The Femur

 

 

 

Lateral Approach Posterolateral Approach

Anteromedial Approach to the Distal Two-thirds of the Femur Posterior Approach

Minimally Invasive Approach to the Distal Femur

Minimally Invasive Approach to the Proximal Femur for Intramedullary Nailing

Minimally Invasive Surgery for Retrograde Intramedullary Nailing of the Femur

Applied Surgical Anatomy of the Thigh Posterior Approach to the Femur

Operations on the femur are extremely common. The lateral approach to the proximal femur, which is used to treat the growing number of patients who have intertrochanteric hip fractures, was before the advent of proximal femoral nailing the most frequently used approach in orthopedic

surgery.

The four basic approaches to the femoral shaft, the lateral, posterolateral, anterolateral, and anteromedial, all penetrate elements of the quadriceps muscle. Only the posterolateral approach uses an internervous plane, but all are relatively safe because the femoral nerve, which supplies the quadriceps femoris muscle, divides proximally in the thigh, allowing the more distal muscle elements to be separated without denervation. (The posterior approach is reserved for exploration of the sciatic nerve and for patients who cannot undergo more anterior approaches because of skin problems.)

The minimally invasive approach to the distal femur utilizes two windows. The lower window is derived from the lateral parapatellar approach to the knee and the upper window from the lateral approach to the femoral shaft. As in all minimally invasive surgical approaches, imaging during surgery is mandatory.

Femoral shaft fractures and extracapsular hip fractures are now most commonly treated with intramedullary nails inserted using a closed technique. The entry point of femoral nails varies with nail design. A minimally invasive approach to the proximal femur for the insertion of intramedullary nails which are straight in the sagittal plane is described.

Because the key vascular structures spiral down the thigh, passing in an anterior to posterior direction, the anatomy of the thigh is discussed in a separate section in this chapter following the descriptions of the surgical approaches. Within this section, the unique anatomic features of each approach are discussed individually.

 

Lateral Approach

The lateral approach is the incision used most often for gaining access to the upper third of the femur. It also can be extended inferiorly to expose virtually the whole length of the bone. Although it is an extremely quick and easy approach, it involves splitting the vastus lateralis muscle. The subsequent blood loss that results from the rupture of vessels during this procedure may make surgery awkward, but rarely is life-threatening. The posterolateral approach to the femur does not involve muscle splitting and for this reason is favored by some surgeons for surgery on the proximal femur.

The uses of the lateral approach include the following:

1. Open reduction and internal fixation of intertrochanteric fractures (this is by far the most common use of the approach)

2. Insertion of internal fixation in the treatment of subcapital fractures or slipped upper femoral epiphysis

3. Subtrochanteric or intertrochanteric osteotomy

4. Open reduction and internal fixation of femoral shaft fractures, subtrochanteric fractures, and supracondylar fractures of the femur

5. Extra-articular arthrodesis of the hip joint

6. Treatment of chronic osteomyelitis of the femur

7. Biopsy and treatment of bone tumors

 

Position of the Patient

 

Patients with trochanteric fractures should be placed on an orthopedic table in the supine position so that their fractures can be manipulated or controlled during surgery. Use an orthopedic table for any procedure that involves the use of an image intensifier (Fig. 9-1). Internally rotate the leg 15 degrees to overcome the natural anteversion of the femoral neck and to bring the lateral surface of the bone into a true lateral position. For most extracapsular hip fractures internal rotation helps fracture reduction. Having the femoral neck parallel to the floor is helpful in positioning the femoral neck guidewire correctly.

For surgery on the shaft of the femur a lateral position can also be used. Place the patient on his or her side, with the affected limb uppermost. Take care to pad the bony prominences of the bottom limb to avoid pressure necrosis of the skin. Place other pillows between the two limbs to pad the medial surface of the knee and the medial malleolus of the side that is being operated on.

Landmarks and Incision Landmarks

The posterior edge of the greater trochanter is relatively uncovered.

Palpate it, moving the fingers anteriorly and proximally to identify its tip.

The shaft of the femur is palpable as a line of resistance on the lateral side of the thigh.

Incision

Make a longitudinal incision, beginning over the middle of the greater trochanter and extending down the lateral side of the thigh over the lateral

aspect of the femur. The length and position of the incision will vary with the requirements of the surgery (Fig. 9-2).

Radiographic control of the length and position of the incision significantly reduces the length of the incision. Because it is accurately sited, this in turn reduces the amount of dissection and soft tissue damage necessary for adequate exposure.

 

 

 

Figure 9-1 Position of the patient on the operating table for the lateral approach to the proximal femur.

 

Internervous Plane

 

There is no internervous or intermuscular plane, because the dissection splits the vastus lateralis muscle, which is supplied by the femoral nerve. The muscle receives its nerve supply high in the thigh, however, so splitting the muscle distally does not denervate it.

 

Superficial Surgical Dissection

 

Incise the fascia lata of the thigh in line with the skin incision. At the upper end of the wound, the distal portion of the tensor fasciae latae may have to be split in line with its fibers to expose the vastus lateralis (Fig. 9-3). This split is needed in about one-third of patients, those who have tensor fasciae latae fibers extending distally beyond the greater trochanter.

 

 

Figure 9-2 Incision for the lateral approach to the proximal femur.

 

 

 

Figure 9-3 Incise the fascia lata in line with the skin incision.

 

Deep Surgical Dissection

 

Carefully incise the fascial covering of the vastus lateralis muscle (Fig. 9-4). Insert a Hohmann or Bennett retractor through the muscle, running the tip of the retractor over the anterior aspect of the femoral shaft. Then, insert a second retractor through the same gap and down to the femoral shaft. Manipulate the second retractor so that it moves underneath the femur, and pull the two retractors apart to split the vastus lateralis in the

line of its fibers (Fig. 9-5).

Continue splitting by blunt dissection. As dissection proceeds, several vessels that cross the field will be exposed. Coagulate them, if possible, before they are avulsed by the blunt dissection. Avoid sharp dissection straight down to the bone. Numerous vessels will be cut and because they retract into the muscle they are often difficult to coagulate or ligate.

Splitting the vastus lateralis reveals the underlying lateral surface of the femur.

 

 

 

Figure 9-4 Incise the fascia covering the vastus lateralis.

 

 

Figure 9-5 Split the fibers of the vastus lateralis. To develop a subperiosteal plane, squeeze two Hohmann retractors down to the femoral shaft and separate them to split the vastus lateralis further.

