Analysis of PITFL injuries in rotationally unstable ankle fractures

Current Concepts in Ankle Fracture Management

Ankle fractures are one of the more common musculoskeletal injuries that are treated by foot and ankle specialists. A thorough understanding of managing these injuries requires the ability to differentiate between stable and unstable fractures. The current literature supports the nonoperative management of stable Weber B ankle fractures, whereas unstable fractures have much better outcomes with surgical intervention. Specifically, we review the fixation strategies for the lateral, medial, and posterior malleolar fractures respectively. Finally, we discuss the current trends in postoperative management of some of the more common fracture patterns, and the safety in early weight-bearing protocols.

Instability of the distal tibiofibular syndesmosis

The distal tibiofibular syndesmosis (DTFS) is more frequently injured than previously thought. Early diagnosis and appropriate treatment is essential to avoid long term complications like chronic instability, early osteoarthritis and residual pain. Management of these injuries require a complete understanding of the anatomy of DTFS, and the role played by the ligaments stabilizing the DTFS and ankle. High index of suspicion, appreciating the areas of focal tenderness and utilizing the provocative maneuvers help in early diagnosis. In pure ligamentous injuries radiographs with stress of weight bearing help to detect subtle instability. If these images are inconclusive, then further imaging with MRI, CT scan, stress examination under anesthesia, and arthroscopic examination facilitate diagnosis. An injury to syndesmosis frequently accompanies rotational fractures and all ankle fractures need to be stressed intra-operatively under fluoroscopy after fixation of the osseous components to detect syndesmotic instability. Non-operative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. Anatomic reduction of the syndesmosis is critical, and currently both trans-syndesmotic screws and suture button fixation are commonly used for syndesmotic stabilization. Chronic syndesmotic instability (CSI) requires debridement of syndesmosis, restoration of ankle mortise with or without syndesmotic stabilization. Arthrodesis of ankle is used a last resort in the presence of significant ankle arthritis. This article reviews anatomy and biomechanics of the syndesmosis, the mechanism of pure ligamentous injury and injury associated with ankle fractures, clinical, radiological and arthroscopic diagnosis and surgical treatment.

Syndesmotic instability can be assessed by measuring the distance between the tibia and the fibula using an ultrasound without stress: a cadaver study

Background

Ultrasound examinations for syndesmosis injury might be useful for the quantitative evaluation of syndesmotic instability. The purpose of this study was to evaluate the efficacy of ultrasound assessment by measuring the tibiofibular distance of syndesmosis injuries in various ligament-injured models and stress load conditions.

Methods

Five normal ankles from Thiel-embalmed cadavers were used. Ultrasound assessment was performed by placing a probe in parallel with the ligament running just above the anterior inferior tibiofibular ligament (AITFL). The distance between the anterior border of the tibia and the fibula was measured in the intact condition. Next, Bassett’s ligament was cut arthroscopically to reduce damage to soft tissues as much as possible and measurement was performed in the same way. After that, the AITFL, interosseous membrane (IOM), deltoid ligament, and posterior inferior tibiofibular ligament (PITFL) were macroscopically cut and measured in that order. Ankle positions were without stress (natural plantar flexion without applying stress to the ankle joint), dorsiflexion stress, inversion stress, and external rotation stress. All stress to the ankle joint was carried out manually to the maximum extent.

Results

As with the without-stress condition, significant increases in tibiofibular distances after AITFL dissection were seen compared with the intact state under all stress conditions (intact: 4.9 ± 1.0 mm without stress, 5.6 ± 1.2 mm with dorsiflexion, 5.9 ± 1.0 mm with inversion, and 6.7 ± 1.3 mm with external rotation; AITFL dissection: 6.7 ± 1.5 mm without stress, 7.3 ± 1.2 mm with dorsiflexion, 7.5 ± 1.4 mm with inversion, and 8.7 ± 1.6 mm with external rotation). AITFL dissection with external rotation stress significantly increased the tibiofibular distance compared to without stress.

Conclusion

Changes in tibiofibular distance with the severity of syndesmosis injury were measured by ultrasound using cadavers. No significant change was seen with Bassett’s ligament injury, but tibiofibular distance increased significantly with injuries of equal to or greater severity than AITFL injury. Results were similar not only for external rotation stress, but also for dorsiflexion stress and inversion stress, and even in unloaded states, significant tibiofibular widening was confirmed with injuries of equal to or greater severity than AITFL injury.

