FIGURE 33-1 Appearance and fusion times of foot ossification centers, with figures in parentheses indicating the time of fusion of the primary and secondary ossification centers (y., years; m.i.u., months in utero). (From Aitken JT, Joseph J, Causey G, et al. A Manual of Human Anatomy. 2nd ed. London: E & S Livingstone;1966:80, with permission).

HISTORY AND EXAMINATION OF FRACTURES AND DISLOCATIONS OF THE FOOT

The history is not always accurate in childhood trauma; however, every attempt should be made to ascertain the mechanism of injury. Often, other children or adults who witnessed the accident can give a more accurate account than the patient. The degree of force, the speed and height of the fall, and the way the foot is twisted all help predict the degree of displacement or severity of the injury. In more subtle injuries, the ability to weight bear, degree of instability, and the location of the pain are vital parts of the history.

Careful examination of the foot will guide the surgeon to the site of injury. The child often complains of the whole foot “hurting”; however, systematic palpation helps localize the most painful site. Appropriate radiographs can then be taken. Bruising and swelling will also help predict the injury pattern. Isolated bruising on the sole of the midfoot often overlies a subtle Lisfranc injury whereas excessive dorsal swelling may predict a more severe fracture-dislocation.¹⁴⁵ In a soft tissue injury such as a crush injury, the possibility of increased compartment pressures should be considered.

Multiple trauma must also be ruled out. A complete secondary survey should be undertaken to exclude other injuries. For example, bilateral calcaneus fractures following a fall may be associated with a tibial fracture or spinal column injury.

TALAR FRACTURES

Management of Talar Fractures

Fractures of the talus are very rare in children and adolescents.^37,124 Talus fractures most commonly occur through the neck and occasionally the body. Although rare, talus fractures are important to recognize because of the possible complication of avascular necrosis (AVN). This can occur because of the precarious blood supply and fracture patterns. In children, AVN seems more prevalent in innocuous fractures when compared to adults with similar injuries.¹⁴⁰ The majority of talus fractures in children can be treated with cast immobilization whereas displaced fractures in adolescents need to be treated operatively similar to an adult fracture.

Mechanism of Injury

A fall from a height is the predominant mechanism of injury causing talar fractures.^79,98,111 The foot is forcibly dorsiflexed and the neck of the talus impinges against the anterior lip of the distal tibia. This shear force usually results in a vertical or slightly oblique fracture line at the junction of the body and neck of the talus. When the dorsiflexion is combined with supination of the foot, the impingement occurs more medially and the medial malleolus may be fractured as well. With displaced fractures, the subtalar joint may become subluxed. The force required to fracture a child’s talus is almost twice that required to fracture the other ankle and tarsal bones.¹³¹ One must be thorough in looking for other injuries that may coexist as a result of the severe trauma. The talus can also be fractured with crushing injuries, and open fractures are well described in lawnmower accidents.¹²⁴ Fractures of the lateral process of the talus have been described recently in snowboarding accidents where the mechanism appears to be forced dorsiflexion and inversion of the ankle.⁹⁵

Signs and Symptoms of Talar Fractures

The history of forced dorsiflexion of the ankle especially associated with a fall from a height should lead to a suspicion of a talus fracture. The same mechanism of injury can cause other foot fractures and dislocations as well. The ankle and foot are extremely swollen and the foot is usually held plantarflexed. Because of this soft tissue swelling, the foot needs to be examined closely for increased compartment pressure. As with all fractures, the soft tissues need to be inspected for any puncture wounds, abrasions, or fracture blisters as these are important in determining the management of the patient.

In these patients, there may be less swelling so careful palpation around the talus is needed to detect the source of the pain. Once the foot has been clinically assessed, the appropriate radiographic investigations can be performed.

Associated Injuries with Talar Fractures

Because of the level of force that is often required to fracture a talus, other injuries often coexist.¹³¹ A number of studies have found fractures of the calcaneus, malleoli, tibia, and lumbar spine in the presence of a talus fracture.^{20,26,65,127,128} Hawkins,⁶⁵ in his study, on adult talus fractures found 64% of the patients had an associated musculoskeletal injury.

Imaging Evaluation of Talar Fractures

The routine radiographs for a fractured talus include an anteroposterior (AP), lateral, and oblique views. Canale and Kelly²⁶ have described a pronated oblique view of the talus which may demonstrate the fracture more clearly. The fractures are not always easy to see in young children, as the talus is largely cartilaginous until the second decade.¹¹¹ The cartilage anlage often leads to an underestimation of fracture displacement. Some authors have even suggested the use of MRI to show the morphology better in children less than 10 years old.^124,173

Once the fracture is identified, a CT scan is useful in assessing the fracture plane, comminution, degree of displacement, and any other associated foot or ankle fractures. This is particularly useful preoperatively when pain prohibits the full range of radiographs mentioned above to be taken. If an open reduction is planned, the CT scan will also aid in the preoperative planning of the size and placement of the screws. Hawkins⁶⁵ described an x-ray classification to define the different types of fractures of the talar neck and used it to predict the risk of AVN (Fig. 33-3):

Type I fracture: Undisplaced talar neck fracture

Type II fracture: Displaced talar neck fracture with subtalar subluxation or dislocation

Type III fracture: Displaced fracture of the talar neck with dislocation of both the subtalar and ankle joints

Hawkins⁶⁵ also described a subchondral lucent line, the “Hawkins sign,’’ that indicates normal blood flow to the talar body. The absence of this lucency may indicate the development of osteonecrosis (see complications of talar fractures).

