Abstract
The interest and use of intramedullary fibular nails for ankle fracture fixation has continued to increase. Studies have reported earlier time to weightbearing, reduced incidence of wound complications, better union rates, and the absence of prominent hardware requiring removal; overall, a lower cost of healthcare delivery compared to plate and screw fixation. Currently, there are two 4th generation intramedullary fibular nails available in the United States. The importance of fracture reduction, anatomic realignment of the syndesmosis, and syndesmotic fixation trajectory along the centroidal axis is paramount, and mitigates postoperative complications. Mal-reduction portends a poorer prognosis, and may result in nail breakage, fracture gapping, non-union, and hardware loosening. The authors preferred technique for arthroscopy assisted open reduction internal fixation of ankle fractures using 4th generation IMFs with direct syndesmotic reduction and realignment with fixation along the centroidal axis is described.
Introduction
The use of intramedullary fibular (IMF) nails for ankle fracture fixation has steadily increased over the past decade. Studies have reported earlier time to weightbearing, reduced incidence of wound complications, better union rates, and the absence of prominent hardware requiring removal, compared to traditional plate/screw (PS) fixation. ,,,,, Moreover, despite the higher up-front initial cost of IMF nails, a lower overall cost of healthcare delivery has been shown compared to traditional PS fixation, given the lower re-operation rate in general, including symptomatic hardware removal.
Currently, 3rd and 4th generation IMFs are commonly utilized in the United States. Third generation IMF nails are bent to match the morphology of the fibula, possess angled syndesmotic slots to approximate the transmalleolar axis, rely on non-locking headed cortical screws for distal fixation, and incorporate proximal fixation for improved axial stability (differentiates it from 2nd generation IMF nails). Similarly, 4th generation IMF nails also include proximal fixation. However, 4th generation IMF nails are differentiated from the former by a straight, semi-flexible design which facilitates nail insertion, non-angled syndesmotic slots (0 to 5 degrees) which mitigate mal-reduction and afford surgeons syndesmotic realignment along the centroidal axis, and headless interlocking screws that can engage the nail itself, rather than relying on cortical bone to mitigate hardware loosening.
There are two 4th generation IMF nails currently available in the United States: “Flexthread” © (Conventus-Flower Orthopedics LLC., Horsham, Pennsylvania) and “FibFix” © (Fusion Orthopedics LLC, Mesa, Arizona). The first of the generation, Flexthread ©, was introduced in 2020. Case series and retrospective comparative cohort studies have reported favorable results at short-term follow-up. , The next of the generation, “FibFix” © was released in early 2026 with both semi-flexible and rigid nail options. A third syndesmotic fixation hole option, fluoroscopic targeting “sights” for fixation on the outrigger guide, intraoperative templating tool to discern appropriate nail diameter, reduction tool with elongated arms for percutaneous reduction, pin-distractor, and a reamers with an elongated blunt tip to prevent cortical breech differentiate the newest IMF addition from its predecessor. However, as with all IMF nails, syndesmotic mal-reduction is still possible, and can lead to aberrant stress(es) on the construct resulting in non-union, fracture gapping, hardware loosening, and nail breakage.
The purpose of the present article is to mitigate potential pitfalls and complications for surgeons using 4th generation IMF nail fixation. The authors preferred technique for arthroscopy assisted open reduction internal fixation of ankle fractures using 4th generation IMFs with direct syndesmotic reduction and realignment along the centroidal axis is described.
Indications
Indications for IMF nailing are similar to traditional plate fixation and include unstable ankle fractures with/without syndesmotic and/or deltoid ligament disruption. Transverse and oblique fracture patterns are particularly suited for IMF nail fixation. However, butterfly, long spiral oblique and comminuted fracture patterns are also amenable to IMF nail fixation. For butterfly fracture patterns, posterior perforation of the canal by the entry wire is prevented using a point to point reduction clamp to hold the posterior fragment. For long spiral oblique fracture patterns, fracture gapping proximally during syndesmotic fixation placement is prevented by maintaining fracture reduction until after syndesmotic fixation is placed. Suture material may also be wrapped circumferentially around the fibula proximally to mitigate proximal gapping. For comminuted fractures, the nails proximal fixation mechanism, and supplemental tri-cortical syndesmotic screw(s) distally ensure maintenance of length. Alternatively, IMF nail fixation may also be used in distal tibia pilon fractures.
Contraindications
General contraindications for the use of IMF nail fixation are distal fibular avulsion type fractures, pathologic fractures, highly comminuted fractures, and neuropathic fractures. Neuropathic ankle fractures should be considered “limb salvage surgery” and are better suited for intramedullary tibiotalocalcaneal arthrodesis. Borderline neuropathy on 5.07 Semmes Weinstein monofilament testing, especially in the setting of uncontrolled diabetes and/or renal disease should also be considered a contraindication, given the propensity for neuropathy progression, and possibility of Charcot arthropalthy with relatively minor postoperative trauma ( Fig. 1 ). ,,
A-B : Charcot arthropathy after minor postoperative trauma.
Technique
The authors preferred technique is summarized in 9–11 steps, depending on the number of fractures:
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1.
Preoperative Planning
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2.
Ankle Arthroscopy
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3.
