Introduction
Background
The calcaneus is the most frequently fractured tarsal bone. Calcaneus fractures may occur as a result of falls from heights or from twisting injuries or through a pathologic process such as osteoporosis, cysts, and tumors. Os calcis fractures can be broadly classified into intra-articular and extra-articular types.
The calcaneus functions as a lever arm for the gastrocsoleus complex, providing a foundation or vertical support for one's body weight and providing support for and maintaining the lateral column of the foot. Any fracture that impairs one of these functions substantially affects the person's gait if not restored.
These fractures may remain undiagnosed clinically, as there may be no obvious deformity. Often, a history of the patient falling from a height and landing on his or her heels is helpful, but radiographic examination is essential to confirm fracture. Management of these fractures depends on the type of fracture. Therefore, imaging plays a primary role.
The management of calcaneus fractures and their associated soft tissue injuries are controversial. Open reduction and stable internal fixation with a lateral plate and without joint transfixation are established as standard therapy for displaced intra-articular fractures.
Good to excellent results are achieved in two thirds to three quarters of all cases, as shown in large clinical series. Anatomic reduction of joint congruity and the overall shape of the calcaneus are important prognostic factors. The quality of joint reduction should be proved intraoperatively with the acquisition of Broden views, high-resolution fluoroscopy, or open subtalar arthroscopy.1,2,3,4,5
Calcaneus, fractures. The Bohler angle. In determining the Bohler angle, a line is drawn between the posterior superior aspect of the calcaneus and the highest point of the posterior subtalar articular surface; a second line, which intersects the first, is drawn from the highest point of the anterior process to the posterior margin of the subtalar surface. The angle that results from their intersection measures 20-40°. If the angle is reduced, a calcaneal fracture is present; however, a normal angle does not exclude a calcaneal fracture.
Calcaneus, fractures. CT scan.
Calcaneus, fractures. Short-tau inversion recovery (STIR) sagittal MRI demonstrates high signal intensity at the anterior and middle processes. This represents bony edema secondary to a fracture, which is not appreciated on the plain radiographs.
Calcaneus, fractures. Technetium-99m diphosphonate bone scan depicts a stress fracture of the calcaneus, which was not apparent on plain radiographs.
Pathophysiology
Injuries associated with fractures of the calcaneus
Calcaneus fractures resulting from falls onto the heels from heights are bilateral in 5-9% of patients; they are associated with compression fractures of the lumbar and/or dorsal spine in 10%. These fractures are complicated by a compartment syndrome in 10% of cases, with half of these involving development of clawing of the lesser toes or other chronic problems, such as stiffness and neurovascular dysfunction.
Other fractures around the ankle and soft tissue injuries are encountered in a quarter of all cases of calcaneus fracture. Soft tissue injuries include subluxation or dislocation of the peroneal tendons from the fibular sulcus, entrapment of neurovascular bundle, and interposition of the flexure hallucis longus tendon between bone fragments from sustentaculum tali (see Images below and Images 4-7 in Multimedia).
Calcaneus, fractures. Location of fracture lines.
Calcaneus, fractures. Essex-Lopresti classification.
Calcaneus, fractures. Rowe classification.
Calcaneus, fractures. Sander CT classification.
Extra-articular and intra-articular fractures of the calcaneus
Calcaneus fractures can be classified as extra-articular (25-30%) or intra-articular (70-75%) fractures.
Extra-articular fractures
Extra-articular fractures can be further subdivided into those involving the anterior process and those of the tuberosity. Extra-articular fractures are more common in people with diabetes than in others.
Atkins and associates reviewed 400 patients with calcaneus fractures who were treated at their institution over a period of 10 years. In about 5% of the patients, the major fracture involved the tuberosity. In 3 cases, the fracture occurred in elderly osteoporotic patients as a result of sudden contraction of the gastrocnemius muscle. In these fractures, a triangular fracture fragment, which included the upper border of the calcaneus and the insertion of the tendo Achilles, was apparently avulsed from the remainder of the bone and displaced upward. In the remaining 17 cases, the fracture occurred in young patients as the result of a significant fall.
In all cases, there was an identical fracture of the medial tuberosity of the calcaneus. This fracture was isolated in 2 cases. In the remaining cases, the triangular fragment described in the osteoporotic avulsion fractures also occurred; however, in 13 cases, its anterior extension involved the posterior facet of the subtalar joint.
Detailed analysis of CT scans showed that, in all cases, the usual coronal primary line described in the standard intra-articular fracture of the calcaneus was absent. The primary fracture line was in the coronal plane, which separates the anterior part of the posterior facet of the subtalar joint from the posterior.