Diagnosis and Classification of Talar Fractures

Fractures of the talus can be classified as occurring either in the body or the neck. Some authors suggest classifying talar fractures based on the age of the patient as children less than 6 years of age generally have a better prognosis.¹¹¹

FRACTURES OF THE TALAR NECK

The majority of talar fractures in children are of the talar neck. Hawkins⁶⁵ has classified these into three different types depending on whether the fracture is displaced and the degree of subluxation of the subtalar and ankle joints (Fig. 33-3). This classification was developed so it could be used to predict if the talus would become avascular because of the disruption of the tenuous blood supply. Canale and Kelly²⁶ later modified the classification (Fig. 33-3) to include a type IV injury in which there is subluxation or dislocation of the ankle, subtalar, and talonavicular joints. In the adult literature, the majority of talar fractures are type II and III.^26,65 This classification of talus fractures can help predict the type of treatment required and the outcome one can expect (Table 33-1).

Treatment of Talar Neck Fractures

The treatment of talar fractures is based on the severity of the fracture and the age of the child. The Hawkins classification system is useful in directing the treatment. In a child less than 8 years of age, a less than perfect reduction of the fracture can be accepted because of the remodeling potential.^79,98,111 Adolescent fractures should be treated the same way as an adult injury.

Hawkins Type I Fractures

Undisplaced fractures of the talar neck can be treated for 6 to 8 weeks non–weight-bearing in a below-knee cast. The child can then start taking full weight if the fracture has healed radiographically. Canale and Kelly²⁶ accepted 5 mm of displacement and 5 degrees of angulation of the talar neck in their series.

Hawkins Type II Fractures

A displaced or severely angulated talar neck fracture usually presents with significant soft tissue swelling and pain. This makes management more difficult than type I injuries. Achieving adequate radiographs to assess the degree of displacement is difficult without sedation. The distal fragment of the neck is usually displaced dorsally and medially.

The fracture and subluxation of the subtalar joint should be reduced under general anesthesia, most often by gentle plantarflexion and pronation of the foot. If a stable reduction is achieved, a well-molded below-knee cast can be applied with the foot in plantarflexion. This initial cast is changed to a more neutral position at 4 weeks and then removed 8 weeks following fracture reduction. Postoperative serial radiographs or a CT scan should be performed as the fracture position may be lost when the soft tissue swelling subsides. If the fracture is unstable after reduction, percutaneous Kirschner wire (K-wire) fixation is useful to hold the fracture. Two K-wires can be passed through a small dorsomedial incision and across the fracture. The incision should be on the medial side of extensor hallucis longus to avoid damage to the tibial vessels. Although the amount of residual displacement or angulation acceptable is not clearly defined, it may be better to accept a few millimeters of offset and up to 10 degrees of angulation rather than perform an open reduction and risk devascularizing the talus further.

Hawkins Type III Fractures

These fractures are a result of a serious injury and require urgent surgery to openly reduce and internally fix the talus.

Surgical Approaches

There are three surgical approaches to the fractured talus:

1. Posterolateral

2. Anteromedial

3. Anterolateral

The decision on the approach depends on the condition of the soft tissues and the familiarity of the approach by the surgeon. Occasionally, more than one approach is required if adequate reduction cannot be achieved. It is preferable to use the posterolateral approach as this causes less potential disruption to the blood supply; however, direct visualization of the talar neck is not possible. The timing of the open reduction of these fractures is somewhat controversial. With such a tenuous blood supply, one would think that urgent reduction and internal fixation is indicated. Lindvall et al.¹⁰² compared the results of surgery within 6 hours to delayed surgery in 26 fractures of the talus in adult patients and found no significant difference in outcome. Kellam et al.,⁸⁴ in another similar study, concluded that the severity of the injury, the quality of the reduction, and the surgical outcomes had a bigger influence on long-term outcome than if the surgery was fixed emergently or delayed (greater than 12 hours).