 

 

Dang

 

 

Vessels

Numerous perforating branches of the profunda femoris artery traverse the vastus lateralis muscle (see Fig. 9-48). They are damaged during the approach and should be ligated or coagulated. These arterial branches can be identified more easily if the muscle is split gently with a blunt instrument rather than cut straight through with a knife.

 

How to Enlarge the Approach

Extensile Measures

The approach is most useful for exposing the proximal third of the bone for internal fixation of a hip fracture. It can be extended to the knee joint, however, to allow full exposure of the lateral aspect of the femoral shaft for reduction and fixation of all types of femoral fractures (Fig. 9-6; see

Fig. 9-51).

 

 

 

Figure 9-6 The incision may be extended distally to expose the entire shaft of the femur.

 

Posterolateral Approach

The posterolateral approach1–3 can expose the entire length of the femur. Because it follows the lateral intermuscular septum, it does not interfere with the quadriceps muscle. Although other lateral approaches involve splitting the vastus lateralis or vastus intermedius muscles, the functional results of the posterolateral approach do not differ significantly from those of other approaches, probably because the vastus lateralis originates partly from the lateral intermuscular septum. As a result, surgery still involves detaching a part of the muscle’s origin and does not use a true intermuscular plane.

The lateral intramuscular septum lies posterior to the femoral shaft at its proximal end. This septum overlies the middle of the shaft at its distal end. The posterolateral approach is therefore ideal for exposure of the distal one-third of the femur. The more proximal the approach, the greater the bulk of the vastus lateralis that will need to be retracted anteriorly and the more difficult the approach will be.

The uses of the posterolateral approach include the following:

1. Open reduction and plating of femoral fractures, especially supracondylar fractures

2. Open intramedullary nail placement for femoral shaft fractures if facilities for closed nailing do not exist

3. Treatment of nonunion of femoral fractures

4. Femoral osteotomy (which is performed rarely in the region of the femoral shaft)

5. Treatment of chronic or acute osteomyelitis

6. Biopsy and treatment of bone tumors

 

Position of the Patient

 

Place the patient supine on the operating table with a sandbag beneath the buttock on the affected side to elevate the buttock and to rotate the leg internally, bringing the posterolateral surface of the thigh clear of the table (Fig. 9-7).

 

 

 

Figure 9-7 Position of the patient on the operating table for the posterolateral approach to the femur.

 

 

Figure 9-8 The internervous plane lies between the vastus lateralis (which is supplied by the femoral nerve) and the hamstring muscles (which are supplied by the sciatic nerve).

 

Landmarks and Incision

Landmarks

Palpate the lateral femoral epicondyle on the lateral surface of the knee joint. The epicondyle actually is a flare of the condyle. Moving superiorly, note that the femur cannot be palpated above the epicondyle.

Incision

Make a longitudinal incision on the posterolateral aspect of the thigh. Base the distal part of the incision on the lateral femoral epicondyle and continue proximally along the posterior part of the femoral shaft. The exact length of the incision depends on the surgery to be performed (Fig. 9-8).

 

Internervous Plane

 

The approach exploits the plane between the vastus lateralis muscle (which is supplied by the femoral nerve) and the lateral intermuscular septum, which covers the hamstring muscles (which are supplied by the sciatic nerve; Fig. 9-9).

 

Superficial Surgical Dissection

 

Incise the deep fascia of the thigh in line with its fibers and the skin incision (Fig. 9-10).

 

Deep Surgical Dissection

Identify the vastus lateralis under the fascia lata (Fig. 9-11). Follow the muscle posteriorly to the lateral intermuscular septum. Then, reflect the muscle anteriorly, dissecting between muscle and septum. Begin at the distal end of the incision where the plane is easiest to identify and develop. Numerous branches of the perforating arteries cross this septum to supply the muscle; they must be ligated or coagulated (Fig. 9-12). If the approach involves the supracondylar region, identify and ligate the numerous branches of the superior lateral geniculate vessels, which cross the operative fields. Failure to do so will result in profuse hemorrhage, which will be difficult to control.

 

 

 

Figure 9-9 Incision for the posterolateral approach to the thigh.

 

 

 

Figure 9-10 Incise the fascia of the thigh in line with its fibers and the skin incision.

 

Continue the dissection, following the plane between the lateral intermuscular septum and the vastus lateralis muscle, detaching those parts of the vastus lateralis that arise from the septum until the femur is reached

at the linea aspera (Fig. 9-13). Incise the periosteum longitudinally at this point and strip off the muscles that cover the femur, using epiperiosteal dissection. Detaching muscles from the linea aspera itself usually has to be done by sharp dissection (Fig. 9-14).

It is very easy to open up the plane between the vastus lateralis muscle and the lateral intermuscular septum in the distal third of the femur. Moving proximally, the muscle becomes thicker, and it becomes more difficult to lift the muscle bulk anteriorly to reveal the femoral shaft. To aid in this process, place a Hohmann or Bennett retractor over the anterior aspect of the femoral shaft, lifting the vastus lateralis forward. A retractor placed on the lateral intermuscular septum will help open up the gap and facilitate proximal dissection.

 

 

 

Figure 9-11 Identify the vastus lateralis under the incised fascia lata.

 

 

 

Figure 9-12 Elevate the vastus lateralis anteriorly, separating the muscle from the septum.

Dang

 

 

Vessels

The perforating arteries (which are branches of the profunda femoris artery) pierce the lateral intermuscular septum to supply the vastus lateralis muscle. They must be ligated or coagulated one by one as the dissection progresses. If they are torn flush with the lateral intermuscular septum, they may begin to bleed out of control as they retract behind it (Fig. 9-51).

The superior lateral genicular artery and vein cross over the lateral surface of the femur at the top of the femoral condyles. These vessels will need to be ligated for exposure to the bone.

 

 

 

Figure 9-13 Detach those portions of the vastus lateralis that arise from the septum until the femur and linea aspera are reached. Then, incise the periosteum longitudinally.

 

 

Figure 9-14 Expose the shaft of the femur.

 

How to Enlarge the Approach

Extensile Measures

The major value of this incision lies in its exposure of the distal two-thirds of the femur. It can be extended superiorly, however, up to the greater trochanter, to expose virtually the entire femoral shaft. Note that, superiorly, the tendon of the gluteus maximus muscle lies behind the lateral intermuscular septum.

The approach can be extended easily into a lateral parapatellar approach to the knee joint. This allows accurate visualization of the entire distal end of the femur. This extension is used to allow reduction and fixation of intra-articular fractures of the distal femur.

 

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 (see Medial Parapatellar Approach in Chapter 10, page 525).

