546861
research-articleXXXX
FASXXX10.1177/1938640014546861Foot & Ankle SpecialistFoot & Ankle Specialist
vol. 8 / no. 2
Foot & Ankle Specialist
〈 Case Report 〉 The “Joint-Elevation” Calcaneus Fracture
A Rare Variant of the Intra-Articular Calcaneus Fracture-Dislocation Abstract: Calcaneus fractures are the most commonly fractured tarsal bone with approximately 75% being intra-articular in nature. Böhler’s angle has been found to be reliable and prognostic, and it has been used as a proxy for joint depression and articular involvement. It often guides the need for advanced imaging and/ or operative intervention. We describe a rare variant of intra-articular calcaneus fracture-dislocation that results in elevation of a portion of the posterior facet above the posterior talus and a seemingly normal or increased Böhler’s angle, which we call the “joint-elevation” calcaneus fracture. Orthopaedic surgeons should be aware of this previously undescribed variant in order to avoid inappropriate treatment or misdiagnosis. Level of Evidence: Therapeutic Level IV: Case Series Keywords: calcaneus fracture; trauma; joint-elevation; fracturedislocation
Timothy J. Miller, MD, and John Y. Kwon, MD
C
intra-articular calcaneus fractures alcaneus fractures are the most typically result in depression of the commonly fractured tarsal bone posterior facet secondary to the overlying with approximately 75% being talus being driven through the calcaneal intra-articular in nature. Typically body, creating primary and secondary occurring from either motor vehicle fracture lines. accidents or falls from height, intraBöhler’s angle, the angle subtended by articular calcaneus fractures occur from 2 lines drawn from the anterior calcaneal an axial load resulting in varying degrees of displacement and articular involvement. A rare variant of intra-articular Several classifications have been proposed over calcaneus fracture-dislocation results in the years. Essex-Lopresti,1 using plain radiographs, . . . a seemingly normal or increased classified calcaneus fractures into joint Böhler’s angle.” depression and tonguetype fractures based on whether the depressed posterior facet process, the posterior facet, and the was separated from or remained in superior posterior calcaneal tuberosity, is continuity with the calcaneal tuberosity, a common radiographic parameter respectively. Sanders2 classified joint measured on plain radiographs for the depression fractures using semicoronal evaluation of calcaneus fractures. Normal CT (computed tomography) imaging values are typically reported as between based on the number and location of 20° and 40°. Found to be reliable and fracture lines through the posterior facet. prognostic, it has been used as a proxy Regardless of classification used, for joint depression and articular
“
DOI: 10.1177/1938640014546861. From the Orthopaedic Foot and Ankle Fellow, Massachusetts General Hospital, Boston, Massachusetts (TJM); and Institute for Foot and Ankle Reconstruction at Mercy, Mercy Medical Center, Baltimore, Maryland (JYK). Address correspondence to: John Y. Kwon, MD, Director of Trauma Services, Institute for Foot and Ankle Reconstruction at Mercy, Mercy Medical Center, 301 St. Paul Place, Baltimore, MD 21202; e-mail: [email protected]. For reprints and permissions queries, please visit SAGE’s Web site at http://www.sagepub.com/journalsPermissions.nav. Copyright © 2014 The Author(s)
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involvement and often guides the need for advanced imaging and/or operative intervention. We describe a rare variant of intraarticular calcaneus fracture-dislocation that results in elevation of a portion of the posterior facet above the posterior talus and a seemingly normal or increased Böhler’s angle, which we call the “joint-elevation” calcaneus fracture. Calcaneus fracture-dislocations have similarly been described where typically the split lateral posterior facet dislocates laterally (but not above) the talus and becomes lodged subfibularly. Surgeons should be aware of this variant of the calcaneus fracture-dislocation because of the possibility of missed diagnosis or inappropriate treatment secondary to underestimation of injury severity.
Figure 1. Case 1: Injury film with Böhler’s angle of 42°.
