2.2 Diaphyseal fractures: principles
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1 Introduction
In the era of minimally invasive surgery, the management of diaphyseal fractures is evolving and progressing. New reduction and fixation concepts are emerging based on better understanding of the biology of fracture repair and the role of soft tissues in the healing process [1].
Restoration of length, axial alignment, and rotation is essential, but anatomical reduction of every fracture fragment is not necessary for normal limb function.
With more options available, decision making has become more complex. The factors relevant to the optimal management of an individual diaphyseal fracture must constantly be reviewed when planning treatment.
2 Functional considerations
The diaphysis of a long bone has many functions. The two most important are to maintain its proximal and distal joints in their correct spatial relationship and to provide attachment for muscles which move them. In the long bones, normal mechanical axis of the limbs should be restored. This requires union without shortening, angulation, or rotational deformity. Good function can be expected, even if individual fracture fragments are not anatomically reduced ( Fig 2.2-1 ).
Some residual deformity can be tolerated in the lower limb without causing functional problems for normal daily activity, eg, shortening of up to 1 cm or minimal angular deformities in the plane of adjacent joints. Up to 10° of anterior or posterior bowing of a healed tibia fracture is compatible with good ankle function, despite cosmetic deformity. However, valgus or varus deformity of even 5° may subject the joint to abnormal forces and lead to posttraumatic osteoarthritis [2]. In athletes with higher functional demands anatomical restoration of axial alignment must be obtained.
Shortening of the humeral shaft produces little functional disability and because the shoulder has the largest range of joint movement in the body, 20° of malrotation or 30° of angular deformity is well tolerated. In contrast, the diaphyses of the radius and ulna, being part of a complex articulation that includes the proximal and distal radioulnar joints, require anatomical reduction for normal limb function.
3 Incidence
In many parts of the world improved car design, drink/drive legislation, road design, and speed restrictions and the use of seat belts have reduced the incidence of diaphyseal fractures. However, in developing countries, the sharp increase of mechanized transport, particularly motorcycles, is producing more diaphyseal injuries. Many of these fractures are open injuries and present late because of delay in transporting victims to hospital. The number of pedestrian trauma injuries is stagnating but the percentage of open fractures is rising. An increasingly aged population [3] has raised the incidence of osteoporotic diaphyseal injuries.
4 Mechanism
4.1 Patterns of injury
Fractures can be caused by direct or indirect forces. Indirect trauma usually involves less energy than a direct blow and causes proportionately less fragment displacement and soft-tissue damage. Open fractures are usually a result of direct rather than indirect forces [4]. The differing injury patterns are recognized in the AO/OTA Fracture and Dislocation Classification [5] (see chapters 1.4, 1.5, and 4.2).
Spiral (A1) fractures result from indirect rotational forces. They have large areas of bone surfaces in contact, and minimal soft-tissue damage. Fracture healing is usually swift and uneventful, although holding the reduction without fixation may be difficult.
Wedge fractures (B2) are produced by bending forces. The force applied to the limb is considerable and the resulting damage to soft tissue and periosteum is significant. Union may take longer and direct surgical approaches to the fracture site will further devitalize the bone.
Transverse fractures (A3), fragmentary wedge fractures (B3) and multifragmentary fractures (type C) are usually caused by direct forces which are often enormous, especially in the femur. If the bone is of normal quality and the fracture is widely displaced, soft-tissue damage will be extensive. Even with intact skin, direct exposure of these fractures results in further injury to the soft tissues. Therefore, fracture type and displacement are good predictors of soft-tissue damage ( Fig 2.2-2 ). The greater the anticipated soft-tissue damage, the more important the timing of surgery and the choice of approach, reduction technique, and implant (see chapters 3.1.2 and 3.1.3).
5 Initial evaluation
5.1 Patient status
A clear case history must be obtained when assessing a diaphyseal fracture, particularly to discover the mechanism and forces which caused the fracture. The force generated when a pedestrian is hit by a car bumper at 50 km/h is approximately one hundred times that generated by a simple fall. Although the x-rays may look similar, the associated soft-tissue injury will be different.
Most displaced fractures are identified by observation. Palpation is only used to elicit bone tenderness if there is no obvious fracture. The most important elements of the physical examination concentrate on detecting any arterial or neurological damage. Anatomical areas where major vessels are close to bone, such as the distal femur or proximal tibia, should attract a high level of suspicion for arterial injury.
An arterial injury will dominate the decision-making process because of the immediate need for arterial repair with appropriate stabilization of the fracture.
Compartment syndrome also requires urgent treatment. It is seen mostly in the lower leg, but can also occur in the thigh, forearm, buttock, and foot.
Compartment syndrome may occur at any time during the first few days after trauma. It is most common in widely displaced fractures but can occur in simple fractures, open fractures, after intramedullary (IM) nailing and joint dislocation especially the knee. The clinical picture and the management are fully described in chapter 1.5.
5.2 Radiographic evaluation
X-rays are the mainstay of diagnosis. AP and lateral views including the adjacent joints will assist in most cases; oblique projections may be helpful in the metaphysis. X-rays allow accurate classification of diaphyseal fractures. Standard views of the opposite side may be useful for preoperative planning (see chapter 2.4). Computed tomographic scan and magnetic resonance imaging have no role in the assessment of acute diaphyseal injuries, although they may be useful when a diaphyseal fracture has an articular extension or in planning reconstructive surgery of complex malunion cases.
5.3 Associated injuries
Soft-tissue injuries always influence and frequently dictate the management options of a diaphyseal fracture. A closed, simple, displaced, transverse fracture of the tibial shaft can be managed by intramedullary nailing, plating, or external fixation. Severe skin contusion excludes the standard open plating option because the surgical approach might further compromise the soft tissues. A badly contaminated wound might be a deterrent to primary nailing because of the risk of sepsis. In this situation, preliminary treatment with an external fixator is the treatment of choice.
Similarly, acute arterial disruption and compartment syndrome both need emergency management. In cases requiring vascular repair or extensive release of the muscle compartments, the associated fracture must be stabilized at the same time. Thus, the associated injury not only dictates the need for stabilization but also determines its timing and the approach. Plating of the fracture through the exposure used for the vascular repair may be the treatment of choice, as there may not be time for anything else.
Management of life-threatening injuries always takes precedence over that of a diaphyseal injury.
The presence of more than one fracture in the same limb is often an indication to fix all the fractures, particularly if the combination has produced a “floating” joint.
Additional fractures in other limbs, eg, bilateral humeral shaft fractures, can render a patient almost helpless. This situation may dictate operative stabilization of a fracture that might well be treated nonoperatively, if isolated.
The increasing number of elderly patients with osteoporosis who have had joint replacement surgery in the past has led to a dramatic increase in the incidence of periprosthetic fractures. This is now the most common reason to plate femurs in the developed world [6].
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