 

Posterior Approach

The posterior approach4 is useful in patients who cannot undergo more anterior approaches because of local skin problems. It provides access to the middle three-fifths of the bone, as well as to the sciatic nerve. Although it is performed rarely, its uses include the following:

1. Treatment of infected cases of nonunion of the femur

2. Treatment of chronic osteomyelitis

3. Biopsy and treatment of bone tumors

4. Exploration of the sciatic nerve

Knowledge of the anatomy that underlies this approach is vital for exploration of wounds in this area.

The approach is unusual in that surgery remains lateral to the biceps muscle in its proximal half, but proceeds medial to it in its distal half. This is because of the relationship of the posterior aspect of the femur to the sciatic nerve.

 

Position of the Patient

 

Place the patient prone on the operating table, supporting the pelvis and chest on longitudinally placed pillows or thick foam pads to allow the abdomen and chest to move freely, ensuring adequate ventilation (Fig. 9-21).

 

Landmark and Incision

Landmark

The gluteal folds are visible clearly on the buttock.

Incision

Make a straight longitudinal incision about 20 cm long down the midline of the posterior aspect of the thigh. The incision should end proximally at

the inferior margin of the gluteal fold, and its length will vary with surgical need (Fig. 9-22).

 

Internervous Plane

 

The plane of dissection lies between the lateral intermuscular septum, which covers the vastus lateralis muscle (which is supplied by the femoral nerve), and the biceps femoris muscle (which is supplied by the sciatic nerve; Fig. 9-23).

 

Superficial Surgical Dissection

 

Incise the deep fascia of the thigh in line with the skin incision, or lateral to it, taking care not to damage the posterior femoral cutaneous nerve, which runs longitudinally under the deep fascia (and roughly in line with the fascial incision), in the groove between the biceps and semitendinosus muscles (Fig. 9-24). Identify the lateral border of the biceps femoris in the proximal end of the wound by palpating it. Then, develop the plane between the biceps femoris and vastus lateralis muscles, which are covered by the lateral intermuscular septum (Fig. 9-25).

 

 

 

Figure 9-21 Position of the patient on the operating table for the posterior approach to the femur.

 

 

 

Figure 9-22 Make a straight longitudinal incision in the midline of the posterior

aspect of the thigh.

 

 

 

Figure 9-23 The internervous plane lies between the vastus lateralis (which is supplied by the femoral nerve) and the biceps femoris (which is supplied by the sciatic nerve).

 

 

 

Figure 9-24 Incise the deep fascia of the thigh in line with the skin incision or just lateral to it, taking care not to damage the posterior femoral cutaneous nerve.

 

Deep Surgical Dissection

 

Begin proximally. Retract the long head of the biceps femoris muscle medially and the lateral intermuscular septum laterally, developing the plane with a finger (see Fig. 9-25). Identify the short head of the biceps as it arises from the lateral lip of the linea aspera. Detach its origin from the femur by sharp dissection, and reflect it medially to expose the posterior aspect of the femur (Fig. 9-26).

In the distal half of the wound, retract the long head of the biceps laterally to expose the sciatic nerve (Fig. 9-27). Be aware that the nerve

may already have divided into its tibial and common peroneal branches in which case two “sciatic nerves” will be found running side by side. Gently retract the sciatic nerve laterally to reveal the posterior aspect of the femur, which is covered with periosteum (Fig. 9-28). Develop an epiperiosteal plane between the periosteum and overlying soft tissues (Fig. 9-29; see Fig. 9-28).

 

 

Dang

 

 

Nerves

The sciatic nerve courses down the back of the thigh in the posterior compartment. Because it lies medial to the biceps muscle in the upper part of the incision, it is protected from damage during the proximal part of the approach as long as the correct intermuscular plane is maintained. Distally, the nerve must be identified and care taken not to retract it overzealously (see Fig. 9-53).

The nerve to the biceps femoris branches from the sciatic nerve and enters the biceps from its medial side well up in the thigh. Because the dissection is on the safe lateral side, the nerve cannot be damaged proximally.

 

How to Enlarge the Approach

 

The approach cannot be extended usefully either superiorly or inferiorly. It is valuable solely for its exposure of the middle three-fifths of the shaft of the femur.

 

 

 

Figure 9-25 Identify the lateral border of the biceps femoris; develop the plane

between the biceps femoris and the vastus lateralis.

 

 

 

Figure 9-26 Detach the origin of the short head of the biceps from the femur by sharp dissection, and reflect it medially to expose the posterior aspect of the femur.

 

 

 

Figure 9-27 Retract the long head of the biceps laterally to expose the sciatic nerve.

 

 

 

Figure 9-28 Retract the sciatic nerve laterally to expose the posterior aspect of the femur. Incise the periosteum.

 

 

 

Figure 9-29 Develop the subperiosteal plane to expose the posterior aspect of the femur.

 

Minimally Invasive Approach to the Distal Femur

 

 

The minimally invasive approach to the distal femur utilizes two windows. The distal window is in effect a lateral parapatellar approach to the knee and allows visualization of the articular surface of the distal femur. The proximal window provides access to the femoral shaft and is a portion of the lateral approach to the femoral shaft (see Fig. 9-6). The minimally invasive approach is indicated for open reduction and internal fixation of distal femoral fractures, especially those that involve intra-articular fractures associated with complex metaphyseal injuries.10–13

 

Position of the Patient

 

Place the patient supine on the table with a bolster under the thigh so that the knee rests in approximately 30 degrees of flexion (Fig. 9-30). This will relax the pull of the gastrocnemius muscles on the distal fragment of the fracture. If a tourniquet is to be used, place the tourniquet high on the patient’s thigh and exsanguinate the limb using a compressive bandage or elevate for 3 to 5 minutes before the tourniquet is inflated. Use a radiolucent table and ensure that adequate imaging can be obtained of the

knee and femoral shaft by using an image intensifier before prepping and draping.

 

Landmarks and Incisions

 

Palpate the lateral joint line of the knee by flexing and extending the joint. The lateral margin of the patella and anterior surface of the lateral femoral condyle are easily palpable. The femoral shaft, however, is merely felt as a resistance beneath the tight iliotibial band.

Incision

Make a 6- to 8-cm longitudinal incision over the anterior half of the lateral femoral condyle, extending upward from the joint line. Make a second proximal longitudinal incision overlying the lateral aspect of the shaft of the femur (Fig. 9-31). The positioning and length of this second incision will relate to the implant being used, and the site of the incision must be determined using image intensification.

 

Internervous Plane

 

Distally, the dissection explores the internervous plane between the vastus lateralis muscle supplied by the femoral nerve and the biceps femoris muscles supplied by the sciatic nerve. Proximally, no internervous plane is available for surgery, but splitting the vastus lateralis muscle usually does not result in significant denervation.

