A guide wire is inserted through the lateral cortex of the femur just above the level of the lesser trochanter and advanced to the fracture line.
If necessary, manipulation of the femoral head is achieved using a small K-wire, inserted into the proximal fragment, as a joystick.
The femoral neck is manipulated gently into position, usually by lifting with a bone hook and manipulating the wires.
Gentle reduction maneuvers are essential in order to prevent secondary damage to the femoral head blood supply.
When acceptable reduction has been obtained, the first wire is advanced across the fracture and into the femoral head. Overpenetration into the hip joint should be avoided.
Insertion of additional guide wires
Additional guide wires are inserted under x-ray control using image intensification according to the two, or three screw configuration desired.
The guide wire positions are confirmed on AP and lateral x-rays, using image intensification.
If using a regular radiolucent table, the guide wire fixation is generally stable enough to allow "frog" lateral view.
The guide wires are repositioned if necessary.
Images at multiple angles are used to confirm that the guide wires do not penetrate into the hip joint.
Measuring screw length
A depth gauge is used to measure screw length.
If a dedicated cannula/depth gauge set is not available, then a K-wire, of the same length as that inserted, is placed onto the lateral cortex adjacent to the inserted wire, and the difference measured to determine the screw length.
If the screw is being used to lag against the lateral cortex, 5mm is subtracted to avoid screw overpenetration.
Drilling screw holes
The guide wires are overdrilled with the appropriately sized cannulated drill bit.
Adolescents in particular have very dense bone in the metaphysis near the growth plate and predrilling of both sides of the fracture line is recommended.
If cannulated screws are not available, then guide wires should be removed one at a time and an appropriate drill used.
Two or three cannulated screws are inserted over the guide wires.
The use of washers is optional.
Image intensification is used to confirm that the screw tip does not penetrate into the hip joint.
Typically, 5 mm of epiphyseal bone/cartilage should remain between the screw tip and joint surface.
Pitfall: Screw penetration can occur, especially with eccentrically placed screws, even if not apparent on AP or lateral x-rays.
Dynamic, real-time image intensification, with a full range of internal and external rotation at different degrees of flexion, is useful to see how close the screw-tip is to the joint surface of the femoral head.
Observing an approach/withdrawal of the screw tip helps in judging its position. Some surgeons supplement this examination with 3-D image intensification for confirmation.
Arthrography is useful to confirm correct screw placement in the younger patient.
Guide wire removal
Guide wires are removed.
5. Hip spica
If solid fixation has been obtained with screws, and the patient/family can reliably comply with toe-touch weight bearing, then a cast is not necessary.
For patients below 5 years of age, a hip spica cast can be used if needed.
Forces through the hip are less with toe-touch weight bearing than with non-weight bearing. Therefore, toe-touch is normally recommended for initial mobilization. This needs to be taught to children by a physiotherapist.
Range of movement
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.