Chapter 93 - Terrible Triad Injuries of the Elbow

Question 1

radial head function in elow stability

Answer 1

secondary stabilizer to valgus stress
primary stabilizer to posterolateral stress

Question 2

coronoid function in elbow stability

Answer 2

primary resrtaint to posterior ulnohumeral translation in flexion >30 degrees
coronoid resection >30% fully destabilizes the elbow if there is a concomitant radial head fracture/resection

Question 3

outcomes of radial head excision in terrible triad injuries

Answer 3

50% redislocation rate at 2 months in triad injuries without ligament reconstruction

Question 4

LCL is injured in what percent of terrible triad injuries

Answer 4

100% of terrible triad injuries and it is most often avulsed off the lateral epicondyle with a portion of the common extensors

Question 5

what portion of the MCL is the priamry restraint to valgus?

Answer 5

anterior bundle of the MCL
- most commonly avulsed off the medial epicondyle
- anterior bundle is ISOMETRIC, that is, it is the same length through fleixon and extension
- it is fight between 30-90degrees of flexion

Answer 6

posterior band of the MCL exhibits the greatest length change from flexion to extension

Question 7

order of fixation in terrible triad

Answer 7

1. radial head orif v replacement
2. coronoid fixation
3. LCL
4. MCL (rarely needed if everything else is good)
5. hinged ex-fix

Question 8

Kocher interval

Answer 8

More posterior on the elbow
- ECU and anconeus
- distal extension may injure the LCL insertion
- if you use this you can also use the Kaplan (ecrl and EDC) to see anterior and to the coronoid

Question 9

EDC split for terrible triad

Answer 9

• distal extension may injure the PIN
• allows both radial head and coronoid work thru same split

Question 10

fixation techniques for coronoid fractures

Answer 10

suture lasso shown to be more stable intraopertively than suture anchor or screw fixation
- screw - increased risk of implant failure
- suture anchor - increased risk of nonunion

Question 11

anteromedial facet fracture fixation

Answer 11

(less commonly seen in terrible triad - result from a posteromedial varus force rather than the TT posterolateral valgus force)
but must be fixed with a buttress plate

Question 12

primary complication following ORIF for TT

Answer 12

stiffness, can expect 30-40 degree ROM improvement after contracture release/ROH

Question 13

what percentage of cases with ex-fix used will result in pin site infection?

Answer 13

40-50%

Question 14

intact MCL splint in what?

Answer 14

pronation

Question 15

repaired both lcl and mcl, splint how

Answer 15

neutral rotation

Question 16

isolated MCL injury (not in a TT but just for remembering), splint how?

Answer 16

full supination

Question 17

psot op rehab

Answer 17

splint in 90 of flexion for one week then intiate ROM exercises but limit full extension shy of 30 degrees

Question 18

what is the isometric point of the LUCL

Answer 18

center of the capitellum
2mm anterior to the LE