 

Superficial Surgical Dissection

 

Begin distally. Incise the skin and subcutaneous tissue in the line of the skin incision. Divide the lateral retinaculum to visualize the joint capsule. At the proximal end of the distal window, develop a plane between vastus lateralis anteriorly and the lateral intramuscular septum posteriorly. Numerous branches of the superior lateral genicular artery with associated veins cross the operating field at this point and will need to be ligated or diathermied.

Proximally incise the subcutaneous fat in the line of the skin incision and then divide the deep fascia overlying the vastus lateralis also in a longitudinal fashion (Fig. 9-32).

 

 

Figure 9-30 Position for the lateral approach to the distal femur.

 

 

 

Figure 9-31 Distally make a 6- to 8-cm incision over the anterior half of the femoral condyle beginning at the joint line. Proximally make a longitudinal incision over the lateral aspect of the femoral shaft. The position and length of the proximal incision depend on the site of the pathology and the implant to be used for treatment.

 

Deep Surgical Dissection

 

Distally divide the knee joint capsule and synovium longitudinally to expose the entire distal end of the femur. Retract the patella using an appropriate retractor and visualize all aspects of the joint by flexing and extending the knee. Proximally split the vastus lateralis muscle in a line of

its fibers to give direct access to the periosteum on the lateral aspect of the femoral shaft (Fig. 9-33). Finally, develop an epiperiosteal plane between the two windows on the lateral aspect of the femur using a blunt dissector or the surgical implant (Fig. 9-34).

 

 

Dang

 

 

The superior genicular artery and veins need to be seen and ligated. These vessels tend to be numerous and are closely adherent to the periosteum. If these vessels are not controlled, a large hematoma will result postoperatively.

 

How to Enlarge the Approach

Local measures

An external fixator or a distraction clamp can be applied to the lateral aspect of the femoral shaft and the lateral aspect of the tibia. This will cause the lateral aspect of the knee to open up, facilitating visualization of the articular surface.

Extensile Measures

The two skin incisions can be united and the vastus lateralis divided in the line of its fibers to provide access to the entire lateral aspect of the shaft of the femur. This maneuver will, of course, increase the degree of soft tissue damage and will reduce the blood supply to the metaphyseal fracture fragments.

 

 

Figure 9-32 Distally incise the subcutaneous tissues in the line of the skin incision to reveal the fascia overlying the vastus lateralis and the lateral patellar retinaculum. Proximally incise the subcutaneous tissues in the line of the skin incision to reveal the fascia covering the vastus lateralis.

 

 

 

Figure 9-33 Distally incise the lateral patellar retinaculum and the underlying joint capsule to enter the knee joint and expose the distal end of the femur. More proximally, incise the deep fascia to reveal the lateral aspect of the distal femur.

Proximally incise the fascia overlying the vastus lateralis and split the fibers of that muscle to expose the periosteum covering the lateral aspect of the femoral shaft.

 

 

 

Figure 9-34 Connect the two incisions by developing an epiperiosteal plane along the lateral aspect of the femur using blunt dissection.

 

Minimally Invasive Approach to the Proximal Femur for Intramedullary Nailing

 

 

The minimally invasive approach to the proximal femur is used for the insertion of intramedullary nails for the treatment of the following:

1. Acute femoral shaft fractures

2. Pathologic femoral shaft fractures

3. Delayed union and nonunion of femoral shaft fractures

The entry point for the insertion of an intramedullary nail into the femur is determined radiographically. It depends on the design of the nail and the anatomy of the proximal femur in the individual patient. The majority of intramedullary nails are straight when viewed in the anterior–posterior plane. The nail should be inserted so that its entry point into the bone is exactly in line with the intramedullary canal on both anterior–posterior and lateral radiographs. The use of preoperative templates overlying radiographs allows for a precise calculation of the entry point.

The nearest anatomical landmark to this entry point is the trochanteric fossa which marks the insertion of obturator externus but it cannot be used reliably in all patients because it does not always line up with the intramedullary canal in both planes. In addition, the fossa cannot be palpated because of overlying musculature.14

For nails that are straight when viewed in the anterior–posterior plane, the skin incision, the entry point of the nail in the bone, and the medullary canal of the femur should all be in a straight line.

Some nails especially those used for fixation of extracapsular hip fractures are angled at their upper end and require insertion via the tip of the greater trochanter. These nails require a skin incision directly over the tip of the greater trochanter.

 

Position of the Patient

 

Two positions are available for the insertion of femoral nails. The supine position allows easier control of fracture reduction and distal locking of the nail (Fig. 9-35). The lateral position allows easier access to the entry point in the proximal end of the femur. It is favored by many surgeons when treating obese patients.

Supine Position

Place the patient supine on a traction table. Employ traction using a supracondylar femoral pin or a traction boot. Adduct the leg as much as possible around the traction post to make it anatomically possible to enter the upper end of the femur via the skin on the lateral aspect of the buttock. Laterally flex the trunk of the patient away from the operative side. Flex and abduct the opposite hip and flex the knee, placing the leg in a support (see Figs. 9-35 and 9-36A). Ensure that adequate anterior–posterior and lateral radiographs of the entry point of the nail and the fracture site can be obtained. Be sure that the fracture is reduced or reducible before commencing surgery. Although this may be time-consuming, it is important to obtain good-quality radiographs before commencing surgery, or you will struggle to obtain quality imaging during the case. Five minutes of preoperative time may shorten your operating time by 2 hours.

 

 

Figure 9-35 Place the patient supine on the traction table. Reduce the fracture by traction and manipulation. Adduct the leg as much as possible around the traction pole. Abduct and flex the opposite hip to allow C-arm access to the whole of the femur.

 

In displaced subtrochanteric femoral shaft fractures, the proximal fragment will flex and abduct due to the unopposed pull of the psoas and the abductor muscles. Displaced proximal femoral fractures cannot be reduced by traction alone. Control of the proximal fragment frequently requires percutaneous insertion of a Steinmann pin into the proximal fragment, allowing its manipulation.

Inserting a nail in a very obese patient cannot be done successfully in the supine position (Fig. 9-36).

Lateral Position

Place the patient in a lateral position on a traction table with the affected limb uppermost. Apply traction to the femur through a distal supracondylar pin or a plaster boot. Adduct the leg over the traction pole. Place the contralateral limb in a flexed position at both hip and knee. Take care to pad the bony prominences of the bottom leg to prevent skin breakdown due to pressure. Ensure that adequate anterior–posterior and lateral radiographs of the entry point and the fracture site can be obtained. The fracture must be reduced or reducible before commencing surgery. Proximal femoral fractures will require ancillary modes of reduction

(Steinmann pins) (see Supine Position above).

