation: femoral.tibial derotation osteotomy

Question 7

overcorrection of lateral patellar dislocations can cause what?

Answer 7

medial patellar dislocation

medial patellofemoral arthritis

** 2/2 extensive lateral retinacular release

Question 8

MRI vs CT in measuring TTTG?

Answer 8

MRI tends to UNDERestimate by 2-3mm

Question 9

patellar tendon rupture happens in what age grou?

Answer 9

<40

Question 10

quadriceps tendon rupture happens in what age group?

Answer 10

> 40

Question 11

pathophysiologic changes in the injured extensor tendon?

Answer 11

angiofibroblastic tendinosis
mucoid degeneration
pseudocyst formation at bony attachments