Case 1 Patient DG is a 58-year-old male who sustained a fall off a ladder approximately 8 ft in height. He complained of isolated right foot pain. His foot was swollen and ecchymotic but his skin was intact and he was grossly neurovascularly intact. Plain radiographs appeared to demonstrate a relatively minimaly displaced calcaneus fracture with Böhler’s angle measuring 42° (Figure 1). CT scan was performed which demonstrated a Sanders type III fracture with extensive articular involvement and displacement of a portion of the fractured posterior facet superiorly above the posterior talar process (Figure 2). The patient was taken to the operating theatre approximately 14 days after injury. An extensile lateral approach was undertaken and given extensive comminution of the posterior facet found intraoperatively, calcaneal open reduction internal fixation with primary subtalar arthrodesis was performed (Figure 3). The patient went on to successful healing.
Case 2 Patient JO is a 57-year-old male, history of liver transplantation, who
Figure 2. Case 1: Computed tomography scan showing articular comminution.
sustained a fall off a ladder approximately 7 ft in height. He complained of isolated left foot pain. His foot was swollen, ecchymotic with extensive fracture blistering along the posterior medial ankle. His skin was intact and he was grossly neurovascularly intact. Plain radiographs appeared to demonstrate a displaced calcaneus fracture with
Böhler’s angle measuring 44° (Figure 4). CT scan was performed, which demonstrated Sanders type III fracture with extensive articular involvement and displacement of a portion of the fractured posterior facet superiorly above the posterior talar process (Figure 5). The patient was taken to the operating theatre approximately 12 days after injury. A
Downloaded from fas.sagepub.com at UNIV OF PITTSBURGH on November 17, 2015
vol. 8 / no. 2
Foot & Ankle Specialist
Discussion
Figure 3. Case 1: Postoperative x-ray with restoration of calcaneal height after calcaneus fixation and primary subtalar fusion.
Figure 4. Case 2: Injury film with Böhler’s angle of 44°.
sinus tarsi approach was undertaken to help mitigate risks of wound-healing complications given his immunosuppressive medication regimen. Intraoperative inspection confirmed the CT findings—a portion of the posterior
facet being displaced superior to the posterior talar process, which was then reduced into anatomic position. Open reduction internal fixation was performed and the patient went on to successful healing (Figure 6).
Multiple classification systems for calcaneus fractures have been proposed in the literature. Essex-Lopresti1 described calcaneus fractures as divided into 2 groups: joint depression type and tongue type fractures. Both fracture types in his classification have a primary fracture line dividing the calcaneus into an anterolateral fragment and a posteromedial fragment at the angle of Gissane. Joint depression type fractures have a secondary fracture line that separates the articular fragment from the tuberosity, whereas in a tongue type fracture the articular fragment and tuberosity remain attached.1 Sanders2 classified calcaneus fractures based on the number of fractures seen on a coronal plane CT scan of the posterior facet. The principal fragments are lateral, central, medial, and the sustentaculum. Fractures are classified as types I through IV, with subclassifications using A, B and/or C depending on which fracture lines are present in a particular fracture.2 There have also been classifications described by Soeur and Remy,3 Zwipp et al,4 Crosby and Fitzgibbons,5 Miric and Paterson,6 and others. None of these classification schemes address calcaneal fracture-dislocations specifically. Böhler’s angle normal ranges have been studied in several population based studies.7-10 These have shown a mean Böhler’s angle of 30° to 36.4° in adults, with an upper limit of normal Böhler’s angle (defined as 2 SD above the mean) of 42° to 44.8°. The patients described in this article presented with a Böhler’s angle of 42° and 44°, respectively. These are at or above the high end of the previously reported normal ranges in these population studies. Joint-elevation calcaneus fractures are exceedingly rare injuries. We retrospectively reviewed all calcaneus fractures that presented to 2 level I trauma centers that share a combined trauma database and found only 2 cases over a 5 year period, from June 30, 2006 to June 20, 2011. A total of 578
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Figure 5. Case 2: Computed tomography scan showing articular comminution.
