Anteromedial Approach to the Distal Two-thirds of the Femur‌

The anteromedial approach provides an excellent view of the lower two-thirds of the femur and the knee joint. Its uses include the following:

1. Open reduction and internal fixation of fractures of the distal femur, particularly those that extend into the knee joint and require medial buttress plating (its major use)

2. Open reduction and internal fixation of femoral shaft fractures

3. Treatment of chronic osteomyelitis

4. Biopsy and treatment of bone tumors

5. Quadricepsplasty

6. Distal femoral osteotomy

Position of the Patient

Place the patient supine on the operating table, and drape the extremity so that it can move freely (Fig. 9-15).

Landmark and Incision

Landmark

The vastus medialis muscle is a distinct bulge superomedial to the upper pole of the patella. Only the inferior portion can be seen and palpated distinctly. The vastus medialis atrophies rapidly in many patients with knee pathology; therefore, it may be difficult to find.

Incision

Make a 10- to 15-cm longitudinal incision on the anteromedial aspect of the thigh over the interval between the rectus femoris and vastus medialis muscles. (There are no specific landmarks for this interval other than the contour of the vastus medialis.) Extend the incision distally along the medial edge of the patella to the joint line of the knee, if the knee joint must be opened. The exact length of the incision depends on the pathology being treated (Fig. 9-16).

Figure 9-15 Position of the patient on the operating table for the anteromedial approach to the femur.

Figure 9-16 Incision for the anteromedial approach to the thigh.

Figure 9-17 Incise the fascia lata in line with the skin incision, and identify the interval between the vastus medialis and the rectus femoris.

Internervous Plane

There is no internervous plane; the dissection descends between the vastus medialis and rectus femoris muscles, both of which are supplied by the femoral nerve. The intermuscular plane can be used safely to expose the distal two-thirds of the femur; however, because both muscles receive their nerve supplies well up in the thigh.

Superficial Surgical Dissection

Incise the fascia lata (deep fascia) in line with the skin incision, and identify the interval between the vastus medialis and rectus femoris muscles (Fig. 9-17). Develop this plane by retracting the rectus femoris laterally (Fig. 9-18).

Deep Surgical Dissection

Begin distally, opening the capsule of the knee joint in line with the skin incision by cutting through the medial patellar retinaculum (see Fig. 9-18). Continue proximally, splitting the quadriceps tendon almost on its medial border. Open up the plane by sharp dissection, staying within the substance of the quadriceps tendon and leaving a small cuff of the tendon with the vastus medialis attached to it. This preserves the insertion of these fibers and allows easy closure. If the vastus medialis is stripped off the quadriceps tendon, it is very difficult to reinsert, and muscle function will be compromised. Next, continue to develop the interval between the vastus

medialis and rectus femoris muscles proximally to reveal the vastus intermedius muscle. Split the vastus intermedius in line with its fibers; directly below lies the femoral shaft covered with periosteum. Continue the dissection in the epiperiosteal plane to get to the bone (Figs. 9-19 and 9-20).

Figure 9-18 Develop the plane between the vastus medialis and the rectus femoris, retracting the rectus femoris laterally. Begin the parapatellar incision into the joint capsule.

Figure 9-19 Continue the parapatellar incision proximally, opening the joint capsule and suprapatellar region. Carry the incision into the substance of the vastus intermedius.

Dang

Vessels

The medial superior genicular artery crosses the operative field just

above the knee, winding around the lower end of the femur. Although it looks small, it must be ligated or coagulated to avoid hematoma formation (see Fig. 10-38).

Muscles and Ligaments

The lowest fibers of the vastus medialis muscle insert directly onto the medial border of the patella. Their main job is to stabilize the patella and prevent lateral subluxation (see Fig. 9-49). The fiber attachments of the muscle inevitably are disrupted during this approach, unless a small cuff of quadriceps tendon is taken with the muscle. Make sure to repair the incision meticulously during closure to prevent subsequent lateral subluxation of the patella.

Figure 9-20 Incise the periosteum of the femur longitudinally, and expose the distal femur by subperiosteal dissection.

How to Enlarge the Approach

Extensile Measures

Superior Extension. The approach can be extended along the same interval between the rectus femoris and vastus medialis muscles. To extend the deep dissection, continue to split the vastus intermedius muscle. The extension offers excellent exposure of the lower two-thirds of the femur. Higher up, however, the femoral artery, vein, and nerve intrude into the dissection; the upper third of the femur is explored best by a lateral approach.

Inferior Extension. Continue the skin incision downward, and curve it

laterally so that it ends just below the tibial tubercle. Incise the medial retinaculum in line with the skin incision, making the patella more mobile and subject to lateral subluxation for full exposure of the knee joint. Take care not to avulse the quadriceps tendon from its insertion during the maneuver