Ankle fractures are among the most common lower extremity injuries in the adult population. Among these, syndesmotic injuries are particularly complex and remain one of the most debated and researched areas of foot and ankle trauma. The syndesmosis, a dynamic ligamentous articulation between the distal tibia and fibula, contributes to ankle stability and allows physiologic motion during weight-bearing and rotation. Despite the proliferation of studies addressing syndesmotic injury, malreduction continues to be a significant postoperative concern.

For example, rates of malreduction following operative treatment of syndesmotic injuries have been reported in 39 % to over 50 % of cases based on computed tomography (CT) imaging. ^, However, definitions of malreduction vary across the literature, influenced by both anatomic variability and imaging criteria. Factors implicated in syndesmotic malreduction include ligamentous disruption, variability in incisura morphology, unaddressed distal fibular fractures, and iatrogenic errors during clamp placement. ^,,

Chart 1 portrays the plain film radiographic criteria for assessing syndesmotic integrity that is traditionally utilized. Although useful, these measurements are limited in their reliability as widening is typically only visible when diastasis exceeds 4 mm. ^,, In lieu of radiographs, CT imaging has become the gold standard in evaluating syndesmotic alignment postoperatively.

CT-based definitions of malreduction typically use a threshold of ≥2 mm difference in tibiofibular diastasis or medialization when compared to the contralateral limb. ^,, However, even with intraoperative CT guidance, malreduction rates have been reported as high as 10 %. Notably, overcompression—characterized by medialization of the fibula by >1 mm on CT relative to the contralateral limb—has been increasingly recognized as a form of iatrogenic malreduction. This may be caused by excessive reduction clamp force or improper technique during dynamic or rigid fixation. ^,,

Dynamic suture button fixation has gained popularity due to its ability to permit physiological motion and reduce malreduction rates compared to rigid screw fixation. ^, Nonetheless, the flexible nature of suture buttons may limit their efficacy in patients with poor bone quality. Cadaveric models have demonstrated overcompression can still occur due to variability in applied tension during suture-button deployment. Additionally, excessive medialization of the fibula following dynamic fixation may alter tibiotalar kinematics, possibly contributing to early ankle arthrosis. ^,

Though they may not receive the academic attention that hip fractures do, geriatric ankle fractures are increasingly recognized for their morbidity particularly in the presence of syndesmotic disruption. Recent population-level studies have shown that nonoperative management in elderly patients correlates with higher one-year mortality compared to surgical treatment. Although bone quality is an important consideration in fixation strategy, the outcomes of osteoporotic ankle fractures treated surgically have not demonstrated inferiority. ^,

Syndesmotic injuries can be complex and require careful attention to intraoperative reduction. This is especially true for patients with compromised bone quality such as in the elderly population. Overcompression and malreduction remain underreported not only in the elderly population, but throughout the foot and ankle literature. This case highlights the importance of evaluating implant choice, fibular reduction, and intraoperative imaging, particularly in patients with compromised bone quality. Understanding the nuances that lead to syndesmosis malreduction is vital to preoperative planning and intraoperative execution.

A 79-year-old female presented to the emergency department after sustaining a bimalleolar ankle fracture-dislocation from a motor vehicle collision. The patient had a complicated past medical history leading to comorbidities that were managed prior to surgical intervention. The only orthopedic related past surgical history present was total right knee arthroplasty. Preoperative vitamin D level was 32.3.

Advanced imaging confirmed that the fibular fracture was obliquely oriented at the level of the distal aspect of the midshaft, well above the ankle joint. Transverse fracture of the medial malleolus with mild displacement was also noted. The tibiotalar joint was disrupted with lateral translation of the talus relative to the tibia. These findings are consistent with a pronation external rotation (PER) ankle fracture consistent with the Lauge Hansen classification system.

Fig. 1 includes original pre-reduction radiographic films portraying the mechanism of injury. The patient had immediate reduction of the dislocation in the emergency department. Post reduction imaging recommended a CT scan for further evaluation. CT imaging then portrayed substantial syndesmotic diastasis which can be appreciated in Fig. 2 . A second attempt at reduction was performed with adequate alignment of the tibiotalar joint and syndesmotic complex. A jones compression dressing and a plaster splint was applied. Due to concerns for soft tissue swelling, surgical intervention was delayed for one week.