The lateral position allows easier access to the proximal femur than the supine position because it allows more adduction, which is particularly useful in obese patients. In cases of extreme obesity, even this position may not permit successful intramedullary nailing; such patients are probably best treated by a retrograde nailing technique with an entry point into the bone in the intercondylar notch.

 

Landmarks and Incision

Landmarks

The greater trochanter is a large mass of bone that projects upward and backward from the junction of the shaft of the femur and its neck (see Fig. 8-43).

The anterior-superior iliac spine can be felt as the anterior margin of the iliac crest (see Fig. 8-43).

 

 

Figure 9-36 A: Adducting the leg moves the skin incision distally. B: In obese patients, nailing in this supine position is impossible. Note that even with maximal adduction, the ideal incision lies above the iliac crest.

The shaft of the femur can be felt as resistance through the massive vastus lateralis muscle on the lateral side of the thigh.

Incision

There are two techniques for planning the correct placement of the incision.

 

Radiographic Technique. Palpate the shaft of the femur on the lateral aspect of the thigh through the bulk of the vastus lateralis muscle. With a marker pen, draw a line on the skin, marking the lateral aspect of the shaft of the femur (Fig. 9-37). This line is curved because the femur is bowed anteriorly when viewed in the lateral plane. Extend this gently curving line proximal to the tip of the greater trochanter, up to the level of the iliac crest (Fig. 9-38).

Place a long guidewire, such as a reaming guidewire, on the anterior aspect of the thigh. Using radiographic control, ensure that the guidewire is overlying the center of the medullary canal when viewed in the anterior–posterior plane (Fig. 9-39).

Take a long artery forceps and move it proximally along the line you have drawn on the skin. Screen this instrument using an image intensifier in the anterior–posterior planes (see Fig. 9-39). When the image of the tip of the forceps coincides with the guidewire radiographically, mark the skin (see Fig. 9-39). This skin mark will be the center of the skin incision. A wire inserted through this incision and through the correct entry point in the bone will pass perfectly down the center of the medullary canal of the femur in both anterior–posterior and lateral planes.

If the patient is obese and/or you are unable to adduct the leg, then this entry point will be above the level of the iliac crest (see Fig. 9-36B). Such an entry point is clearly not usable. If this is the case, then alternative techniques using curved instrumentation will need to be used through a more proximally based incision.

 

Landmark Technique. Palpate the shaft of the femur through the bulk of the vastus lateralis muscle. With a marker pen, draw a curved line on the skin of the lateral aspect of the thigh, marking the shaft of the femur (see Fig. 9-37). Extend this line proximally beyond the tip of the greater trochanter, curving it slightly posteriorly.

Palpate the anterior-superior iliac spine. Draw a line perpendicularly downward from the iliac spine toward the buttock. The incision should be centered at the point where these two lines cross (Fig. 9-40).

 

 

Figure 9-37 Palpate the shaft of the femur through the vastus lateralis muscle. Draw a line on the skin, marking the line of the shaft of the femur. Note that this line is curved.

 

 

 

Figure 9-38 Extend the drawn line above the tip of the greater trochanter to the level of the anterior-superior iliac spine.

 

Incision

Make a longitudinal incision centered on the skin mark. The size of the incision depends on the type of nail to be used. Nails that have proximal interlocking jigs that are considerably offset from the nail can be inserted through a 3-cm incision. Nails whose proximal jigs attach close to the nail require a longer skin incision (up to 7 cm).

 

Internervous Plane

 

There is no internervous plane or intermuscular plane. The dissection splits fibers of the gluteus maximus and gluteus medius but does not denervate either muscle.

 

Superficial Surgical Dissection

 

Incise the subcutaneous fat and the fascia overlying the gluteus maximus in line with the incision. Split the fibers of gluteus maximus for 3 cm in the line of its fibers using a curved clamp.

Deep Surgical Dissection

 

Continue the dissection distally using a long curved clamp to split the fibers of the gluteus medius muscle to gain access to the proximal femur. Careful use of a finger as a blunt dissector to identify the medial aspect of the greater trochanter is often helpful as well. Insert a marker wire (or rod) through the completed dissection onto the proximal end of the femur, and adjust the position of the wire using x-ray control in both anterior–posterior and lateral planes until the wire is at the correct entry point into the bone. The wire must line up with the intramedullary canal on both anterior–posterior and lateral planes (Figs. 9-41 and 9-42).

The exact techniques for entering the proximal femur vary from nail to nail. You must consult the appropriate literature to ensure that the instrumentation is used correctly.

 

 

 

Figure 9-39 Place a long guidewire on the anterior surface of the thigh and position it under image intensifier control so that its image overlies the center of the medullary canal of the femur. Take a long artery forceps and move it

proximally along the drawn line on the lateral aspect of the thigh. When the image of the forceps coincides with the image of the guidewire radiographically, mark the skin.

 

 

Dang

 

 

Bone Deformity

The presence of an incorrect entry point is potentially hazardous in intramedullary nailing of the femur.

An entry point that is too far lateral commonly occurs. This will create a varus deformity at the fracture site if the nail used is rigid, and the fracture is in the proximal third of the femur. Lateral entry points may also create an iatrogenic fracture of the medial femoral cortex during nail insertion.

An entry point that is too far medial may create an iatrogenic fracture of the femoral neck, usually a vertical basicervical fracture. On occasion, medial entry points may also damage the blood supply to the femoral head, creating avascular necrosis.

Nerves

The superior gluteal nerve runs posteriorly to anteriorly through the substance of the gluteus medius muscle 3 to 5 cm above the tip of the greater trochanter. If the femur is adducted, the nerve will not be damaged during insertion of a nail. If, however, a retrograde nailing technique is used when the femur is not necessarily abducted, then damage to the nerve may occur.

 

How to Enlarge the Approach

 

This approach cannot be usefully enlarged proximally or distally because it does not utilize an internervous plane.

 

 

Figure 9-40 Landmark technique. Draw a line perpendicularly downward from the anterior-superior iliac spine. Where this line crosses the previously drawn line on the lateral aspect of the thigh, mark the skin.

 

 

 

Figure 9-41 Split the fibers of the gluteus maximus in line with the skin incision. Deepen the incision down to the femur by splitting the fibers of the gluteus medius.

 

 

Figure 9-42 Insert a guidewire (or rod) into proximal femur, checking its position in both A-P and lateral planes using a C-arm.

