Talus (Astragalus) Fractures
It takes tremendous force to have a fracture of the talus (astragalus) bone. This is a dense bone and injury to it is relatively uncommon and represents less than 1% of all factures. It is the second largest bone of the tarsus after the calcaneus (heel bone). It carries a high-risk injury, very difficult to manage and does present a challenge to the orthopedic surgeon. We will try to review the basic management of such injury and discuss some of the practical surgical procedures used to repair such fracture in order to obtain the best outcome.
Talus fractures occur as a result of a high-injury trauma, notably from a motor vehicle accident. They can be isolated but more often they are accompanied with neighboring bones fractures and dislocations. Jumpers landing from high jumps represent most of the victims. Skiers and snowboarders are frequently injured in practicing their favorite sports because of the stress placed on the talus at landing especially on the lateral process.
The talus bone is the connector between the lower leg and the foot, bearing mainly the weight of the body through it superior surface, called the dome. It is composed almost entirely of coarse bone, largely covered by an articular cartilage, a slippery material which allows the smooth gliding of the superior surface over the neighbor bones. A talus fracture represents a break in one of the bones that forms the ankle with the tibia and fibula. It is represented by a head, a neck and a body part. The ankle allows the foot to move up and down in flexion or extension mainly. While the talus sits on the top of the calcaneus (heel’s bone), forming with it, the subtalar joint, it allows the foot to move inward and outward which brings it importance in walking on uneven surfaces. This type of fracture often occurs during a high-energy event, such as a motor vehicle accident or a jump from significant height.
Because of its importance in the range of motion of the ankle joint, a fracture of the talus bone may alter the functioning of the joint resulting in substantial loss of motion and stability. Poor healing of a talus fracture can lead to complications, including a painful limp, degenerative arthritis, chronic pain, deformity and avascular necrosis. For these reasons, most displaced fractures involving the talus may require a surgical approach.
The talus bone sits between the bones of the lower leg and the calcaneus (heel bone)
All parts of the Talus bone can get involved in a fracture. A break through the mid portion is through the neck which is between the head and the body. The body sits under the tibia and the head articulates distally in the foot with the tarsal bones (Navicular and Cuneiforms). Fractures of the talus although rare, presents with serious consequnces. The vast majority of them are intra-articular because the talus is a bone almost completely covered with articular cartilage. They can be seen in closed or open injury but most ot the time it will requiere a special attention for evalation and treatment.
The talus may also fracture through a prominence on the outside of the bone called the lateral process out to the side which occur when the ankle is forced out in snowboarders. Fractures of the talus are classified by the numbers of fragments into minimally displaced or stable fractures. In these cases, the fragments are held together and remain aligned. Even in a minimally displaced fractures, the fragments may stand together and not requiring surgical treatment. In a displaced fracture, the fragments move out of their anatomical position. The amount of displacement relates to the force at impact. A highly comminuted and displaced fracture is more likely to be unstable but only a restoration in the alignment can predict a functional outcome.
A talus fracture through the neck portion is depicted above.
Talus fractures can be classified by how much the pieces of bone have moved out of their normal position. Minimally displaced or stable fractures are barely out of place. The broken ends of the bone line up correctly or almost correctly. In a minimally displaced fracture, as well, the bones fragments usually stay in place and rarely will require surgical repair.
A displaced fracture occurs when the bone breaks into pieces to lose their anatomic position. The mechanism of injury and the force at impact will determine the amount of displacement. I will repeat it as often as possible that a displaced talus fracture is unstable and can be treated only by surgical means. A good restoration in the anatomical alignment can dictate the return to functionality. An open fracture by definition is an emergency and will require surgical attention with irrigation and debridement of the surrounding muscles, ligaments and bone as well as an open reduction and internal fixation. Such fractures are prone to infection and can take more time for healing.
At physical examination, the physician should look for any sign suggesting an open injury. A punctiform wound may be the door of exit of a bony fragment through the skin, any ecchymosis showing signs of oozing blood or any large laceration and bleeding over the ankle or any deformity are looked for. The patient is unable to bear weight on the injured lower extremity. The foot and ankle are carefully examined on such findings. The blood supply may be jeopardized due to compression of the vessels by displaced bony fragments. Sensation in the foot as well as the range of motion of the toes will allow to check on functionality. Assess the calf muscles for a possible increase in compartmental pressure or in loss of sensation of the foot requiring any emergent treatment. Often, these patients are polytraumatized and the Advanced Trauma Life Support Protocol is expected to be part of the initial evaluation for the extremities, the pelvis as well as the spine. A splint for comfort is necessary while further radiologic studies are warranted.