Acute syndesmotic injuries in ankle fractures: From diagnosis to treatment and current concepts

A stable and precise articulation of the distal tibiofibular syndesmosis maintains the tibiofibular relationship, and it is essential for normal motion of the ankle joint. The disruption of this joint is frequently accompanied by rotational ankle fracture, such as pronation-external rotation, and rarely occurs without ankle fracture. The diagnosis is not simple, and ideal management of the various presentations of syndesmotic injury remains controversial to this day. Anatomical restoration and stabilization of the disrupted tibiofibular syndesmosis is essential to improve functional outcomes. In such an injury, including inadequately treated, misdiagnosed and correctly diagnosed cases, a chronic pattern characterized by persistent ankle pain, function disability and early osteoarthritis can result. This paper reviews anatomical and biomechanical characteristics of this syndesmosis, the mechanism of its acute injury associated to fractures, radiological and arthroscopic diagnosis and surgical treatment.

Imaging Techniques for Assessment of Dynamically Unstable Sports Related Foot and Ankle Injuries

Foot and ankle instability can be seen both in acute and chronic settings, and isolating the diagnosis can be difficult. Imaging can contribute to the clinical presentation not only by identifying abnormal morphology of various supporting soft tissue structures but also by providing referring clinicians with a sense of how functionally incompetent those structures are by utilizing weight-bearing images and with comparison to the contralateral side. Loading the affected joint and visualizing changes in alignment provide clinicians with information regarding the severity of the abnormality and, therefore, how it should be managed.

Anatomy of the Insertion of the Posterior Inferior Tibiofibular Ligament and the Posterior Malleolar Fracture

BACKGROUND

Our aim in this study was to identify the extent of the posterior inferior tibiofibular ligament (PITFL) insertion on the posterior tibia and its relation to intra-articular posterior malleolar fractures.

METHODS

Careful dissection was undertaken on 10 cadaveric lower limbs to identify the ligamentous structures on the posterior aspect of the ankle. The ligamentous anatomy was further compared with our ankle fracture database, specifically posterior malleolar fracture patterns, demonstrating a rotational pilon etiology (Mason and Molloy type 2A and B). Computed tomography imaging was used to measure the dimensions of the fracture fragments.

RESULTS

The superficial PITFL was found to have a transverse component and an oblique component. The average size of the tibial insertion was 54.9 mm (95% CI, 51.8, 58.0) from joint line and 47.1 mm (95% CI, 43.0, 51.2) transverse. From our database of ankle fractures involving the posterior malleolus, 80 Mason and Molloy type 2 fractures were identified for analysis. Of these, 33 were type 2A and 47 were type 2B. The posterolateral fragments had an average size of 26.3 mm (95% CI, 25.0, 27.7) height and 22.1 mm (95% CI, 21.1, 23.1) width. The posteromedial fragments had an average size of 22.0 (95% CI, 18.9, 25.1) height and 19.8 (95% CI, 17.5, 22.0) width.

CONCLUSION

The superficial PITFL insertion on the tibia is broad. In comparison with the average size of the posterior malleolar fragments, the PITFL insertion is significantly larger. Therefore, for a posterior malleolar fracture to cause posterior syndesmotic instability, a ligamentous injury must also occur.

CLINICAL RELEVANCE

Posterior syndesmotic instability results from injury to the PITFL. It has been widely reported that a posterior malleolar fracture will also give rise to posterior syndesmotic instability due to the insertion of the deep PITFL on the posterior tibia. On the contrary, in this paper, we have shown that the superficial PITFL insertion on the tibia is very large, much greater than the average size of the posterior malleolar fragments. Therefore, for a posterior malleolar fracture to cause posterior syndesmotic instability, a ligamentous injury will also have to occur.

MRI for high ankle sprains with an unstable syndesmosis: posterior malleolus bone oedema is common and time to scan matters

PURPOSE

Early clinical examination combined with MRI allows accurate diagnosis of syndesmosis instability after a high ankle sprain. However, patients often present late. The aims of the current study were to describe MRI characteristics associated with syndesmosis instability and to test the hypothesis that MRI patterns would differ according to time from injury.