Posterolateral Approach. This approach is commonly used to internally fix fractures of the talar neck once it has been reduced. The patient is positioned supine so the other approaches can be utilized if necessary. The incision is made just lateral to the Achilles tendon. Blunt dissection is then carried out down to the joint capsule avoiding damage to the sural nerve. The posterior joint capsule can then be opened if not already torn by the injury and the posterior process of the talus can be identified. If possible, two partially threaded cannulated 4.5- or 6.5-mm screws can be used to provide compression across the fracture. It is preferable to use titanium screws which are MRI compatible to allow investigation of AVN during fracture healing if necessary. If only one screw is used, a separate K-wire should also be passed across the fracture for rotational stability. These posterior screws are more stable biomechanically than anterior screws (Fig. 33-4).¹⁶⁶

Anteromedial Approach. This approach is useful to visualize the talar neck and directly reduce the fracture. Often, there is comminution of the medial wall of the neck which makes restoring length difficult. With the patient supine, the incision is made from just anterior to the medial malleolus and directly distally down the midfoot. Deeper dissection is carried out medial to the tibialis anterior and the extensor hallucis longus tendons. The dissection down to the capsule is in the interval between the tibialis anterior and tibialis posterior tendons. This approach avoids damage to the deltoid branch of the posterior tibial artery and the medial branches of the anterior tibial artery. This approach is potentially less harmful to the blood supply of the talus when compared to the anterolateral approach.³

Anterolateral Approach. One advantage of this approach is that it permits excellent exposure of the lateral talar neck which is not usually comminuted allowing anatomic reduction. The approach also gives good access to the subtalar joint. The disadvantage to this approach is that it may disrupt the blood supply more than the other approaches. The incision starts at the tip of the lateral malleolus and extends to the base of the fourth metatarsal. Care must be taken to avoid damaging the sural nerve with deeper dissection. In the base of the incision is the artery of the sinus tarsi which should be visualized if possible.

Following open reduction and internal fixation of talar neck fractures, the foot is placed in a non–weight-bearing below-knee cast for 6 to 8 weeks. Radiographs are then taken to assess fracture healing and the presence or absence of the Hawkins sign. If the subchondral lucent line is present, one can assume there is adequate blood supply to the body of the talus and osteonecrosis is unlikely to occur. If the fracture has also healed, the child can start progressive weight bearing as tolerated. The absence of a subchondral lucency during healing should alert the surgeon to the possible development of osteonecrosis (Fig. 33-5). The patient should continue to be non–weight-bearing until the lucency is present. If it is still not present 3 months postinjury, an MRI scan should be performed which will assess the vascularity more accurately.⁶⁷ The use of titanium screws in the open reduction makes this possible. The decision on the amount of weight bearing in the presence of altered blood supply to the talus is not clear. AVN of the talus often takes 18 months to 2 years to revascularize so it would be impractical, if not impossible, to keep a child non–weight-bearing for this period in the hope it will prevent premature collapse of the body.

Surgical and Applied Anatomy of Talar Neck Fractures

The talus is comprised of three parts: A body, neck, and head. Ossification starts from one center that appears in the sixth intrauterine month. The talus ossification process starts in the head and neck and proceeds in a retrograde direction toward the subchondral bone of the body. Approximately two-thirds of the talar body is articular cartilage with just a small area of bare bone on the neck where the bone receives its nutrient blood supply. There are no tendon insertions into the talus. The stability is provided by the capsular and ligamentous attachments to the surrounding bones.

The superior articular surface of the talus is wider anteriorly than it is posteriorly. Traditional teaching suggests the foot should generally be immobilized in neutral dorsiflexion so this widest part of the talus is engaged in the ankle mortise to help prevent an equinus contracture. This is of less importance in younger children who are less likely to develop equinus contractures. The lateral wall of the superior articular surface curves posteriorly whereas the medial wall is straight. The two walls converge posteriorly to form the posterior tubercle of the talus. Often, there is a separate ossification centre (os trigonum) that appears here on radiographs at 11 to 13 years of age in boys and 8 to 10 years of age in girls. It usually fuses to the talus 1 year after it appears (Fig. 33-6).¹¹³

The short neck of the talus is medially deviated approximately 10 to 44 degrees and plantarflexed between 5 and 50 degrees in relation to the axis of the body.⁵⁶ Beneath the talar neck is the tarsal canal, a funnel-shaped area that contains the anastomotic ring formed between the artery of the tarsal canal and the artery of the tarsal sinus.¹¹⁸ The broad interosseous ligament joining the calcaneus and talus is also within the canal.

The tarsal canal is conical in shape and runs from posteromedial (apex) to anterolateral where the base of the cone is known as the sinus tarsi (Fig. 33-7).

The lateral process of the talus is a large wedge-shaped process that is covered in articular cartilage. It articulates with the fibular superiorly and laterally and with the subtalar joint inferiorly. The lateral talocalcaneal ligament is attached to the most distal part of the process.^64,66

The head of the talus is entirely cartilaginous, convex, and articulates with the concave surface of the navicular. The undersurface of the talus is comprised of three articulating surfaces for the calcaneus: The posterior, middle, and anterior facet. Between the posterior and middle facets is a transverse groove which forms the roof of the tarsal canal.

