Arthroscopic assessment of syndesmotic instability: Are we pulling correctly in the coronal plane?

Intraoperative assessment of syndesmotic instability: What technique minimizes surgeon error?

BACKGROUND

Assessment of intraoperative syndemsotic instability remains a controversial topic. To date, no study has directly compared 5 available methods.

MATERIALS AND METHODS

The purpose of the present study was to assess the reliability of five stress assessment methods (Cotton Hook, External Rotation, Arthroscopic, Direct Palpation, and Direct Visualization) across various syndesmotic injury conditions (ventral disruption, 2-ligament injury, and 3-ligament injury) in an in-vitro model. It was hypothesized that the Cotton Hook (CHT) and External Rotation (ER) methods would be the least reliable. A cadaveric model of syndesmotic injury was employed in eight through the knee specimens and assessments were performed.

RESULTS

Overall, direct visualization was most reliable for discerning syndesmotic disruption, irrespective of the injury condition (p = 0.01). Arthroscopic assessment was reliable in 2 and 3-ligament injury conditions (p < 0.05); while Cotton Hook and External Rotation were reliable in 3-ligament injuries (p = 0.01, p = 0.04). Arthoscopic, Cotton Hook, and External Rotation assessment(s) were unreliable for discerning isolated ventral disruption (anterior inferior tibiofibular ligament).

CONCLUSIONS

In the present cadaveric model, direct visualization of the anterolateral articular surface of the ankle was the most reliable method for discerning syndesmotic injury. Discontinuity of the articular surface between the anterolateral tibia and anteromedial fibula was readily identified in all injury conditions. Surgeons should be cognizant of the inherent subjectivity, and limited reliability of historically popularized syndesmotic stress assessment methods.

LEVEL OF EVIDENCE

Level V, cadaveric.

Syndesmotic Malreduction Prevention, Assessment, and Treatment

Syndesmotic instability or malreduction is an independent risk factor for an impaired patient-rated outcome. If a syndesmotic injury is suspected, a stepwise diagnostic approach including plane radiographs, MRI, and bilateral stress radiographs should be conducted to differentiate stable from latent unstable and frank diastasis cases. The basic requirement for any surgical treatment approach is a stable and anatomically reduced distal tibio-fibula joint. The best treatment approach for a 2-ligament injury (anterior inferior tibio-fibular ligament [AiTFL] + interosseous ligament [IOL]) seems to be the suture-button system, for a 3-ligament injury (AiTFL + IOL + posterior inferior tibio-fibular ligament), 2 fixation devices.

[Injuries of the ankle ligaments]

Lateral ligament injuries are the most common injuries of the ankle joint and are usually treated with early weight bearing after a short period of immobilization. If the clinical presentation is suspicious, additional injuries to the deltoid ligament complex and the syndesmosis should be considered. The indications for additional diagnostics should be generously applied. Injuries to the deltoid ligament usually occur as part of a complex ankle injury and should also be addressed in the surgical treatment of accompanying injuries. Chronic instability in this area necessitates complex bony and soft tissue procedures. Syndesmotic injuries with insufficiency of the capsule-ligament apparatus are frequent in ankle fractures and are stabilized during fracture treatment. Isolated syndesmotic instability should also be surgically treated as chronic injuries are usually associated with poor clinical results and early osteoarthritis.