Open Reduction and Internal Fixation of Ankle Fracture

Examiner Question: "How do you assess the soft tissue envelope for surgery timing?"

Model Answer: "I assess for the 'wrinkle sign' - the ability to wrinkle the skin over the ankle with passive dorsiflexion indicates adequate soft tissue recovery and it's safe to proceed. If the skin is tense without wrinkles, I delay surgery 5-14 days with elevation and ice. Operating through swollen tissues leads to 20-30% wound complication rates versus 2-5% with recovered soft tissues."

Critical Setup Point: The bump under the hip (15-30° internal rotation) brings the lateral malleolus UP - this provides optimal access to the fibula. Testing fluoroscopy BEFORE prepping is essential - a true mortise view (15-20° internal rotation of the leg) must be achievable.

Examiner Question: "Where do you place your lateral incision for fibula ORIF?"

Model Answer: "I place my incision POSTERIOR to the fibular shaft, not directly lateral. This protects the superficial peroneal nerve which emerges from the anterior compartment 10-12cm proximal to the lateral malleolus tip and runs anterolaterally. By staying posterior, I avoid this nerve. I make an 8-10cm incision centered on the fracture site, and perform subperiosteal dissection to protect the peroneal tendons posteriorly."

Examiner Question: "How do you achieve lag screw fixation for a spiral fibula fracture?"

Model Answer: "Lag screw technique requires a glide hole (3.5mm) in the near cortex and a thread hole (2.5mm) in the far cortex. The screw must be perpendicular to the FRACTURE LINE, not the bone axis - this provides compression across the fracture. I then add a neutralization plate to protect the lag screw from rotational and bending forces. For spiral fractures greater than 2x fibula diameter, I place the lag screw outside the plate. For shorter spirals, the lag screw can go through the plate."

Examiner Question: "What parameters do you assess on intraoperative fluoroscopy after fibular fixation?"

Model Answer: "I assess the MORTISE parameters: Medial clear space should be less than 4mm and equal to the superior joint space. Tibiofibular clear space should be less than 6mm. Tibiofibular overlap should be greater than 6mm on AP and greater than 1mm on mortise. I also confirm fibular length and rotation on lateral view. If the medial clear space remains greater than 4mm despite anatomic fibular reduction, this indicates either deltoid ligament rupture or syndesmotic injury requiring further intervention."

Examiner Question: "What prevents anatomic reduction of a medial malleolus fracture?"

Model Answer: "The most common cause of inability to reduce a medial malleolus fracture is interposed deltoid ligament in the fracture site. The ligament can get pulled into the fracture gap during injury and physically blocks reduction. I always carefully inspect the fracture site and remove any interposed soft tissue before attempting reduction. Additionally, periosteal interposition can occur. Direct visualization and clearing of the fracture site is essential before reduction."

Examiner Question: "Describe your screw configuration for medial malleolus fixation."

Model Answer: "I use two parallel 4.0mm partially-threaded cancellous screws. Partially-threaded screws provide compression by having threads only in the far fragment while gliding through the near fragment. The entry point is at the tip of the malleolus, directed toward the posterolateral metaphyseal bone where the bone density is best for purchase. I keep the screws parallel - convergent screws can spread the fracture apart, and divergent screws reduce purchase. For vertical fractures (SA pattern), I may use an antiglide plate or buttress plate. For comminuted or osteoporotic bone, buttress plating provides superior fixation."

Examiner Question: "How do you assess syndesmotic stability intraoperatively?"

Model Answer: "I perform syndesmotic stress testing ONLY after all bony fixation is complete - you cannot accurately assess the syndesmosis with unstable malleoli. I perform the external rotation stress test with the ankle in dorsiflexion (talus is widest anteriorly), neutral rotation, and apply external rotation force to the foot while observing under fluoroscopy. Abnormal findings include tibiofibular clear space greater than 6mm, loss of tibiofibular overlap, or medial clear space widening greater than 4mm. I also perform the Cotton test (hook test) - applying lateral force to the talus and fibula should not cause greater than 2mm lateral displacement. Weber C fractures ALWAYS have syndesmotic injury and require fixation. Weber B fractures have 50% syndesmotic injury rate, so I stress test all Weber B fractures."

Examiner Question: "Why must the ankle be dorsiflexed during syndesmotic reduction?"

Model Answer: "The talus is 2-4mm wider anteriorly than posteriorly. When I dorsiflex the ankle, I bring the wider anterior portion of the talus into the mortise, which forces the fibula into its anatomic position within the incisura. If I reduce the syndesmosis with the ankle in plantarflexion, the narrower posterior talus allows the fibula to sit too close to the tibia - this causes syndesmotic malreduction and the patient loses dorsiflexion post-operatively. I apply the reduction clamp with the ankle dorsiflexed, in neutral rotation (internal rotation causes malreduction), 2-3cm proximal to the joint, in an AP direction. I confirm reduction on fluoroscopy before fixing with either two 3.5mm cortical screws or suture-button device."

Examiner Question: "When do you fix the posterior malleolus and how?"

Model Answer: "I fix the posterior malleolus when it involves greater than 25-33% of the articular surface OR if there is any posterior talar subluxation - subluxation is the more important indication regardless of fragment size. A 20% fragment with posterior subluxation needs fixation. I have two techniques: Indirect fixation using A-P lag screws through the lateral approach is faster with less dissection, but provides no direct visualization. Direct fixation via a posterolateral approach allows direct visualization and buttress plating, achieving better reduction but requiring more dissection and often prone positioning. The posterior malleolus is important because the PITFL attaches to it, so its fixation can contribute to syndesmotic stability."

Examiner Question: "What are the key radiographic parameters you assess at the end of ankle fracture ORIF?"

Model Answer: "I use the MORTISE parameters for quality control. Medial clear space should be less than 4mm and equal to the superior joint space. Tibiofibular clear space should be less than 6mm. Tibiofibular overlap should be greater than 6mm on AP and greater than 1mm on mortise view. I confirm there is no talar subluxation and the articular surface is congruent with no step greater than 1mm. All screws must be out of the joint - I obtain lateral and mortise views to confirm. If I fixed the posterior malleolus, I confirm its reduction. If any parameter is outside acceptable range, I DO NOT leave the operating theatre - I revise immediately. Delayed revision for malreduction has worse outcomes."

Examiner Question: "What is your post-operative protocol after ankle fracture ORIF?"

Model Answer: "Immediate post-operatively, I apply a well-padded posterior splint or bulky Jones dressing to protect the reduction and control swelling. The leg is elevated above heart level. I initiate DVT prophylaxis - typically LMWH or aspirin depending on risk factors. For weeks 0-2, the patient is non-weight bearing in a splint. At 2 weeks, I reassess the wound and convert to a removable boot. The patient remains non-weight bearing until 6 weeks, but begins gentle active ROM exercises out of the boot. From 6-12 weeks, I progressively increase weight bearing to full weight bearing as tolerated. Strengthening and proprioception work begins at 12 weeks with formal physiotherapy. For syndesmotic fixation, if I used screws, some surgeons remove them at 12 weeks - this is controversial. If I used suture-buttons, no removal is needed."