Blood Supply

The blood supply of the talus has been extensively studied.^9,62,118 The nutrient arteries are derived from the three major vessels that cross the ankle joint: Posterior tibial artery, tibialis anterior artery, and peroneal artery (Fig. 33-8). Branches of these three vessels perforate circumferentially the short talar neck which is the only part of the talus denude of articular cartilage. A fracture in this area can disrupt this intricate anastomosis of vessels and lead to AVN of the body of the talus.

The main blood supply to the talus is through the artery of the tarsal canal. This artery branches off the posterior tibial artery approximately 1 cm proximal to the origin of the medial and lateral plantar arteries. It passes between flexor digitorum longus and flexor hallucis longus before entering the tarsal canal where it anastomoses with the artery of the tarsal sinus. Before entering the canal, the artery of the tarsal canal gives off a deltoid branch that penetrates the deltoid ligament and supplies the medial third of the talar body.⁵⁷ A dorsal vessel of the deltoid branch anastomoses with the medial branch of the dorsalis pedis artery to enter the talar neck.

The second source of blood supply is from the anterior tibial artery and its terminal extension, the dorsalis pedis artery. Multiple vessels from these arteries penetrate the dorsal neck of the talus. The third source of blood supply is from the peroneal artery. Small branches supply the posterior process of the talus and a larger branch forms the artery of the sinus tarsi to supply the lateral aspect of the talus.

Within the capsular and ligamentous attachments to the talus there are small vessels that also contribute to the blood supply.¹³⁰

FRACTURES OF THE TALAR BODY AND DOME

Fractures of the talar body are less common than of the neck. In 1977, Sneppen et al.¹⁶³ described a classification system based on the anatomic position of the fracture in the talus. This was later modified by DeLee⁴² and the result is a five-part classification.

Fractures of the talar body are rare in adults and children (Table 33-2). In a long-term follow-up of 14 talus fractures in children Jensen et al.⁷⁹ found only four (29%) were fractures through the body. Undisplaced fractures can be treated in a non–weight-bearing below-knee cast for 6 to 8 weeks until the fracture is healed and the outcome is excellent. Undisplaced intra-articular fractures can be treated in the same way; however, serial radiographs must be taken to confirm displacement does not occur. Anatomic reduction of displaced fractures has been recommended because residual displacement of the articular surfaces leads to degenerative osteoarthritis.⁹⁷

FRACTURES OF THE LATERAL PROCESS OF THE TALAR BODY

Fractures of the lateral process of the talus are rare in adults and children, and a high level of suspicion is required if the diagnosis is to be made. The lateral process is a wedge-shaped prominence that forms almost the whole lateral wall of the talus. It is covered entirely in articular cartilage and is the articulating surface of the talus with the fibular. The talocalcaneal ligament inserts into the tip of the lateral process. The mechanism of injury is a forced dorsiflexion injury with inversion of the foot.⁶⁴ The talocalcaneal ligament may avulse the lateral process.

Isolated fractures of the lateral process of the talus are often not recognized on the initial radiographs.^64,66,112 Leibner et al.⁹⁵ suggested that this may occur in 46% of the cases. The lateral process is best visualized on the mortise view so the fibula is not overlying it. On the lateral radiograph, the lateral process is seen just superior to the angle of Gissane.⁶⁶ This is the angle between a line drawn along the lateral border of posterior facet and a line drawn along the anterior process (Fig. 33-9). If there is persistent pain laterally around the ankle following an inversion ankle injury, one should have a high suspicion for a lateral process fracture or an osteochondral injury. If not clearly seen on the plain films, a CT scan should be performed to assess the talus and rule out any other coexisting fractures.^87,123

The incidence of this rare injury is increasing because of the increased popularity of snowboarding.^87,95,122 Kirkpatrick et al.⁸⁷ reviewed 3,213 snowboarding injuries and found an unusually high incidence of lateral process fractures. They comprised 34% of all ankle fractures.⁸⁷

The treatment of nondisplaced fractures of the lateral process is with a non–weight-bearing cast for 6 to 8 weeks. Displaced fractures are best treated with open reduction and internal fixation; however, the degree of displacement that is acceptable in a child is not clearly defined. What may be more important is the congruity of the joint surface of the talus. A step or gap in the articular surface of more than 2 to 3 mm may be useful criteria as to when to open reduce the fracture. The fracture can be held with one 3.5-mm partially threaded cancellous screw inserted from lateral to medial perpendicular to the fracture line. A below-knee cast is then worn for 6 weeks.^64,66,95,172

