This document summarizes recent developments in the understanding and treatment of posterior malleolar fractures of the ankle. While fractures involving over 25% of the articular surface were previously thought to require fixation, several studies found no relationship between fragment size and functional outcomes or arthritis development. Instead, postoperative intra-articular step-off over 1mm is a risk factor for worse outcomes. Anatomic reduction and fixation of all posterior fragments is recommended to prevent step-off. Open reduction and internal fixation via a posterolateral approach provides better reduction and outcomes than percutaneous anterior-to-posterior screw fixation.

1. Posterior Malleolar Fractures: Recent Developments
and Changing Concepts

2. ● Posterior malleolar fractures are observed in approximately 14%–44% of all ankle
fractures.
● The most common type of posterior malleolar fracture involves the posterior
tubercle, resulting in an avulsion of the posterior inferior tibiofibular ligament
(PITFL) following a rotational ankle injury
● Posterior malleolus fractures associated with more severe injury and worse
outcome so proper treatments need to be understood (Tejwani J Trauma 2010)
According to AO, a posterior fragment comprising more than 25% of the intra-articular
surface needs to be fixated
However, recent literature seems to suggest otherwise...
Overview

3. Does size affect functional outcomes?
Comparing functional outcome (AOFAS, AAOS, and Weber scores) with
respect to size of the posterior fragment
● Langenhuijsen et al. (2002), n=57, retrospective cohort
● Xu et al. (2012), n=102, retrospective cohort
● Drijfhout et al. (2015), n=131, retrospective cohort
● Evers et al. (2015), n=42, retrospective cohort
Could NOT find a significant difference in function outcome with respect to
different posterior fragment sizes.

4. Does size affect development of arthritis?
● Xu et al. (2012), n=102, retrospective cohort
● Drijfhout et al. (2015), n=131, retrospective cohort
● Verhage et al. (2019), n=169, retrospective cohort
Found NO relation between fragment size and development of osteoarthritis.

5. If not size, then what influences outcomes?

6. Intra-articular step-off
Xu et al., Drijfhout et al., and Verhage et al. found that persisting postoperative
intra-articular step-off of the posterior fragment (> 1 mm) was a significant risk
factor for the development of osteoarthritis and worse functional outcome.
Advised to anatomically reduce all posterior fragments with intra-articular
involvement
Fixation is needed to prevent redislocation and thus a persistent postoperative
step-off

7. Anatomic Location
Bartonicek and Rammelt Three-Dimensional Computed Tomography Classification (2015)
Type 1: Extraincisural fragment
Type 2: Posterolateral fragment
Type 3: Posteromedial, two part fragment
Type 4: Large, posterolateral triangular fragment

9. Treatment recommendations
Type 1 (Extraincisural) : non-operative
Type 2 (Posterolateral): ORIF
Type 3 (Two-part): ORIF
Type 4 (Large triangular): ORIF

10. Why fixating posterior malleolar fractures beneficial
Restoration of articular congruence -> posterior ankle stability
Restoration of the integrity of the fibular notch -> reduction of the distal fibula
● Miller et al. (2010) : With PM reconstruction, the distal fibula is reduced more
accurately into the restored fibular notch
Restoration of the competence of the PITFL -> syndesmotic stability

11. Posterior Malleolus vs Transyndesmal Fixation

12. Posterior Malleolus versus Transyndesmal Fixation
As PM fractures should be considered bony avulsions of the PITFL, anatomic reduction of the PM is hypothesized to restore
syndesmotic stability.
Gardner et al. (2006)
70% stiffness of the distal tibiofibular articulation was restored by reducing and stabilizing the posterior malleolus compared
to 40% through the use of a syndesmotic screw.
Miller et al. (2010)
Suggested that fixation of posterior malleolus fracture is more likely to restore stability to the syndesmosis compared to
trans-syndesmotic fixation alone.
Baumbach et al. (2019)
Study demonstrated a 60% decrease in trans-syndesmotic fixation following ORIF of the PM fragment
ORIF of the posterior malleolar fracture, no matter what size, can provide adequate
stabilization of the syndesmosis through the PITFL.

13. What type of fixation for posterior malleolar
fractures?

14. “A to P” Screw vs Posterolateral Plate Fixation
CRIF
-Percutaneous anterior to posterior screw
fixation after closed reduction through
ligamentotaxis
ORIF
-Direct open reduction and fixation via
posterolateral approach with plate fixation

15. Comparing step-off rates
Huber (1996) retrospective study, n=60
AP: 73 %
ORIF: 17%
O’Connor (2015) retrospective cohort, n = 27
AP: 18%
ORIF: 13%
Shi (2017) prospective cohort, n= 116
AP: 17%
ORIF: 8%

16. Fixation of the posterior malleolus via an open posterolateral approach is superior
to percutaneous anterior-to-posterior fixation
- Radiographically superior with decreased incidence of step-off
- Functionally superior with better AOFAS scores

17. In conclusion
Fixate posterior malleolar fractures regardless of size
Posterior malleolus fixation is superior to transsyndesmotic screws
Fixation of the posterior malleolus via an open posterolateral approach is superior
to percutaneous anterior-to-posterior fixation

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