Abstract
Syndesmotic instability occurs in up to 20 % of ankle fractures and may lead to asymmetric tibiotalar loading and early arthrosis if inadequately reduced. Traditional metallic fixation techniques, though effective, are associated with hardware removal rates exceeding 40 % and malreduction rates approaching 35 %. Bio-integrative fixation composed of continuous mineral fibers within a PLDLA matrix provides strength retention during healing while eliminating permanent hardware. We describe a reproducible technique utilizing OSSIOfiber® bio-integrative suture anchors for dynamic syndesmotic fixation. Under fluoroscopic guidance, a 2.5 mm tibial anchor is deployed through a 4.75 mm fibular tunnel, tensioned, and secured with a second anchor to achieve physiologic syndesmotic stabilization. Technical pearls, reduction verification, and postoperative assessment are outlined. This technique provides a minimally invasive, dynamic alternative for syndesmotic stabilization with the potential to reduce implant removal and malreduction risk. Early results and comparative evidence suggest equivalent fixation strength and radiographic outcomes to metallic devices, supporting bio-integrative fixation as a viable option for surgeons seeking a non-metallic solution.
Introduction
Syndesmotic compromise can occur up to 10–20 % of all ankle fractures, and 17 % of isolated ankle sprains. , Peak contact pressures can increase up to 42 % and decrease symmetrical surface contact down to 60 % with just 1 mm of translation of the talus when syndesmotic compromise occurs. , When neglected this increase in asymmetric peak pressures can lead to posttraumatic arthritis at an earlier and advanced rate. There has been much debate with respect to dynamic and static fixation of the syndesmosis, both of which have documented hardware removal rates of 3.7 % and 9 % respectively. Titanium implants have largely dominated the market over stainless steel since the 1980′s secondary to its elastic modulus, osseointegration, and corrosion resistance and biocompatibility. Despite the better characteristics of titanium, there can be the occurrence of a rare titanium allergy. In recent years there has been a demand from both surgeons and patients for less metallic implants. A bio-integrated fiber-reinforced implant was demonstrated in an animal model to maintain strength throughout the bone healing cascade while mitigating the local inflammatory response. A two year follow up in proximal interphalangeal joint arthrodesis demonstrated a 96 % fusion rate with comparable clinical outcomes to traditional fixation. The global market for polymer-based implants was predicted to increase 8.5 % from USD 1.2B in 2024 to 2.5B market by 2033.
There are controversies on the best angle for placement of the syndesmotic fixation, irrespective of the implant utilized. Boffeli et al. demonstrated that the angle of fixation changes depending on level of placement above the ankle joint based on weight-bearing CT scans. This work challenged a recommended 30° fixation angulation and found that the average angle at the 2 cm level has an average at 19.7° and at the 3.5 cm level has an average at 24.8° for best anatomical alignment. Malreduction has been reported as up to 35 % and another demonstrated postoperative diastasis at 24 % and up to 52 % had incisura incongruity on postoperative CT scans. , However, risk of malreduction stabilization can be mitigated with dynamic stabilization. More recently there has been a plethora of literature with results pointing towards dynamic stabilization having better outcomes and postoperative reduction even when drill tunnels are off axis in postoperative CT scans. This mechanism of a more anatomical compensation and physiological motion has been deemed the “self centering” theory. ,,
We present a novel technique utilizing OSSIOfiber® bio-integrative suture anchors composed of mineral fibers (silica, calcium oxide, magnesium oxide, sodium oxide, boron trioxide, and phosphorus pentoxide) in a poly-L-lactic-co-D, L-lactide (PLDLA) matrix for dynamic syndesmotic fixation.
Level of clinical evidence: level V technique guide
Technique guide
Patients are selected on a radiographic and clinical diagnosis. In the surgical theater, the patient is placed in a supine position on the operative table and general anesthesia is induced, followed by a popliteal and saphenous nerve block. The extremity is prepared in standard fashion. Further confirmation of syndesmotic instability can be evaluated with a stress exam under fluoroscopy and/or direct visualization with arthroscopy with stressing and drive through sign.
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1.
Under fluoroscopy the syndesmotic area is triangulated. If no other ancillary procedures are committed to the lateral ankle a linear incision around 2 cm is made along the distal fibula. A combination of blunt dissection is taken down to the level of the fibula.
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2.
Under fluoroscopy the exact syndesmosis level (surgeon preference) is mapped out on AP/Mortise x-ray for anchor placement.
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3.
The tapered 3 mm to 4 mm “Big” drill “bit for a 4.75 mm anchor was drilled into the fibula from lateral to medial with a slight influence anteriorly, demonstrated in Fig. 1 . Care is taken not to violate the tibial cortex.
Fig. 1 Demonstrates the tapered 3 mm to 4 mm drill against the fibula with anterior influenced direction prior to drilling a tunnel in the fibula. This should be down under fluoroscopy to ensure parallel tunnel to the tibial plafond.
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4.
The 1.8 mm “Small” drill bit for the 2.5 mm anchor is passed through the fibular large drill hole and under fluoroscopy was drilled into the tibia in the same transverse path going lateral to medial with a slight anterior influence, demonstrated in Fig. 2 . This is done until the positive stop reaches the tibia and is fluoroscopically guided, demonstrated in Fig. 3 .
Fig. 2 Demonstrates the 1.8 mm drill advanced through the prior larger fibula drill tunnel. The tip of the drill is against the tibia, keeping the same anteriorly directed influence of direction. This should be down under fluoroscopy to ensure parallel tunnel to the tibial plafond.
Fig. 3 A-P radiograph demonstrating the 1.8 mm drill with positive stop advanced through the fibula and into the tibia with positive stop.
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5.
The 2.5 mm suture anchor, demonstrated in Fig. 4 , is passed through the larger fibula tunnel and seated into the tibia, which can be visualized under fluoroscopy. The anchor is seated into the tibia with the two 1.4 mm suture tapes attached to the 2.5 mm anchor remaining outside of the fibula anchored to the anchor into the tibia. The tapes are then placed on tension to test pull out strength, demonstrated in Fig. 5 .
Fig. 4 Demonstrates the 2.5 mm suture anchor loaded on the insertional handle.
Fig. 5 Left image, demonstrates A-P radiograph with 2.5 mm suture anchor seated within the tibia. Middle image, demonstrates clinically the 2.5 mm suture anchor insertion handle advanced through the fibula and seated within the tibia. Right image, demonstrates removal of the insertion handle with the two 1.8 mm sutures being pulled from the 2.5 mm suture anchor within the tibia and through the drill tunnel in the tibia.
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