The authors postulated that, in the younger patients, the fracture of the medial calcaneus tuberosity occurred first and weakened the surrounding bone so that the triangular fragment of the upper part of the tuberosity of the calcaneus was avulsed by the pull of the gastrocnemius. In osteoporotic patients, the bone is sufficiently weak that the upper part of the tuberosity can be avulsed without a prior fracture of the medial process. Thus, the medial-process fracture and the osteoporotic fracture seen in elderly patients form 2 ends of a spectrum of tuberosity fractures.
Intra-articular fractures
Approximately 70-75% of all calcaneus fractures are intra-articular fractures. A wide spectrum of associated fragment displacement is seen. The fracture lines may adopt 1 of 2 patterns. The primary fracture line runs from the plantar aspect obliquely upwards into the posterior facet, which divides the calcaneus into anteromedial and posterolateral fragments. The secondary fracture line begins at the angle of Gissane and extends posteriorly.
Essex-Lopresti subdivided these fractures into 2 distinct subtypes. The first, the tongue type, occurs when the secondary fracture line extends directly posteriorly, producing a large superior, posterior, and lateral fragment, with the rest of the body forming the inferior fragment. The second, the joint-depression type, which is the more frequent of the two, occurs when the secondary fracture line begins at the crucial angle, extends posteriorly, but deviates dorsally to exit the bone just posterior to the posterior articular facet. This fragment contains most of the posterior facet.
Types of calcaneus fractures
Rowe analyzed 154 calcaneus fractures and classified them into 5 groups.
Types I-III do not involve the subtalar joint. Type I fractures represent approximately 20% of cases. The fracture line may be through the tuberosity, the sustentaculum tali, or the anterior process of the calcaneus. Type II beak fractures are uncommon. Type III fractures represent almost 20% of cases; these are oblique fractures.
Types IV and V involve the subtalar joint; they represented almost 60% of the analyzed group. Type V fractures are comminuted fractures with a centrally depressed fragment.
Stress fractures of the calcaneus
Stress fractures of the calcaneus are uncommon. Maenpaa and associates reviewed 24 cases involving stress fractures in the metatarsal bones or in the ankle region in 17 patients with inflammatory arthritides.6 Of these, 16 were metatarsal fractures, 4 were distal fibular fractures, 2 were distal tibial fractures, and 2 were calcaneus fractures. Radiographic analyses were performed to determine whether predisposing factors for stress fractures were present. Metatarsal and ankle-region stress fractures were analyzed separately.
Stress fractures occurred most frequently in the second and third metatarsals. In metatarsal fractures, varus alignment of the ankle tended to cause fractures of the lateral metatarsal bones and valgus alignment of the medial metatarsal bones. Among patients with fractures of the ankle region, valgus deformity of the ankle was present in those patients with distal fibular fractures. Calcaneus fractures showed neutral ankle alignment. Malalignment of the ankle and hindfoot is often present in distal tibial, fibular, and metatarsal stress fractures.
Additionally, the patients tended to have long histories of osteoporosis and of treatments with diverse medications and reconstructive surgeries. The authors concluded that if such patients experience sudden pain, tenderness, or swelling in the ankle region, stress fractures should be suspected, and the necessary examinations should be performed.
Mortality/Morbidity
Patients with extra-articular calcaneus fractures generally do well in terms of functional recovery and fracture healing. The results are good, even if there is displacement at the fracture site. Fracture union always occurs, and with early movement, joint stiffness is a minimal long-term problem. See also Outcomes, Clinical Details.
Race
- There is no racial predilection with calcaneus fractures.
- Igbigbi and Mutesasira reported racial differences in the calcaneal angle (see Anatomy, below).7
Sex
Pester and Smith found a significant gender difference in the anatomic distribution of stress fractures.8
- In a 4-year study of stress fractures of the lower extremities in soldiers undergoing basic training at Fort Dix, New Jersey, 1338 stress fractures were confirmed in 1050 soldiers from a total training population of 109,296, resulting in an incidence of 0.96%. Among 76,237 men, 691 (0.91%) had stress fractures; among 33,059 women, 359 (1.09%) did.
- Significant gender differences were observed in the anatomic distribution of fractures as well. In men, common sites of stress fracture were the metatarsals (66%), the calcaneus (20%), and the lower leg (13%). In women, common sites of stress fracture were the calcaneus (39%), the metatarsals (31%), and the lower leg (27%).
- Female soldiers had more than twice the number of bilateral stress fractures than male soldiers had. The specific week of basic training that marked the onset of stress fractures varied in accordance with the sex of the soldier.
