G. James Sammarco
SURGICAL MANAGEMENT
Patient Positioning
The patient is positioned supine under appropriate anesthesia, with thigh tourniquet control and a bolster beneath the ipsilateral buttock. The leg, ankle, and foot are prepared and draped from below the knee distally.
Approach
For a medial lesion a 7-cm anteromedial longitudinal incision is made over the ankle joint parallel to the medial talar facet.
The soft tissue is dissected to the ankle joint and a capsulotomy performed.
Enough capsule is stripped from the tibia to expose the medial half of the joint.
A synovectomy is performed if needed.
TECHNIQUES
TIBIAL OSTEOTOMY USING THE TRAP DOOR
Opening the Tibial Trap Door
Strip the periosteum proximally along the distal tibial metaphysis to the upper limit of the wound.
Make a 1-cm mark on the medial tibial plafond beginning at the angle of Hardy (TECH FIG 1).
Make a second mark 3 cm above the joint line.
Drill two transverse parallel holes across the tibial metaphysis beneath the cortex where the tibial trap door is to be removed. Absorbable pins will be inserted into these predrilled holes when the trap door is replaced after the graft has been inserted in the talar dome.
Make two vertical parallel saw cuts with a Hall microoscillating saw using a no. 64 saw blade (Zimmer, Warsaw, IN) to a depth of 2 cm at the joint surface (TECH FIG 2).
Taper these cuts proximally and upward to the anterior tibial metaphysis 3 cm above the joint.
To protect the talar surface, insert a Freer elevator between the tibia and talus.
TECH FIG 1 • A 7-cm anteromedial incision exposing the medial half of the ankle joint, showing the angle of Hardy (arrow).
Make a third horizontal saw cut connecting these cuts at their upper limit.
Angle the saw inferiorly and 22 degrees posteriorly from the anterior metaphysis toward the joint surface.
Use a thin 10-mm osteotome to mobilize the trap door. Remove the trap door and place it aside (TECH FIG 3).
Coring Out the Lesion
Plantarflex the ankle to deliver the osteochondral lesion into view (TECH FIG 4).
Probe the lesion to determine its exact location.
Select the appropriate-size coring instrument (Arthrex,
MA): 6, 8, or 10 mm.
Place the coring instrument at right angles to the talar dome and extract the lesion.
The removed bone is to be used later.
TECH FIG 2 • Saw cuts are made 1 cm wide, 3 cm high, and 2 cm deep (not seen), creating a trap door (arrow).
TECH FIG 3 • The trap door is removed and set aside to be replaced after the graft is inserted. A probe has been inserted into the lesion (arrow).
Harvesting the Graft
Expose the medial facet of the talar body using a miniHohmann retractor with the ankle in plantarflexion.
Position the harvesting instrument on the medial facet 4 mm beneath the talar dome.
Harvest the graft in such a way that when inserted into the recipient site, the slightly elevated inferior margin of the graft from the medial facet will be oriented toward the medial border of the talar dome, approximating the shape of the normal talar weight-bearing surface (TECH FIG 5).
Inserting the Graft
Débride the talar recipient site and tap the osteochondral graft into place with the inferior medial facet portion oriented toward the medial border of the talus (TECH FIG 6).
Filling the Donor Site
Insert the material that was removed, including the osteochondral lesion, in the donor site.
This can be augmented with cancellous bone taken from the distal tibia.
TECH FIG 4 • The ankle is plantarflexed to expose the lesion and a premeasured 8-mm coring device is used to remove the lesion (arrow).
TECH FIG 5 • The osteochondral graft is harvested from the anterior portion of the medial facet 4 mm below the articular surface of the talar dome and at least 10 mm away from the recipient site (arrow).
Closing the Trap Door
Insert the tibial bone block back into its bed and insert bioabsorbable pins (Biosorb, Johnson & Johnson, Princeton, NJ) into the predrilled holes to secure the bone block in place (TECH FIG 7).
Wound Closure and Postoperative Care
Approximate the deep tissues with 3-0 absorbable suture and close the skin with 3-0 monofilament nylon.
Apply a compression dressing and posterior splint; they are changed at the first follow-up visit.
Sutures are removed at 2 weeks and a non–weight-bearing short-leg cast is used for 1 month.
A range-of-motion boot is then prescribed with 50% weight bearing for 3 weeks, after which physical therapy is instituted.
TECH FIG 6 • The osteochondral graft has been inserted into the recipient site (upper arrow) and the bony material removed, including attached remaining cartilage from the defect that has been inserted into the donor site (lower arrow).
TECH FIG 7 • The trap door is replaced and secured with bioabsorbable pins (arrows) placed into predrilled holes.
ADDITIONAL TECHNIQUE
If the bone at the base of recipient site is excessively sclerotic, it may be drilled using a 0.045 Kirschner wire before inserting the graft in order to encourage vascular ingrowth.
For lesions on the lateral talar dome, use the same technique but make the most lateral vertical saw cut 2 mm away from the distal tibiofibular syndesmosis to avoid violating the joint.
PEARLS AND PITFALLS
This technique avoids the need for a medial malleolar osteotomy. It provides excellent visualization of and access to the lesion through a single incision while avoiding a second procedure on an asymptomatic knee to harvest the graft.
The procedure is best suited for lesions up to 10 mm in diameter and up to 10 mm deep located in the anterior two thirds of the medial or lateral talar dome margins.
The graft can be placed just beneath the subchondral bone of the medial or lateral facet since these surfaces bear minimal weight, and no complications have been noted in the medial or lateral gutters.
The surgeon should avoid making the vertical saw cuts more than 3 cm deep at the joint surface or 4 cm in height since this increases the risk of a medial malleolar stress fracture.
In harvesting the osteochondral graft, the surgeon should avoid taking the graft too near the talar surface or too near the recipient site in order to avoid a stress fracture of the talar dome.
Patients with arthritis can have progression of the condition even though the graft becomes incorporated and survives.
The most common minor complaint is occasional aching at the anteromedial joint line with activity.
REFERENCE
1. Sammarco GJ, Makwana NK. Treatment of talar osteochondral lesions using local osteochondral graft. Foot Ankle Int 2002;22:693–698.