Homepage Articles The Posterolateral Approach to the Posterior Malleolus: An Alternative Surgical Strategy for Unstable Trimalleolar Ankle Fractures


The Posterolateral Approach to the Posterior Malleolus: An Alternative Surgical Strategy for Unstable Trimalleolar Ankle Fractures


Ross A. Benthien, MD, MPH*wz

Summary: The large posterior malleolus fragment seen in many

unstable trimalleolar ankle fractures can be safely and effectively

approached through the posterolateral approach to the ankle. This

approach allows for thorough debridement of the fracture and ankle

joint and anatomic reduction of the posterior malleolus with secure

plate fixation on the posterior tibia. This approach also allows for

reduction and posterior fixation of the related fibula fracture and in

combination with reduction of the posterior malleolus, may reduce and

secure the distal tibiofibular syndesmosis without the need for transosseous

fixation of the syndesmosis. With prone positioning, fixation

of a related medial malleolus fracture and intraoperative imaging is

easily facilitated.

Key Words: posterior malleolus—posterolateral approach—trimalleolar

ankle fracture.

(Tech Orthop 2014;29: 8–12)

Displaced trimalleolar ankle fractures often represent a

complex injury that results in malalignment of the tibiotalar

joint, disruption of the weight-bearing portion of the tibial

plafond, and possible disruption of the distal tibiofibular syndesmosis.

Not surprisingly these injuries have poorer outcomes

than more straightforward ankle fractures and the source of this

increased disability is very likely multifactorial.Although the

tendency toward worse outcomes may be the result of factors

such as higher-energy injuries or osteopenia, the lack of a

comprehensive approach to address all components of these

injuries may also play a significant role.

The posterior malleolus historically has been treated as an

afterthought in the surgical management of ankle fractures, and

no consensus currently exists on when fixation should be

pursued.Anatomic reduction and rigid fixation of medial and

lateral malleolus fractures have routinely been the key components

of surgical strategy, with posterior malleolus fractures

comprising up to 25% of the anterior-posterior dimension of

the distal tibia often left untreated. Some reports have supported

this “benign neglect” of the posterior malleolus based

upon clinical observation, despite the fact that biomechanical

evaluations have clearly shown that tibiotalar joint contact area

decreases along with the size of the posterior fracture fragment.

3–5 Others have demonstrated in biomechanical studies

that the posterior malleolus is not a primary restraint to posterior

subluxation of the talus but they did not assess the

impact on joint contact area. None of these investigations

assessed joint contact pressures or syndesmotic alignment.6,7

All but the smallest fractures of the posterior malleolus

represent intra-articular fractures of the ankle, a major weightbearing

joint of the lower extremity. These fractures can be

highly variable, involving the medial malleolus in up to 20% of

cases and computed tomography scans can be helpful in

defining the fracture anatomy.In addition, the posterior

malleolus acts as the origin of the posterior ankle joint capsule

and attachment of the posterior-inferior tibiofibular ligament

(PITFL), a key stabilizer of the distal tibiofibular syndesmosis.

Open reduction and rigid internal fixation of the posterior

malleolus fracture fragment holds the promise of restoring

tibiotalar contact area, facilitating anatomic alignment of the

syndesmosis and prevention of posterior capsular contracture

and the resultant loss of ankle dorsiflexion.

Recent clinical and biomechanical studies have demonstrated

that the standard method of syndesmotic fixation, with

clamp reduction and transosseous syndesmotic screws, may

lead to subluxation of the fibula or overcompression of the

syndesmosis, and this raises the possibility of degenerative

changes and persistent postinjury impairment.9–11 Gardner

et al12 demonstrated by magnetic resonance imaging an intact

PITFL in all 15 patients with pronation-external rotation type

ankle fractures and in a related biomechanical model of this

injury type, showed that repair of the posterior malleolus

fracture resulted in greater stiffness of the syndesmosis than

traditional screw fixation. Direct fixation of the posterior

malleolus holds the promise of reducing the need for syndesmotic

fixation, the potential for malreduction, and subsequent

surgery for syndesmotic screw removal.

