Direct visualization of the syndesmosis for evaluation of syndesmotic disruption: A cadaveric study

A 3-Ligament Syndesmotic Injury Is at Higher Risk for Malreduction Than a 2-Ligament Injury: A CT-Based Analysis

BACKGROUND

Syndesmotic malreduction is common and has been associated to an impaired outcome. Various risk factors for DTFJ malreduction have been postulated. The aims of this study were to assess the DTFJ malreduction rate based on (1) the severity of the syndesmotic injury, (2) the anatomy of the tibial incisura, and (3) the fixation device used in patients treated with suture-button systems.

METHODS

This retrospective, radiographic study included all adult patients who were treated for an acute, unilateral, and unstable syndesmotic injury with a suture-button system and postoperative bilateral CT imaging. Included were isolated syndesmotic injuries and fracture cases. The number of syndesmotic ligaments injured, that is, 2-ligament (AiTFL+IOL) and 3-ligament (AiTFL+IOL+PiTFL), was rated for each patient. The quality of DTFJ reduction, as well as the anatomy of the tibial incisura, was rated based on the postoperative, bilateral CT images and the intraoperative DTFJ reduction was recalculated based on the drilling-tunnel deviation. The possible influence on the DTFJ malreduction rate was assessed.

RESULTS

A total of 147 patients were included, and 94 and 53 patients had a 2- and 3-ligament syndesmotic injury, respectively. In addition, 113 patients were treated with a single-button system, 26 with a double suture-button system, and 8 with a hybrid fixation (suture-button + screw). Malreduction was significantly higher in 3-ligament compared with 2-ligament injuries, both intraoperatively (51% vs 27%; P = .003) and postoperatively (28% vs 11%; P = .006). The tibial anatomy had no significant influence on the malreduction rates. No significant differences were seen per the different fixation devices used independent of the number of ligaments injured.

CONCLUSION

This study did not find an influence of the incisura's anatomy on the DTFJ malreduction rate. However, we did find that 3-ligament syndesmotic injuries carried a higher risk of intra- and postoperative malreduction compared with 2-ligament injuries.

Standardized analysis of syndesmosis stability in ankle trauma with an innovative syndesmosis-test-tool: a biomechanical study

When treating ankle fractures, the question of syndesmosis complex involvement often arises. So far, there is no standardized method to reliably detect syndesmosis injuries in the surgical treatment of ankle fractures. For this reason, an intraoperative syndesmosis-test-tool (STT) was developed and compared to the recommended and established hook-test (HT). Tests were performed on cadaveric lower legs (n = 20) and the diastasis was visualized by 3D camera. Tests were performed at 50, 80, and 100 N in native conditions and four instability levels. Instability was induced from anterior to posterior and the reverse on the opposite side. The impact on diastasis regarding the direction, the force level, the instability level, and the device used was checked using a general linear model for repeated measurement. The direction of the induced instability showed no influence on the diastasis during the stability tests. The diastasis measured with the STT increased from 0.5 to 3.0 mm depending on the instability, while the range was lower with the HT (1.1 to 2.3 mm). The results showed that the differentiation between the instability levels was statistically significantly better for the developed STT. The last level of maximum instability was significantly better differentiable with the STT compared to the HT. An average visualizable diastasis of more than 2 mm could only be achieved at maximum instability. In conclusion, the newly developed STT was superior to the commonly used HT to detect instability.

Quantitative Evaluation of the Influence of Posterior Malleolus Fracture and Fixation on the Rotational Stability of the Ankle

Background

This study aimed to analyze quantitative correlation between the posterior malleolus fracture and fixation and the rotational stability of the ankle and to explore supplementary surgical indications for posterior malleolus fracture.

Methods

Twenty fresh frozen cadaver specimens were selected and dissected. Based on the tibial insertion of the ligament complex, the model for the supination external rotation stage 3 ankle fracture with a posterior malleolar fragment and syndesmosis diastasis was created. The area threshold of the posterior tibial insertion of posterior malleolus fracture was biomechanically assessed and the difference of the antirotating ability stiffness of the ankle between simple posterior malleolus fixation and simple syndesmotic fixation was analyzed statistically.

Results

The tibial insertion of posterior inferior tibiofibular ligament and inferior transverse tibiofibular ligament complex was relatively broad, and its width decreased as the distance from the joint line increased. Biomechanical analysis showed that: the threshold of posterior area of posterior malleolus fracture was 1/4S; posterior malleolus fixation provided better rotational stability than syndesmotic fixation (P < 0.01).