Figure 6. Case 2: Postoperative x-ray with restoration of calcaneal anatomy.
calcaneus fractures were documented during that time period with 97 fractures being extra-articular and 13 fractures involving skeletally immature patients. A total of 468 calcaneus fractures were intra-articular in nature. We estimate the incidence of this variant to be less than 0.2% of intra-articular calcaneus fractures; 6 other calcaneal fracturedislocations were identified but they exhibited lateral posterior facet dislocation and not direct superior elevation (further discussed later in the text). However, given that these fractures may present with a normal
appearing Böhler’s angle on plain imaging, additional CT imaging of such patients may not have been performed such that the incidence is possibly higher than what we could determine on retrospective review. Surgeons should be aware of this variant, which to our knowledge has not been previously described, because of the possibility of missed diagnosis or inappropriate treatment secondary to underestimation of injury severity. This may be the case given the relative normal appearance of the calcaneus on lateral plain radiographs. In both our
cases however, although the calcaneus fracture appeared relatively nondisplaced on plain radiographs, Böhler’s angle measured higher than the typical range considered normal as described in the literature because of the elevation of the posterior facet. Therefore, we recommend surgeons have a lower threshold to obtain CT imaging of any obvious calcaneus fracture that exhibits an increased Böhler’s angle. Böhler’s angle has been used to assist in diagnosis,11 as well as evaluating the injury severity.12 It has also been correlated to outcomes.13 Kim et al reported on the double density sign (dual radiodensities noted from superior dislocation of the fracture fragment) variant in fracturedislocations of the calcaneus.14 Originally described by Sanders,2 they similarly reported an increased initial Böhler’s angle with subsequent CT demonstrating fracture dislocation subfibularly. Schepers et al15 reported on clinical outcomes from 17 cases of calcaneal fracture-dislocations, the largest series in the literature. While they reported 16 out of 17 cases demonstrating the double density sign, they did not specifically report on Böhler’s angle. In contrast to this report, they reported fracturedislocations as occurring from the posterolateral fragment dislocating laterally to the talus resulting in locked dislocation between the lateral talus and fibula. The joint-elevation fracture is likely a variant of injuries as previously characterized. The precise mechanism that causes joint-elevation fractures as opposed to joint depression, tongue type or previously reported lateral subfibular fracture-dislocations is unclear. Previous reports of calcaneal fracture dislocations have suggested rupture of the lateral calcaneofibular ligament or associated distal fibula fracture.16 We doubt that differences in foot or ankle position at the time of axial load lead to this injury, as the rarity of this injury would preclude this as a hypothesis. Athavale et al17 looked at the internal
Downloaded from fas.sagepub.com at UNIV OF PITTSBURGH on November 17, 2015
vol. 8 / no. 2
Foot & Ankle Specialist
architecture of the various compression and tension trabeculae and hypothesized that relative areas of hypodensity, as well as differences in lamellar density and structure, lead to the development of the primary and secondary fracture lines commonly seen. We hypothesize that differences in lamellar density may account for this rare variation. Increased lamellar density at the superior portion of the posterior facet in some individuals may cause creation of the secondary fracture below this area of hyperdensity which results in elevation of the posterior facet. An intact lateral calcaneofibular ligament without associated fibular fracture may cause superior displacement of the posterior facet as opposed to laterally as previously described.
Summary These cases illustrate a rare variant of calcaneus fracture-dislocation, where the Böhler’s angle is at or above the upper limit of normal. We call this the “jointelevation” calcaneus fracture. Orthopaedic surgeons should be aware of this previously undescribed variant in order to avoid inappropriate treatment or misdiagnosis.
