Primary total talus arthroplasty for Hawkins type IV talar neck fracture dislocation

Abstract

A woman in her 40s was involved in a motor vehicle collision and sustained a closed Hawkins type IV talar neck fracture dislocation. The injury was treated with reduction, percutaneous pinning and spanning external fixation, followed by definitive treatment with total talus arthroplasty (TTA) 2 months following injury. This is a unique example of definitive management for a severe talar neck fracture dislocation with arthroplasty in the subacute setting. TTA is perhaps a primary option for these injuries at high risk for avascular necrosis, non-union, malunion and post-traumatic arthritis.

Background

Talar neck fracture dislocations are rare injuries and can have devastating consequences even with prompt, sound treatment.¹ The surface of the talus is covered in over 60% cartilage, and the periosteal blood supply does not significantly contribute to its perfusion.^{2 3} It is mainly vascularised by branches of the posterior tibial and peroneal arteries.² Talar neck fractures themselves represent up to 50% of fractures of the talus and result from high-energy mechanisms of axial load with ankle dorsiflexion.⁴ Displaced fractures, in particular, can lead to significant clinical complications including stiffness, deformity, avascular necrosis (AVN), non-union, malunion and post-traumatic arthritis, with the majority of these sequelae carrying with them substantial pain and dysfunction.¹ Conventional, definitive treatment for displaced talar neck fractures has been open reduction and internal fixation (ORIF) with the risk of AVN higher with greater initial fracture displacement (as opposed to surgical timing).⁵ Acute (at least subtalar) arthrodesis for severe injuries at high risk of complications is another option, yet can be challenging as the hopes of success may hinge on fusing a live bone to a potentially dying one. Total talus arthroplasty (TTA) has been described as a treatment option for patients with advanced talar AVN, but it has traditionally been for atraumatic aetiologies.⁶ Removal of the talar body and implantation of a replacement prosthesis anchored to the talar neck was first described in 1997 with development of the total talar arthroplasty in 2005.^{7 8} Arthroplasty allows for preservation of the tibiotalar, subtalar and talonavicular articulations before substantial arthritis has set in, and in our case it was done also before deformity could develop. This is a case description of TTA in lieu of ORIF or primary arthrodesis for a traumatic talar fracture dislocation.

Case presentation

A woman in her 40s was involved in a motor vehicle collision and sustained a right, closed Hawkins type IV talar neck fracture dislocation with fracture extension into the talar dome and body (figure 1). She underwent some closed reduction of her injury (of the tibiotalar joint) in the emergency department and was immobilised in a short-leg splint, followed by CT (figure 2). The following morning, during intramedullary nail fixation of her contralateral, segmental tibia fracture with the on-call, weekend team, the patient underwent open reduction of the right talus. A small incision was made over the sinus tarsi, and a freer elevator was used to reduce the posterior talus at the subtalar joint. The tibiotalar joint stayed reduced, and the talonavicular joint was unable to be reduced (figure 3).

Figure 1.

Right lateral ankle radiograph depicting Hawkins type IV talar fracture dislocation.

Figure 2.

(A) Lateral CT slice depicting closed reduction of the tibiotalar joint in the emergency room and residual fracture dislocation at the subtalar joint. (B) Lateral CT slice depicting residual fracture dislocation of the talonavicular joint. (C) Coronal CT slice depicting substantial medial dome comminution and residual fracture dislocation of the subtalar joint.

Figure 3.

Lateral fluoroscopic view after injury day 1 depicting operative closed reduction of the subtalar joint with residual dislocation of the talonavicular joint.

Differential diagnosis

The diagnosis was confirmed as a Hawkins type IV talar neck fracture dislocation by plain radiographs and CT scan. Other differential diagnoses prior to imaging included ankle fracture, distal tibia and fibula fracture, calcaneus fracture or Lisfranc injury.

