How to perform a lateral ankle approach
Source
Surgeon:
Lasse Rämö (orthopedic surgeon)
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Summary
Focus: Safe and adequate access to the lateral malleolus or distal fibula fracture site.
Key elements: Incision planning, protection of the superficial peroneal and sural nerves, fracture exposure, fixation considerations, wound closure, pitfalls, and complications.
Indications and Clinical Context
General
Medical experts: Lasse Rämö (orthopedic surgeon), Thomas Schlenzka (orthopedic surgeon), Mikael Åkerback (orthopedic surgeon)
Name of Procedure: Lateral ankle approach
Goal of Operation
To ensure safe and adequate access to the fracture site, as well as to restore the anatomy of the ankle mortise and the function of the ankle joint by fixating the fracture.
Problem
A fracture leading to a deformed or unstable ankle joint.
Diagnosis
Fracture of the lateral malleolus (ICD-10: S82.6)
Short Pathophysiological Description
The malleoli of the tibia and fibula hold the talus stable against the distal surface of the tibia at the talocrural joint. These three structures—the malleoli and the distal articular surface of the tibia (= the tibial plafond)—form the ankle mortise. Ankle syndesmosis is a ligament complex binding the distal tibia and fibula together, ensuring the stability of the ankle mortise, which is crucial for its function. Some ankle fractures deform the ankle mortise or destabilize it, compromising joint functionality. In addition, fracture displacements at the joint surfaces may lead to post-traumatic arthritis. These types of fractures often require surgical treatment.
Presented on our platform are three approaches that should provide adequate exposure for the majority of common malleolar fractures, either isolated medial/lateral, bimalleolar, or trimalleolar. The “third” malleolus stands for the posterior aspect of the tibial plafond, referred to as the posterior malleolus.
Generally, isolated fractures of the lateral malleolus and distal fibula can be approached via the lateral approach, fractures of the posterior malleolus via the posterolateral approach (which also allows exposure of the distal fibula), and fractures of the medial malleolus via the medial approach.
Key Anatomical Structures
Fibula
Tibia
Talus
Syndesmosis
Peroneal muscles: tertius, longus, and brevis
Superficial peroneal nerve
Sural nerve
Small saphenous vein
Step-by-Step Technique
Patient Positioning, Anesthesia and Preparation
The patient is either in lateral decubitus position (isolated lateral fractures) or supine with the leg rotated internally.
Both general and spinal anesthesia are applicable.
Landmarks
Locate the lateral malleolus and the palpable distal portion of the shaft of the fibula. Mark the planned incision line.
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Skin Incision
Make a longitudinal incision along the fibula.
The incision can be slightly anterior or posterior to the midline of the bone, depending on which structures you need to access.
In fracture surgery, you should try to center the incision at the level of the fracture.
If the subcutaneous tissue layer is really thin, the incision should be slightly anterior or posterior to, and not directly on top of, the planned fixation plate to avoid soft tissue problems post-operatively.
Advancing Through Subcutaneous Tissue
Advance through the subcutaneous tissue with careful blunt dissection to prevent iatrogenic damage to nerve structures. The superficial peroneal nerve most often runs close to the anterior border of the fibula and should be protected when visualized. The more proximal the fracture is, the more likely it is to encounter the superficial peroneal nerve. Keep in mind that numerous variations of the location and course of the superficial peroneal nerve have been reported.
The sural nerve may run over the lateral malleolus in a posterior-to-anterior direction. When visible, make sure not to damage it.
When using the retractors for optimal visibility, and otherwise handling the soft tissues, keep in mind that excessive stretching, such as spreading the wound aggressively, may cause soft tissue damage.
Expose the Fracture Site
Identify the three peroneal muscles: tertius, longus, and brevis.
Advance between these muscles, with the peroneus tertius anteriorly and the peroneus longus and brevis posteriorly, to expose the fracture.
There can be debris at the fracture site, interposed between the fragments. All debris interfering with fracture reduction should be carefully removed.
However, try to minimize stripping the periosteum in order to preserve as much blood supply of the bone as possible.
Expose the posterior edge of the fibula. This is often the only area where you can properly evaluate the accuracy of your reduction when the fracture is comminuted.
Keep in mind the sural nerve, which might come near to the operation site posteriorly. The small saphenous vein might also run along the posterior border of the lateral malleolus.
This is the end of the approach section. In fracture surgery, you would now reduce and fixate the fracture.