References 1. Essex-Lopresti P. The mechanism, reduction technique, and results in fractures of the os calcis. Br J Surg. 1952;39:395-419. 2. Sanders R. Displaced intra-articular fractures of the calcaneus. J Bone Joint Surg Am. 2000;82:225-250. 3. Soeur R, Remy R. Fractures of the calcaneus with displacement of the thalamic portion. J Bone Joint Surg Br. 1975;57:413-421. 4. Zwipp H, Tscherne H, Thermann H, Weber T. Osteosyntheses of displaced intraarticular fractures of the calcaneus. Results in 123 cases. Clin Orthop Relat Res. 1993;(290):76-86. 5. Crosby LA, Fitzgibbons T. Computerized tomography scanning of acute intraarticular fractures of the calcaneus. A new classification system. J Bone Joint Surg Am. 1990;72:852-859. 6. Miric A, Patterson BM. Pathoanatomy of intra-articular fractures of the calcaneus. J Bone Joint Surg Am. 1998;80:207-212. 7. Willmott H, Stanton J, Southgate C. Böhler’s angle—What is normal in the uninjured British population? Foot Ankle Surg. 2012;18:187-189. 8. Khoshhal KI, Ibrahim AF, Al-Nakshabandi NA, Zamzam MM, Al-Boukai AA, Zamzami MM. Böhler’s and Gissane’s angles of the calcaneus in the Saudi population. Saudi Med J. 2004;25: 1967-1970. 9. Seyahi A, Uludag˘ S, Koyuncu LO, Atalar AC, Demirhan M. The calcaneal angles
in the Turkish population. Acta Orthop Traumatol Turc. 2009;43:406-411. 10. Chen MY, Bohrer SP, Kelley TF. Boehler’s angle: a reappraisal. Ann Emerg Med. 1991;20:122-124. 11. Isaacs JD, Baba M, Huang P, et al. The diagnostic accuracy of Böhler’s angle in fractures of the calcaneus. J Emerg Med. 2013;45:879-884. 12. Su Y, Chen W, Zhang T, Wu X, Wu Z, Zhang Y. Böhler’s angle’s role in assessing the injury severity and functional outcome of internal fixation for displaced intraarticular calcaneal fractures: a retrospective study. BMC Surg. 2013;13:40. 13. Loucks C, Buckley R. Böhler’s angle: correlation with outcome in displaced intra-articular calcaneal fractures. J Orthop Trauma. 1999;13:554-558. 14. Kim DH, Berkowitz MJ. Double density sign variant in fracture-dislocation of the calcaneus: clinical tip. Foot Ankle Int. 2012;33:524-525. 15. Schepers T, Backes M, Schep NW, Carel Goslings J, Luitse JS. Functional outcome following a locked fracture-dislocation of the calcaneus. Int Orthop. 2013;37: 1833-1838. 16. Court-Brown CM, Boot DA, Kellam JF. Fracture dislocation of the calcaneus. A report of two cases. Clin Orthop Relat Res. 1986;(213):201-206. 17. Athavale SA, Joshi SD, Joshi SS. Internal architecture of calcaneus: correlations with mechanics and pathoanatomy of calcaneal fractures. Surg Radiol Anat. 2010;32:115-122.
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research-articleXXXX
FASXXX10.1177/1938640014546861Foot & Ankle SpecialistFoot & Ankle Specialist
vol. 8 / no. 2
Foot & Ankle Specialist
〈 Case Report 〉 The “Joint-Elevation” Calcaneus Fracture
A Rare Variant of the Intra-Articular Calcaneus Fracture-Dislocation Abstract: Calcaneus fractures are the most commonly fractured tarsal bone with approximately 75% being intra-articular in nature. Böhler’s angle has been found to be reliable and prognostic, and it has been used as a proxy for joint depression and articular involvement. It often guides the need for advanced imaging and/ or operative intervention. We describe a rare variant of intra-articular calcaneus fracture-dislocation that results in elevation of a portion of the posterior facet above the posterior talus and a seemingly normal or increased Böhler’s angle, which we call the “joint-elevation” calcaneus fracture. Orthopaedic surgeons should be aware of this previously undescribed variant in order to avoid inappropriate treatment or misdiagnosis. Level of Evidence: Therapeutic Level IV: Case Series Keywords: calcaneus fracture; trauma; joint-elevation; fracturedislocation
Timothy J. Miller, MD, and John Y. Kwon, MD
C
intra-articular calcaneus fractures alcaneus fractures are the most typically result in depression of the commonly fractured tarsal bone posterior facet secondary to the overlying with approximately 75% being talus being driven through the calcaneal intra-articular in nature. Typically body, creating primary and secondary occurring from either motor vehicle fracture lines. accidents or falls from height, intraBöhler’s angle, the angle subtended by articular calcaneus fractures occur from 2 lines drawn from the anterior calcaneal an axial load resulting in varying degrees of displacement and articular involvement. A rare variant of intra-articular Several classifications have been proposed over calcaneus fracture-dislocation results in the years. Essex-Lopresti,1 using plain radiographs, . . . a seemingly normal or increased