In Brief: Closed Tibial Shaft Fractures

Introduction

Fractures of the tibial shaft are the most common long bone fractures, with an incidence greater than 75,000 per year in the US [14]; most of these fractures are found in young males (thought to be related to sports or motor vehicle accidents) with a second peak of incidence among elderly patients, whose injuries likely resulted from a simple fall [18]. Although intramedullary fixation has become the mainstay of treatment, many of these fractures are amenable to closed treatment.

Structure and Function

The tibia carries nearly five times body weight of axial force during walking [23]. It also is subject to bending and twisting forces, especially when the foot is planted, although its resistance against these loads is far less than seen with compression. The tibia is subcutaneous for much of its course, which subjects it to direct injury and might make healing more difficult. The strong, noncompliant fascia completely surrounds the muscles accompanying the tibia, and in the absence of a large rent in the fascia increases the likelihood of a compartment syndrome compared with other long bone injuries. The anterior tibial artery, which gives rise to several periosteal vessels, often is damaged as it passes through a hiatus in the interosseous membrane; when the tibia fractures, this artery can be the source of substantial bleeding and elevated compartment pressure.

Injury Considerations

The majority of tibial shaft fractures in younger patients result from a direct, high-energy mechanism of injury. These injuries often cause a displaced, comminuted fracture pattern often accompanied by substantial soft tissue damage. Sports-related injuries usually result from a bending mechanism, producing a spiral or oblique fracture, and occasionally a butterfly fragment. Elderly patients often sustain indirect, torsional, low-energy injuries. Although these mechanisms usually cause a spiral, nondisplaced fracture pattern with minimal soft tissue damage, more complicated patterns can occur in patients with osteoporotic bone [7].

Attention must be paid to the soft tissue. Because the bone is subcutaneous, a closed fracture can easily become an open fracture, as the bone spikes through the skin. In addition, bleeding or swelling in the soft tissues can increase the interstitial pressure and block blood flow, leading to ischemic necrosis of muscle or nerve, ie, compartment syndrome.

Diagnosis and Classification

Because the tibia is subcutaneous, the diagnosis of a fracture is usually obvious. Rather, the diagnostic challenges are to exclude an open fracture when there are associated breaks in the skin, an incipient compartment syndrome, or an associated injury to the ligaments of the knee and ankle. Plain film radiography is often sufficient to show the injury and delineate the best treatment option for the patient.

Management and prognosis of tibial shaft fractures are influenced by their location in the bone (proximal, middle, or distal third) and their orientation (transverse, oblique, spiral, or comminuted). Displacement and angulation play a role when determining treatment.

The AO/OTA classification designates the region of the bone by a letter (A, B, C) for the severity of the fracture, and a number (1, 2, 3) indicating increasing complexity and comminution [12]. This classification is not frequently used clinically, but helps standardize fracture descriptions for research purposes. Tscherne and Gotzen developed a classification system to evaluate soft tissue injury in closed tibial shaft fractures [22]. A Type 0 injury usually results from an indirect, torsional force resulting in a simple fracture pattern and minimal soft tissue injury. These fractures can be managed operatively or closed depending on the severity of displacement and angulation and convey a good prognosis. Type 1 represents mild to moderately severe fractures with superficial abrasions or contusions. High-energy fractures and deep abrasions with associated swelling comprise Type 2 injuries, often with impending compartment syndrome. Finally, Type 3 injuries include extensive skin and muscle damage, often caused by a crush injury, a severe fracture pattern, and compartment syndrome. Types 2 and 3 injuries almost always are managed operatively, with poorer outcomes related to the severity of soft tissue injury and fracture comminution [22].

Treatment

The goals of treatment are pain-free function of the lower limb. Achieving these goals usually requires (1) establishing bone union; (2) establishing and maintaining normal length, alignment, and rotation of the bone; and (3) establishing and maintaining the normal anatomic relationships between the knees and ankles for weightbearing, motion, and propulsion. Whether these can be best met with surgery (intramedullary nailing or external fixation) or with closed treatment (usually cast immobilization followed by functional bracing) depends on the particular circumstances of the injury. Many such treatment recommendations are based on expert opinion rather than high-quality studies with high levels of evidence.

According to one group of experts [18], nonoperative management may be used when there is minimal soft tissue injury and when there is no substantial displacement or deformity of the fracture. The upper limits of tolerable deformity are reportedly 5° angulation in the coronal plane, 10° angulation in the sagittal plane, 5° rotational deformity, and shortening less than 1 cm [18].

If pursuing closed treatment, the patient should wear a long leg cast with the ankle in neutral and the knee positioned in 10° to 15° flexion to initiate early weightbearing. The supracondylar area should be carefully molded to prevent cast slippage. Radiographs should be taken at 1- to 2-week intervals to verify maintenance of the reduction. Although some shortening from the initial reduction is to be expected, if greater than 1.5 cm of shortening is seen or the alignment criteria for closed management is no longer met, operative fixation may be indicated [18]. As soon as the patient can comfortably bear weight, transition to a patellar bearing functional brace can be made.

