Presented: Yes
Presented at: Published as technical tip JOT 2016

Authors: R Bruce Simpson, MD and Darryl A Auston MD/PhD
Author Affiliations: DAA Lutheran Medical Center, Wheat Ridge, Colorado

Summary:

Fractures of the talar neck with subtalar and tibiotalar joint dislocation (AO/OTA 81-B3) represent a treatment challenge for the orthopaedic surgeon.  The magnitude of deformity and complexity of the pathoanatomy add to concerns for soft tissue embarrassment to convey an urgency of surgical intervention. Previous studies have described the technique for medial malleolar osteotomy, or posteromedial incision to facilitate relocation at the time of definitive open treatment. 

We describe a simple technique for stepwise surgical intervention utilizing adjuncts to reduction on the surgical field that facilitate an atraumatic relocation of the displaced body fragment through a standard lateral incision, simplifying fixation of the residual talar neck fracture. A reasonable metaphor for the technique is its similarity to reducing an obstetric shoulder dystocia in the delivery of a newborn infant.

Technique:

Our patients are frequently offered regional blocks with ultrasonically-guided nerve sheath catheters for postoperative pain. After obtaining satisfactory general anesthesia, including muscle relocation with non-depolarizing blockade, the patients undergo nerve block placement.  They are then positioned in a modified supine position, with a well padded roll under the ipsilateral hip on a fully radiolucent OR table to allow easy fluoroscopy during the procedure.  A well-padded tourniquet is placed on the affected leg, and the leg is prepped and draped. Following a surgical time-out, the leg is elevated and exsanguinated, and the tourniquet inflated to 250mm Hg. 

A medium-size femoral distractor (Synthes USA, Paoli, PA) is used to facilitate restoration of tibiocalcaneal height. Two stab incisions are placed laterally: one over the anterolateral musculature adjacent to the lateral tibial crest, and one over the lateral portion of the posterior process of the calcaneus, adjacent to the Achilles insertional apophysis. After clearing the overlying soft tissues, a triple sleeve trochar is used to guide pre-drilling with a 3.5mm drill for a 5mm Shantz pin.  The femoral distractor is mounted on the pins, and a slow and steady distraction is used to open the tibiocalcaneal interval. With fluoroscopic guidance, the interval is opened through indirect distraction.

A modified Böhler is then made using an anterolateral extension over the sinus tarsi. The incision is brought proximally over the lateral edge of the anterior musculature, developing the interval between the peroneus tertius and the anterior edge of the fibula. This proximal interval exposes the Chaput tubercle, anterolateral joint capsule, and the anterior inferior talofibular ligament, which is variably intact. Distally, the interval extends over the sinus tarsi fat, and the extensor digitorum brevis aponeurotic tendon of origin and musculature.  The anterior capsular remnants are encountered and sharply excised. The hematoma in the vacant joint space is evacuated.

After careful debridement of the fracture hematoma off of the joint surfaces, an inspection of the joint content and anatomy will reveal the presence of the fracture surface posterior to the arc of the tibial plafond. Often, we have found the tarsal canal to be the feature that acts as a consistent point of orientation, running cephalo-caudal in its displaced position.  The articular surface of the talar posterior facet is often nearly vertical, and seemingly locked behind the posterior edge of the calcaneal posterior facet. 

Once the relevant pathoanatomy is visualized, the relocation maneuver is planned. Appropriate distraction can be adjusted through the use of the femoral distractor, and a small 1.6mm Kirshner wire is placed in the most anterior (extraarticular) portion of the plafond, anticipating the reduction of the body segment. With visualization of the fracture surface in the post-articular recess, a 3.5 mm pilot hole for a 5mm Shantz pin is drilled into the body segment through the fracture in a specific inclination and angulation anticipating the reduction maneuver. The trajectory we recommend is inferior and medial. A 5mm Shantz pin is then threaded into the talar body. The average bone distance is 45mm, and we thread the pin in to an estimated depth of 35-40mm based on the remaining exposed thread distance in the wound. After confirming the absence of articular penetration on lateral fluoroscopy, the relocation is attempted. 

Critical to the success of the reduction is that the surgeon must have an understanding of the dorsiflexion of the dome segment and the relationship between the fibula and the lateral process of the talus. In its pathologic position in the posterior recess, the laterally protruding lateral process of the talus abuts the posterior edge of the fibula when an anteriorly directed force is applied. Through rotating the body segment in the axial plane (medially and laterally), the lateral process can be visualized and bypassed. 

It is through the correct combination of distraction, plantar flexion, and axial rotation that the anterior directed force will succeed in clearing the ankle structures.  Most often, we find that the plantar flexion should be applied first, followed by a rotation opposite the rotation of the displaced fragment. 

Figure 5.pdf

Once the fragment is relocated, the distractor is relaxed, limiting the tendency of the talar body segment to re-dislocate. Kirshner wires are inserted to facilitate “joystick” reduction of the talar neck, and the pre-placed wire is advanced into the extraarticular portion of the body adjacent to the neck fracture to hold the body segment in tibiotalar alignment during reduction of the neck fracture. Definitive reduction and fixation of the neck fracture proceeds at this point, with a medial incision made at the surgeon’s discretion.