Posterior/Anterior Malleolar Fracture Fixation
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4.
Medial Malleolar Fracture Fixation
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5.
Intramedullary Fibular Nailing
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6.
“Center- Center Position”, and “Centroidal Axis”
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7.
Manual Syndesmotic Reduction
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8.
Direct Syndesmotic Reduction Assessment
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9.
Syndesmotic Fixation Trajectory Check
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10.
Syndesmotic Repair
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11.
Syndesmotic Stress Assessment to Confirm Stability
“Preoperative planning”
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1. Preoperative radiographs allow for templating and planning of the nails length and diameter. The anticipated length of the nail prior to surgery is important to discern, as the diameter of the fibula canal widens more proximally. The anticipated diameter preoperatively at that length is then compared to the tactile feedback during sequential proximal reaming to determine the definitive intraoperative diameter.
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2. Preoperative computed tomography (CT) allows for assessment of anterior (Tillaux) and/or posterior malleolar (PM) fracture morphology and size, identification of any intercalary fragment(s), as well as syndesmotic alignment on axial images 1 cm proximal to the ankle joint ( Fig. 2 ).
Fig. 2 A-D : Preoperative computed tomography (CT) for assessment of anterior (Tillaux) and/or posterior malleolar (PM) fracture morphology and size, identification of any intercalary fragment(s), as well as syndesmotic alignment.
“Ankle arthroscopy”
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3. The patient is positioned on a radiolucent table, either in the supine or lazy lateral with/without a bean bag depending on surgeon preference. The limb must be able to externally rotate for appropriate positioning on a Ferkel leg holder for the ankle arthroscopy portion of the procedure ( Fig. 3 ). A bump and bone foam are also set aside, for placement under the ipsilateral limb after arthroscopy is completed.
Fig. 3 The patient is positioned and the limb externally rotate for positioning on a Ferkel leg holder for gravity distraction during arthroscopy.
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4. Prophylactic antibiotics are administered prior to insufflation of the tourniquet to 300–350 mmHg. The limb is scrubbed, prepped, and draped to the knee.
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5. Ankle arthroscopy with gravity distraction using 2-portals is performed after insufflation of the joint with 10cc of local anesthesia/saline. The joint is lavaged to evacuate any proinflammatory cytokines and fracture hematoma, osteochondral lesions of the talus/tibia are identified and addressed, and stress assessment of the syndesmosis (using 4–5 mm probe) and deltoid ligament (discern the presence of a “drive through sign”) is performed ( Fig. 4 ).
Fig. 4 A-C: Ankle arthroscopy A) AITFL rupture, B) Syndesmotic instability confirmed with placement of shavers/probes proximally within the tibial incisura, C) Deltoid ligament avulsion.
Posterior/Anterior malleolar fracture fixation
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6. Following arthroscopy, posterior, anterior, and medial malleolar fractures are addressed according to surgeon preference. The authors preferred order of operation is posterior, anterior, medial, and then lateral. Posterior malleolar fractures without extension medially/intercalary fragments are amenable to percutaneous reduction. The screw trajectory is dependent on fracture morphology and size; larger oblique fractures are better suited for placement oriented from anteromedial to posterolateral perpendicular to the fracture, while smaller less oblique fractures are suited with fixation oriented from anterolateral to posterolateral. The authors preference is for provisional fixation placement for the PM fracture from anterior to posterior, followed by screw fixation from posterior to anterior. Through an extension of the anterolateral arthroscopy incision, any anterior malleolar fracture avulsion is addressed with fragment excision for later ventral syndesmosis repair or fixation. The provisional wire for the PM fracture is then advanced and dorsiflexion of the ankle and/or use of a periosteal elevator facilitates fracture reduction maintenance during provisional fixation, and subsequent screw insertion ( Fig. 5 ). Additionally, provisional clamp reduction of the lateral malleolus may be performed to help facilitate PM fracture reduction. It is important to be cognizant of the posteromedial medial vertical syndesmotic line (PVSL) on the mortise image, and ensure screw placement remains medial to it, to avoid breeching the incisura laterally ( Fig. 6 ). Washers are avoided with percutaneous PM fixation by the author to mitigate FHL irritation. More complex PM fracture morphologies may warrant plate fixation ( Fig. 7 ).
Fig. 5 A-C: PM fracture, A/B) provisional reduction and fixation placement from anterior to posterior, followed by C) screw fixation from posterior to anterior.
Fig. 6 PM fixation trajectory assessment on mortise imaging referencing the posteromedial medial vertical syndesmotic line (PVSL) for reference.
Fig. 7 Plate fixation for a Mason Type 2B PM fracture morphology.
Medial malleolar fracture fixation
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7. Medial malleolar fractures are amenable to fixation using either a percutaneous, or mini open technique. The authors preference is for a small 1 cm incision directly over the fracture line for the removal of any invaginated periosteum and hematoma prior to fracture reduction, and screw fixation ( Fig. 8 ). The number of screws is dependent on fracture morphology and size. The authors preference is for 2 fully threaded, headless screws when possible, excluding a subset of smaller MM fracture morphologies (Hersovichi A) where a headed screw and washer are more appropriate. Headless screw fixation mitigate the risk of hardware irritation and the need for subsequent removal.