FRACTURES OF THE OSTEOCHONDRAL SURFACE OF THE TALUS

Damage to the osteochondral surface of the talus can be caused by direct trauma or may be caused by an underlying osteochondral lesion (osteochondritis dissecans [OCD]) that may have been present for some time and has been made symptomatic by the injury. The pathogenesis and etiology of OCD are controversial; however, most authors report preceding trauma as a cause of the defects (Canale and Bedding²⁵ 80%, Letts et al.⁹⁷ 79%, Higuera et al.⁶⁹ 63%, and Perumal et al.¹²⁹ 47%). The medial lesion is usually deeper and cup-shaped compared to the thinner “wafer” type lateral lesion. The lateral lesion is more often associated with trauma and more symptomatic than the medial lesions. It is postulated that the medial lesions may be because of more repetitive microtrauma.^25,26 Berndt and Harty,¹² in 1959, used freshly amputated legs to biomechanically reproduce injuries to the ankle and observe the injuries inflicted. They showed that the anterolateral talus hits the medial aspect of the fibula with dorsiflexion and inversion and that plantarflexion and inversion caused posteromedial osteochondral lesions (Fig. 33-10).

The initial radiographs following an ankle injury in a child should be closely assessed for an osteochondral injury. If pain and swelling persist for over 2 months after an “ankle sprain,’’ then further investigations should be carried out to look for an osteochondral lesion. This will initially be a further radiograph series; however, an MRI scan is often more useful at this stage to look for an osteochondral lesion as a small percentage are purely cartilaginous. Some consider an MRI arthrogram useful in further determining whether the fragment is detached or not as occasionally the arthrographic contrast can be seen deep to the osteochondral lesion. The bone scan has largely been superseded by the MRI scan in the diagnosis and assessment of these lesions. The bone scan is useful, however, when it is not clear if the pain in the child’s ankle is coming from the osteochondral lesion or some other pathology. A normal bone scan in the presence of a stage I or II osteochondral lesion may indicate a soft tissue lesion as being a source of the pain.

Mechanical symptoms of locking and catching are not as common as one would think but can occur with these lesions if the loose fragment becomes trapped within the joint. The pain seems to be related to the synovitis and effusion that develops secondary to the uneven articular surface. On examination, the ankle is slightly swollen and can be painful on passive movement as the loose fragment passes under the tibia. With plantarflexion of the foot, the anterolateral talus can be palpated directly and a lesion here can be painful on direct pressure.

Classification of Osteochondral Fractures

Berndt and Harty¹² classified osteochondral fractures of the talar dome into four stages based on radiographic criteria (Fig. 33-11):

Stage I: Subchondral trabecular compression fracture (not seen radiographically)

Stage II: Incomplete separation of an osteochondral fragment

Stage III: The osteochondral fragment is unattached but undisplaced

Stage IV: A displaced osteochondral fragment

Anderson et al.⁸ modified this classification after correlating clinical findings with radiographs and MRI scans. They described the stage I lesion as not visible on plain radiographs but visible on an MRI scan. They also introduced a stage IIa lesion, which is an undisplaced osteochondral lesion with a subchondral cyst adjacent to the floor of the lesion. Anderson et al.⁸ felt a stage IIa lesion should be treated surgically whereas a stage II lesion can initially be treated nonoperatively (Fig. 33-12).

A further classification was proposed by Pritsch et al.¹³⁵ in 1986 based on the arthroscopic appearance of the articular cartilage at the time of surgery. The quality of the articular cartilage was placed into one of three grades:

Grade I: Intact, firm, and shiny articular cartilage

Grade II: Intact but soft articular cartilage

Grade III: Frayed articular cartilage

They used this classification to determine which lesions should be treated with activity modification (grade I), who should have arthroscopic drilling (grade II), and finally which patients require arthroscopic curettage and microfracture (grade III).

Treatment of Osteochondral Fractures

The treatment of osteochondral lesions of the talus in children is challenging. Only a few papers purely address this condition in children,^69,97,129 and the rest of the literature is a combination of adult and childhood lesions. It is important to distinguish between an acute osteochondral fracture and a chronic osteochondral lesion as the two may require different treatment strategies.

To enable thorough assessment, these patients need to be followed up for a minimum of 2 years as it takes this long for the lesion to become radiographically healed despite the child often being clinically normal.¹²⁹

Nonoperative Management

Most authors agree that the primary treatment of stage I and stage II lesions is nonoperative.^12,69,97,129 The symptomatic patient can be immobilized for 6 weeks in a below-knee walking cast or a Cam walker (Fig. 33-13). This usually relieves the acute symptoms; over the next 6 weeks, the patient has activity modification maintaining a pain-free range of movement. This allows the fracture to heal before returning to active sport. Higuera et al.⁶⁹ treated their stage III lesions nonoperatively as well and all seven patients had good outcomes.

Surgical Treatment

The outcomes of surgery for osteochondral fractures of the talus are controversial. It is hard to compare results between authors as they have often used different outcome measures. Some authors use pain as their primary outcome⁹⁷ whereas others also consider radiologic healing. The long-term outcome of an asymptomatic subchondral lucency in the talar body is unknown. In some series, the patients have had arthrotomies⁹⁷ whereas others had arthroscopic debridement.¹²⁹ The staging of the lesions are also subject to interobserver variability.⁹⁷ Letts et al.⁹⁵ performed surgery in 24 patients with osteochondral lesions. They used arthroscopy in three patients only and two of those patients required arthrotomy as well.⁹⁵ With modern ankle arthroscopy equipment and newer surgical techniques, ankle arthroscopy has become the primary surgical treatment for both medial and lateral lesions of the talar dome. The anterolateral lesions are more accessible; however, with good ankle distraction and different portal placement posteromedial lesions are accessible.

