Essentials of Orthopedic Surgery, third edition / 02-Skeletal Trauma

70 J.N. Delahay and S.T. Sauer

FIGURE 2-17. Locations of femoral neck fractures. Displacement is important to note.

blood supply is precarious. It originates from the medial and lateral femoral circumflex arteries at the base of the femoral neck and the extracapsular arterial ring. These vessels nourish the head of the femur. Any disruption of the femoral neck is likely to interfere with the blood supply of the head of the femur, thus causing avascular necrosis, which occurs in more than one-third of displaced femoral neck fractures. Nonunion, the other complication of femoral neck trauma, is related to the presence of synovial fluid, which bathes the fracture site. It is more difficult for the bone to heal in this environment, and it is difficult to reduce the fragments anatomically. No displaced femoral neck fracture, therefore, can heal when treated nonoperatively.

Fractures of the neck of the femur are classified into nondisplaced and displaced (Fig. 2-17). Nondisplaced (so-called impacted valgus fractures) are inherently stable and may heal without surgery. However, they are generally treated by open reduction and internal fixation (ORIF) using a compression screw placed up in the neck; this may be done percutaneously or through a small incision and is a relatively minimal procedure. These fractures, nondisplaced or valgus impacted, will normally heal, and the patient is allowed to get up and move about with partial weight-bearing until healing takes place; usually this occurs in 6 to 8 weeks. When a fracture of the neck of the femur is displaced, an effort may be made to do a closed reduction in the operating room, which must be confirmed radiographically. Then, similar screws may be put across the fracture site for stabilization. In patients generally under age 60 years and those with a vigorous lifestyle, ORIF is the preferred treatment. In the older and frail patient, it may be

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more advantageous to avoid the possibility of nonunion, avascular necrosis, and an invalid life for several months by removing the head of the femur and replacing it with an endoprosthesis. This device enables patients to walk the day after the operation bearing most of their body weight. These prostheses can last anywhere from 10 to 15 years, and, therefore, in a young person every effort should be made to save the native femoral head. If a reduction of the fracture is performed and avascular necrosis or a nonunion occurs, a total hip replacement is the usual solution.

Intertrochanteric Fractures

Intertrochanteric fractures occur at or below the line between the greater and lesser trochanter and lie outside the capsule (Fig. 2-18). The blood supply, therefore, is not jeopardized by the fracture. On physical examination in the emergency room, these patients, similar to those with the displaced femoral neck fractures, will manifest shortening and external rotation. If an attempt were made to treat such a fracture without operative intervention, the patient would likely not survive protracted bed rest. Such a patient is likely to die of pneumonia, pulmonary emboli, bedsores, urinary tract infections, or the emotional damage that occurs in an old person when bedridden. Therefore, surgery is the norm. The compression hip screw with side plate is generally used (Fig. 2-19). Review of the X-rays allows one to determine whether the fracture is stable or unstable. When the proximal femur is fractured into three to four separate fragments, and especially if the lesser trochanter with its posteromedial cortex is one of these fragments, the fracture is unstable. In these cases, fixation must be rigid, and full weight-bearing often cannot be allowed for quite a few months. Because of the high incidence of implant failure seen with unstable fractures, other

FIGURE 2-18. Intertrochanteric femoral fracture. Involvement of the lesser trochanter defines an unstable fracture pattern.

FIGURE 2-19. Intertrochanteric fracture.

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solutions have been sought, one of them being a prosthetic replacement of all the fragments that are damaged. This procedure is a larger operation than the endoprosthesis for a femoral neck fracture and, therefore, is not often done. Healing in the intertrochanteric fracture usually proceeds well, assuming the fixation is adequate.

Subtrochanteric Fractures

Subtrochanteric fractures occur through an area below the lesser trochanter and are not quite as rapid to heal as the intertrochanteric injuries. In the younger population, subtrochanteric fractures usually follow the severe trauma of motor vehicle accidents. In the elderly, they are the result of severe osteoporosis or a pathologic process in the subtrochanteric area. Fixation is either by a standard hip screw, as described for the intertrochanteric fracture, but with a longer side plate or an intramedullary nail with proximal and distal locking screws.

