ABFAS EXAM QUESTIONS WITH CORRECT ANSWERS GRADED A+

ABFAS EXAM QUESTIONS WITH CORRECT
ANSWERS GRADED A+
Diastasis for Lisfranc = a fracture is present
2-5 mm of diastis betwen 1st and second mt base

Chronic lisfrancs--->ct=1 mm diastasis betwen 1st and 2nd mt or an increase of more than 15 degrees
in the tarso-metatarsal joint


signs of lisfranc on xray
fleck sign (1 and 2 met bases)
first ray elevated
arch flattens


MCC direction lisfranc displaces
Dorsal and Lateral


When to sx correct lisfranc
>2mm displaced
wait 14 days if too much edema


Approach to ORIF lisfranc fx
middle cunii start proximal superior medical >to the base of the 2nd mt possibly, 3rd mt.

the first lag screw=KEY to REDUCTION. T

if needed do a few more lag screws from the the bases metatarsals >cuni.

If cuni instability **screw across the cunis.communition=plates.


Rules for bunions in the Juvenile pt
14-16 yrs. Ideal time frame to do sx for them is near skel. Maturity 11-15 yoa.

Don't do anything joint destructive /don't remove the fib sesamoid.

take mt adductus into consideration in a peds patient.

Transpositional osteotomies ideal e.g. austin, kalish, offset V for rectus foottype and mod. IMA. But if
they have Mt Adductus, really high IM or really high PASA


Distal metaphyseal peds osteotomies
Austin, offset v, reverdin, mitchell, wilson and peabody. Mitchell and wilson SE including shortening,
transfer lesions, elevatus, metatarsalgia


How to fix bunion in a peds pt with IM >15
Base procedure aka proximal metaphyseal osteotomy.
-closed or open base wedge, cresentic procedure, lapidus =goal to make first and 2nd mt parallel
without damaging the open physeal plate.

,base of proximal phalanx (aka proximal akin) of hallux what does it correct
Distal Angle DASA

Fix pasa with mt head osteotomy like REVERDIN=lat cortex intact proximal cut parallel to 1st mt and
distal cut parallel to articular surface
Fix DASA W/ proximal akin


disadvantage of the fusion vs plasty is the
fusion has less hallux propulsion and it can shorten which can then lead to contracture of the ehl or
fhl


You can walk it immediately vs plasty you cant


cancellous vs cortical screws
Cannulated cancellous screws are used for metaphyseal fractures while cannulated and
noncannulated cortical screws are used as lag screws for fixation of diaphyseal fractures.

The main advantage of cannulated screws is that they can be inserted over a guide wire or guide pin.
The diameter of the guide pin is much smaller than the cannulated screw

Cannulated screws have a hollow central shaft. Both cortical and cancellous screws can be
cannulated.


1st MPJ arthrodesis position
neutral rotation of the hallux,
10-15 degrees of valgus
20-30 degrees of dorsiflexion in reference to the axis of the first metatarsal


Which does not affect bone healing:
1. Nutritional status, Rheumatoid or methotrexate patient, DM, tobacco hx, extent of initial injury,
osteoporosis, other metabolic diseases, neuropathy
all do


mcc for ex fix
1. m/c complications involve bone healing and not infection

others: 1. delayed, nonunion, implant loosening, fracture, chronic pain, soft tissue inflammation,
ulceration, or gross infection including osteomyelitis


blood supply to talus
i.posterior tibial artery, artery of the tarsal canal
dorsalis pedis artery,
perforating peroneal artery.


MCC of talar AVN
post-traumatic talar fracture

,Pain, swelling, with a history of previous injury or trauma. May have mechanical symptoms such as
clicking, locking, or grinding.
AVN
diagnose by a. Plain XR and MRI remain the most used and beneficial modalities.


Classification of AVN
i. Hawkins type I fractures are non displaced vertical neck fractures.
AVN is 10%.
ii. Hawkins type II fractures consist of a vertical talar neck fracture with either subluxation or
displacement of the STJ.
AVN is 42%.
iii. Hawkins type 3 fractures are characterized by a vertical talar neck fracture with subluxation or
dislocation of both the ankle and STJs.
AVN 91%.
iv. Hawkins type IV fractures vertical talar neck fracture with subluxation or dislocation of the ankle,
STJ, and the TNJ.
AVN of 100%.


what is Hawkins sign
AVN=Hawkins sign: subchondral radiolucent line along the superior aspect of the talar dome, which
classically begins on the medial side of the talar dome, and appears 6-8 weeks after injury.

indicative of talar revascularization; seen on AP or mortise view.


