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Talar Dome Fractures
from: Dr. Jeffrey A. Oster, Medical Director Of Myfootshop.com.The human ankle is a complex joint that consists of three bones, the tibia, fibula and talus. These three unique bones work in a way to provide the range of motion necessary to complete our daily activities such as walking, jumping or running. The ankle, in fact, is so unique in its' range of motion that man has not been able to successfully duplicate the joint with an implant. As a result, injuries to the ankle joint can be complex and debilitating. One injury to the talus is the talar dome fracture, also referred to as a talar dome lesion or transchondral fracture.
Injuries to the joint surface of the talus have been discussed in the medical literature since the mid nineteenth century. Berndt and Hardy, in 1959, were the first to recognize the unique nature of this injury that they termed a transchondral fracture. What Berndt and Hardy described was a classification of fractures found in the bone of the talus immediately beneath the surface of the cartilage of the ankle joint. Berndt and Hardy described four stages of transchondral fractures. Each of these stages describes findings seen in x-rays of the ankle.
Berndt and Hardy Classification of Talar Dome Fractures
Stage I Focal compression of the subchondral bone (bone beneath the cartilage)
Stage II Focal compression of the subchondral bone with partial detachment of a fragment of cartilage
Stage III Focal compression of the subchondral bone with a fully detached fragment of cartilage, still situated in place at the site of injury
Stage IV Focal compression of the subchondral bone with a fully detached fragment of cartilage, detached from the site of injury and floating in the joint space
Transchondral referred to an injury applied across the cartilage. This is actually a very accurate description of this injury. Think of an injury to an apple when it falls off the tree. The skin appears normal, yet the supporting structure of the flesh of the apple is damaged. This example is very similar to what happens in a talar dome fracture. As the force of an injury is applied to the cartilage, the subchondral bone collapses in a localized fracture. As a result, the surface of the ankle joint becomes irregular. Motion on this irregular surface creates pain and inflammation. In severe cases, such as stages III and IV, the injured fragment of bone and cartilage becomes detached creating even greater irregularities in the surface of the joint.
In a talar dome fracture, the injury to the subchondral bone crushes the normal blood supply to the site of the injury. The term aseptic necrosis is used to describe this type of an injury to bone. Aseptic (no infection) necrosis (death) is the single greatest influence that inhibits healing of talar dome fractures. Its' interesting to note that the cartilage of the ankle derives most of it's nourishment from the fluid in the ankle joint, called synovial fluid, and not from the same blood supply that supplies the damaged bone. This explains why the cartilage at the site of the talar dome fracture can remain viable as the bone beneath it fails to heal.
The vast majority of transchondral fractures of the talus occur following ankle sprains. Approximately 2-6% of acute ankle sprains have transchondral fractures of the talar dome. Additionally, ankle fractures of the tibia (inside ankle bone) and the fibula (outside ankle bone) may include transchondral dome fractures.
Treatment of transchondral talar dome fractures
Talar dome fractures are a difficult injury to diagnose. Initial treatment of talar dome fractures is often delayed due to the fact that the symptoms of a talar dome fracture are very similar to an ankle sprain. The decision to treat conservatively or surgically is based upon the radiographic appearance, size, location within the joint and stage. Stages I through IV may at some time require surgical correction based upon the response to conservative care. The following table summarizes the treatment of talar dome fractures.
Treatment of Talar Dome Fractures
Stage I Weight bearing/non-weight bearing casting, rest, physical therapy
Stage II Arthroscopic debridement of the injury with subchondral drilling
Stage III Arthroscopic debridement of the injury, subchondral drilling and synovectomy of the joint
Stage IV Arthroscopic debridement with subchondral drilling and possible revision of the injured talus with a bone graft
Stage I defects may respond to rest. The size and location of the talar dome fracture plays a big role in the time that it takes to return to normal, pain free activity. Once a Stage I lesion has fully healed, a residual flat spot, or defect may remain on the surface of the talus. If this defect results in chronic pain with activity, it may require surgical repair.