Age
Calcaneus fractures are encountered in all age groups: 5% occur in pediatric patients. In adults, 75% of all calcaneus fractures are intra-articular, compared with 8-37% in children.
Mora and associates retrospectively reviewed 22 skeletally immature patients with 23 calcaneus fractures before their distal tibial physis had fused. Eighteen fractures (78%) were intra-articular; five (22%) were extra-articular. Nine patients underwent follow-up examinations for an average of 4.4 years; of these, 8 were treated nonoperatively, and 1 was treated with open reduction and internal fixation.
A modification of the American Orthopaedic Foot and Ankle Society scoring system, which focuses on residual pain, work or sports restrictions, and the patient's ability to walk on different surfaces and gait abnormalities, was used to assess outcomes. Seven of the 9 patients were free of pain, had unrestricted foot function, and possessed no apparent gait abnormalities. Two had activity- and cold weather – related pain.
The excellent prognosis both for patients with intra-articular fractures and for those with extra-articular fractures was thought to result from several factors: First, the immature talus and calcaneus have a superior capacity to remodel. Second, pediatric calcaneus fractures are usually the consequence of low-energy trauma. Third, a favorable intra-articular fracture pattern, unique to the skeletally immature calcaneus, may exist and may be conducive for a good prognosis.
Anatomy
The superior surface of the calcaneus is divided into 3 articular facets: (1) the posterior facet, which is the largest in surface area and has a convex shape; (2) the middle facet, which overlies the sustentaculum tali and which is concave in shape; and (3) the anterior facet, which is concave and is often confluent with the middle facet (see Images below and Images 1-3 in Multimedia).Calcaneus, fractures. Calcaneus anatomy.
Calcaneus, fractures. Calcaneus anatomy.
Calcaneus, fractures. Calcaneus anatomy.
The calcaneal groove lies between the middle and posterior facets. The anterior surface is saddle shaped, articulating with the cuboid bone.
The calcaneus functions as a lever arm for the gastrocsoleus complex, providing a foundation or vertical support for one's body weight and providing support for and maintaining the lateral column of the foot.
Igbigbi and Mutesasira reported racial differences in the calcaneal angle.7 They investigated the calcaneal angle on 206 unilateral radiographs of the lateral aspect of the foot in Ugandans (114 men, 92 women; age range, 20-40 y). In men, the mean angle was 35.1°; the standard deviation (SD) was 7.5°. In women, the mean angle was 37.6°; the SD was 5.6°. The range of the angle for both sexes together was 20-50°; women had a significantly higher mean value than men (P <0.01).
The authors observed a significant difference in the calcaneal angle in Ugandan men and Nigerian men (P <0.01); they observed a similar difference in the calcaneal angle in Ugandan women and Nigerian women (P <0.001). Their reported range was the widest that has been documented so far in Africans. The study reinforced the need to establish the normal range of the angle in a given population; it also highlights the clinical importance of the calcaneal angle to orthopedic surgeons managing calcaneus fractures in different parts of the world.
Presentation
History
Patients with calcaneus fractures present with a history of trauma. Older children may give a history of falls from heights or sport-related injuries.
Physical examination
Patients with calcaneus fractures present with pain, swelling, and deformity; they have a history of trauma. Toddlers with calcaneus fractures may present with limping and an inability to bear weight; there may be associated swelling and tenderness around the heel.
OutcomesIn 1964, Lance reviewed 227 intra-articular fractures. In this study, results of conservative treatment were favorable in only 55% of patients, although this rate was better than that of the group treated operatively.
Lindsay and Dewar reviewed 147 patients. After 8 years, results of conservative treatment were good in 76% of patients, whereas the results were good in only 60% of patients treated with primary or late arthrodesis. The ultimate results depend on several prognostic factors: (1) the degree of displacement of the posterior facet, (2) the degree of reduction of Bohler tuber angle, and (3) the patient's age.
Essex-Lopresti recommended that patients older than 50 years should not be treated as aggressively because the results are worse in this group of patients.9
In 5-15% of intra-articular fractures, the fractures are so comminuted that they are not amenable to surgery; in such cases, the outcome is poor.
Premature weight bearing before 6 weeks is associated with repeat displacement of the fracture fragments. Therefore, weight bearing after surgery should be delayed for 12 weeks.
Persistent pain around the ankle
Persistent pain around the ankle and in the heel may follow calcaneus fractures; the cause of the pain is multifactorial.
Patients with secondary osteoarthritis in the subtalar joint may present with pain on weight bearing; the pain is aggravated by inversion and eversion. Subtalar arthrodesis alone may not control the symptoms, because unrecognized degenerative changes in the calcaneocuboid or talonavicular joint will not be corrected through a limited hindfoot fusion.