METHODS

Over a 5-year period, 164 consecutive patients who had arthroscopically proven syndesmosis instability requiring fixation were retrospectively studied. Patients with distal fibula fractures were not included. Injuries were classified as acute in 108 patients (< 6 weeks), intermediate in 32 (6-12 weeks) and chronic in 24 patients (> 12 weeks).

RESULTS

Posterior malleolus bone oedema was noted in 65 (60.2%), and posterior malleolus fracture in 17 (15.7%) of acute patients, respectively, which did not significantly differ over time. According to MRI, reported rates of posterior syndesmosis disruption significantly differed over time, observed in 101 (93.5%), 28 (87.5%) and 13 (54.2%) of acute, intermediate and chronic patients, respectively (p < 0.001). Apparent rates of PITFL injury significantly reduced with time (p < 0.001).

CONCLUSIONS

MRI detected a posterior syndesmosis injury in 93.5% of patients acutely but became less reliable with time. The clinical relevance of this study is that posterior malleolus bone oedema may be the only marker of a complete syndesmosis injury and can help clinically identify those injuries which require arthroscopic assessment for instability. If suspicious of a high ankle sprain, we advocate early MRI assessment to help determine stable versus unstable injuries as MRI becomes less reliable after 12 weeks.

LEVEL OF EVIDENCE

III.

Imaging in syndesmotic injury: a systematic literature review

OBJECTIVES

To give a systematic overview of current diagnostic imaging options for assessment of the distal tibio-fibular syndesmosis.

MATERIALS AND METHODS

A systematic literature search across the following sources was performed: PubMed, ScienceDirect, Google Scholar, and SpringerLink. Forty-two articles were included and subdivided into three groups: group one consists of studies using conventional radiographs (22 articles), group two includes studies using computed tomography (CT) scans (15 articles), and group three comprises studies using magnet resonance imaging (MRI, 9 articles).The following data were extracted: imaging modality, measurement method, number of participants and ankles included, average age of participants, sensitivity, specificity, and accuracy of the measurement technique. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to assess the methodological quality.

RESULTS

The three most common techniques used for assessment of the syndesmosis in conventional radiographs are the tibio-fibular clear space (TFCS), the tibio-fibular overlap (TFO), and the medial clear space (MCS). Regarding CT scans, the tibio-fibular width (axial images) was most commonly used. Most of the MRI studies used direct assessment of syndesmotic integrity. Overall, the included studies show low probability of bias and are applicable in daily practice.

CONCLUSIONS

Conventional radiographs cannot predict syndesmotic injuries reliably. CT scans outperform plain radiographs in detecting syndesmotic mal-reduction. Additionally, the syndesmotic interval can be assessed in greater detail by CT. MRI measurements achieve a sensitivity and specificity of nearly 100%; however, correlating MRI findings with patients' complaints is difficult, and utility with subtle syndesmotic instability needs further investigation. Overall, the methodological quality of these studies was satisfactory.

Comparing Functional Outcomes After Injury-Specific Fixation of Posterior Malleolar Fractures and Equivalent Ligamentous Injuries in Rotational Ankle Fractures

OBJECTIVES

To evaluate the effect of posterior bony versus ligamentous injury pattern on functional outcomes in operatively treated rotational ankle fractures.

DESIGN

Retrospective cohort analysis of prospective registry.

SETTING

Academic Level I trauma center.

PATIENTS/PARTICIPANTS

Operatively treated supination external rotation IV and pronation external rotation IV ankle fractures.

INTERVENTION

Lateral malleolus plate fixation with either posterior malleolus (PM) plate fixation or posterior inferior tibiofibular ligament (PITFL) repair.

MAIN OUTCOME MEASUREMENTS

Foot and ankle outcome scores at minimum 12 months postoperatively.

RESULTS

One hundred seventy-eight fractures were treated with injury-specific anatomic fixation of a PM fracture (n = 122) or torn PITFL (n = 56). The PM group was significantly older, contained more women, and had lower mean body mass index versus the PITFL group. There was a higher rate of medial malleolar fracture in the PM group; other fracture and baseline characteristics were similar between groups. Univariate and multivariable analysis revealed no difference in foot and ankle outcome scores for any of the 5 summary domains (symptoms, pain, activities of daily living, sports, or quality of life) at the time of most recent follow-up. The median length of follow-up was 16.3 and 12.8 months in the PM and PITFL groups, respectively.

