- Lateral approach (MIO)
The lateral approach is used for insertion of fixation devices after closed reduction of a proximal femoral fracture. Reduction of a displaced fracture is usually done with a fracture table, or alternatively a large distractor spanning the hip joint.
After satisfactory reduction is confirmed by image intensifier, the lateral approach can be used for insertion of a sliding hip screw or multiple screws. The approach provides limited access to the lateral surface of the femur sufficient for hardware placement.
The incision can be extended proximally to accommodate a trochanteric stabilizing plate (TSP), or even anteriorly so that it becomes an anterolateral approach with direct, although limited, access to the femoral neck.
The tensor fasciae latae is anterior, between layers of the fascia. Incising the fascia posterior to the tensor avoids injuring this muscle.
The deeper muscles are the gluteus medius proximal to the greater trochanter, and the vastus lateralis which covers the femoral shaft distal to the trochanter. No nerves or blood vessels are encountered until the first circumflex artery and vein cross the femur from posteriorly 5 cm distal to the trochanter.
The vastus lateralis is either reflected anteriorly, if bulky, or split longitudinally, if atrophic, to expose the lateral femoral surface.
The hip capsule can be palpated anterior to the trochanter.
Determine placement of the incision
The location of the incision depends on the selected fixation device. Screws must be in line with the axis of the femoral neck. A sliding hip screw is also aimed along the center of the femoral neck, but exposure of the femoral shaft must also accommodate the length of the selected side plate.
Image intensification may be helpful for proper placement of the incision.
The illustrations show how soft-tissue thickness affects incision placement. A more distal incision is required for the larger thigh.
Incise the skin
For insertion of multiple screws, the incision is centered over the femoral neck axis line, and slightly posterior to the palpable mid line of the trochanter.
For a sliding hip screw, the plate angle and length will affect the lateral incision. For example, for a two-hole 135º side plate, the incision usually begins a few centimeters beyond the palpable greater trochanter and extends 10 cm further distally, over the femoral shaft.
For a 95º condylar screw or plate a longer incision is required, depending upon the fracture anatomy and length of plate.
If the soft tissues are thick, the incision may need to be more distal or longer.
Incision of the fascia lata
Sharply expose the fascia lata distal to the greater trochanter, and incise it in line with the skin incision, staying posterior to the tensor muscle fibres, which are palpable in the anterior fascia lata.
Beneath the fascia lata, bluntly expose the vastus lateralis. Retracting the mobile muscle mass anteriorly, bluntly divide its fibres to expose the lateral femur.
The first perforating vessels are typically found distally to the location of a short DHS side plate. They should be anticipated if exposure of more than 5 cm below the vastus lateralis ridge (inferior border of greater trochanter) is required.
If divided carelessly, it may cause persistent bleeding.
Exposure of the femoral shaft
Use one or two small elevators to expose the femoral shaft, and place a Hohmann retractor anteriorly. Expose only enough lateral femoral surface for satisfactory hardware placement.
Option 1: anterior reflection of vastus lateralis
For muscular patients, or for increased proximal femoral shaft exposure, the vastus lateralis can be reflected anteriorly by adding an anterior transverse limb to the incision as illustrated.
Proximal extension of the skin incision aids this variation.
Beginning proximally and posteriorly, the muscle mass is elevated from the femur and reflected anteriorly. The first perforating vessels lie on the lateral femur, approximately 5 cm below the vastus lateralis ridge (inferior border of greater trochanter). They should be identified and ligated or coagulated, if small.
Option 2: Proximal extension for trochanteric stabilizing plate (TSP)
Proximal extension of the incision through skin and subcutaneous tissue, and fascia lata provides access to the proximal surface of the greater trochanter and insertion of gluteus medius.
Option 3: Anterior extension through hip capsule
For direct access to a femoral neck fracture, the lateral incision can be extended proximally and anteriorly. First incise skin, subcutaneous tissue and fascia towards the anterior-superior iliac spine. Then retract the gluteus medius posteriorly and incise the anterior fibres of the hip capsule. Continue this incision onto the anterior lip of the acetabulum. The hip labrum must be preserved. Transverse capsular incisions anteriorly and posteriorly allow greater exposure, which is always a bit limited.
For a full description see the anterolateral approach.