 

Minimally Invasive Surgery for Retrograde Intramedullary Nailing of the Femur

 

 

The minimally invasive approach for retrograde intramedullary nailing utilizes a small portion of the medial parapatellar approach to the knee. It allows excellent percutaneous access to the distal femoral intercondylar

region. Its sole use is for the insertion of retrograde intramedullary nails used to treat femoral shaft fractures.

 

Position of the Patient

 

Place the patient supine on a radiolucent table. Place a large triangular ridge underneath the knee to allow the knee to flex to 90 degrees. Finally, place a small sandbag under the ipsilateral buttock to correct the natural external rotation of the limb and ensure that the patella faces directly anteriorly. Ensure that this sandbag does not block radiographic visualization of the trochanteric region of the femur where proximal locking may be needed. This will allow you to more accurately access rotational control during fracture reduction and fixation.

 

Landmarks and Incision

 

Palpate the medial border of the patella. Make a 3-cm longitudinal incision approximately 1 cm from the medial border of the patella, beginning about 2 cm proximal to the distal pole of the patella (Fig. 9-43).

 

Internervous Plane

 

There is no internervous plane available for this approach. The approach is merely through the medial patellar retinaculum and synovium.

 

 

Figure 9-43 Make a 3-cm longitudinal incision approximately 1 cm from the medial border of the patella, beginning about 2 cm proximal to the distal pole of the patella.

 

Superficial Surgical Dissection

 

Deepen the incision through subcutaneous tissue in the line of the skin incision. Identify the capsule of the knee joint and divide it longitudinally (Fig. 9-44).

 

Deep Surgical Dissection

 

Divide the underlying synovium of the knee. Insert two retractors to

visualize the intercondylar notch. The insertion point and direction of guidewires used for nail introduction must be confirmed using appropriate x-ray control (Figs. 9-45 and 9-46).

 

 

Dang

 

 

The infrapatellar branch of the saphenous nerve should lie distal to the distal end of the incision. It is only in danger if the incision is extended distally.

The posterior cruciate ligament inserts into the lateral aspect of the medial femoral condyle. The insertion may be damaged by the intramedullary nail or the reamers used to create the opening if the entry point is not correctly located.

 

How to Enlarge the Approach

Local Measures

The approach can be extended a short distance both proximally and distally, and this may be required in obese patients. The skin incision may be extended distally and an extra-articular approach to the proximal tibia may be used to insert a tibial nail in cases of floating knee. (See Minimally Invasive Approach for Tibial Nailing in Chapter 11, page 626.)

 

 

Figure 9-44 Deepen the incision through subcutaneous tissue in the line of the skin incision. Identify the capsule of the knee joint and divide it longitudinally.

 

 

Figure 9-45 Divide the underlying synovium of the knee. Insert two retractors to visualize the intercondylar notch and the insertion of the posterior cruciate ligament onto the lateral aspect of the medial femoral condyle.

 

 

Figure 9-46 Insert a guidewire into the distal femur. The entry point in the intercondylar notch varies with the implant to be used, and accurate positioning of the guidewire must be confirmed by C-arm imaging at the time of surgery.

 

Applied Surgical Anatomy of the Thigh

 

Overview

Muscle Groups

There are three major muscle groups in the thigh (Figs. 9-47 to 9-49):

1. The adductors of the hip are supplied by the obturator nerve and occupy the medial segment of the thigh. The adductor magnus both adducts and

   extends the hip, and it has a dual nerve supply, the obturator and sciatic nerves.

2. The extensors of the knee are supplied by the femoral nerve and occupy the anterior segment of the thigh.

3. The flexors of the knee (which also extend the hip) are supplied by the sciatic nerve and lie in the posterior segment of the thigh.

The knee extensors are separated from the hip adductors by the thin medial intermuscular septum and from the knee flexors by the tough lateral intermuscular septum. The adductors and flexors are not separated by an intermuscular septum.

Nerves

Three major nerves run down the thigh. The obturator nerve, which arises from the lumbar plexus (L2-4), runs in the adductor group, supplying all these muscles.

The sciatic nerve, which arises from the lumbosacral plexus (L4-5, S1-3), lies in the posterior segment of the thigh, supplying the hamstrings and the extensor portion of the adductor magnus. Running deep to the long head of the biceps and lying on the adductor magnus, it ends medial to the biceps as the muscle crosses from the ischial tuberosity toward the head of the fibula (see Fig. 9-53).

 

 

Figure 9-47 The superficial musculature of the lateral aspect of the thigh. The iliotibial band (tract) overlies the vastus lateralis proximally.

 

 

Figure 9-48 The tensor fasciae latae, the vastus lateralis, and a portion of the vastus intermedius have been resected to reveal the femur and the lateral intermuscular septum. Note the perforating vessels as they pierce the septum. Note that the vastus lateralis bulges posteriorly.

 

 

Figure 9-49 The superficial musculature of the anterior aspect of the thigh.

 

Rectus Femoris. Origin. Reflected head from just above acetabulum and anterior capsule of hip joint; straight head from anterior-inferior iliac spine. Insertion. Upper border of patella, tibial tubercle. Action. Powerful extensor of knee and weak flexor of hip. Nerve supply. Femoral nerve (L2-L4).

 

The femoral nerve, which is a branch of the lumbar plexus (L2-4), divides into its branches soon after entering the thigh and supplies all the extensors of the knee and the sartorius and pectineus (Fig. 9-50).

Vessels

The femoral artery is the artery of transit through the thigh. Its major branch, the profunda femoris artery, is the main blood supply of the thigh musculature. After the femoral artery gives off the profunda femoris artery in the femoral triangle, it gives off no other major branches of importance in the thigh (Fig. 9-51).

The femoral artery actually enters the thigh under the inguinal ligament at the midinguinal point, directly over the head of the femur, which is why the femoral pulse is the surface marking of the femoral head. The artery then travels distally on the iliopsoas and the pectineus muscle and disappears at the bottom of the femoral triangle beneath the sartorius muscle, running on the adductor longus muscle. There, the artery lies in a depression known as the subsartorial canal of Hunter. The canal runs between the extensor and adductor compartments of the thigh and is roofed by a thick fascial layer and the sartorius muscle. The posterior wall is formed by the adductor muscles (the adductor longus superiorly and the adductor magnus inferiorly), and the anterior wall is formed by the vastus medialis muscle. Running with the artery in the canal is the saphenous nerve (a cutaneous nerve that is derived from the femoral nerve), the femoral vein, and, in the upper half, the nerve to the vastus medialis muscle.