CONCLUSIONS

In our cohort of ankle fractures, we have demonstrated comparable outcomes in stage IV rotational ankle fractures with and without PM fractures, indicating that the presence of a PM fracture may not result in inferior outcomes compared with ligamentous equivalent injuries if these fractures are addressed in an injury-specific manner.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Repair of syndesmosis injury in ankle fractures: Current state of the art

Conventional treatment of syndesmosis injuries in rotationally unstable ankle fractures is associated with an unacceptably high rate of malreduction, and this has led to a paradigm shift in the approach to a newer concept of anatomical repair.

In the anatomical approach, the principle is to ‘directly fix what is broken and repair what is torn’. The approach is effective in reducing the rate of syndesmosis malreduction, increasing the biomechanical strength of syndesmosis fixation and avoiding the need for trans-syndesmotic fixation and its secondary removal.

The objective of this review article is to compare the conventional treatment of these injuries (accepted usage, general consent, traditional, generally accepted) with a newer anatomical approach to be considered as a shift in thinking.

Cite this article: EFORT Open Rev 2018;3:24-29. DOI: 10.1302/2058-5241.3.170017

Operative Treatment of Posterior Malleolar Fractures

Fractures of the posterior malleolus can occur in conjunction with fibular and medial malleolar fractures or in isolation. The indications for fixation of the posterior malleolus remain controversial except for the fragment sizes. A number of different surgical approaches and techniques for internal fixation of posterior malleolar fractures have been reported. Newer techniques such as direct exposure and plating of the posterior malleolus are chosen more frequently than traditional techniques of indirect reduction and percutaneous screw fixation. These attributes help to minimize the occurrence of postoperative complications.

State-of-the-Art in Ankle Fracture Management in Chile

The ankle represents the most commonly injured weightbearing joint in the human body. They are typically the result of low-energy, rotational injury mechanisms. However, ankle fractures represent a spectrum of injury patterns from simple to very complex, with varying incidence of posttraumatic arthritis. Stable injury patterns can be treated nonoperatively; unstable injury patterns are typically treated operatively given that they could lead to severe arthritis if not properly addressed.

Anatomic Ligament Repair Restores Ankle and Syndesmotic Rotational Stability as Much as Syndesmotic Screw Fixation

OBJECTIVES

To compare the external rotation stability of 3 different syndesmotic stabilization techniques in a cadaveric ankle fracture model.

METHODS

Nondestructive external rotation stresses of 4 N·m were applied to 8 cadaveric limbs using a hydraulic loading frame. Four conditions were tested using a repeated-measures design: intact and 3 repair conditions after a destabilizing ligamentous ankle injury with syndesmotic disruption. The 3 repair conditions were tricortical trans-syndesmotic screw fixation, posterior inferior tibiofibular ligament (PITFL) repair, and combined PITFL and deltoid ligament repair. External rotation of the ankle joint and syndesmosis was measured using a motion capture system and compared for each test condition. Repeated-measures 1-way analyses of variance statistical tests were performed to compare the ankle and syndesmotic rotation findings between the 3 repair conditions and intact condition.

RESULTS

Rotational ankle stability was not fully restored by any of the 3 repair constructs. The intact ankle joint externally rotated approximately half as many degrees as the 3 repair conditions (intact: 10.9; trans-syndesmotic screw: 17.0; PITFL: 21.4; and PITFL/deltoid: 15.6). The intact condition also demonstrated significantly fewer degrees of syndesmotic rotation than the repair constructs (intact 2.4; trans-syndesmotic screw 5.2; PITFL 8.5; and PITFL/deltoid 6.9). Each of the repair conditions resulted in an externally rotated fibula when no loads were applied. The ligamentous repairs externally rotated the fibula twice as much as the trans-syndesmotic screw (P < 0.016).

CONCLUSIONS

We found that combined repair of the PITFL and deltoid ligament restores an equivalent amount of ankle and syndesmotic rotational stability when compared to trans-syndesmotic screw fixation. Based on our findings, ligamentous repair can potentially be a viable treatment alternative in unstable ankle fracture patients with syndesmotic disruption.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.