Stage II lesions rarely respond to rest and typically will require at least an arthroscopic procedure to repair the residual defect found in the surface of the talus. Arthroscopic procedures are performed through small 1/4" incisions to gain access to the ankle joint. Arthroscopy is used to debride, or grind away the damaged bone and cartilage. In addition to arthroscopic debridement, subchondral drilling is used to stimulate blood flow to the injury site. Subchondral drilling is a surgical technique used to break through the thick subchondral bone (beneath the cartilage). This can be accomplished with a drill or wire and completed through the same small incisions used for arthroscopic surgery.
Stage III and IV lesions may respond to arthroscopic techniques. In a limited number of cases, the body of the talus may require bone grafting to insure proper healing. Stage III and IV case requires careful evaluation prior to surgical correction.
Long term follow-up of talar dome lesions shows that despite the type of treatment, most patients with talar dome lesion will continue to have ankle pain and swelling over the course of their lives.
Nomenclature:
Transchondral - across the cartilage
Chondral - refers to cartilage
Anatomy:
Transchondral talar dome fractures occur at the anterior later edge of the talus and less commonly at the posterior medial shoulder of the talus.
Biomechanics:
Transchondral talar dome fractures occur secondary to trauma such as an ankle fracture or sprain.
Symptoms:
Most talar dome fractures are the result of trauma. The type of trauma may vary and can be as simple as an ankle sprain. Talar dome fractures are also seen in complex trauma such as a fall from a roof or ladder or perhaps an automobile accident. In most cases, the initial injury will show no immediate signs of a talar dome fracture and will subsequently be treated as a simple ankle sprain.
Follow-up examination, several weeks after the original injury may allow an opportunity to see a new set of symptoms, different than what was originally thought to be a sprain. Symptoms of a sprain tend to be localized to the ligament that was injured. In the ankle, the majority of sprains are on the outside of the ankle (fibula).
Talar dome fractures exhibit more diffuse symptoms. Pain is not localized to the outside segment of the ankle, but is diffuse through-out the entire ankle. Pain may or may not be present with weight bearing. Talar dome fractures will increase in pain with activity. Swelling may be present and is typically diffuse and found across the entire front of the ankle joint.
X-rays of the joint show a small area of darkened bone adjacent to the surface of the talus. This area correlates to the area of injury. Occasionally, a corresponding injury of the tibia may also be visualized on x-ray.
Differential Diagnosis:
The differential diagnosis of this condition should include;
Arthritis
Septic joint
Soft tissue adhesion
Additional references include;
Draper, S. D., Fallat, L. M. Autogenous Bone Grafting for the Treatment of Talar Dome Lesions. J. of Foot Surg. 39:15-23, 2000
Berndt, A.L., Harty, M. Transchondral Fractures of the Talus. J. Bone Joint Surg. 41-A:988-1020, 1959
Anderson, I.F., Crichton, K.J., Grattan-Smith, T., Cooper, R.A., Brazier, D. Osteochondral Fractures of the Dome of the Talus. J. Bone Joint Surg. 71-A:1143-1152, 1989
Hutchison, B.L., Wardle, D.J. Diagnosis and treatment of talar tilt and its relationship to the occurrence of transchondral fractures: as retrospective study. J. Foot Surg.30:151-155, 1991
Loomer, R., Fisher, C., Lloyd-Smith, R., Sisler, J., Cooney, T. Osteochondral lesions of the talus. Am. J. Sports Med. 21:13-19, 1993
Ly, P.N., Fallat, L.M. Transchondral fractures of the talus: a review of 64 cases. J. Foot Ankle Surg. 32:352-374, 1993
Parisien, J.S., Arthroscopic treatment of osteochondral lesions of the talus. Am. J. Sports Med. 14:211, 1986
Ewing, J.W. Arthroscopic management of transchondral talar dome fractures and anterior impingement lesions of the ankle joint. Clin. Sports. Med. 10:677-687, 1991
About the Author
Jeffrey A. Oster, DPM, C.Ped is a board certified foot and ankle surgeon. Dr. Oster is also board certified in pedorthics. Dr. Oster is medical director of Myfootshop.com and is in active practice in Granville, Ohio.
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