Recently, Perumal et al.¹²⁹ reviewed 31 patients with juvenile OCD with a minimum of 6-month follow-up. They recommended nonoperative treatment with an ankle brace and activity modification in most cases for 6 months. Only 16% of the lesions healed radiographically in that timeframe. If pain continues after this time and the lesion is still present, further immobilization and activity modification is recommended. They recommend arthroscopic surgery for patients with type II lesions who are not prepared to modify their activities longer than 6 months and patients with type III lateral lesions and all stage IV lesions. Thirteen of the 31 patients were treated surgically.

Arthroscopic treatment options include:

1. Drilling the lesion (antegrade or retrograde)⁸⁸

2. Curettage and microfracture

3. Internal fixation with bioabsorbable nails

4. Bone grafting and internal fixation

In stage II lesions with intact articular cartilage, Kumai et al.⁵⁶ showed excellent results drilling through the lesion into the subchondral bone. They also found that in skeletally immature patients, there may be an increased tendency for the lesion to heal when compared to the adult patients. Retrograde drilling can be performed using specific tip directed instrumentation.¹⁶⁸ This avoids damage to the articular cartilage and may prevent fragmentation of a small lesion. Access to a posteromedial lesion can be difficult. One approach is to use a transmalleolar portal after drilling a 3.5-mm drill through the medial malleolus or to use a posteromedial portal taking care to avoid damaging the neurovascular bundle.

Curettage and microfracture is a very effective, relatively straightforward procedure. It is particularly useful in small stage III and stage IV lesions where the fragment is too small to internally fix or there is no subchondral bone on the lesion for healing. The articular cartilage is debrided back to stable tissue and the subchondral bone is curettaged until bleeding occurs. Either a microfracture pick or 2-mm drill is then used in the subchondral bone. Anderson et al.⁸ would suggest this treatment for all stage IIa lesions where a subchondral cyst is present.

Internal fixation with or without bone grafting is a difficult procedure for the inexperienced arthroscopist. It is preferable to use absorbable pegs or nails rather than metallic implants. In large stage III and IV acute osteochondral lesions, this is probably the treatment of choice rather than excising the fragment.

AUTHOR’S PREFERRED TREATMENT

CALCANEAL FRACTURES

Epidemiology of Calcaneal Fractures

Fractures of the calcaneus are rare in children with an incidence of only 1 in 100,000 fractures.¹⁸¹ The treatment of these fractures has historically been nonoperative, relying on the largely cartilaginous bone to remodel with time. The majority of fractures in children less than 14 years old are extra-articular whereas in older children the fracture pattern resembles those in adults. Children appear to have more coexisting lower limb fractures than adults but fewer fractures of the axial skeleton.¹⁵⁶

Calcaneal fractures in young children are often missed or are diagnosed late on radiographs or bone scan when the child is still limping long after the injury. At the other end of the spectrum, the adolescent patient has often had a major fall and has a displaced intra-articular fracture. This older age group should be treated like the adult population with open reduction and internal fixation restoring the joint congruity and calcaneal height and width. The challenge for the surgeon is at what age and what degree of displacement is this more aggressive treatment indicated in a group of patients traditionally treated nonoperatively.

Management of Calcaneal Fractures

Mechanism of Injury

The most common mechanism of injury is a fall from a height. This axial load drives the talus into the calcaneus resulting in the fracture. The degree of comminution appears to be less in children even though they often fall from greater heights than adults.²⁰ Wiley and Profitt¹⁸¹ found that in young children, the fall was usually less than 4 feet and in children older than 10 years the fall was greater than 14 feet. They noted that the minor falls in the younger children often resulted in undisplaced fractures that were diagnosed late.

Schmidt and Weiner¹⁵⁶ reviewed 56 children with calcaneal fractures of which 25 (45%) were caused by a fall from a height. They also found that children less than 14 years of age predominantly had extra-articular fractures, hypothesizing that the calcaneus in this age bracket absorbs the compression force rather than dissipating it through the joint.

Vehicle-related injuries were the second biggest cause of calcaneal fractures in both Schmidt and Weiner¹⁵⁶ and Wiley and Profitt’s reviews.¹⁸¹

Fractures of the calcaneus can also occur in major crush injuries when compartment syndrome may coexist and open fractures are common in lawnmower injuries.

Signs and Symptoms of Calcaneal Fractures

Any child who has fallen from a height and landed on their feet should be examined carefully for a calcaneal fracture. Associated injuries should also be evaluated with a thorough secondary survey, especially of the lower limbs and spine.