An ankle film with multiple views will confirm the clinical diagnosis of a talus fracture but the CT scan with cross-sectional images of the foot, remains the study of choice. It will provide sufficient information on the fragments to plan any surgical treatment. The best classification used to help the orthopedist to take a choice of treatment is the Hawkins’s classification dealing with the fracture interesting the neck of the talus. A picture below is depicting this atypical fracture that all us will find difficult to treat. I can’t go over all the fractures type like the head, the lateral process, the body etc but I will choose the fracture of the neck to better present the difficulties in treating such injury and appreciate the importance of the blood supply of the bone itself. At the end I will hope that our lector will understand the importance of this bone and that our residents will comprehend the need to give a special attention to the Talus bone.
Hawkins’s classification of a neck fracture of the talus.
I would like to go over a recent case of mine: A 24-year-old young lady is examined by me in the Emergency room following a Motor Vehicle Accident in which she was an unrestrained driver involved in a head-on car accident. She has a one system injury and was cleared by the trauma team. She was found intoxicated with alcohol and has also shown multiple narcotics in her system. She is in pain and the right ankle showed an obvious deformation. At examination, the talus is deformed and displaced but her neurovascular status in intact and more, the right calf muscle is soft to palpation. This is a closed fracture which is going to ask for an immediate attention. A well-padded posterior splint is applied and she is sent for regular X-rays and CT scan study of the ankle.
Such a case is a challenge at 1:30 AM, for the most experienced orthopedic surgeon. I would like to review it with you. The blood supply of such a bone is precarious and it becomes important for the patient to be treated in an expeditive way to prevent any future complications. By far the biggest handicap with this injury is the way the blood supply is presented to the bone itself, from distal to proximal. Let me start with a little reminder on the blood supply to the talus bone.
Many vessels bring a rich blood supply to the talus but a fracture through the neck especially can destroy the entire vasculature. Mainly three important vessels bring a sufficiently rich vascularization to the entire bone:
1- The “Dorsalis Pedis artery” supplies the head and the neck of the talus bone while contributing to supply the arteries of the tarsal canal and the tarsal sinus (beneath the talar neck). This represents the main vascular supply to the head and neck portion but one can understand that a displaced fracture at that level may destroy the way the blood is supplied.
2- The “Peroneal artery” provides some branches laterally especially to the lateral process. It also contributes to the artery of the sinus tarsi.
3- The “Posterior tibialis artery” supplies the dorsal aspect of the talar neck and also aliments the blood supply to the sinus tarsi artery.
4- The artery of the sinus tarsi canal is then supplemented with anastomotic branches which supply the talar neck. The main artery supplying the body of the talus comes from the artery of the tarsal canal.
In a non-displaced (less) or in a displaced talar neck fracture, we can understand how the vasculature to the entire talus can be jeopardized. If a non-displaced fracture of the neck can disrupt intraosseous branches at the tarsal sinus or the tarsal canal, one can be lucky to have in a Hawkins type 1 or even a Hawkins type 2, a preservation of some of the blood supply. Unfortunately, when we deal with a Hawkins type 3 or a type 4, the mechanism of injury and the displacement of the fragments bring to the anatomical area such a destruction that the almost entire blood supply described, is lost.
This is why these fractures become a nightmare for the orthopedic surgeon and their approach imposes a methodical way in the goal of avoiding further destruction to the precarious remaining blood supply. It will be repetitive for me to mention again that the biggest problem with such injury is the loss of the entire blood supply to the talus bone. The more destruction or displacement, the more certain the chances in developing an Avascular Necrosis will be present.
Let us return to our 24-year-old patient who was a victim of a Motor Vehicle Accident and presented via ambulance as a trauma patient at 1.30 AM. After damage control like the orthopedist like to say, radiologic studies and CT scans revealed an injury classified as a Hawkins “3” like shown on the pictures below, because the head of the talus was still in place, undisturbed but the body of the talus was extruded and displaced behind the distal tibia.
Radiographic studies showed a Hawkins 3 talus fracture with some comminution and a body extruded and posteriorly displaced. The head of the talus is still in its anatomical position articulating the tarsal bones:
Coronal and sagittal views of the right ankle
A CT Scan showing the absence of the talar body in the subtalar space and a talar head still articulating with the tarsal navicular and cuneiforms bones. I have exposed the “puzzle” and we will need to find a solution to the problem in order to save this young lady lower extremity.
What are my options as an orthopedist in such a Talus fracture (Hawkins 3)?
A talus fracture is a painful event. We may want to apply a well-padded splint from toe to upper calf to protect the extremity which I reported earlier, was performed as soon as we had trauma clearance with elevation of the right lower extremity by two pillows above the level of the heart.