In children, intertrochanteric and subtrochanteric fractures are generally treated in traction, whereas the very rare fracture of the femoral neck, even in a child, must be surgically treated in an effort to achieve union and avoid avascular necrosis.

Femoral Shaft Fractures

Femoral shaft injuries usually follow significant trauma. In children, they are treated by skeletal traction with a pin placed in the distal femur, followed by a spica cast. There has been an increased interest in fixation of pediatric fractures with either flexible intramedullary nails or external fixation. In adults, these fractures are almost always treated by intramedullary rods that are locked at both ends, inserted using closed techniques. Although the fractures do not heal faster with this treatment, the patient is able to walk and function, at first with crutches, and soon without crutches, while the fracture heals. This approach markedly decreases the length of the hospital stay (Fig. 2-20).

Dislocation of the Hip

Dislocation of the hip typically occurs from the impact between the dashboard and the knee in a motor vehicle accident. This impact drives the hip out posteriorly and, as expected, often damages the blood supply to the head of the femur as well as the sciatic nerve. The latter happens to lie immediately in the path of the dislocating femoral head. Most dislocations of the hip are posterior, and early reduction will decrease the incidence of avascular necrosis. Reduction in less than 6 to 8 hours is thought to be essential to reduce this risk. A hip that has been dislocated for more than 24 hours almost assuredly will undergo necrosis.

74 J.N. Delahay and S.T. Sauer

FIGURE 2-20. Femoral shaft fracture.

Fractures About the Knee

Distal Femoral Fractures

Fractures of the lower end of the femur in the region of the condyles may be supracondylar or Y- or T-shaped, the latter types entering the joint. If displaced, these fractures are generally treated surgically, and an effort is made to obtain an anatomic reduction of the articular surfaces. The reconstructed articular surface is then affixed to the distal femoral shaft. Anatomic restoration is necessary to prevent significant traumatic arthritis of

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the knee. Fixation to the shaft is necessary to allow early motion. Generally speaking, weight-bearing is delayed for 3 months, but early motion begins within a couple of days of the fixation process. Frequently, a continuous passive motion (cpm) machine is valuable in the early stages to maximize motion.

Fractures of the Tibial Plateau

These intraarticular fractures of the tibial plateau typically occur on the lateral side of the tibia when the patient is struck, for example, by the bumper of a car. A large hemarthrosis can occur and, on aspiration, fat globules floating on the aspirated blood indicate that the bone marrow of the metaphyses has extravasated. Treatment is similar to that of the lower end of the femur and depends on the degree of displacement and comminution. Nondisplaced fractures may be treated by both relieving the patient of weight-bearing and initiating early motion. Displaced fractures are best treated surgically, including anatomic reduction of the fracture fragments, placement of bone graft under the fracture fragments if the bone has been compressed down, and fixation by means of a plate and screws. Early motion is begun immediately, but full weight-bearing should be delayed for 8 to 12 weeks because the cancellous bone is compressible before that time.

Fractures of the Patella

The patella is a sesamoid bone that gives the quadriceps mechanism a mechanical advantage in extending the knee. If the fracture is nondisplaced, closed treatment for up to 6 weeks is preferred. However, there usually is displacement, and then an open reduction and internal fixation is the treatment of choice. As we have seen in the fracture of the olecranon (Fig. 2-21), a tension-banding procedure works well. Rarely, in extremely comminuted fractures, a patellectomy may be the only option to avoid irregular patellar fragments causing painful traumatic arthritis of the patellofemoral joint.

Dislocation of the Knee

This injury is the result of very severe trauma. When a patient gives a history that the “knee came out of place,” either the patella dislocated (or subluxed) or a piece of meniscus or loose body of cartilage was caught in the knee joint. True dislocation of the knee is a very serious injury notable for producing arterial damage to the popliteal vessels. The popliteal artery is fixed anatomically at the level of the proximal tibia by the interosseous membrane and, therefore, is placed at great risk when the knee dislocates. Arteriography can be used following immediate closed reduction of the dislocation if vascular compromise is suspected. The results of angiography will then determine whether arterial repair is necessary. Some would argue

76 J.N. Delahay and S.T. Sauer

FIGURE 2-21. Patella fracture.

that if pulses do not return after closed reduction, then the patient should be taken to the operating room emergently for vascular exploration or operative angiography. Late ligamentous repair may or may not be necessary after early, emergent reduction and vascular management have been accomplished.

