- See:
-
technique of snydesmotic fixation:
-
syndesmotic sprain
- Anatomy:
- syndesmosis is made up of anterior-inferior tibiofibular ligament,
interosseous ligament,
and posterior-inferior fibular ligaments, inferior
transverse tibiofibular ligament, and
interosseous ligament;
- these stabilize the mortise by opposing the fibula in the fibular
notch (incisura fibularis tibiae);
- section of the anterior tibiofibular ligament results in diastasis of 2.3
mm;
- section of anterior tibiofibular ligament and interosseous ligament will
result in diastasis of 4.5 mm;
- when all 3 ligaments are sectioned, diastasis measures 7.3 mm;
- syndesmotic injuries are unusual in displaced Weber B fractures;
- in the anatomic study by MH. Snedden and JP. Shea, the authors noted that
the
interosseous ligament, may have a variable attachment
on fibula, differing between specimens
in its distance above the synovial reflection or
joint line;
- low fibula fracture would disrupt the interosseous ligament, can
explain the anatomic
basis
for infrequent diastasis in these ankle fractures;
- Diastasis With Low Distal Fibula Fractures An Anatomic
Rationale. Snedden COOR
2001 January;2001(382):197-205
-
Objective Diagnosis of Syndesmotic Injury:
- Injury Patterns:
-
isolated
syndesmotic injury:
- syndesmotic injury & fibular frx;
- w/ syndesmosis & fibula disruption, talus can shift laterally 2 to
3 mm, even w/ deep
deltoid ligament intact;
- syndesmotic injury + medial injury:
- > 3 mm displacement indicates that either the deep deltoid ligament
or medial malleolus must be disrupted;
- if
medial
malleolus
syndesmosis
fixation unnecessary;
- Indications for Syndesmotic Fixation::
- combination of
irreparable medial joint injury
joint (
Weber C Frxx
- hence standard teaching is that w/ rigid ORIF of the
medial
malleolus
generally
not be required);
- between 3 to 4.5 cm indication for fixation remains unclear;
- in contrast to the standard teaching, the report by P. Tornetta MD (JBJS
Jun 2000, Vol 82-A, No 6)
demonstrated using an in vivo radiographic model that
in bimalleolar fractures, the medial injury may be an
osseous avulsion, leaving the deltoid intact on the
displaced fragment, or it may be a combination of ligamentous
and osseous injury with disruption of the deep
portion of the deltoid ligament;
- in the later case, ORIF of the medial malleolus may not restore
function to the deltoid ligament;
- in this case, it is unclear whether syndesmotic fixation would be
required;
- in the report by JG Kennedy et al (JTO Vol 14, No 5, p 359-366), the
authors examined the effect of
syndesmotic screws in low Weber C fractures;
- low
Weber C fractures are defined as being within 5 cm of the jiont;
- 26 patients had ankle ORIF with syndesmotic fixation and 19 had
ORIF w/o a syndesmotic screw;
- there was no significant difference between either group using
subjective and objective criteria;
-
high
fibular frx
- even w/ anatomic fixation of medial malleolar frx, syndesmotic
screw fixation is indicated for fibular
frxs
occurring more than 15 cm above the joint;
- syndesmotic fixation is recommeded w/ medial ligamentous injury,
syndesmotic disruption, & talar shift
w/o frx of fibula (diastasis);
-
case example:
- 40 year old prisoner who sustained this Weber C frx which was fixed
w/o a syndesmotic screw;
- 7 years later the patient had significant arthritis and
significant pain;
- notice the heterotopic calcification along the interosseous
membrane;
- Contra-indications for Syndesmotic Fixation (w/ Syndesmotic Injury):
- w/ < 3 cm of sydesmotic disruption above plafond, there is little or no
alteration was seen of ankle loading characteristics;
- anatomic reduction of fibula, esp if frx is w/in 4 cm of joint, tends to
reduces talus in Mortise &
restores syndesmotic stability;
- if
medial
malleolus is frxed &
deltoid ligament
fixation unnecessary;
- Fixation Techniques::
-
screw insertion technique for snydesmotic fixation:
- K wire fixation:
- two 1.5 mm K wires can be inserted obliquely across the distal
tibio-fibular syndesmosis;
- is a less rigid form of fixation, which allows more physiologic
ankle function, and does not require
early hardware
removal;
- suture fixation:
- involves the creation of two small drill holes through the fibula
and tibia (separated 7-10 mm) above the
ankle syndesmosis
(between 2-5 cm), through which is passed a single No 5 Ethibond suture to form
a loop;
- the suture is tied over the fibula, securing the fibula to
the tibia;
- advantages: there is no need for hardware removal and nor is there
risk of hardware failure;
- in the study by RS Miller et al (JTO 1999), the suture technique
showed similar strength characteristics
to tricortical
screw fixation techniques;
- references:
- Comparison of tricortical screw fixation vs a modified
suture construct for fixation of ankle
syndesmotic injury: A biomechanical study. JOT Vol 13. p 39-42.
- Repair of the tibiofibular syndesmosis with a flexible
implant. WH Seitz et al. Journal of
Orthopaedic Trauma. Vol 5. 1991. p 78-82.
-
Comparison of a Novel FiberWire-Button Construct versus Metallic Screw Fixation
in a
Syndesmotic Injury Model
Mechanical considerations for the syndesmosis screw. A cadaver study.
Instability of the distal tibiofibular syndesmosis after bimalleolar and
trimalleolar ankle fractures.
The tibiofibular syndesmosis. Evaluation of the ligamentous structures, methods
of fixation, and radiographic assessment.
Operative treatment of syndesmotic disruptions without use of a syndesmotic
screw: a prospective clinical study.
Clinical use of a syndesmosis screw in stage IV pronation-external rotation
ankle fractures. Orthop Rev. Vol 23, 1994. p 23-28.
Ankle mortise stability in Weber C fractures. Indications for syndesmotic
fixation. J. Orthop. Trauma. Vol 5, 1991. p 190-195.
The influence of a diastasis screw on the outcome of Weber type C ankle
fractures. HR Chissell, J Jones. JBJS 77-B, 1995. p 435-438.
Competence of the Deltoid Ligament in Bimalleolar Ankle Fractures After Medial
Malleolar Fixation* Tornetta JBJS Jun 2000, Vol 82-A, No 6. p 843
Tibiotalar joint dynamics: indications for the syndesmotic screw: a cadaveric
study. WC Burns. Foot Ankle 1993. Vol 14. p 153.
A biomechanical evaluation of clinical stress tests for syndesmotic ankle
instability.
Instability of the tibio-fibular syndesmosis: have we been pulling in the wrong
direction?
Examination and Repair of the AITFL in Transmalleolar Fractures.
Outcome after
fixation of ankle fractures with an injury to the syndesmosis
No difference in functional and radiographic results 8.4 years after
quadricortical compared with tricortical syndesmosis fixation in ankle fractures.
Functional outcomes after syndesmotic screw fixation and removal.
Outcome after unstable ankle fracture: effect of syndesmotic stabilization.
Functional and radiographic results of patients with syndesmotic screw fixation:
implications for screw removal.
