The syndesmosis, the ligamentous complex connecting the tibia and fibula above the ankle joint, can be torn even when the ankle appears structurally intact, making high ankle sprains a commonly misdiagnosed injury.
Unlike lateral ankle sprains, which often heal within weeks, syndesmotic injuries typically require a longer recovery and may require surgical intervention to restore joint stability. Comprising four key structures, the syndesmosis maintains precise alignment between the tibia and fibula during weight-bearing, and even minor disruption can reduce joint contact and accelerate cartilage wear.
Ankle syndesmosis treatment depends on injury severity, ranging from protected weight-bearing in stable cases to surgical fixation for complete tears with joint widening.
Mechanism of Injury and Clinical Presentation
Syndesmosis injuries typically occur through external rotation of the foot with the ankle in dorsiflexion—the position where the wider anterior portion of the talus (ankle bone) wedges between the tibia and fibula. Contact sports, skiing accidents, and falls from height commonly produce this mechanism.
Athletes often report feeling a “pop” at the time of injury. Immediate difficulty bearing weight follows. Unlike lateral ankle sprains, which improve rapidly in the first few days, high ankle sprains are associated with persistent pain with walking and an inability to push off during the gait cycle. Swelling appears higher on the leg than in typical ankle sprains, often extending above the ankle joint.
The squeeze test, compressing the tibia and fibula together at the mid-calf level, reproduces pain at the syndesmosis when positive. External rotation stress testing, where the foot is rotated outward while stabilising the leg, provides additional diagnostic information. Pain with this manoeuvre suggests ligament disruption even when initial imaging appears normal.
Imaging Assessment and Classification
Weight-bearing radiographs (X-rays taken while you stand on the injured leg) serve as the initial imaging study for suspected syndesmosis injuries. Specific measurements help identify subtle joint widening. The tibiofibular clear space should measure less than a certain threshold on anteroposterior views. Tibiofibular overlap should exceed a certain threshold on the same projection.
Stress radiographs, taken whilst applying external rotation force to the ankle, can reveal instability that standard views may miss. Comparison with the uninjured side helps identify asymmetric widening that indicates ligamentous incompetence.
MRI provides detailed visualisation of each syndesmotic ligament. This allows grading of partial versus complete tears. This imaging also identifies associated injuries, deltoid ligament tears, osteochondral lesions, and bone bruising that influence treatment planning and prognosis. The AITFL tears most commonly, followed by the interosseous membrane and PITFL.
CT scanning with bilateral comparison offers precise measurement of syndesmotic relationships. It proves particularly valuable for detecting malreduction (incorrect bone alignment) following surgical fixation. Three-dimensional reconstructions help visualise complex injury patterns involving both the syndesmosis and surrounding structures.
Non-Surgical Management Protocols
Stable syndesmosis injuries without frank diastasis (visible widening between the bones) on stress imaging respond to conservative treatment. Initial management involves immobilisation in a walking boot with restricted ankle motion. This protects healing ligaments whilst preventing complete deconditioning.
Protected weight-bearing progresses based on pain response rather than arbitrary timelines. Most patients tolerate full weight-bearing in a boot within the first two weeks. They transition to supportive footwear by six weeks if clinical examination shows resolved tenderness and negative stress testing.
Rehabilitation focuses on restoring dorsiflexion range, often limited after syndesmotic injury, followed by progressive strengthening and proprioceptive training (exercises that improve your body’s awareness of joint position and movement). Return to sport for athletes typically requires several months for isolated stable injuries. This is considerably longer than lateral ankle sprains of a similar mechanism.
Surgical Indications and Timing
Frank diastasis on standard weight-bearing radiographs mandates surgical stabilisation. Other indications include:
- Persistent widening on stress views despite adequate immobilisation
- Associated fibula fractures (Weber C pattern)
- Deltoid ligament ruptures that destabilise the medial ankle
Surgery performed within the first two weeks after injury generally achieves effective outcomes. Chronic syndesmotic instability presents greater technical challenges. It may require ligament reconstruction (a procedure in which the surgeon rebuilds damaged ligaments using tissue grafts) rather than simple repair.
Examination under anaesthesia at the time of surgery confirms instability before fixation. The Cotton test—lateral translation of the fibula within the incisura, and external rotation stress assessment, guides the extent of fixation required.
Screw Fixation Techniques
Traditional syndesmotic screw fixation remains an established stabilisation method. Surgeons place screws parallel to the tibial plafond, approximately a certain distance above the joint line. These compress the fibula into the tibial incisura and maintain reduction during ligament healing.
Debate continues over the optimal screw configuration: tricortical screws (engaging three cortices, both the fibular and the near tibial cortices) versus quadricortical screws (engaging all four cortices). Quadricortical fixation provides greater stability but may increase the risk of screw breakage as the syndesmosis attempts normal motion during healing.
One versus two screws depends on injury severity and surgeon preference. Purely ligamentous injuries often require only single-screw fixation. Injuries with associated fractures or extensive ligament disruption may benefit from two-screw constructs.
Suture Button Fixation Systems
Flexible suture button devices offer an alternative to rigid screw fixation. These implants—consisting of metal buttons connected by high-strength suture- allow physiological motion at the syndesmosis whilst maintaining reduction.
Proposed advantages include:
- Elimination of routine hardware removal
- More anatomical fibular motion during healing
- Potential for earlier return to activity
The suture button permits the small amounts of rotation and translation that occur at the normal syndesmosis during gait.
Clinical studies comparing suture buttons to screws show similar functional outcomes at one year. Suture button patients demonstrate earlier return to baseline activity in some series. Hardware-related complications requiring removal occur less frequently with flexible fixation.