Most commonly, the posterior malleolus is addressed

after fixation of the medial and lateral injuries and often with

the patient positioned supine. Although alignment of the posterior

malleolus is routinely improved with reduction of the

fibula, because of the intact PITFL, in many cases gaps and

step-off of the joint surface often persists, likely because of the

result of interposed fracture debris or imperfect reduction of

the fibula. An alternative approach to the treatment of trimalleolar

ankle fractures is anatomic reduction of the posterior

malleolus as the first step in repair of the unstable ankle, which

arguably addresses the most important intra-articular portion of

the fracture and through attachments of the PITFL, also helps

to reestablish the length and rotation of the distal fibula.

The use of the posterolateral approach for displaced ankle

fractures has been well described in the literature, and although

the results have been comparable to those of operative ankle

fractures in general, the number of patients has been limited, as

have the follow-up and outcomes.13–16


Surgery is routinely performed on an ambulatory basis, in

the prone position, under tourniquet control, with general

From the *Orthopedic Associates of Hartford; wBone and Joint Institute

at Hartford Hospital; and zDepartment of Orthopaedic Surgery, University

of Connecticut School of Medicine, Hartford, CT.

The authors declare that they have nothing to disclose.

Address correspondence and reprint requests to Ross A. Benthien, MD,

MPH, 85 Seymour Street, Suite 607, Hartford, CT 06106.

E-mail: rossbenthien@gmail.com.

Copyright 2014 by Lippincott Williams & Wilkins


| www.techortho.com Techniques in OrthopaedicsVolume 29, Number 1, 2014

anesthesia and popliteal and saphenous nerve blocks. Prone

positioning provides a number of advantages including: easy

access to all fracture components with minimal manipulation

of the limb, the decreased need for surgical assistants, ease of

soft-tissue retraction, and improved surgeon comfort. In addition,

prone positioning with a bump under the leg facilitates

reduction of the posteriorly displaced fibula and posterior

malleolus fracture fragments through gravity and direct

downward pressure on the posterior malleolus during reduction.

If medial fixation is required it can be helpful to place a

bump under the contralateral hip to allow for better visualization,

and flexing the knee intraoperatively can also be

helpful by elevating the medial malleolus above the table and

the nonoperative limb. Both prone and lateral decubitus positioning

have been advocated for the posterolateral approach to

the ankle.13–16

Minifluoroscopy is utilized during surgery and with

experience, posteroanterior, mortise, and lateral views can

easily be obtained. Placing the ankle on a bump during surgery

allows for easier lateral imaging by raising the operative leg

above the contralateral limb. Stress radiographs are routinely

obtained to check for stability of the tibiotalar joint and the


A longitudinal incision is made midway between the posterior

border of the fibula and the lateral border of the Achilles

tendon (Fig. 1A). The incision is carried no more distal than the

tip of the fibula and the sural nerve is rarely visualized, although

care should be taken to prevent nerve injury as anatomy can

be variable. The fascia overlying both the peroneal and flexor

hallucis longus muscle bellies is divided separately and allows

for muscle mobilization.

The flexor hallucis longus in retracted medially with a

Homan retractor placed over the medial border of the tibia.

The periosteum of the posterior malleolus is elevated to allow

for mobilization of the posterior malleolus. Care must be taken

to leave the attachments of the PITFL on the fibula and posterior

malleolus undisturbed. With a smooth lamina spreader,

even in osteopenic bone, the malleolus is distracted and the

articular surface of the talus is visualized (Fig. 1B). Fracture

debris is often removed from the joint with a pituitary rongeur

and the tibial joint surface can be reduced if local impaction

has occurred. The posterior malleolus is then reduced and

secured with K-wires and then rigidly fixed, typically with a

combination of partially threaded cannulated screws and a one

third tubular buttress plate (Fig. 1C).