The femoral artery ultimately pierces the adductor magnus muscle one handbreadth above the knee to join the sciatic nerve in the popliteal fossa before entering the posterior compartments of the thigh. There, it lies deep and medial to the sciatic nerve (Fig. 9-53).

The femoral artery is lateral to the femoral vein in the femoral triangle, but medial to it in the popliteal fossa, perhaps as a result of the rotation of the limb that occurs during fetal development.

The artery also changes position in relation to the femur; it is anterior to it at its upper end, medial to it in its middle portion, and behind it at its lower end. These changes influence not only the planning of approaches, but also the insertion of skeletal pins for traction and the application of external fixators.

The profunda femoris artery supplies the thigh musculature. It arises from the femoral artery in the femoral triangle, coming off its lateral side before passing behind it quickly. The two arteries then leave the femoral triangle. The profunda femoris artery passes behind the adductor longus muscle, whereas the femoral artery passes anterior to it. Thus, the muscle is sandwiched between the two arteries (Fig. 9-50; see Fig. 9-51).

Four of the perforating branches of the profunda femoris artery pass posteriorly through the medial compartment of the thigh. They wind around the femur just as the medial femoral circumflex artery does and enter the anterior compartment again by piercing the lateral intermuscular septum. They must be ligated at that point in the posterolateral approach to the femur (see Fig. 9-51).

The medial femoral circumflex artery passes between the iliopsoas and pectineus muscles to lie on the upper border of the adductor longus muscle. From there, it winds around the interval between the quadratus femoris and adductor magnus muscles, where it divides. The ascending branch runs along the superior border of the quadratus femoris, where it may be cut in posterior approaches to the hip, causing troublesome bleeding. The horizontal branch passes between the quadratus femoris and the adductor magnus to form one limb of the cruciate anastomosis (see Fig. 9-51).

The lateral femoral circumflex artery passes lateral to the rectus femoris muscle, where it appears in the upper part of the anterolateral approach. There, it divides into three branches:

1. The ascending branch runs upward toward the anterior-superior iliac spine in the intermuscular interval between the sartorius and tensor fasciae latae muscles. There, it requires ligation in the anterior approach to the hip.

2. The transverse branch continues to wind around the femur and joins the transverse branch of the medial femoral circumflex, contributing to the cruciate anastomosis.

3. The descending branch passes along the interval between the vastus intermedius and vastus lateralis muscles, where it is encountered in the

anterolateral approach to the femur (see Fig. 9-51).

The saphenous vein arises on the dorsum of the ankle at the medial end of the dorsal venous arch. Passing anterior to the medial malleolus (where it can be found during cutdown for the insertion of intravenous lines), it passes behind the knee before spiraling forward on the medial side of the thigh into the femoral vein. The saphenous vein is the major superficial vein of the thigh, but although it frequently is the object of general surgical procedures, it has little importance for the orthopedic surgeon.

 

Landmark and Incisions

Landmark

Most of the femur is cloaked deeply in muscle; only the greater trochanter and the femoral condyles are easily palpable. The femur has a natural anterior bow, which is important for the design of intramedullary rods.

The angle between the femoral shaft and the femoral neck varies but is usually about 130 degrees. The femoral neck is displaced about 15 degrees in anteversion on the femoral shaft. These angles should be borne in mind when pins or nails are inserted up the femoral neck.

 

 

Figure 9-50 The sartorius, the rectus femoris, the tensor fasciae latae, the vastus lateralis, and the vastus intermedius have been resected to reveal the course of the femoral and profunda femoris arteries; note the relationship of the arteries to the quadriceps and the adductor muscles.

 

Vastus Lateralis. Origin. Upper half of intertrochanteric line. Vastus lateralis ridge, lateral lip of linea aspera, and upper two-thirds of lateral supracondylar line of femur. Also from lateral intermuscular septum. Insertion. Lateral border of patella and tibial tubercle. Action. Extensor of knee. Nerve supply. Femoral nerve (L2-L4).

Vastus Intermedius. Origin. Anterior and lateral aspect of upper two-thirds of femoral shaft. Insertion. Tibial tubercle. Action. Extensor of knee. Nerve supply. Femoral nerve (L2-L4).

Vastus Medialis. Origin. Medial lip of linea aspera and spiral line of femur. Insertion. Tibial tubercle and medial border of patella. Action. Extensor of knee. Nerve supply. Femoral nerve (L2-L4).

 

 

Figure 9-51 The complete course of the femoral artery and profunda femoris artery. Note the perforating branches of the profunda femoris artery. Note that the adductor longus muscle has been resected to show the course of the profunda femoris artery, which runs posterior to it.

 

 

Figure 9-52 The superficial musculature of the posterior aspect of the thigh. Note the central course of the posterior femoral cutaneous nerve.

 

Biceps Femoris. Origin. Long head from ischial tuberosity. Short head from linea aspera and lateral supracondylar line of femur. Insertion. Head of fibula. Action. Flexor of knee, extensor of hip, and lateral rotator of leg. Nerve supply. Long head: sciatic nerve (tibial division) (L5, S1, S2). Short head: sciatic nerve (common peroneal division) (S1-S2).

Semimembranosus. Origin. Ischial tuberosity. Insertion. Medial condyle of tibia. Action. Weak extensor of hip, flexor of knee, and medial rotator of leg. Nerve supply. Tibial nerve (L5, S1, S2).

Semitendinosus. Origin. Ischial tuberosity (common origin with biceps femoris). Insertion. Subcutaneous surface of tibia. Action. Flexor of knee, extensor of hip, and medial rotator of leg. Nerve supply. Tibial nerve (L5, S1, S2).

 

 

Figure 9-53 The course of the sciatic nerve and the anatomic location of the linea aspera. The gluteus maximus and hamstring muscles are resected.

 

Incisions

Longitudinal incisions in the thigh parallel the lines of cleavage of the skin; the resultant scars usually are cosmetically acceptable.

 

Superficial and Deep Surgical Dissection

 

Four of the approaches to the femur penetrate the knee extensor compartment. (The posterior approach penetrates the hamstring compartment and is considered separately.)

The knee extensor compartment consists of a single muscle that arises from four heads and inserts through the extensor apparatus of the knee into the tibial tubercle. This muscle, the quadriceps femoris, is the largest muscle in the body. It is supplied by the femoral nerve (see Figs. 9-49 to 9-51).

Different muscle elements in the quadriceps group contract differently. Because the gliding that occurs between muscle elements is so vital to function, any incision that penetrates the muscle may endanger its efficacy. The distal third of the quadriceps is free to glide over the anterior aspect of the femur, because no part of the muscle is attached to that part of the bone.