Treatment

Extensive discussion between multiple orthopaedic trauma surgeons regarding optimal definitive management of the severe talar injury ensued Monday morning. ORIF, acute arthrodesis and TTA were given extensive consideration. Discussion of treatment options with the patient involved the severity of the injury along with the high risk of complications including AVN and post-traumatic arthritis. The patient considered the risks and benefits, and the decision was made to proceed with provisional temporising, percutaneous reduction and fixation with definitive plan for TTA when soft-tissue swelling subsided and the prosthesis could be manufactured. During her first stage, the subtalar joint was found to be redislocated, and with reopening of her prior approach, it was reduced again. Her talonavicular joint was reduced percutaneously followed by pins and a spanning external fixator (figure 4). She was placed on an extended prophylactic antibiotic to protect the pin sites and was discharged from the hospital. A pin-site holiday was administered in the clinic (figure 5), and her second stage with TTA was performed 2 months following injury. With CT guidance of the contralateral talus, 95% and 100% Restor3D (Durham, North Carolina) cobalt-chrome implants were manufactured. This anatomical ‘match’ is what confers so much stability to the prosthesis itself (and its surrounding articulation) that otherwise does not receive ligamentous repair. In the past, attempts have been made to reattach the deltoid and anterior talofibular ligament to a porous-coated surface, and a technique has been described for internally bracing released ligaments.^{9 10} Much of our technique was adapted from a 2019 technical paper, and some are described here.¹¹ Under tourniquet control, a direct anterior approach to the ankle was performed in between the tibialis anterior and extensor hallucis longus tendons with the latter protecting the anterior tibial and deep peroneal neurovascular bundle. The tibiotalar joint capsule was incised (with flaps developed and tagged), and dissection was taken down distal to the level of the talonavicular releasing all capsular and ligamentous attachments of the talus to the navicular dorsally. Safe retraction throughout the case was key to avoid a wound complication. The talar head was removed from its deficient articulation with the navicular with attempted preservation of the plantar calcaneonavicular (spring) ligament medially. Fractured neck pieces were removed along the way. A saw and osteotome were used to divide the talar body and remove it with release of the anterior talofibular ligament laterally and deltoid complex medially. We paid careful attention to preserve portions of the deltoid ligament not inserting on the talus. Ostensibly, the superficial deltoid fibres, including the tibionavicular and tibiocalcaneal fibres, were preserved; however, the posterior tibiotalar and deep deltoid (anterior tibiotalar) fibres were released. Remaining fragments in the subtalar joint were debrided off their talocalcaneal interosseus ligament. Care was taken to preserve the calcaneofibular ligament with talar body resection laterally. Dissection was taken back under her flexor hallucis longus tendon posteromedially to make sure everything was completely removed. Complete removal was confirmed with fluoroscopy, the surrounding cartilage was inspected, and as expected there was no obvious degeneration to the tibial plafond, subtalar calcaneal facets or navicular. The 100% implant was trialled and determined to be most satisfactory based on clinical and radiographic evaluation. The implant would subluxate at the talonavicular joint with extreme plantarflexion, but this was deemed to be acceptable. Dorsiflexion at the ankle to 10 degrees past neutral was obtained, and thus a gastrocnemius recession or tendoachilles lengthening was not needed. Her ankle was stable with varus and valgus stress. The trial was removed, and the wound was copiously irrigated. The final implant was placed, and its fit and fill were confirmed with fluoroscopy (figure 6). The wound was irrigated once more, and as alluded to above, no ligament repair, reconstruction or internal bracing was pursued. Vancomycin powder was placed, and the capsule and extensor retinaculum were closed in separate layers with Vicryl suture to enhance prosthetic stability and to eliminate dead space. The skin was closed with Monocryl and nylon. The tourniquet was deflated, haemostasis was confirmed to prevent a wound-compromising haematoma and she was placed into a well-padded, short-leg splint (posterior slab and sugar tong U shape) with the foot plantigrade and the ankle in neutral dorsiflexion to allow her prosthesis to ‘sock-in’ to its surrounding soft-tissue structures and for wound rest.

Figure 4.