The fibula fracture is approached through the same incision

after secure fixation of the posterior malleolus. Simple

fracture patterns are opened and reduced in the typical manner

and then secured with interfragmentary fixation and a neutralization

plate placed either posterior or lateral. A posterior

plate is often applied to the fibula, especially for more proximal

fractures and for comminuted fractures wherein a bridgeplating

technique is being utilized (Fig. 1D). Attention must be

paid to the peroneal tendons, making sure that fixation devices

are not prominent distally and that the retinaculum is intact

distal to the tip of the fibula to prevent peroneal tendon


Medial fixation is based upon the fracture pattern and

may require typical open interfragmentary fixation, percutaneous

cannulated screws, or buttress plates for vertical sheartype

fractures. Medial fractures are approached through a

separate medial longitudinal incision. Purely ligamentous

medial injuries are not routinely repaired. Wounds are closed

in layers and a bulky Jones type dressing is applied in the

prone position with neutral ankle dorsiflexion.


Patients are followed up back in the office at 2 weeks,

radiographs are obtained, a CAM boot is supplied, and active


FIGURE 1. A, Patient is positioned prone and posterolateral incision is marked equidistant between the posterior border of the fibula

and the lateral border of the Achilles tendon. B, Flexor hallucis longus reflected medially with smooth lamina spreader in the posterior

malleolus fracture site. C, Posterior plating of the fibula with the peroneal muscles retracted laterally. D, One third tubular plate on the

posterior tibia securing the malleolus fracture.

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range of motion is initiated. Typically, at 6 weeks from surgery,

weight-bearing radiographs are performed and weightbearing

and formal physical therapy is initiated. In most cases

patients are maintained on aspirin for 4 to 6 weeks for DVT



Case #1

Closed, unstable trimalleolar ankle fracture was sustained by a

42-year-old, diabetic, motorcycle racer. The fracture was reduced and

splinted at an outside hospital (Figs. 2A, B). The large, comminuted

posterior malleolus fracture was particularly amenable to direct

reduction and posterior plating, and the fibula was also reduced and

secured through the same incision. Intraoperative stress maneuvers

showed the syndesmosis to be stable. A medial buttress plate secured

the vertical shear-type medial malleolus fracture through a medial,

longitudinal incision (Figs. 2C, D). Partial weight-bearing was initiated

at 6 weeks in a CAM walker and full weight-bearing with an ankle

brace was allowed at 9 weeks. Final follow-up was at 7 months with

healed fractures, anatomic alignment, and full range of motion.

Case #2

Closed, unstable trimalleolar ankle fracture was sustained in a

work-related slip and fall injury by a 38-year-old diabetic patient with

a body mass index of 42. The comminuted posterior malleolus fracture

included an interposed fragment that would have likely prevented

anatomic alignment and the posterolateral approach was chosen as it

allows for more thorough joint debridement and secure fixation of large

fracture fragments (Figs. 3A, B). Intraoperative imaging demonstrated

anatomic alignment of the ankle mortise and a stable syndesmosis.

Weight-bearing was permitted at 5 weeks in a CAM walker with

weaning to an ankle brace with physical therapy. The small medial

malleolus fracture fragment was not directly addressed at the initial

surgery, but persistent pain in this area ultimately resulted in ankle

arthroscopy, fragment excision, and deltoid ligament repair. At 18

months, range of motion was full, no degenerative changes were evident,

and the patient had no work restrictions.

Case #3

Closed, unstable ankle fracture was observed in a 52-year-old as

a result of a slip and fall on a wet subway platform. The fracture was

reduced and splinted at an outside hospital. Radiographs revealed a

nearly 50% posterior malleolus fracture with local comminution. The

medial injury was deltoid ligament rupture (Figs. 4A, B). The posterior

malleolus was addressed with a cannulated screw and buttress plate

and the comminuted fibula fracture with bridge plating. Intraoperative

imaging confirmed a stable syndesmosis. Weight-bearing was initiated

at 6 weeks in a CAM walker with weaning to an ankle brace with

physical therapy. At 4 months the patient was brace-free with nearly

full range of motion, and radiographs showed anatomic alignment of

the ankle (Figs. 4C, D).


