Open reduction, headless screw fixation

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.

This procedure is normally performed with the patient in a lateral position.

See also the additional material on preoperative preparation.

The preferred approach is via a surgical hip dislocation. This approach offers optimal assessment, reduction, and fixation.

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.

After surgical stabilization, the construct should be sufficiently robust to allow protected weight bearing. Smaller children may not be able to comply with this and may need immobilization.

See the additional material on postoperative infection.

Forces through the hip are less with toe-touch weight bearing than with no weight bearing. Therefore, toe-touch is normally recommended for initial mobilization. This needs to be taught to children by a physiotherapist.

Range-of-movement exercises should start in the immediate postoperative period to prevent stiffness. Surgeons should indicate if any extremes of movement are forbidden.

Having started with toe-touch weight bearing, children progress to partial weight bearing and then to full weight bearing according to their age and the predicted rate of healing of their fracture.
Even older adolescents should be fully weight bearing without aids at three months.

Swimming can be allowed as soon as partial weight bearing is permitted.
Contact sports should be avoided for at least six months.

X-rays are generally taken immediately after the surgery and at 6 and 12 weeks.

Implants that cross the physis should be removed if there is significant growth remaining. The fracture should be healed and consolidated prior to removal (see Healing times).

Implants in young children should always be removed to prevent them from being covered by bony overgrowth.

Implant removal is not compulsory in adolescents.