Conclusion

The surgical indications for posterior malleolus fracture should consider simultaneously the restoration of the axial and rotational stability of the ankle. Simple posterior malleolus fracture fixation is recommended when the syndesmosis is unstable and the area ratio of posterior tibial insertion of posterior malleolus fracture is greater than or equal to 1/4. Syndesmotic fixation is proposed to restore and maintain the rotational stability of the ankle when the syndesmosis is unstable and the area ratio is less than 1/4. Regardless of the area ratio, the surgical indication only depends on the impact of the posterior malleolus fracture on the axial stability of tibiotalar joint, the involved articular surface area, and the displacement degree of posterior malleolus fragment, when the syndesmosis is stable.

A systematic review and meta-analysis on the value of the external rotation stress test under fluoroscopy to detect syndesmotic injuries

Purpose

Methods

Results

Conclusion

Revision Strategies for the Aseptic, Malaligned, Surgically Treated Ankle Fracture

Although surgical fixation can take many forms depending on ankle fracture morphology, the goals of open reduction internal fixation are to restore fracture alignment, re-establish ankle stability, and achieve an anatomic mortise. A subset of patients may present postoperatively with evidence of suboptimal open reduction internal fixation. Increased contact pressures across the tibiotalar joint, increased talar shift, and pathologic joint loading leading to the development of post-traumatic arthritis are common sequela of the malaligned mortise. Treatment necessitates a comprehensive approach. This article describes our preferred systematic approach for diagnosis and treatment of the aseptic, malaligned, surgically treated ankle fracture.

Epidemiology of syndesmotic fixations in a pediatric center: A 12-year retrospective review

Syndesmosis injuries need to be accurately diagnosed and managed to avoid chronic pain, early arthritis, and instability. To this end, the present study aimed to analyze the epidemiology of syndesmotic injuries in a pediatric ankle fracture cohort and identify patient and surgery-related characteristics.A retrospective review of all the ankle fractures during a 12-year period at a single pediatric referral center was conducted. Inclusion criteria were: a fractured ankle that underwent a surgical fixation, at least 1 radiograph available for review before fixation, available information regarding surgery, including operative report and fluoroscopic images, and younger than 18 years at the time of surgery. Demographic information, trauma, radiographs, surgical details, clinical examination, follow up, outcomes, and physeal status (skeletally immature, transitional, or mature) were recorded. Finally, patients were divided in 2 groups: with or without syndesmotic fixation. Statistical analysis included descriptive statistics, Mann-Whitney test for nonparametric data to compare continuous parameters, and χ test for categorical parameters.A total of 128 patients were included with a mean age of 14.1 years. There were 80 boys and 48 girls. There were 51 skeletally immature patients, 23 with transitional fractures, and 54 that were skeletally mature. The main finding of this study is that only 11 patients from the mature group underwent syndesmotic fixation. There were no cases of syndesmotic fixation in the skeletally immature and transitional groups.This is the first retrospective study to focus specifically on syndesmotic injuries in a pediatric population who underwent ankle fracture fixation. Only 11 skeletally mature patients underwent syndesmotic fixation out of 128 patients in this cohort. This result raises the question of whether there are accurate diagnostic tools to evaluate syndesmosis in children.

Intraoperative Torque Test to Assess Syndesmosis Instability

BACKGROUND:

In this cadaveric study, a new "torque test" (TT) stressing the fibula posterolaterally under direct visualization was compared with the classical external rotation stress test (ERT) and lateral stress test (LST).

METHODS:

The anteroinferior tibiofibular ligament (AiTFL), the interosseous membrane (IOM), and the posteroinferior tibiofibular ligament (PiTFL) were sectioned sequentially on 10 fresh-frozen human ankles. At each stage of dissection, instability was assessed using the LST, ERT, and TT under direct visualization. Anatomical tibiofibular diastasis measurements were taken directly on cadavers and compared using the Wilcoxon signed rank test.

RESULTS:

All 3 tests showed statistically significant motion in the syndesmosis when at least 2 ligaments were sectioned. The mean increase across diastasis with a 2-ligament section was 3.0 mm ( P = .005), 3.2 mm ( P = .005), and 4.8 mm ( P = .005) for the LST, ERT, and TT, respectively. The largest mean increase in diastasis was obtained with a complete injury using the TT and was 6.2 mm ( P = .008). With the TT, a 3.5-mm tibiofibular diastasis was 90% sensitive and 100% specific when 2 or more syndesmotic ligaments were sectioned.

CONCLUSION:

The TT was a more sensitive and specific tool for detecting syndesmosis instability than classic LST and ERT.

CLINICAL RELEVANCE:

Stressing the fibula in a posterolateral direction created a larger distal tibiofibular diastasis, which would be easier to detect in the intraoperative setting. The TT was more sensitive and specific to detecting a 2-ligament syndesmotic injury than the classic test and required less force to perform.