Fracture of the Tibial Shaft

This diaphyseal fracture of the tibial shaft presents a major problem from the standpoint of bony union. Because of the tenuous blood supply of the

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shaft of the tibia, fractures, particularly at the junction of the middle and distal third, are notorious for the high incidence of nonunion. Nondisplaced or minimally displaced tibial fractures are generally treated by the application of a long leg cast. When some union has occurred, a shorter, so-called patella tendon-bearing cast may be applied, ideally within 6 to 8 weeks. Operative treatment includes: percutaneous or open plating of distal fractures, external fixation, and intramedullary nailing of displaced and comminuted shaft fractures with locking screws above and below the fracture site. As has been mentioned in other locations, intramedullary nailing allows relatively early function and healing while the patient temporarily depends on the intramedullary rod for stability. As in other bones, one might think in terms of a race occurring between the bone healing and the metal failing from metal fatigue.

Ligamentous Injuries to the Knee

The knee is a relatively incongruous joint that is stabilized through an elaborate system of ligaments; most noted are the medial and lateral collateral ligaments and anterior and posterior cruciate ligaments. Many sports-related ligament injuries of the knee are seen on a regular basis and, generally speaking, are first treated conservatively by immobilization, then by physical therapy and muscle strengthening. After 6 weeks of rehabilitation, gaining quadriceps strength and a good range of motion, repair of the torn anterior cruciate ligament is frequently considered (see Chapter 6, Sports Medicine).

Fractures Around the Ankle

Fractures of the lower end of the tibia, through the articular weightbearing surface, may be quite serious. They are called pilon fractures, and unless early, excellent anatomic restoration and fixation are accomplished, traumatic arthritis of the ankle will follow. Fractures of the ankle itself—the distal end of the fibula (lateral malleolus), the medial malleolus, and the so-called posterior malleolus (a fragment of the posterior portion of the distal tibia) —are very common. While a nondisplaced fracture of the lateral malleolus may generally be treated by a simple below- the-knee immobilization cast, displaced ankle fractures are a different problem. If the student becomes familiar with any classification system, the Lauge–Hansen (Fig. 2-22) classification of ankle fractures would seem to be recommended. The first word in each heading of this classification system is the position the foot was in at the time the force was applied. The second word denotes the mechanism of load application. In any case, the importance of ankle fractures is the status of the mortise, that is, the joint in which the talar dome lies. Proximal is the distal tibia, medial is

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the medial malleolus, and lateral is the distal portion of the fibula or lateral malleolus. The ankle is very unforgiving. Perfect reduction is mandatory to produce an acceptable functional result. Just about all displaced ankle fractures, therefore, are treated surgically. Open reduction and internal fixation are performed, with the fibula being the critical segment; length and rotation must be corrected before fixation. Avoidance of any weight-bearing for 6 weeks is generally advised with or without the cast, depending on the reliability of the patient. Weight-bearing is then gradually advanced. (See Chapter 13 for further details about fractures around the ankle and foot.)

Supination—Eversion

Supination—Adduction

Fracture at level of

joint line

FIGURE 2-22. Lauge–Hansen classification of ankle fractures.

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Pronation—Abduction

Pronation—Eversion

FIGURE 2-22. Continued.

Fractures and Soft Tissue Injuries of the Foot

Fractures of the Os Calcis (Heel Bone)

The os calcis is unique in that it is essentially a cancellous bone (not unlike the vertebral body), yet it takes a great deal of load. If that load is applied vertically and quickly, crushing of the calcaneus can occur; this produces injury to the subtalar joint, and ultimately results in a certain degree of stiffness no matter what type of treatment is provided. Concurrent fractures of the lumbar spine are not infrequent and should be sought out. Treatment of the os calcis fracture is often closed, but in expert hands open reduction and fixation may give a better result.