The posterolateral approach is most helpful in those trimalleolar

fractures that include a large posterior malleolus

fracture, generally 20% to 50% of the distal tibia, and an

associated fibula fracture. This approach allows for direct

inspection of the injury, direct assessment of reduction quality,

and application of robust fixation constructs.

For the author this approach resulted in few superficial

wound complications and no cases of sural neuropathy or

complex regional pain syndrome was reported. Fixation

hardware on the posterior tibia is deep and to this point

removal has not been necessary. Similarly, fixation hardware

on the posterior fibula is less prominent than typically noted

with lateral placement and to this point has not been a problem.

Others have reported the need for removal of symptomatic

hardware and sural nerve-related pain and neuropathy at rates

similar to other approaches to ankle fractures.13–16

FIGURE 2. A and B, Anteroposterior and lateral radiographs of a pronation-external rotation type ankle fracture with a posterior

malleolus fracture estimated at 50% of the anterior-posterior depth of the distal tibia. Although somewhat obscured by overlying cast

material, the posterior malleolus is comminuted. C and D, At 7 months’ follow-up, the joint surfaces are in anatomic alignment, all

fractures are healed, and degenerative changes are not evident.

Benthien Techniques in OrthopaedicsVolume 29, Number 1, 2014

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A significant potential advantage of this approach to

unstable trimalleolar ankle fractures is reduction and stabilization

of the syndesmosis through rigid fixation of the posterior

and lateral malleolus. Traditional syndesmotic fixation has

come under increasing scrutiny as a potential source of malreduction

and degenerative changes within the distal tibiofibular

articulation. The PITFL is consistently intact in these

fracture patterns, and anatomic, secure reduction of these

fractures should limit the need for transosseous fixation of the

syndesmosis. It has been the author’s experience that with

stable fracture fixation, syndesmotic fixation has been unnecessary.

It is of course possible to have an unstable syndesmosis

even after rigid fracture fixation and this should

always be evaluated with intraoperative stress maneuvers.

Intraoperative observation generally shows the posterior

periosteum to be intact and with division and elevation, the joint

FIGURE 3. A and B, Initial radiographs showing a trimalleolar ankle fracture with comminution of the fibula, interposed fracture

fragments at the posterior fracture site, and a small medial malleolar avulsion fracture. C and D, Final follow-up radiographs demonstrating

anatomic alignment of the ankle mortise and well-healed fractures. Note that the suture anchor is placed medially after excision

of a symptomatic medial malleolus avulsion fracture.

FIGURE 4. A and B, Initial radiographs showing comminuted posterior malleolus and fibula fractures with posterolateral subluxation of

the talus. C and D, Anatomic reduction is achieved with a cannulated screw and buttress plate on the posterior malleolus and posterior

plating of the fibula has reestablished length and rotation.

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can be visualized in all cases. This allows for thorough joint

debridement and irrigation, which holds the possibility of less

postsurgical cartilage damage and more precise fracture reduction.

Cortical fracture lines and intraoperative imaging allows for

anatomic or near-anatomic reduction of all fractures. Anatomic

alignment and rigid fixation has always been the “gold-standard”

for the operative treatment of intra-articular fractures as this is felt

to reestablish normal joint mechanics and load distribution.

Lindsjoshowed that up to one third of patients with posterior

malleolus fractures large enough to violate the weight-bearing

portion of the tibial plafond developed posttraumatic arthrosis,

twice the rate seen with small extra-articular fractures. This certainly

suggests that anatomic reduction may decrease the rate of

arthrosis and potentially patient outcomes.


The posterolateral approach toward unstable trimalleolar

may offer a number of potential advantages, including

improved joint debridement, improved reduction of the

weight-bearing portion of the distal tibia, and possibly secure,

anatomic fixation of the syndesmosis, minimizing the need for

more traditional fixation methods. Complications are few,

comparable to those seen in ankle fractures more generally.


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Benthien Techniques in OrthopaedicsVolume 29, Number 1, 2014

12 | www.techortho.com _2014 Lippincott Williams & Wilkins