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Fix the Fracture
This is where the technical description of the approach ends. During surgery, however, there is still usually a fracture to fixate. This can be done in several ways, largely depending on the type of fracture in question. Here we describe briefly how to fixate a simple oblique fracture.
In simple oblique fractures, you can use a lag screw for fixation. This should keep the reduction stable while you place the neutralization plate.
Start by drilling both cortices and then choose a drill bit with the same diameter as your screw. Then measure and insert the lag screw before putting in the plate.
If the ankle mortise is unstable (syndesmotic injury), a syndesmotic screw or other implants can be used to stabilize it. Before you do this, make sure that the length of the fibula is restored (that no shortening due to the fracture remains), that no rotational displacement is left, and that it is correctly positioned in the tibial groove.
When satisfied, you can drill the hole for your implant. Remember that in the coronal plane, the fibula is positioned at the posterior aspect of the tibia. Therefore, you should drill with an angulation 30 degrees posterior-to-anterior. Start slightly proximal to the inferior tibiofibular joint and direct the screw parallel with the tibial plafond and the ankle in neutral position.
Wound Closure
The aim is to cover the plate with the maximum number of tissue layers. Ideally, the fascia should be closed (e.g. with 0 Vicryl), but it is often difficult and may have to be left open.
The subcutis is closed with continuous absorbable sutures (e.g. 2-0 Vicryl). Subcutaneous bites should be made superficially, observing the course of the sural nerve and the superficial peroneal nerve branch.
Close the skin with sutures or surgical staples.
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Piftalls and Complications
Pitfalls
Incorrect Site of Incision
An incision made too anterior may cause injury to the superficial peroneal nerve branch. An incision made too posterior may cause injury to the sural nerve or the small saphenous vein.
When planning the incision site, the location of the fracture and the intended fixation material should also be noted. The incision site should not be directly over the site of the planned fixation plate if possible.
Careless Tissue Handling
The skin incision should be sufficiently superficial in order to not cause injury to the superficial peroneal nerve branch. Blunt advancement through the subcutis is important, particularly in the cranial part of the incision, where the nerve branch is most likely to be in the operation field. When using the retractor, remember that undue tension may cause injury to the adjacent tissues. When closing the incision wound, the course of the sural nerve and the superficial peroneal nerve should be noted to avoid an accidental suture of the nerve.
Complications
Injury to the Superficial Peroneal Nerve Branch
The superficial peroneal nerve branch may be injured if the skin incision is too deep or in the wrong location. This nerve is also at risk when wound closure is performed, so the subcutaneous suturing should be carried out superficially. Injury to this nerve may result in neuralgia or paraesthesia in the dorsal region of the foot.
Note that the course of the superficial peroneal nerve can vary at the level of the ankle. The variants usually pass across the surgical site in the proximal part of the wound, but the nerve can pass over the fibula at almost any level.
Injury to the Sural Nerve
The course of the sural nerve posteriorly to the lateral malleolus should be noted when planning the incision site. Injury to this sensory nerve may cause neuralgia or paraesthesia in the lateral region of the foot. The course of the sural nerve can also vary at the level of the ankle.
Injury to the Small Saphenous Vein
The small saphenous vein runs along the sural nerve. If injured during an operation, however, ligation of the vein can be performed.
Infection
Infection is a potential complication of surgery that can result in significant morbidity and healthcare resource utilization. Infections associated with implanted surgical devices are particularly difficult to deal with because they can require prolonged antibiotic treatment and repeated surgical procedures. Prevention of infection is an imperative part of any surgical procedure.
Aftercare
General Guidelines
Casting, weight-bearing, and other rehabilitation guidelines depend largely on the type of fracture treated.
FAQ
What is the goal of the lateral ankle approach?
The goal is to ensure safe and adequate access to the fracture site, as well as to restore the anatomy of the ankle mortise and the function of the ankle joint by fixating the fracture.
Which nerves should be protected during the lateral ankle approach?
The superficial peroneal nerve and the sural nerve should be protected. The superficial peroneal nerve most often runs close to the anterior border of the fibula, and the sural nerve may run over the lateral malleolus in a posterior-to-anterior direction.
Why should the incision not be directly over the planned fixation plate if possible?
The incision site should not be directly over the planned fixation plate if possible to avoid soft tissue problems post-operatively.
What can be used if the ankle mortise is unstable due to syndesmotic injury?
If the ankle mortise is unstable, a syndesmotic screw or other implants can be used to stabilize it.
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