Acute Ankle Diastasis Injuries

---

Introduction

• Ankle injuries are among the most common lower limb injuries, ranging from simple sprains to complex fractures.

• The distal tibiofibular syndesmosis is essential for ankle stability and consists of:

  • Anterior inferior tibiofibular ligament

  • Posterior inferior tibiofibular ligament

  • Interosseous ligament

  • Interosseous membrane

• Acute ankle diastasis injury refers to disruption of the distal tibiofibular syndesmosis, either as:

  • An isolated ligamentous injury, or

  • An injury associated with malleolar fractures

• Approximately 65.8 percent of ankle fractures are associated with acute syndesmotic injury.

---

Consequences of Inadequate Treatment

Untreated or poorly reduced syndesmosis injuries can result in:

• Chronic ankle pain

• Post-traumatic osteoarthritis

• Persistent ankle instability

• Poor long-term functional outcomes

---

Clinical Significance

• Given the high incidence and morbidity of these injuries, a clinically effective and cost-efficient treatment strategy is essential.

• There is no universal consensus regarding:

  • Optimal diagnostic methods

  • Implant selection

  • Surgical technique

  • Postoperative rehabilitation protocols

---

Treatment Modalities

Three primary treatment strategies are used for acute ankle diastasis injuries:

Static Fixation

• Utilizes syndesmosis screws:

  • One or two tricortical or quadricortical screws

  • Screw diameter ranges from 3.5 to 6.0 millimeters

• Widely used traditional method

• Common complications include:

  • Screw breakage

  • Need for routine implant removal

  • Increased reoperation rates

Dynamic Fixation

• Uses a suture button device consisting of:

  • Two metallic buttons

  • A high-strength connecting suture

• Provides elastic fixation

• Allows physiologic micromotion of the syndesmosis

Anatomic Ligament Repair

• Involves direct repair of the anterior inferior tibiofibular ligament using a suture anchor

• Syndesmosis reduction performed under direct visualization

• Reduction confirmed with intraoperative imaging

---

Management of Combined Injuries and Rationale for Review

• In ankle fractures involving syndesmotic injury:

  • Malleolar fractures are stabilized first, usually with plate fixation

  • Disrupted syndesmotic ligaments are then repaired anatomically

  • Additional fixation is added if reduction remains unstable

• Ongoing controversy exists regarding the most effective treatment method.

• Previous studies typically compare only two techniques.

• The purpose of this analysis was to compare:

  • Static fixation

  • Dynamic fixation

  • Anatomic repair

• The goal was to identify the most effective and reliable treatment strategy for acute ankle diastasis injuries.

---

Methods

• A systematic review and meta-analysis methodology was used.

• Literature searches were conducted using major medical databases.

• Search terms focused on syndesmosis fixation techniques and anatomic ligament repair.

---

Study Selection Criteria

Included Studies

• Randomized controlled trials

• Prospective cohort studies

• Retrospective cohort studies

Required Comparisons

• At least two treatment methods, such as:

  • Dynamic versus static fixation

  • Static fixation versus anatomic repair

Required Outcomes

• American Orthopaedic Foot and Ankle Society score

• Visual Analog Scale pain score

• Implant failure or irritation

• Infection rates

• Reoperation rates

Excluded Studies

• Meta-analyses and systematic reviews

• Studies without defined outcome measures

• Studies with unclear or poorly defined comparison groups

---

Data Compilation Strategy

• No direct comparative studies between dynamic fixation and anatomic repair were identified.

• To address this limitation:

  • Data from studies using dynamic fixation were pooled

  • Data from studies using anatomic repair were pooled

• Outcomes analyzed included:

  • Functional scores at 1 year

  • Pain scores at 1 year

  • Reoperation rates

---

Quality Assessment

• Study selection and evaluation were performed independently by multiple reviewers.