(A) Lateral fluoroscopic image after injury day 10 depicting our percutaneous reduction of the talonavicular and subtalar joints (the latter which was found to be redislocated). (B) Lateral radiograph depicting our temporising wire and external fixation.

Figure 5.

(A, B) Mortise and lateral radiographs during our pin-site holiday before total talus arthroplasty.

Figure 6.

(A, B) Mortise and lateral fluoroscopic images depicting final total talus arthroplasty placement.

Outcome and follow-up

She was made strictly non-weight-bearing for 6 weeks and was placed on extended antibiotic prophylaxis for 2 weeks to try and prevent infection in this high-stakes procedure. She was placed on aspirin for 1 month for venous thromboembolism prophylaxis. She was seen 2 weeks postoperatively with appropriate healing of her incision, adequate pain control and was transitioned to a short-leg cast. Postoperative X-rays demonstrated maintained position of the implant. She was then seen at 6 weeks postoperatively with full, healthy healing of her incision, maintained radiographic implant position and had 15 degrees of both active ankle dorsiflexion and plantarflexion. She was started in physical therapy at this time and transitioned to full weight-bearing with a boot as needed. She was then seen at 3 months postoperatively with complete resolution of all pain except for sporadic nightly pain. She had increased active ankle dorsiflexion to 20 degrees and active plantarflexion to 30 degrees. At her 1-year follow-up, she had complete resolution of pain, ankle dorsiflexion to 15 degrees, plantarflexion to 35 degrees and full return to all activities of daily living (figure 7). The American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score is used in patients with ankle or hindfoot injuries that involves a questionnaire about functional outcomes and pain.¹² She had an AOFAS score of 96 at 1 year postoperatively. For reference, the AOFAS is out of a total of 100 points, with 100 points associated with the most superior functional and pain outcomes. For further reference, a 2014 study showed that talar body replacement had excellent outcomes up to 10–36 years postoperatively with AOFAS scores ranging from 66 to 76, and a more recent systematic review of TTA showed a postoperative increase in AOFAS score from 28 to 82.^{13 14} Of note, at latest follow-up, we did not specifically recommend restricting any activity like avoiding strenuous endurance or high-impact activities.¹¹

Figure 7.

(A, B) Mortise and lateral radiographs 13 months after total talus arthroplasty.

Discussion

Talar fracture dislocations remain challenging injuries to treat, and devastating complications can occur even with excellent reduction and fixation. In 1970, Dr Leland Hawkins first described a classification system for talar neck fractures, including: type I: non-displaced fracture, type II: associated subtalar dislocation and type III: associated subtalar and tibiotalar dislocations.¹⁵ In 1978, Canale and Kelly first described a type IV: talar neck fracture with associated subtalar, tibiotalar and talonavicular dislocations which is a de facto pantalar dislocation.¹⁶ The Hawkins classification helps predict outcomes and guide treatment. The risk of AVN has been well described historically as: type I: 0–13%, type II: 20–50%, type III: 20–100% and type IV: 70–100%.¹⁷ The talus is particularly susceptible to AVN as 60% of its surface area is articular cartilage along with its tenuous bloody supply.³ Historically, it has been thought that early definitive fixation of talar fracture dislocations led to decreased rates of AVN, however, recent data have not supported this.^{5 18 19} Non-union rates have been published to be less than 5% in talar neck and body fractures, and malunion rates have been reported between 0% and 37%; however, this is likely under-reported due to limitation of plain radiography in assessing articular and axial alignment.¹⁹ Malunions can generate pain, increase joint contact forces and pressure and increase the risk of post-traumatic arthritis across the tibiotalar and subtalar joints.¹⁹ The rate of AVN is quite increased and even higher with open injuries, but up to 50% of these patients will undergo revascularisation of the talar body without collapse.¹⁹ The most common complication following talar fracture dislocations is indeed post-traumatic arthritis, and over 50% of patients with adequate, timely surgical fixation will go on to develop arthrosis within the subtalar joint and less commonly the tibiotalar joint.¹⁹ Post-traumatic arthritis though seems to get much less notoriety still in our literature. A recent study evaluating 798 patients with talar neck and/or body fractures demonstrated a 42% rate of AVN after a mean period of 26.2 months of follow-up, with more severe injuries having higher rates of AVN.²⁰ For neck fractures, 47% developed AVN with rates per type seemingly lower than their historical norms cited above, and the only treatment factor associated with increased risk was dual surgical approaches for ORIF suggesting a possible iatrogenic role for (further) disruption of the blood supply in complex cases. What was reinforced was that 26% of isolated talar body fractures developed AVN. An arguably distant secondary measure for all fractures was post-traumatic arthritis which was reported radiographically in 59.9% of patients in either the subtalar (43.5%), tibiotalar (33.6%) or talonavicular (9.8%) joints. It should be noted that more recent data have confirmed 44% of AVN cases did go on to revascularise in a 2014 series of 81 talar neck and/or body fractures which suggests that not all AVN goes on to debilitating dome collapse in need of surgery.²¹