Interlocking reamed intramedullary nailing has become the standard for treating displaced tibial shaft fractures [10] (Fig. 1). For displaced tibial fractures, or those with major soft tissue injuries, two studies [3, 10] suggest intramedullary fixation results in quicker union, less malunion, and faster return to work than closed management.

Fig. 1A–C.

A 35-year-old woman sustained a closed midshaft tibial fracture with mild comminution. She underwent operative fixation with a reamed, statically locked, intramedullary nail. Radiographs were obtained (A) after closed reduction in the emergency room, (B) immediately postoperative, and (C) 3 months after surgery.

Although reamed IM nails reportedly result in a lower reoperation rate than unreamed nails in closed tibial shaft fractures [21], the debate over reaming is ongoing [9]. Reaming might disrupt the endosteal blood supply, theoretically, yet one experimental study suggests it is reestablished before healing [15], and some clinical studies report better outcomes with reaming [9, 17]. Reaming enlarges the canal and permits insertion of a larger nail, thus reducing the risk of fatigue failure of the implant.

If the fracture is transverse, the mechanical properties of the bone-implant construct allow for immediate weightbearing.

Fractures of the proximal third of the tibia shaft present a unique fixation challenge and special consideration. Malunion is an unfortunate consequence of nailing these fractures, occurring in 84% of patients in one case series [11], versus as much as 37% of all closed tibial shaft fractures in another study [24]. Careful selection of a starting point and proper use of blocking screws can help prevent deformity [4, 18].

For simple fracture patterns, immediate weightbearing is encouraged after nailing. However, when comminution is present and the injury is not length-stable, there is substantial soft tissue injury, or plate fixation is selected, weightbearing may be delayed for 6 to 8 weeks after surgery. Early ROM exercises of the ankle and knee should be instituted in the immediate postoperative period unless precluded by soft tissue injury. Activities are increased commensurate with healing and fracture pattern but in general, normal gait and full motion are goals at 6 months with return to unrestricted activity at 1 year.

Because of the lack of soft tissue covering the tibia and a mechanical disadvantage, internal fixation with plates generally is avoided. Plating is a reasonable treatment option for management of tibial shaft nonunions or for fractures with articular or periarticular extension.

External fixation may be used instead of intramedullary nails in patients with severe soft tissue injury or with damage-control surgery in patients with polytrauma [8]. If converting to an intramedullary nail, the procedure should be performed as soon as possible, preferably within 4 weeks to minimize the likelihood of pin sepsis [6].

Outcomes

The prognosis after tibial fracture depends on the extent of bone and soft tissue damage. Most low-energy closed tibial fractures achieve union by 10 to 13 weeks. High-energy fractures often can require as much as 20 weeks to achieve union [20]. The expected union rate for tibial diaphyseal fractures (in the absence of extensive soft tissue damage) is approximately 95% or greater [16]. Even among patients with high-energy tibial fractures, 76% who were working at the time of injury eventually returned to work in an average of 11 months [2]. Despite high general healing rates and good return to function, tibial shaft fractures still pose a surgical challenge. Complications of closed tibial shaft fractures include vascular injury, fat embolism, and compartment syndrome. Two studies reported rates of compartment syndrome in AO Type A fractures from 5.8% to 15.6%, in Type B from 11.4% to 16.7%, and in Type C from 9.6% to 28.6% [1, 13].

Infection is a rare complication in closed fractures, with an incidence less than 1% [19]. Intramedullary fixation generally is well tolerated, but can be complicated by nonunion, malunion, and implant failure [4]. Anterior knee pain is not uncommon after tibial nailing [5], an observation that should be conveyed to the patient early during treatment. Although the exact cause of knee pain is unknown, it can lead to substantial functional impairment. In one study, 33.7% of patients reported pain at rest, 57% with running, and 92% with kneeling [5].

Pearls

1. Tibial shaft fractures are associated with compartment syndrome. Consider admitting and observing all patients treated with cast immobilization, even if they appear comfortable enough for discharge from the emergency department.

2. Classic cast immobilization of a long bone fracture involves the joint above and the joint below. For tibia fractures, prolonged immobilization of the joint above and the joint below might impede knee and ankle function, even after the cast is removed. Consider converting to a patella-bearing functional brace as soon as possible.

3. There are putative benefits to reaming and not reaming, and the debate remains unsettled.

4. Many patients with delayed union ultimately achieve healing. Consider waiting at least 6 months before reoperating on a tibia fracture that has not healed.

5. Small screws can be inserted into the tibia, adjacent to the canal, before insertion of the intramedullary nail to guide the passage of the nail. These so-called ‘blocking screws’ are especially useful in the prevention of malreduction of proximal tibial shaft fractures, where the metaphyseal canal is much wider than the nail.