Combined constructs using both a syndesmotic screw and suture button provide greater stability for severe injuries with complete ligament disruption. The screw protects the construct during early healing. The suture button provides ongoing support after screw removal.
Anatomical Ligament Repair and Reconstruction
Direct repair of torn syndesmotic ligaments has gained renewed interest with improved arthroscopic (minimally invasive surgery using a small camera and instruments inserted through tiny incisions) and open techniques. Suture anchor fixation of the AITFL to its tibial or fibular footprint restores the anatomical restraint rather than simply maintaining bone relationships.
When primary repair is not feasible, typically in chronic cases with ligament retraction or degeneration, reconstruction using tendon grafts recreates syndesmotic stability. Various graft configurations route tissue through bone tunnels in the tibia and fibula. These replicate the orientation of native ligaments.
Anatomical reconstruction shows promising results for chronic syndesmotic instability that failed prior treatment. The procedure requires precise tunnel placement to restore normal kinematics and avoid over-constraining the joint.
Postoperative Rehabilitation Framework
Early rehabilitation following syndesmotic fixation emphasises protecting the repair whilst preventing stiffness. Non-weight-bearing typically continues for six weeks with screw fixation. Suture button constructs may allow earlier protected weight-bearing based on the surgeon’s protocol.
Phase 1 (Weeks 0-6)
Ankle immobilisation in a boot or cast, focusing on knee and hip strengthening to maintain overall conditioning. Gentle ankle range of motion may begin at two to three weeks for suture button fixation.
Phase 2 (Weeks 6-12)
Progressive weight-bearing in a walking boot, transitioning to supportive shoes. Range-of-motion exercises emphasise dorsiflexion recovery. Pool-based exercises reduce joint loading during gait retraining.
Phase 3 (Weeks 12-20)
Full weight-bearing with focus on single-leg balance, progressive resistance exercises, and sport-specific movement patterns. Running progression begins when single-leg hop testing shows minimal asymmetry.
Phase 4 (Weeks 20+)
Return-to-sport criteria include full strength, normal range of motion, completion of sport-specific drills without pain, and psychological readiness for competition.
Factors Affecting Recovery Outcomes
Injury severity correlates strongly with recovery duration. Isolated AITFL injuries return to function faster than complete syndesmosis disruptions involving all four structural components.
Associated injuries, particularly cartilage damage and deltoid ligament tears, extend recovery and may limit ultimate function. Pre-existing ankle arthritis or prior injury to the same ankle predicts slower rehabilitation progression.
Anatomical reduction quality, confirmed by postoperative CT, strongly influences long-term outcomes. Even small amounts of malreduction, fibular shortening, external rotation, or posterior translation increase contact pressures within the ankle joint and accelerate degenerative changes.
Patient factors, including age, activity demands, body weight, and rehabilitation compliance, also affect results. Younger athletes typically recover more completely than older recreational patients. All groups benefit from structured rehabilitation programmes.
When to Seek Professional Help
- Ankle injury with immediate inability to bear weight
- Swelling extending above the ankle joint after a twisting injury
- Persistent pain with walking beyond several days despite rest and ice
- Tenderness when pressing above the ankle rather than at the ankle bone
- Pain with external rotation of the foot
- Inability to perform single-leg heel raises without pain
- Prior ankle surgery with new onset of instability or giving way
- Failure to improve with conservative treatment after six weeks
Commonly Asked Questions
How long will it take before I can return to sports after syndesmotic surgery?
Most athletes require several months before returning to competitive sport following surgical syndesmotic stabilisation. Your doctor will set return-to-sport criteria based on your specific injury severity, associated injuries, and the demands of your particular sport rather than time alone. Contact sports and activities that involve cutting movements typically have the longest recovery periods.
Will I need the screws removed after surgery?
Screw removal practices vary amongst surgeons. Some routinely remove syndesmotic screws after several months to restore normal motion. Others only remove hardware if it causes symptoms. Suture button devices typically remain permanently and rarely require removal.
Can a syndesmotic injury heal without surgery?
Stable syndesmotic injuries without widening on stress radiographs can heal with immobilisation and protected weight-bearing. However, injuries with joint widening or instability on examination generally require surgical stabilisation to reduce the risk of chronic pain and arthritis.
What happens if a syndesmotic injury goes untreated?
Untreated syndesmotic instability leads to abnormal joint mechanics. This causes accelerated cartilage wear and post-traumatic arthritis. Patients develop chronic ankle pain, swelling with activity, and progressive loss of function. Late reconstruction proves more complex and less predictable than acute treatment.
Is physical therapy necessary after syndesmotic treatment?
Structured rehabilitation can significantly improve outcomes after both surgical and non-surgical syndesmotic treatment. Therapy addresses range-of-motion deficits, strength imbalances, and proprioceptive dysfunction that persist after ligament healing. Athletes particularly benefit from sport-specific training before returning to competition.
Next Steps
Accurate diagnosis determines whether a syndesmotic injury can be managed conservatively or requires surgical fixation. Unstable injuries with joint widening need prompt surgical stabilisation. Delayed treatment increases the complexity of repair and reduces the likelihood of full recovery. Postoperative CT confirmation of anatomical reduction is a critical determinant of long-term outcome and should be standard following any syndesmotic fixation procedure.
If you are experiencing swelling above the ankle joint after a twisting injury, persistent pain with weight-bearing, or tenderness above the ankle rather than at the ankle bone, consult an orthopaedic specialist to assess syndesmotic stability and determine whether surgical fixation is required.