All talus fractures do not require surgical treatment. If they are stable and non-displaced or the bony fragments are in good alignment, immobilization in a short leg cast or even a Cam-Walker supplemented with crutches ambulation with toe touch to a non-weight bearing, will allow the fracture to heal. This non-weight bearing protocol will need to be absolutely implemented for at least 6 to 8 weeks and then a rehabilitation may be necessary. Functional Bracing can be equally used in treating an un-displaced or minimally displaced fractures.
On the contrary, when a talus fracture is displaced like we see here in our patient with a Hawkins 3 or four, there is no other option than to perform an open reduction and an internal fixation using K wires, plates or different kind of screws or even plates. Nowadays it has become more practical to use cannulated screws going front to back or inversely going to back to front to stabilize the fragments. The purpose of the surgical treatment is to perform a good debridement and allow an apposition of the broken fragments and to hold them in position and build up a stable construct. The clinical outcome will depend on the quality of the reduction and the comminution at the fracture site, re-enforced by the most stable fixation possible.
So, here we are. facing this young lady at 2 AM, ready for the surgical treatment. Often, I like to approach such injury medially and if necessary open as well the lateral side for exposure. The blood supply is already compromised but you want to manage the soft tissue envelope carefully, avoiding more destruction to the remaining vascular envelope. Surely, you want the best option whenever possible. It is imperative to save the fragments, align them to allow a possible reconstruction.
So, through a medial approach, using a 5 centimeters-oblique incision starting anteriorly to the medial malleolus and extending obliquely and distally between the insertion of the anterior tibialis and posterior tibialis tendons. Attention was well taken to avoid disturbing more of the venous or arterial blood supply to the area. The capsule was found destroyed medially and the body of the talus was discovered, displaced posteriorly behind the tibial pilon. Attempts at relocating the body of the talus failed at first until I was able to pre-drill and osteotomize the medial malleolus for a wider exposure. Then, it becomes easier to relocate the body of the talus to its anatomical position. I had no other choice than to stabilize the comminuted fracture with three transfixing “K’ wires left above skin.
I wish to have been able to insert at least one additional cannulated screw but the fracture component to the head and neck was so oblique that it would shear the cortex. The “K” wires were placed under C-Arm control. We did reconstruct the dome and perform a good apposition of the fragments, in a precarious stability. Copious irrigation and splinting were performed after an anatomical reconstruction and then fixation of the transected medial malleolus. Immediate intra-operative films are shown here:
An anterior view in the immediate post-operative period with a transfixing a comminuted talus fracture and a cannulated screw holding well the osteotomized medial malleolus. The 3 “K” wires were left above the skin, percutaneously holding on a comminuted fracture of the talus (Hawkins 3).
A lateral view of the immediate post op is also shown with hardware holding on a comminuted fracture of the talus.
The immediate post op was uneventful and she tolerated the procedure well. One will hope that her problems are over and she will need to wait for further healing of the fracture. The talus is not always predictable and in some 6 weeks we will need to look for an important sign (Hawkins’s sign) which is of prognosis value. We wish that such process in a talus fracture was so simple. In anyway, she did good with the crutches and was discharged home on pain medication.
What are the complications we can face in such a case?
In any unstable fracture of the talus, the blood supply may be disrupted at the time of injury but it is also possible to expect a certain return to the destroyed vasculature. It may return to the bone providing adequate healing of the fracture. Often, the bone may die without sufficient blood supply, leading to a progressive collapse, often painful. This phenomenon is called Avascular Necrosis (AVN) or Aseptic Necrosis or Osteonecrosis. The reduction in the perfusion to the bone with it precarious blood supply coming from distal to proximal is responsible of this problem. Whenever the bone collapses in this condition, there may be a complete destruction of the articular cartilage with chondrolysis allowing a constant rubbing of the bony fragments and resulting in further degenerative arthritis.
In the past such a painful situation was treated with an ankle fusion bur nowadays, more and more one will suggest an ankle hemi-arthroplasty or a total ankle replacement to resolve such painful problem. One may also say that an ankle replacement does not offer the longevity of a total hip or a total knee replacement but the alternative on a long range to avoid a painful situation, will bring such patient to embrace the choice. I wish I were able to discuss in more details, different points of view in the orthopedic literature but I would not like to entertain our lectors on this problem.
I tried to present simply, a complicated case for which I used my surgical skills recently. In a way, I wanted to present the difficulties encountered by the orthopedic surgeon in any comminuted fracture of the talus bone. Although those fractures are serious, I hope I was convincing enough to expose the sense of urgency to our AMHE Newsletter lectors in instilling a better understanding in the emergent treatment of such a fracture. I wish also to dedicate this paper to all of our hard-working orthopedic residents in Haiti or in the United States who may have faced such injury during their residency training or during their far away assignment. They certainly will understand better the seriousness of the injury, the approach to the problem and the amount of disability such fracture carries with it.
Maxime Coles MD
Boca Raton FL
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