Large osteochondral fragments can be reattached with cannulated headless screws.
As headless screws are not resorbable, it is important that the ends of the screws are below the cartilage. The bony part of the fragment must therefore be large enough to accommodate the proximal thread of the headless screw.
Note: The osteochondral fragment can become necrotic, leading to prominence of the screw end. This is suggested by pain during movement, and mandates screw removal.
At least two divergent screws should be used to provide satisfactory fixation and some axial compression.
Once the femoral head is dislocated, the fragment is anatomically reduced.
If there is a delay to surgery, swelling of the cartilage of the fragment may be seen. This may need to be trimmed in order to reduce it fully.
The fragment is then secured with finger pressure and two or three divergent guide wires (corresponding to the screw size) are inserted.
When the fragment is anatomically reduced, screws with a length of approximately 2/3 of the femoral head diameter are inserted over the guide wires.
Completely intraepiphyseal placement is preferred.
The guide wires are removed.
After fixation, the hip is reduced and free movement of the head is checked without moving the fragment.
Only controlled range of motion, without forced movements, is permitted for 4-6 weeks postoperatively.
Full weight bearing is permitted after wound healing.
The onset of pain and reduction in the range of motion may indicate prominence of the screws.
CT scan and dynamic arthrography are useful in assessment of screw position and stage of healing. Prominent screws must be removed.