The foot will often be extremely swollen with bruising around the heel and dorsum of the foot. Symptoms and signs of compartment syndrome, including excessive pain, pallor, paresthesia, and pulselessness should be assessed. In more subtle injuries, careful palpation is necessary to elucidate areas of pain which may disclose an underlying undisplaced fracture.

Many calcaneal fractures in children are initially missed and diagnosed late. Often, the fracture line is not evident on the initial radiographs. Inokuchi et al.⁷⁵ reported that 44% of fractures in their series were initially missed, as were 55% of those reported by Schantz and Rasmussen¹⁵⁴ and 44% of those reported by Wiley and Profitt.¹⁸¹

A differential diagnosis must be kept in mind for other causes of heel pain in a child. These include Sever disease, osteomyelitis, a unicameral bone cyst, or a stress fracture.¹²⁶

Associated Injuries with Calcaneal Fractures

Schmidt and Weiner¹⁵⁶ reviewed 59 children with 62 calcaneal fractures and found a number of associated injuries. These included fractures of the lumbar spine, lower limb fractures, a pelvic fracture, and upper extremity fractures. These other skeletal injuries were more frequent in children over 13 years of age. Associated lower limb fractures occurred twice as frequently as in adults; however, injuries to the axial skeleton occurred half as often as in adults. Wiley and Profitt,¹⁸¹ however, only had two patients with accompanying significant injuries in their series of 32 pediatric calcaneal fractures.

Diagnosis and Classification of Calcaneal Fractures

Plain Radiographs

Calcaneal fractures in children often missed as the radiographic findings are usually more subtle than in adults.^{89,110,156,165,181} Subsequent radiographs at 10 to 14 days often show the fracture line. The majority of these missed fractures are extra-articular.¹⁵⁶

The standard views for a suspected calcaneal fracture are posteroanterior, lateral, and axial views. The posteroanterior view shows the calcaneocuboid and talonavicular joints well. The lateral view is excellent at showing the congruity of the posterior articular facet and allows calculation of Bohler angle (Fig. 33-9). The axial view demonstrates the tuberosity, the body, the sustenaculum tali, and the posterior facet of the calcaneus Oblique views are also useful and will show a fracture of the anterior process more clearly (Fig. 33-14).¹⁴² The oblique views also define the subtalar joint well so are very useful in intra-articular fractures. Broden views can also be taken that look at the posterior facet of the calcaneus. These are taken with the leg internally rotated 40 degrees and the x-ray beam angled between 15 to 40 degrees toward the head.¹⁸ This is a difficult radiograph for the technicians to master and almost the same information can be achieved by ordering a mortise view of the ankle and looking at the posterior facet of the subtalar joint.

The lateral view is useful for measuring the Bohler angle. This is the angle between a line drawn from the highest point of the anterior process to the highest point of the posterior facet and a line drawn tangential to the highest point of the calcaneal tuberosity. The normal value in an adult is between 20 and 40 degrees. In a child, the angle is slightly less than in an adult and may be caused by the incomplete ossification of the calcaneus. It is advisable to perform a lateral radiograph of the contralateral calcaneus to use as a comparison rather than accept the absolute value of Bohler angle. The child’s calcaneus does not resemble that of an adult until after 10 years of age.^{71,73,124,173} Another angle which is not so easy to measure is “the crucial angle of Gissane.” This is the angle formed by two strong cortical struts seen on the lateral radiograph. One runs along the lateral margin of the posterior facet and the other runs up to the anterior process of the calcaneus. The angle between them ranges from 95 to 105 degrees (Fig. 33-9).⁵¹

When reviewing radiographs of children’s feet, it is always important to be cognizant of the normally appearing ossification centers and accessory bones about the growing foot, which often are confused with fractures (Figs. 33-1 and 33-2).²⁷ The os calcis is the earliest tarsal bone to ossify with the primary ossification center appearing in the third intrauterine month. The secondary ossification center appears around 6 to 8 years and is the crescentic epiphysis seen posteriorly that gives rise to Sever disease. This epiphysis fuses to the body of the calcaneus when the adolescent is 14 to 16 years old.

The use of a technetium-labeled bone scan in diagnosing calcaneal fractures is uncommon with the ready availability of MRI scans. The bone scan is useful in evaluating a nonlocalized painful limp in a toddler and in this setting a calcaneal fracture may be diagnosed. Laliotis et al.⁸⁹ used bone scans and identified five calcaneal fractures in seven toddlers less than 36 months of age who had no history of significant injury. Bone scanning is sensitive for bone pathology but not specific and will be positive when other conditions are present like infection, Sever disease, juvenile arthritis, and some neoplasms. A CT scan is a useful investigation to evaluate the positive bone scan.