Initial injury radiographs: (A) AP view, (B) Mortise view, (C) Lateral view.

Preoperative CT taken in emergency dept. prior to reduction.

During the index surgery and prior to performing definitive fixation, arthroscopic assisted reduction and technique was utilized to assist in visualizing the syndesmotic disruption, evaluate for osteochondral lesions of the talus, and evaluate the extent of injury within the ankle joint complex. Intraoperative images can be appreciated in Fig. 3 . The surgical procedure consisted of a standard open lateral approach for insertion of a lag screw across the fracture line per AO technique. A point-to-point reduction clamp was used to hold reduction of the fracture fragment. A 1/3 tubular plate was then applied for a neutralization function. Once the fibular fracture was reduced and the plate was applied in an appropriate position confirmed with fluoroscopy imaging, a combination of nonlocking and locking 3.5 mm screws were placed per AO guidelines.

Intraoperative arthroscopic images showing hemarthrosis, two separate osteochondral lesions, one medial and one lateral as well as frank diastasis and disruption of the syndesmosis.

Next, the medial malleolar fracture was addressed with a curvilinear medial incision overlying the fracture line. A point-to-point reduction clamp was utilized to reduce and manipulate the fragment. Two cannulated 4.0 screws were placed with AO technique. Adequate alignment was confirmed with fluoroscopy. The syndesmosis was assessed, and there was instability noted with an intraoperative hook test. Using a point-to-point clamp, the syndesmosis was reduced, and a dynamic fixation suture button was placed 1.3 cm above the tibiotalar joint. The dynamic fixation suture button was placed through the fibular plate after drilling was performed and the medial cortex of the tibia was penetrated. Post implant there was over compression noted of the syndesmosis. The dynamic fixation was removed and intraoperatively exchanged for a second form of dynamic fixation. Stability and alignment of the ankle mortise was appreciated. Final intra-operative radiographs revealed well aligned tibiotalar joint with the fibula out to length.

Postoperative radiographs performed in PACU revealed anterior fibular malreduction and syndesmotic overcompression ( Fig. 4 ). CT measurements were 2.47 mm and 5.71 mm between the anterior and posterior facets of the fibularis incisura, respectively. The patient was seen in the office the following day, and a post-operative CT was completed confirming the radiographic findings. Discussion was had with the patient that the initial reduction was not anatomic, and the patient was amenable to proceeding with revisional correction. When comparing the post operative CT scan with a previous contralateral scan, significant difference was appreciated in syndesmotic alignment. The patient did undergo contralateral open reduction internal fixation (ORIF) of the ankle many years prior from a previous ankle injury. ( Fig. 5 ).

Post op radiograhs. (A) AP, (B) mortise, and (C) lateral. Red arrows demonstrating lateral displacement of the fibula and medial malleolus. Red arrows demonstrating anterior subluxation of the talus (right).

Post operative CT scan of the operative (left) and contralateral (middle image) extremity for comparison of syndesmotic malreduction 1 cm above ankle joint, with post operative sagittal view CT of operative extremity (right) demonstrating displacement of fibula. Patient had ORIF of contralateral lower extremity one decade prior, unrelated to current clinical event.

Revision ORIF was performed due to persistent malreduction and anterior subluxation of the talus. Subsequently, there was syndesmotic malalignment demonstrated on immediate postoperative radiographs and confirmatory CT ( Fig. 5 ). Through the prior lateral incision, direct visualization allowed assessment of the over-compressed and malreduced syndesmosis. All lateral hardware—including the previously placed one-third tubular plate, associated screws, 3.0-mm lag screw, and the dynamic suture-button construct—was removed. During re-reduction, multiple clamps and provisional K-wires were used to manipulate the fracture until anatomic length, rotation, and angulation were restored. Given the fracture morphology and compromised bone quality, additional lag screw fixation was avoided to prevent further fragmentation. An anatomic distal fibular plate was pinned in place, then secured with distal 2.7-mm locking screws and proximal 3.5-mm non-locking screws following AO principles, with fluoroscopic confirmation in (anterior- posterior) AP, mortise, and lateral views. ( Fig. 6 )

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