The rationale for this particular procedure reported here on our patient with severe neck and body fractures was to substantially decrease the risk of post-traumatic arthritis and eliminate the risk of AVN, which must be considered to be on a spectrum along with non-union. Additionally, arthroplasty, as opposed to an acute or delayed arthrodesis procedure, spares motion and can protect against adjacent joint degeneration. While acute arthrodesis was strongly considered, the patient and surgeon opted for a motion-preserving procedure and one not requiring any bony healing. TTA in a relatively acute traumatic setting has not been reported until now. A recent study has shown that 3D-printed TTA performed for talar AVN has long-term, statistically significant maintenance of range of motion and improvement in pain, quality of life and patient-reported outcomes.²² A recent study evaluating 18 patients with minimum 10-year follow-up after TTA for osteonecrosis of the talus showed improvement in all pain and functional scores and an average of 45 degrees of ankle range of motion despite proliferation of pre-existing osteophyte formation in adjacent joints.⁵ While historically, severe talus fracture dislocations have been treated with ORIF or acute arthrodesis, we propose a role for this relatively novel procedure in the realm of chronic and even relatively acute traumatic conditions with hopefully similarly acceptable outcomes.

However, TTA is not without complication; a recent systematic review looking at over 160 patients described an overall complication rate of 9.3%.¹⁴ The most common complications were wound complications (3.1%), replacement or implantation of a tibial component (2.5%) and postoperative medial malleolus fractures (1.9%). Other complications reported include osteosclerosis of the navicular (9%), calcaneus (35%) and distal tibia (44%) whose real significance we are not sure of. They also reported an average talar tilt of 5 degrees on inversion stress which the author did not cite as a problem.⁸

While TTA is generally reserved as a treatment option for chronic, atraumatic AVN, it perhaps represents a viable option for definitive management in patients with severe talus trauma that are at high risk of post-traumatic arthritis and AVN.

Patient’s perspective.

I am overall pleased with my progress following a right total talus replacement. I have been able to return to daily activities including work around the house. I do things such as take daily walks for exercise, feed chickens on my property, and cook for my family. I do have occasional aching at the end of a busy day in my ankle, but the function of my ankle is much improved following this total talus replacement.

Learning points.

• Talar fracture dislocations remain difficult injuries to treat with associated devastating complications regardless of type of talus-preserving surgery; total talus arthroplasty helps mitigate postoperative sequelae including non-union, malunion, post-traumatic arthritis and avascular necrosis (AVN).

• Total talus arthroplasty may be a possible treatment option in the acute or subacute setting for patients with severe talar neck fracture dislocations as an alternative to open reduction and internal fixation or arthrodesis.

• Total talus arthroplasty has conventionally been used to treat patients with talar AVN with excellent long-term results in pain reduction, quality of life and patient-reported outcomes; however, this is the first study to describe total talus arthroplasty in a relatively acute traumatic setting.

• While historically, severe talus fracture dislocations have been treated with open reduction and internal fixation or arthrodesis, we propose a role for total talus arthroplasty with hopeful successful outcomes.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).