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Osteochondral Defects 

     



What is an osteochondral defect?
 

An osteochondral defect (OCD) is an area of damaged cartilage found in a joint.  The most common location for an OCD is the knee joint.  However, in regards to the foot and ankle, this is usually seen in the ankle joint.  This is where an area of normally healthy cartilage has been damaged and is either partially/completely detached, or has developed into an area with no cartilage present at all.  The ankle joint is comprised of three bones: the tibia and fibula (longer bones), and the talus (connects to the heel bone).  The talus bone is the most common location to find an osteochondral defect in the foot and ankle. The drawing below shows the ankle from the side view.


Other names for an osteochondral defect include osteochondral fracture, osteochondral lesion, osteochondritis dessicans, transchondral fracture, flake fracture, and intra-articular fracture. 


Etiology:

An osteochondral defect is most often caused by trauma.  One ankle injury per 10,000 people per day occurs.  These injuries range from simple sprains to complex fractures and dislocations.  With lateral ankle ligament ruptures, the incidence of lateral OCD is 5-9%.  Medial OCD lesions are suspected to be close in frequency.  For more information on ligament ruptures and sprains of the ankle, click here.  An ankle sprain is generally the result of a twisting type of motion to the ankle joint, or a direct blow that forces the ankle out of its normal anatomic alignment.  Ankle sprains can occur while doing virtually any activity although they are most common while playing sports or while wearing inappropriate shoes. 
The severity of an ankle sprain is dependent upon whether the ligament is stretched, partially torn, or  completely torn, as well as the number and location of the ligaments that are affected.  If ankle sprain symptoms do not resolve after 3-6 weeks, and OCD should be suspected.


OCD lesions can also develop following ankle fractures due to the significant force and trauma associated with these injuries.  For more information on ankle fractures, click here.  After an ankle fracture, pain is normal for an extended period of time, but if this pain fails to subside months after injury, an appropriate work-up for an OCD might be of value. 


Symptoms:

Generally an OCD will present with persistent symptoms of pain and a limited range of motion.  Locking and catching are symptoms of a displaced fragment of cartilage.  It is difficult to distinguish the pain of an acute situation from that of an OCD lesion which can persist after the initial injury (whether a sprain, rupture, or fracture) has healed.  Lateral OCD lesions are typically more painful than medial lesions.  A chronic lesion is usually a deep lateral or medial ankle pain that is associated with weight-bearing.  Swelling and stiffness is seen much of the time.  An OCD can still be present even without catching, locking, or swelling. 


Diagnostic Work-up:

After an initial thorough history and physical exam, plain film xrays will be taken.  Xrays may show an area of detached bone or a visible lucency (lighter area on the bone).  Initially the damage may be too small to see on plain xrays.  Sometimes repeat xrays will show a lesion as it changes with time.  An initial insult of trauma may not show up at all on xrays but later may develop into these lesions. 

An MRI is often used to detect these lesions.  Initally an MRI may show bone edema (a bruise deep within the bone) without an obvious OCD lesion.  What is seen initally is not always the way things look over time.  There is a progression of damage that can set in over time. 

A CT can be used to image these lesions as well.  A CT can help determine the exact size and location of the lesion.  A CT and MRI are equally as valuable


Conservative Treatments:

The treatment indicated is determined by the amount of symptoms.  Small OCD lesions of 5-6mm may cause significant pain for certain individuals, whereas larger OCD lesions up to 10-12mm in size can be seen with little discomfort.  There is a great amount of variability in presentation of these lesions.  Treatments must be designed on a very individual basis and depending on pain and symptoms. 

For small lesions that are not displaced, cortisone injections may provide adequate relief.  Custom orthotics or prefabricated orthotics may provide enough biomechanical support to offload the affected part of the joint.  Immobilization in a CAM walker or a cast may be needed to give these lesions a chance to heal on their own.  Physical therapy can help with range of motion and pain symptoms.

Complete immobilization in a cast non-weight bearing would give the greatest offloading of this lesion possible. 


Surgical Options:


Arthroscopic Treatment:
Initial surgical treatment generally consists of arthroscopic surgery.  This is where very small incisions are made and instruments are inserted percutaneously into the ankle joint.  There is always a microscopic camera used for visualization of the joint and then there are various debriders, biters, shavers, burrs, graspers, etc for cleaning up the joint.  Often times with  ankle trauma (sprains, contusions, fractures, etc) there will be bleeding into the joint which will ultimately turn into chronic fibrous adhesions and fibrous bands which can limit motion, cause pain and be disabling.  Additionally, there is often a chronic type of inflammatory tissue within the joint which causes impingement, pain, and limited motion.  Neither fibrous banding or inflammatory tissue will show up on xrays, MRI, or CT a lot of the time. 

Arthroscopic treatment of OCD lesions includes debridement of the associated fibrous banding and inflammatory tissue.  Additionally, the loosely attached or detached cartilage associated with an OCD is debrided.  This creates a smoother surface of cartilage in this region of the joint.  A "micro fracture" is the performed to the dense bone beneath this removed cartilage.  This is performed by creating microscopic holes in this dense bone.  This stimulates bleeding which creates a fibrin plug in the defect area that later turns into fibrocartilage.  Fibrocartilage is not the same consistency or durability as hyaline cartilage (normally present in the joint) but it is generally provides much relief for pain and symptoms. 

Full weight bearing after an arthroscopic repair of an OCD up to 1cm in size is allowed with in 2 weeks.  All patients are encouraged to move their ankle up and down after this procedure.  For larger lesions and more anterior lesions, partial weight bearing is recommended until the 6 week mark.  Running is generally allowed in 3 months.  Return to full activity and sports is generally within 4-6 months. 

....images coming soon.


Open Cartilage Repair:

Open surgical procedures are generally performed after an arthroscopic procedure has been attempted, or if an OCD lesion is extremely large.  If an OCD is found in certain locations of the joint, an open procedure may need to be performed (Certain areas are not accessible with arthroscopic instruments).  Open procedures have a much longer recovery period and are therefor performed as a last resort. 

With these procedures, an osteotomy (bone cut) in either the tibia or fibula generally is made to access this defective area of the joint.  This is later repaired with plates or screws.  The OCD is removed as a cylindrical plug and a plug of the same diameter and depth is transplanted to the area.  These plugs can come from the patient's knee, sometimes other joints in the foot, a fresh cadaver, or as a man-made synthetic graft.  Sometimes multiple smaller plugs are used to fill the defect. 

If an osteotomy (bone cut) is made,non-weight bearing is recommended for 6 weeks.  Without an osteotomy, non-weight bearing is for 3weeks.  After this period of time, 70 lbs of weight bearing is allowed for the next 3 weeks to stimulate incorporation of the graft.  Athletic activities can generally begin at approximately 6 months post-operatively. 



.....Images coming soon.




 

 





 

 

 

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