MRI presentation of AVN
i. MRI is the most widely used modality to dx and potentially prevent further talar damage due to
AVN.


a. Normal T1 images will show a strong SI due to bone marrow elements in trabecular bone.
b. In early AVN, diffuse marrow edema produces low signal intensity on T1 images and high SI on T2.
c. In advanced stages, the diagnosis of AVN on MRI includes decreased SI on both T1 and T2 weighted
images indicative of areas of devascularization or necrotic bone.


Why perform arthroscopy for AVN
a. Arthroscopic Debridement and Core Decompression:
i. Rationale: Thought to enhance revascularization and decrease intraosseous pressure.
1. Indicated in treatment of F&A stages I and II (partial AVN and those without collapse).
ii. Technique: Standard AM and AL portals used for arthroscopy with a lateral sinus tarsi (lateral
process) approach for retrograde drilling.


post op avn sx
Posterior splint until sutures removed followed by NWB cast for 4 weeks.

1.

5-6 weeks PO, patient placed into a patellar tendon WB boot walker or brace but still kept strictly
NWB (NWB ROM exercises started).
2. 8 weeks PO, XR are taken and the integrity of the talus is judged, PWB allowed on the PTB boot and
as healing continues WB is progressed. Patient is then in rigid AFO for the first 6 months.

, types of Bone Grafts for Talar AVN
1. Nonvascularized cancellous autograft can be taken from the iliac crest, calcaneus, or femoral head.
Useful only in small, contained defects since this does not supply structural support.
2. Vascularized pedicle autograft:
Rationale: limited area of necrotic bone can be debrided and removed and a vascularized graft is
plugged in to bring in fresh, viable bone and perfusion.
3i. Bone allograft:
1. Nonvascular bulk allografts using fresh cadaver talus are a viable option for partial talar AVN.
2 Fresh talar bulk allograft


i. Vascularized EDB pedicle graft surgical technique:
1. Incision made 2 cm anterior to the tip of the lateral mal, curving toward the base of the 3rd MT.
2. Deep dissection carried down to lateral EDB muscle. An OT of the anterior calcaneal tubercle is
performed, preserving the EDB muscle attachment.
3. Bore hole made into the lateral talar half of the talar neck extending into the talar body. Thorough
curettage of the subchondral necrotic bone through the tunnel is performed.
4. Vascularized bone graft then contoured and snugly fit into the talar body without fixation.
5. PO Course: NWB cast 6-8 weeks with gentle ROM beginning at 6 weeks. Protected WB in fracture
boot for another 4 weeks, then PT. Restriction of activity for the first year PO.


Discuss Nonvascular bulk allografts using fresh cadaver talus for partial talar AVN.
a. Matched for side, gender, and approximate size and contain living cartilage.
b. Rationale: fresh talar allografting may be selected over core decompression or EDB pedicle transfer
when early collapse or overlying cartilage death has occurred and in cases in which clear margins of
viable and necrotic bone are present.
i. Allows large portion of diseased talus to be excised and replaced.


Discuss Fresh talar bulk allograft surgical technique:
a. Often lateral, medial, or both malleoli OTs required for adequate exposure.
b. MC, the MM is OT- curvilinear incision made over the medial gutter, and the MM is predrilled with
2 4.0mm cannulated cancellous screw guide pins. The wires are measured and the proximal cortex is
overdrilled prior to removal of the guide pins.
c. Chevron OT performed to flap down the MM with the deltoid ligaments still attached to expose the
medial shoulder of the talar dome. Posterior structures must be protected.
d. Access to lateral talar lesions may require transection of the lateral collateral ligaments or fibular
OT. A 5-hole 1/3 tubular plate is contoured and pre-drilled to stabilize the lateral OT to assist in
assuring exact reduction at the completion of the case; the OT is made transversely under power at
the level of the AJ.
e. An anterior approach is used for central defects or in cases in which the partial AVN affects the
entire talar ankle joint surface (between EHL and TA tendons).
f. Once exposure is adequate, the talar defect is inspected; margins of necrotic bone are probed and
identified. This is debrided down to vascular, bleeding bone.
g. The base and edges of diseased bone are cut squarely with a saw and the inner surfaces is cut with
a curved osteotome to construct a geometric shape.
h. The donor site is reinspected for viable bone and cartilage margins, making sure that all necrotic
bone is resected.
i. Location of AVN and dimensions of the recipient's excavated bone are used to determine the exact
matching site for harvesting the donor allograft. It is advised to slightly oversize measurements.
j. The bulk talar allograft is press fit into the recipient's matching void.
k. Chondral darts and resorbable or headless screws are used to permanently fixate the graft into
place. Malleolar OT is realigned with their pre-drilled hardware.
l. PO Care: Strict NWB for at least 8 weeks with gentle ROM exercises beginning at 4 weeks, protected
WB in PTB boot is usually allowed at 8-10 weeks, depending on radiographic healing. Progression to
protective brace or AFO at 4 months with protection from impact activities for 1 year.