Secondary osteoarthrosis of the calcaneocuboid joint may be another source of pain; should symptoms persist, treatment usually is with local steroid injections or a triple fusion.
The exact incidence of peroneal tendinitis occurring as a complication of calcaneus fractures is not known. Stenosing tenosynovitis of the peroneal tendon sheath may occur as a complication in such fractures. Surgical decompression and rerouting of the tendons can give relief.
Heel spurs may occur in association with fracture malunion. Such spurs can become painful. Primary treatment involves use of pressure-relieving pads. Surgical excision should only be undertaken as a last resort.
Nerve entrapment may occur with calcaneus fracture and may be a source of constant causalgia.
Jung and associates reported 2 cases of calcaneus fractures with posterior heel pain associated with a prominent superior calcaneal tuberosity impinging on the Achilles tendon after a tongue-type fracture. Malunion of the tongue fracture fragment resulted in the symptomatic bony prominence, which has been defined as the secondary Haglund deformity. In both cases reported by Jung et al, the patients continued to experience symptoms after nonsurgical treatment; they subsequently underwent resection of the superior calcaneal tuberosity. The clinical results of the operations were satisfactory, and both patients had complete pain relief.
Open calcaneus fractures are associated with a high risk of deep infection, despite the use of an aggressive treatment protocol to prevent it.
Preferred Examination
Physical examination
Physical examination usually is required to assess the integrity of tendons and ligaments. Approximately 75% of calcaneus fractures are intra-articular and involve the subtalar articular surface. Because these injuries are associated with a poor prognosis, it is important to identify patients with these fractures.
Imaging examinations
Conventional radiographs provide a benchmark for the diagnosis of fractures around the ankle in general, and they usually suffice for the diagnosis of the osseous component of the injury.
In general, conventional radiographs suffice; however, in most cases, supplemental imaging is needed to define characteristics fully, owing to the complex anatomy of this region. Comminuted fractures with fragment displacement of the calcaneus are common, and the relationship of the multiple fragments is difficult to appreciate on conventional radiographs.
Tenography is useful for assessing large lesions of the tendons.
CT is the investigation of choice in calcaneus fractures. Coronal and axial views are generally taken. CT best defines the relationship of bone fragments.
MRI is increasingly being used to characterize ankle sprains, occult fractures, bone bruises, growth-plate injuries, and ligamentous/tendon injuries. MRI is the criterion standard for identifying peroneal tendon injury. This injury is identified by the high signal intensity in tendon on T2-weighted axial views.
Scintigraphy may be useful in occult fractures and in the differential diagnosis of pathologic fractures. Pathologic features may become apparent on scintigraphy a few weeks before they become apparent on plain radiographs because the increased osteoblastic activity associated with stress fractures is more easily detected with scintigraphy.10
Limitations of Techniques
Conventional radiographs may be negative in cases involving subtle fractures, particularly in cases involving stress fractures. Comminuted fractures and displacement are common in fractures of the calcaneus, and the relationship of the multiple fragments is difficult to appreciate on conventional radiographs.
CT is the modality of choice, especially in complex fracture patterns, although it is expensive and it imparts a relatively high dose of radiation; it should be used sparingly in young patients or in pregnant patients. It is noteworthy that CT tends to be somewhat overutilized in the United States; this tendency has increased in recent years.
MRI is expensive and may cause problems in patients with claustrophobia. MRI is sensitive in the immediate documentation of stress changes in osseous structures. MRI is well known to show even minor stress changes (eg, after a marathon) that occur before the actual stress fracture.
A severe bone contusion is associated with multiple microfractures, whereas a stress fracture involves a linear component; the distinction between the 2 diagnoses may seem arbitrary.
In the absence of a linear component, it may be difficult to distinguish an underlying severe stress reaction associated with a bone contusion from a stress fracture on MRI. Bone contusion associated with a stress fracture may be difficult to distinguish from red marrow. With MRI, it may be difficult to detect small intra-articular fragments — a fact that likely limits the use of MRI on a routine basis.
Scintigraphy is sensitive in imaging bone trauma but lacks the specificity and the spatial resolution that MRI provides. A physiologic periosteal reaction, bone tumor, avascular necrosis, plantar fasciitis, or bone spur can cause false-positive findings.
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Further Reading
Keywords
calcaneus fracture, calcaneal fracture, tarsal fracture, foot fracture, heel fracture, talus fracture, calcaneum fracture, os-calcis fracture, os calcis fracture, Lover fracture, Lover's fracture
