What are the consequences of a syndesmotic injury in an ankle fracture if left surgically unaddressed?

Consequences of Untreated Syndesmotic Injury in Ankle Fractures

Failure to surgically address a syndesmotic injury in an ankle fracture leads to chronic ankle instability, progressive post-traumatic arthritis, persistent pain, and significantly impaired function that may ultimately require salvage procedures.

Primary Complications

Chronic Syndesmotic Instability

• Untreated syndesmotic injuries result in persistent widening of the ankle mortise and chronic instability of the distal tibiofibular joint 1, 2.
• This instability causes abnormal biomechanics with altered load distribution across the ankle joint 1.
• The incongruous ankle mortise cannot be adequately managed with conservative treatment alone once chronic instability develops 1.

Post-Traumatic Ankle Arthritis

• Chronic syndesmotic instability directly leads to progressive post-traumatic osteoarthritis of the ankle joint 3, 1.
• The arthritic changes develop because the unstable mortise creates abnormal contact pressures and joint incongruity 1.
• Even in young, active patients (such as a 21-year-old in one case series), ankle arthritis with joint space narrowing can develop within years of the initial untreated injury 3.

Functional Consequences

Pain and Activity Limitation

• Patients with chronic untreated syndesmotic injuries experience long-term pain that significantly reduces ankle function 4.
• The pain pattern is persistent and activity-related, limiting both daily activities and athletic participation 4.
• Maximum walking distance becomes progressively restricted as the condition worsens 1.

Gait Abnormalities

• Chronic syndesmotic instability causes measurable gait disturbances that affect overall mobility 1.
• The altered biomechanics force compensatory movement patterns that can lead to secondary problems in adjacent joints 1.

Radiographic Deterioration

Progressive Mortise Widening

• Key radiographic parameters deteriorate over time, including increased medial clear space, abnormal talocrural angle, and progressive talar tilt 1.
• The tibiofibular distance progressively increases as the chronic diastasis worsens 4.
• Weight-bearing radiographs demonstrate the functional instability that may not be apparent on non-weight-bearing films 5.

Salvage Treatment Challenges

Complex Reconstructive Surgery Required

• Once chronic instability develops, salvage procedures such as distal tibiofibular arthrodesis become necessary 3, 1.
• These salvage procedures are technically demanding and carry significant complication rates, including hardware-related pain in up to 27% of cases 4.
• Despite surgical salvage, approximately 64% of patients still demonstrate progression of osteoarthritis on follow-up imaging 4.

Alternative to Ankle Fusion

• Distal tibiofibular arthrodesis can postpone or potentially avoid the need for total ankle arthrodesis or arthroplasty 1.
• However, this represents a more extensive procedure than would have been required with acute treatment 1.

Critical Clinical Pitfall

The most important pitfall is failing to recognize syndesmotic injury at the time of initial ankle fracture treatment. 2, 6

• Syndesmotic injuries accompany approximately 10% of operatively treated ankle fractures, particularly Weber type B or C fractures 6.
• MRI is the reference standard for assessing syndesmotic ligament injuries and determining their grade (1,2, or 3), which is critical for treatment planning 7.
• Failure to adequately identify and treat syndesmotic injuries at the time of initial fracture fixation results in continued ankle instability and poor patient outcomes 2.
• Intraoperative assessment of syndesmotic reduction accuracy using standard fluoroscopy alone is difficult and may miss malreduction 6.

Long-Term Prognosis Without Treatment

• The natural history of untreated syndesmotic injury is progressive deterioration rather than spontaneous improvement 1.
• Even after eventual salvage surgery, patients require extended follow-up (mean 41-45 months in published series) to achieve functional improvement 1, 4.
• No patient with chronic untreated syndesmotic injury achieves the same functional outcome as those treated acutely 1.