The four heads of the quadratus femoris are as follows:

1. Rectus femoris. The rectus femoris is bipennate in structure, like the feathers of an arrow. It is the only part of the quadriceps that crosses two joints, the hip and knee, as it descends the thigh over the vastus intermedius. Its ability to slide over the vastus intermedius during movement of the knee is the result of the presence of a thick fascial layer on its underside. Because its origins are so close to the hip joint, both heads of the rectus femoris must be detached to allow access to the anterior aspect of the hip and to the inner and outer walls of the pelvis at the upper margin of the acetabulum.

2. Vastus lateralis. The plane between the lateral intermuscular septum and the vastus lateralis is difficult to define, and dissection is bloody, mainly because the muscle arises in part from the septum itself. Following the plane between the lateral intermuscular septum and the muscle leads to the posterior aspect of the femur at the linea aspera (the origin of the muscle) and not onto the lateral aspect of the bone. The plane is defined

   most easily and is most useful in the distal third of the femur.

   The vastus lateralis glides on the vastus intermedius during movement. As is true for the rectus femoris, its deep surface is covered with a thick fascial attachment.

3. Vastus intermedius. The vastus intermedius cloaks the anterior and lateral aspects of the upper two-thirds of the femoral shaft and forms the innermost layer of the quadriceps. This muscle is split during most approaches to the femur.

4. Vastus medialis. The nerve supply of the vastus medialis is the largest branch of the femoral nerve, a branch that contains a large number of proprioceptive fibers. When trauma affects the knee, fibers of the vastus medialis that attach to the patella tend to lose tone quickly, possibly because of a neuromuscular reflex mediated via the nerve to the vastus medialis. Wasting of these muscle fibers produces a subjective sense of instability that persists until the muscle bulk returns to normal. Therefore, rehabilitating the vastus medialis is vital in the treatment of any knee injury.

   The lowest fibers of the vastus medialis insert into the patella, pulling it medially. They are crucial in preventing lateral subluxation of the patella during flexion of the knee.

    

   Posterior Approach to the Femur

   The posterior approach involves dissection of the posterior compartment of the thigh (see Fig. 9-52). The key to the approach lies in understanding the anatomy of the sciatic nerve and its relationship to the biceps femoris muscle.5

   The sciatic nerve runs vertically down the thigh more or less in a straight line. The biceps femoris muscle angles across the posterior aspect of the thigh in a medial to lateral direction, forming a bridge under which the sciatic nerve runs. The nerve, therefore, lies underneath the biceps femoris in the proximal thigh and medial to it in the distal thigh. Hence, during exposure of the proximal half of the posterior aspect of the bone, the biceps should be retracted medially, taking with it and protecting the sciatic nerve. For more distal exposures, the biceps requires retraction laterally, and the nerve must be retracted with it. If a wide exposure of the whole length of this piece of the bone is required, the long head of the

   biceps should be divided; the proximal half of the muscle, together with the short head, should be retracted medially with the sciatic nerve.

   The three hamstring muscles arise from the ischium and run down the posterior compartment of the thigh. All cross two joints, the hip and the knee, and all act as hip extensors and knee flexors. The hamstring muscles are supplied by branches of the sciatic nerve.

    

   Semimembranosus Muscle

    

   The insertions of the semimembranosus muscle greatly reinforce the posterior and posteromedial joint capsule of the knee (see Applied Surgical Anatomy of the Medial Side of the Knee in Chapter 10). The muscle may be transferred to the anterior surface of the lateral femoral condyle, together with the semitendinosus tendon, to correct internal rotation deformity of the hip in patients with a variety of neurologic lesions, a technique that is used only rarely.6

    

   Semitendinosus Muscle

    

   As its name implies, the semitendinosus muscle has an extremely long tendon in relation to the size of its muscle belly. The tendon is at least 13 cm long and can be used in a variety of surgical procedures. It may be left attached to the tibia, even as it is attached via a drill hole to the patella, to hold that bone medially in cases of recurrent dislocation.7 It also may be used for posterior8 and anterior9 cruciate reconstruction; in that procedure, the tendon is separated from the muscle at the musculotendinous junction and is threaded through the femur so that it mimics the function of the missing cruciate ligaments. In addition, it may be used to reinforce a torn medial collateral knee ligament.

    

   REFERENCES

   1. MARCY GH: The posterolateral approach to the femur. J Bone Joint Surg. 1947;29:676–678.

   2. THOMPSON JE: Anatomical methods of approach in operations on the long bones of the extremities. Ann Surg. 1918;68:309-329.

   3. HENRY AK: Exposure of the humerus and femoral shaft. Br J Surg.

      1924;12:84–91.

   4. BOSWORTH DM: Posterior approach to the femur. J Bone Joint Surg.

      1944;26:687–690.

   5. GRAY H: Anatomy of the Human Body. 27th ed. Goss CM, ed. Philadelphia, PA: Lea & Febiger; 1959:1049.

   6. SUTHERLAND DH, SCHOTTSTAEDT ER, LARSEN LJ ET AL: Clinical and

      electromyographic study of seven spastic children with internal rotation gait. J Bone Joint Surg Am. 1969;51:1070–1082

   7. GALBAZZI R: Nuove applicazion del trapianto muscolare e tendineo (XII Congress Societa Italiana di Ortopedia). Archivo di Ortopedia. 1922:38.

   8. KENNEDY JC, GRAINGER RW: The posterior cruciate ligament. J Trauma. 1967;7:367–377.

   9. CITO KO: Reconstruction of the anterior cruciate ligament by semitendinosus tenodesis. J Bone Joint Surg Am. 1975;57:608–612.

   10. FAROUK O, KRETTEK C, MICLAU T ET AL: Effectors of percutaneous and conventional plating techniques on the blood supply to the femur. Arch Orthop Trauma Surg. 1998;117:438–441.

   11. KREGOR PJ, STANNARD J, ZIOWODZKI M ET AL: Distal femoral fracture fixation utilizing the less invasive stabilization system (LISS). The technique and early results. Injury. 2001;32(suppl):SC 32–SC 47.

   12. KRETTEK C, MULLER M, MICLAU T: Evolution of minimally invasive plate osteosynthesis (MIPO) in the femur. Injury. 2001;32(suppl):SC 14–SC 23.

   13. KRETTEK C, MICLAU T, STEPHAN C: Trans-articular approach and retrograde plate osteosynthesis for complex distal intra-articular femur fractures. Tech Orthop. 1999;14:219–229.

   14. LAKHWANI OP, MITTAL PS, NAIK DC: Piriformis fossa—an anatomical and orthopedics consideration. J Clin Diagn Res. 2014;8(3):96–97.