Computed Tomography Scanning

CT scanning has evolved as the best method to evaluate the fractured calcaneus. Not only does it clearly show the fracture lines and altered anatomy, but also reveals injuries to adjacent bones. Sanders et al.¹⁵² have used CT scans to develop a classification system that is particularly useful in the preoperative planning of open reduction of these fractures. The primary and secondary fracture lines are identified and the degree of comminution and position of the fragments is more accurately seen than in the radiographs. The primary fracture line usually runs obliquely from plantar medial to dorsolateral exiting the posterior facet. Secondary fracture lines that develop off this primary line are also seen and their pattern determines the classification of the fracture (Fig. 33-15). The CT scan also allows a three-dimensional reconstruction to be made which again is useful in visualizing the fracture lines for possible internal fixation.

Buckingham et al.²⁰ and Ogden¹²⁴ reviewed nine patients with 10 calcaneal fractures and performed CT scans on all of them. They found the fracture patterns in these adolescents (average 13.4 years old) to be very similar to those found in adults. They did find less comminution in children than in adults, even though the children reportedly had fallen from greater heights.

The use of MRI scans is largely unnecessary for the majority of calcaneal fractures. They can be useful in young children when the calcaneus is still largely cartilaginous and a fracture is not seen on plain films or CT.

Classification of Calcaneal Fractures

Children’s calcaneal fractures were traditionally classified according to their adult counterparts using the Essex-Lopresti⁵¹ and Letournal⁹⁶ classifications. Schmidt and Weiner¹⁵⁶ reviewed 62 calcaneal fractures in children and compared them to the adult literature.¹⁴⁷ They used the classification systems of Essex-Lopresti⁵¹ and Chapman and Galway³² and added a new fracture type (type VI) to develop a classification for pediatric calcaneal fractures which is in routine use today (Fig. 33-16).

For adolescent fractures, it is probably more appropriate to use the Sanders classification.¹⁵² This is an adult classification system that was developed after reviewing the CT scans on 120 cases preoperatively and at minimum 1-year follow-up. The follow-up CT scans were correlated with the clinical outcome scores to help validate the classification system used.

Surgical and Applied Anatomy of Calcaneal Fractures

The calcaneus is the largest tarsal bone and has quite an unusual shape. It has three articular facets (anterior, middle, and posterior) on the superior surface where it articulates with the talus to form the subtalar joint (Fig. 33-7) and anteriorly there is a saddle-shaped articular surface for the cuboid. The posterior facet is the largest facet and is slightly convex. The middle facet is anterior and medial to the posterior facet lying on the sustenaculum tali. It is concave like the anterior facet with which it is often contiguous. Between the middle and posterior facets lies the calcaneal groove, which forms the inferior wall of the sinus tarsi. Posteriorly, the tendoachilles inserts into the tuberosity of the calcaneus which is the whole area behind the posterior facet. On the lateral surface of the calcaneus are two shallow grooves with a small ridge in between (the peroneal trochlea). The peroneus longus and brevis run either side of this trochlea. The medial side is concave and is structurally stronger than the lateral side. The sustentaculum tali projects from the medial wall and supports the middle articular facet on its surface. The tendon of flexor hallucis longus runs on the undersurface of the sustenaculum. On the plantar surface are the medial and lateral processes for the origin of the abductor hallucis and abductor digiti minimi muscles, respectively (Fig. 33-17).

Secondary ossification occurs in the calcaneal apophysis between the ages of 6 and 10 years. Inflammation in the apophysis around this age causes heel pain and is referred to as Sever disease.

The use of CT scans has defined the surgical anatomy of the calcaneus to help make treatment decisions. The coronal views show the important posterior facet and the sustenaculum tali and the height and width of the heel. The position of the peroneal tendons and flexor hallucis tendon can also be seen. The sagittal views provide additional information about the posterior facet and also show the anterior process well. The axial views visualize the calcaneocuboid joint well, the anterior-inferior aspect of the posterior facet, and the sustenaculum tali. This information can then be used in planning the reconstruction of the calcaneus.^149,150

Current Treatment Options for Calcaneal Fractures

Calcaneal fractures in growing children are usually less severe than in the adult population and often do well without operative intervention. The adolescent, on the other hand, often has fracture patterns similar to adults and requires open reduction and internal fixation. The challenge to the orthopedic surgeon is to recognize the patient that requires this form of surgery. There is a degree of remodeling that will take place in the child and hence the amount of growth remaining, degree of ossification, and difference in morphology from the contralateral side all need to be considered in making the treatment decisions.

Extra-articular fractures of the calcaneus are treated by cast immobilization for 6 weeks. The child can start weight bearing in this cast when comfortable and can be changed to a Cam walker for the final few weeks if necessary.^19,75

Tongue-type fractures can be treated nonoperatively if the posterior gap is less than 1 cm and the Achilles tendon has not been significantly shortened by bringing the fragment up proximally. Occasionally, the technique described by Essex-Lopresti⁵¹ for percutaneous reduction of tongue-type fractures (Fig. 33-18) is useful.

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