The human ankle is a complex load bearing joint that consists of
just three bones. These three bones include the tibia, fibula and talus. These
three unique bones work in conjunction to provide the
range of motion necessary to complete our daily activities such as walking,
jumping or running. Injuries of the ankle joint can be complex
and debilitating. This article discusses injuries of the talar dome.
The talar dome is the rounded portion on the top of the talus that articulates
with the bones of the leg (tibia and fibula). Injuries to the talar dome
are called talar dome lesions, transchondral
fractures, osteochondral fractures, bone contusions or osteochondral defects (OCD's).
Injuries of the
talar dome have been discussed in the medical literature
since the mid nineteenth century. In 1959, Berndt and Hardy
were the first to recognize the unique nature of these injuries. They
called these injuries transchondral fractures. What Berndt and Hardy
described was a classification of fractures found
immediately beneath the surface of the cartilage of the talar dome.
Berndt and Hardy described four stages of transchondral fractures.
Berndt and Hardy
Classification of Talar Dome Fractures
- Focal compression of
the subchondral bone (bone beneath the cartilage)
II - Focal
compression of the subchondral bone with partial detachment of a
fragment of cartilage
III - Focal
compression of the subchondral bone with a fully detached
fragment of cartilage, still situated in place at the site of injury
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
term transchondral refers to an
injury applied to the bone across the cartilage. 'Across the cartilage' is actually a very
accurate description of
how transchondral fractures occur. As an analogy, think of
the injury sustained by an apple when it
falls from a 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 transchondral 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 within the joint. 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 a 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 result in transchondral talar dome fractures. The
tibia and fibula, in addition to the talar dome, may also sustain transchondral
Diagnosis of Transchondral Fractures of the Talar Dome
The diagnosis of a transchondral fracture of the
dome of the talus is often missed during early examination of an ankle sprain or
ankle fracture. Transchondral dome fractures are usually
identified when patients fail to respond to conservative care for sprains and
fractures. Follow-up examination at 6-8 weeks post injury should include
an x-ray. Plain x-ray can often identify a transchondral fracture.
If clinical suspicion exists but no sign of fracture is seen on x-ray, and MRI
or CT scan can be used to further identify these lesions. MRI will often
find bone edema or swelling of the bone following injury suggestive of a stage 1
OCD. Bone scans and arthrography are not typically used to diagnose OCD's
due to their poor specificity for these lesions.
Treatment of Transchondral Talar Dome Fractures
treatment of talar dome fractures is often delayed due to the fact that
the symptoms of a talar dome fracture are very similar to the symptoms
of 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.
of Talar Dome Fractures by Stage
bearing/non-weight bearing casting, rest, physical therapy.
Stage I defects may respond
to rest. Rest may include decreased activity, use of an
ankle brace or use of a
walking cast. 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. Also,
stage I lesions do not result in significant collapse of the talar dome or
focal avascular necrosis. Therefore, the prognosis for stage I OCD's
is very good. 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. Healing of stage I OCD's may take up
to 12 months.
debridement of the injury with subchondral drilling.
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 or collapsed 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. Medial dome lesions can be difficult to access
through an anterior approach. Medial dome lesions can be accessed
by drilling through the medial malleolus using a
Vector Drill Guide available from Smith Nephew Orthopedics.
Arthroscopic debridement of the ankle (with or without drilling) is
performed in a hospital or surgery center. Anesthesia is usually a
general although a spinal block can be used. The procedure takes about
45 minutes to perform. Most patients are able to bear weight the same day. Sutures will be in place for two weeks during which
time, the patient will be allowed to return to many of their normal
activities. The majority of healing following this procedure takes
place within the first two months after surgery although remodeling of the
cartilage may take up to a year to complete.
debridement of the injury, subchondral drilling and synovectomy
of the joint.
Stage III lesions may
respond to arthroscopic techniques and transchondral drilling. In many cases, the body of the talus may require bone grafting to
insure proper healing. This type of grafting incorporates both donor bone
and donor cartilage in a technique called an OAT's procedure
(osteo-articular transfer procedure). Osteochondral grafts are performed
for two reasons; (a) restore the supporting surface of the joint and (b)
replace damaged bone and cartilage that has failed to heal after a
reasonable period of conservative care. Donor graft for an OAT's
procedure can come from three different sources.
(1) Autogenous osteochondral (bone and cartilage) can be harvested from
non-weight bearing surfaces of the knee and transplanted into the sited of
the talar fracture. (2) A number of companies manufacture synthetic graft
material that can also be used including
(3)Fresh frozen osteo-chondral allografts may be used for OAT's procedures
with success rates reported as high at 75% at 5 years post surgery and 63%
at 14 years post surgery. (1,2,3,4,5) An allograft is a graft
taken from a human donor other than the recipient. Fresh means that the
graft was harvested within 24 hours of the donor's death and the time from
graft harvest to implantation is 7 days or less. Recent studies have
shown that fresh allografts can be refrigerated prior to implantation for up
to 44 days with chondrocyte viability of 67%. This time between
harvest and implantation is important in that it allows the graft supplier
adequate time to prepare, test and sterilize the graft.