• Study quality focused on:

  • Comparison of functional outcomes

  • Analysis of complication profiles across all treatment methods

Assessment Tools

• Randomized studies evaluated using the Cochrane Risk of Bias Tool

• Non-randomized studies evaluated using the Newcastle–Ottawa Scale

---

Outcome Measures

• Functional outcomes:

  • American Orthopaedic Foot and Ankle Society score

  • Visual Analog Scale pain score

• Complications:

  • Implant failure

  • Implant irritation

  • Infection

  • Reoperation

---

Statistical Analysis

• Analysis performed using dedicated meta-analysis software.

• Continuous outcomes reported as mean and standard deviation.

• Categorical outcomes reported as event rates.

• Mean differences used for functional scores.

• Odds ratios used for complications.

• Statistical significance defined as p ? 0.05.

---

Study Demographics

• Total studies included: 21

• Total patients: 1,059

• Treatment distribution:

  • Dynamic fixation: 452 patients

  • Static fixation: 529 patients

  • Anatomic repair: 78 patients

---

Clinical Outcomes

Dynamic Fixation versus Static Fixation

• Higher functional scores with dynamic fixation at:

  • 3 months

  • 1 year

• Lower pain scores at 12 months

• Interpretation:

  • Dynamic fixation provides superior short- and long-term functional outcomes compared to static fixation

Anatomic Repair versus Static Fixation

• Higher functional scores with anatomic repair at:

  • 6 months

  • 1 year

• Pain scores were similar between groups

• Interpretation:

  • Anatomic repair improves functional recovery compared to static fixation

Dynamic Fixation versus Anatomic Repair

• Higher functional scores with dynamic fixation at:

  • 6 months

  • 12 months

  • 1 year

• Slightly lower pain scores with anatomic repair at 12 months

• Interpretation:

  • Dynamic fixation offers superior functional recovery, while anatomic repair may provide marginal pain relief at later follow-up

---

Complication Profile

Dynamic Fixation versus Static Fixation

• Significantly fewer implant failures

• Lower reoperation rates

• No significant difference in infection or implant irritation

Anatomic Repair Comparison

• No significant difference in implant-related complications compared to static fixation

• Higher reoperation rates compared to dynamic fixation

---

Overall Findings

• Dynamic fixation demonstrates:

  • Best functional outcomes

  • Lowest implant failure rates

  • Lowest reoperation rates

• Anatomic repair shows:

  • Improved functional outcomes compared to static fixation

  • No clear advantage in complication reduction

• Static fixation shows:

  • Higher rates of implant-related complications and reoperation

---

Comparison With Existing Evidence

• Previous analyses have shown superior outcomes with dynamic fixation compared to static fixation.

• Findings from this analysis are consistent with existing literature.

• A major advantage of dynamic fixation is reduced risk of malreduction of the distal fibula within the tibial incisura.

---

Insights on Anatomic Repair

• Evidence directly comparing anatomic repair with dynamic fixation is limited.

• Available data suggest:

  • Earlier rehabilitation

  • Improved function in daily activities

• Small sample size limits definitive conclusions.

---

Reasons for Superiority of Dynamic Fixation

• Restores ligament continuity while stabilizing fractures

• Permits physiologic micromotion

• Allows earlier weight-bearing and rehabilitation

• Results in:

  • Better functional recovery

  • Fewer complications

  • Lower reoperation rates

---

Study Limitations

• Unequal sample sizes across treatment groups

• Inconsistent outcome reporting

• Inclusion of both randomized and observational studies

• Variability in injury patterns and surgical techniques

• Risk of bias related to:

  • Blinding

  • Allocation concealment

  • Incomplete data

• Despite these limitations, pooled analysis reduces individual study bias.

---

Conclusion

• Dynamic fixation demonstrates superior early clinical outcomes, fewer complications, and lower reoperation rates compared to static fixation and anatomic repair.

• Long-term differences between treatment methods are minimal.

• Anatomic repair provides better functional outcomes than static fixation but no clear advantage in complication rates.

---

Future Directions

• Dynamic fixation appears to be the most effective overall treatment for acute ankle diastasis injuries.

• Static fixation remains widely used but carries higher risks of hardware-related complications.

• Anatomic repair is promising but requires further high-quality evidence.

• Large, well-designed comparative studies with balanced sample sizes are needed to confirm long-term outcomes and cost-effectiveness.