Osteochondral Transfer for Osteochondral Lesions of the Talus



Osteochondral Transfer for Osteochondral Lesions of the Talus


Mark E. Easley

Justin Orr





DEFINITION



  • Medium-sized osteochondral defects of the talar dome



    • May approach the talar shoulder (transition of superior dome cartilage to the medial or lateral talar cartilage)


    • Often associated with subchondral cysts


  • Osteochondral defect is reconstructed with a cylindrical osteochondral graft. To provide stability to this graft, the osteochondral defect in the native talus must be contained (have circumferential cartilage and subchondral bone).


ANATOMY



  • Sixty percent of the talus’ surface area is covered by articular cartilage.


  • The talus is contained within the ankle mortise.



    • Superior talar dome articulates with the tibial plafond.


    • Medial dome articulates with the medial malleolus.


    • Lateral dome articulates with the lateral malleolus.


  • Talar blood supply



    • Posterior tibial artery



      • Artery of the tarsal canal


      • Deltoid ligament branch


    • Peroneal artery



      • Artery of the tarsal sinus


    • Dorsalis pedis artery


PATHOGENESIS



  • The pathogenesis for osteochondral lesions of the talus (OLTs) is not fully understood.


  • Theories include the following:



    • Trauma


    • Idiopathic focal avascular necrosis


NATURAL HISTORY



  • In general, OLTs do not progress to diffuse ankle arthritis.


  • However, large volume OLTs may lead to subchondral collapse of a substantial portion of the talus and thus create deformity, higher contact stresses, and a greater concern for eventual ankle arthritis if left untreated.


PATIENT HISTORY AND PHYSICAL FINDINGS



  • Patients may or may not report a history of trauma.


  • Ankle pain, typically on the anterior aspect of the ankle, is a common complaint.



    • Pain is usually experienced on the side of the ankle that corresponds with the OLT, but it may be poorly localized to the site of the OLT. In fact, sometimes, medial OLTs produce lateral ankle pain and vice versa.


    • Pain is rarely sharp, unless a fragment of the OLT should act as an impinging loose body in the joint.


    • Typically, the pain is a deep ache, with and after activity, and is usually relieved with rest.


  • Antalgic gait


  • May be associated with malalignment or ankle instability


  • Typically, tenderness on side of ankle that corresponds with OLT but not always


  • Rarely crepitance or mechanical symptoms


  • With chronic OLT, some degree of ankle stiffness is anticipated.


IMAGING AND OTHER DIAGNOSTIC STUDIES



  • Plain radiographs



    • Obtain weight bearing, three views of the ankle


    • Small OLTs may be missed.


    • Large OLTs are usually identified on plain radiographs (FIG 1).


    • Often limited in characterizing OLT because the twodimensional study cannot define the three-dimensional OLT


    • Particularly useful in assessing lower leg, ankle, or foot malalignment that needs to be considered in the management of OLTs


    • May detect incidental OLTs (patient has a radiograph for a different problem and an OLT is incidentally identified on plain radiographs)


  • Magnetic resonance imaging (MRI)



    • Excellent screening tool when OLT or other foot-ankle pathology is suspected


    • Will identify incidental OLT but defines other potential soft tissue pathology


    • Demonstrates associated marrow edema that may lead to overestimation of the OLT’s size


  • Computed tomography (CT) (FIG 2)



    • Ideal for characterizing OLT, particularly large volume defects


    • Defines OLT size without distraction of associated marrow edema


    • Defines the character of the OLT and extent of its involvement in the talar dome


  • Diagnostic injection



    • Intra-articular


    • An anesthetic versus anesthetic plus corticosteroid


    • May have some therapeutic effect, even for several months


    • If the source of pain is the OLT, then intra-articular injection should relieve symptoms from OLT. If the pain is not relieved, then other diagnoses should be considered.


DIFFERENTIAL DIAGNOSIS



  • Loose body in ankle joint


  • Ankle impingement (anterior or posterior)


  • Chronic ankle instability (medial, lateral, or syndesmotic)







    FIG 1 • Radiographs. A. AP radiograph of the ankle suggests symmetric alignment and a medial talar dome defect. B. Mortise view also suggests medial OLT. C. Lateral view shows anatomic alignment, with OLT less obvious.


  • Ankle synovitis or adjacent tendinopathy


  • Early ankle degenerative change


NONOPERATIVE MANAGEMENT



  • Activity modification


  • Bracing


  • Physical therapy if associated ankle instability


  • Nonsteroidal anti-inflammatories or COX-2 inhibitors


  • Corticosteroid injection


  • Viscosupplementation


SURGICAL MANAGEMENT


Preoperative Planning



  • Indications for this surgery include the following:



    • Medium-sized OLTs not amenable to other joint-sparing procedures. If associated with a large subchondral cyst, then arthroscopic débridement and microfracture may not be effective, and some surgeons recommend osteochondral transfer as a primary procedure.






      FIG 2 • CT. A. Coronal view with medial OLT that approaches talar shoulder but appears contained. B. Sagittal view demonstrating rather medial OLT. C. Axial view with posteromedial OLT.


    • Failed arthroscopic (débridement and microfracture) management


  • Potential sites for graft harvest



    • Patient’s ipsilateral knee (superolateral femoral condyle, intracondylar notch)


    • Allograft talus


  • Ipsilateral knee versus talar allograft



    • Knee is autograft; however, knee cartilage is thicker than ankle cartilage and may have different biomechanical properties.


    • Allograft talus offers nearly the same cartilage thickness and harvest from the exact location of the native talus defect; however, it is not the patient’s own tissue.


  • The surgeon should check for associated pathology that may need to be addressed at the time of allograft talar reconstruction:



    • Osteophyte removal


    • Ligament reconstruction


    • Corrective osteotomies (calcaneal, supramalleolar)


  • Patient education



    • This is a complex procedure.



    • The patient must understand that the intent is to transfer cartilage and bone from one location to another and expect it to incorporate into the native talus.


    • If allograft is used, there is a negligible but real risk of disease transmission and possible graft rejection by the host.


    • There is no guarantee that the procedure will work, and a revision procedure may be required, such as structural allograft reconstruction or potentially ankle arthrodesis.


Positioning



  • The patient is positioned supine (FIG 3).


  • For a lateral OLT, a bolster under the ipsilateral hip typically affords better access to the lateral talar dome.


  • We routinely use a thigh tourniquet.


Approach



  • The surgeon must determine the optimal surgical approach:



    • Medial talar dome (usually centromedial or posteromedial) typically warrants a medial malleolar osteotomy.






      FIG 3 • Positioning is supine, with easy access to the medial ankle but without too much external rotation, which would make access to the lateral knee cumbersome.


    • Lateral talar dome (often centrolateral) typically necessitates ligament releases (anterior talofibular and calcaneofibular) with or without lateral malleolar osteotomy.


  • The key is that exposure must allow perpendicular access to the OLT; otherwise, the dedicated instrumentation for the osteochondral transfer cannot be used.




TECHNIQUES


▪ Medial Approach for a Medial Osteochondral Lesion of the Talus

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Jul 24, 2016 | Posted by in ORTHOPEDIC | Comments Off on Osteochondral Transfer for Osteochondral Lesions of the Talus

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