The method of treatment for stage III lesions
varies, therefore it is difficult to determine normal healing times for
repair of stage III lesions.
In most cases, we can assume that the treatment for stage III lesion will be
similar to stage II but the operative time and healing time will take a bit
longer than that of a stage II lesion. Many cases will require a
period on non-weight bearing in a hard cast below the knee.
debridement with subchondral drilling and possible revision of
the injured talus with a bone graft.
Stage IV lesions may
respond to arthroscopic techniques but typically require open revision
with curettage or OAT's grafting. Most lateral dome fractures can be
reached with arthroscopic techniques since they tend to occur in the
anterior lateral aspect of the ankle. Medial dome lesions, on
the other hand, tend to occur in the posterior aspect of the ankle
and are difficult to access with arthroscopy. To access the
medial aspect of the ankle, the tibia often has to be broken and
retracted to visualize the medial dome lesion.
location of the transchondral fracture is important when determining
the type of graft to be used in a stage III-IV lesion.
Autogenous grafts taken from the knee can only be used in areas that
are flat. Flat grafts are appropriate for the central dome.
But most transchondral fractures of the talus occur on the shoulders
of the talus. Since the shoulders are round, a rounded graft
is needed to contour to the shape of the talus.
The following images show a
trans-tibial approach for a stage 4 medial talar dome lesion with a
free osteochondral graft taken from the great toe joint.
Medial talar dome lesions are typically found in the central to
posterior aspect of the talar dome and are therefore often
inaccessible to arthroscopic procedures and techniques.
Therefore, an osteotomy must be placed through the tibial to access
the ankle. Image 1 shows access to the ankle through the tibia
and site preparation of the talar dome. Due to hardening of
the talar dome, a new fresh bone bed is stimulated by drilling the
bone and placing synthetic bone dowels in the dome of the talus.
Image 2 shows the graft donor site (under the text) and
osteochondral graft ready for placement. Image three shows the
graft in position and held in place by two small 1.5mm screws.
Post-operative management for this case includes 6 weeks in a hard
cast followed by 4 weeks in a walking cast.
Long term follow-up of talar
dome lesions shows that despite the type of treatment, many patients
with talar dome transchondral fractures will continue to have ankle pain and swelling
over the course of their lives. The prognosis for transchondral
fractures depends in part upon the severity of the injury, the age and
general health status at the time of injury and whether the patient is a
smoker. Grafting used in stage III and IV lesion is rarely
successful in patient who are smokers. Both autogenous and
allogenic grafts depend upon the ingrowth of new blood vessels.
This process is called angiogenesis. Angiogenesis is significantly
inhibited in smokers.
Transchondral - across the cartilage.
Chondral - refers to cartilage.
Transchondral talar dome fractures occur at the anterior lateral
shoulder of the talus and less commonly at the posterior medial shoulder of the
talus. The shoulder(s) of the talus is the transitional curve between the flat upper dome and the sides of the talus.
Transchondral talar dome fractures occur
secondary to trauma such as an ankle fracture or sprain.
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.
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 simple 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
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.
The differential diagnosis of this
condition should include;
Soft tissue adhesion
Products Recommended for Talar Dome Fracture:
This article was written by Jeffrey A. Oster, DPM and last updated
1. Garrett J: Osteochondritis dissecans. Clin Sorts Med
2. Garrett J: Osteochondral allografts for reconstruction of
articular defects of the knee. Inst Course Lect 47:517-522, 1998
3. Gross A: Fresh osteochondral allografts for post-traumatic knee
defects: Surgical technique. Operative TechniquesOrthop 7(4):334-339, 1997
4. Gross A, Langer F, Houpt J, et al: Allotransplantation of
partial joints in the treatment of osteoarthritis of the knee. Transplant Proc
8(2 Supp 1): 129-132, 1976
5. Pearsall A, tucker J, et al: Chondrocyte viability in
refrigerated osteochondral Allografts used for transplantation within the knee.
Am J Sports Med, 32(1):125-131, 2004
Additional references include;
Draper, S. D., Fallat, L. M. Autogenous
Bone Grafting for the Treatment of Talar Dome Lesions. J. of Foot Surg.
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
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.
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
Schoenfeld AJ, Leeson MC, Grossman JP.
Fresh-rozen Osteochondral Allograft Reconstruction of a Giant Cell Tumor of the
Talus. J Foot ankle Surg. 46:144-148, 2007
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