classified calcaneus fractures into joint Böhler’s angle.” depression and tonguetype fractures based on whether the depressed posterior facet process, the posterior facet, and the was separated from or remained in superior posterior calcaneal tuberosity, is continuity with the calcaneal tuberosity, a common radiographic parameter respectively. Sanders2 classified joint measured on plain radiographs for the depression fractures using semicoronal evaluation of calcaneus fractures. Normal CT (computed tomography) imaging values are typically reported as between based on the number and location of 20° and 40°. Found to be reliable and fracture lines through the posterior facet. prognostic, it has been used as a proxy Regardless of classification used, for joint depression and articular
“
DOI: 10.1177/1938640014546861. From the Orthopaedic Foot and Ankle Fellow, Massachusetts General Hospital, Boston, Massachusetts (TJM); and Institute for Foot and Ankle Reconstruction at Mercy, Mercy Medical Center, Baltimore, Maryland (JYK). Address correspondence to: John Y. Kwon, MD, Director of Trauma Services, Institute for Foot and Ankle Reconstruction at Mercy, Mercy Medical Center, 301 St. Paul Place, Baltimore, MD 21202; e-mail: [email protected]. For reprints and permissions queries, please visit SAGE’s Web site at http://www.sagepub.com/journalsPermissions.nav. Copyright © 2014 The Author(s)
Downloaded from fas.sagepub.com at UNIV OF PITTSBURGH on November 17, 2015
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involvement and often guides the need for advanced imaging and/or operative intervention. We describe a rare variant of intraarticular calcaneus fracture-dislocation that results in elevation of a portion of the posterior facet above the posterior talus and a seemingly normal or increased Böhler’s angle, which we call the “joint-elevation” calcaneus fracture. Calcaneus fracture-dislocations have similarly been described where typically the split lateral posterior facet dislocates laterally (but not above) the talus and becomes lodged subfibularly. Surgeons should be aware of this variant of the calcaneus fracture-dislocation because of the possibility of missed diagnosis or inappropriate treatment secondary to underestimation of injury severity.
Figure 1. Case 1: Injury film with Böhler’s angle of 42°.
Case 1 Patient DG is a 58-year-old male who sustained a fall off a ladder approximately 8 ft in height. He complained of isolated right foot pain. His foot was swollen and ecchymotic but his skin was intact and he was grossly neurovascularly intact. Plain radiographs appeared to demonstrate a relatively minimaly displaced calcaneus fracture with Böhler’s angle measuring 42° (Figure 1). CT scan was performed which demonstrated a Sanders type III fracture with extensive articular involvement and displacement of a portion of the fractured posterior facet superiorly above the posterior talar process (Figure 2). The patient was taken to the operating theatre approximately 14 days after injury. An extensile lateral approach was undertaken and given extensive comminution of the posterior facet found intraoperatively, calcaneal open reduction internal fixation with primary subtalar arthrodesis was performed (Figure 3). The patient went on to successful healing.
Case 2 Patient JO is a 57-year-old male, history of liver transplantation, who
Figure 2. Case 1: Computed tomography scan showing articular comminution.
sustained a fall off a ladder approximately 7 ft in height. He complained of isolated left foot pain. His foot was swollen, ecchymotic with extensive fracture blistering along the posterior medial ankle. His skin was intact and he was grossly neurovascularly intact. Plain radiographs appeared to demonstrate a displaced calcaneus fracture with
Böhler’s angle measuring 44° (Figure 4). CT scan was performed, which demonstrated Sanders type III fracture with extensive articular involvement and displacement of a portion of the fractured posterior facet superiorly above the posterior talar process (Figure 5). The patient was taken to the operating theatre approximately 12 days after injury. A
Downloaded from fas.sagepub.com at UNIV OF PITTSBURGH on November 17, 2015
vol. 8 / no. 2
Foot & Ankle Specialist
Discussion
Figure 3. Case 1: Postoperative x-ray with restoration of calcaneal height after calcaneus fixation and primary subtalar fusion.
Figure 4. Case 2: Injury film with Böhler’s angle of 44°.
sinus tarsi approach was undertaken to help mitigate risks of wound-healing complications given his immunosuppressive medication regimen. Intraoperative inspection confirmed the CT findings—a portion of the posterior
facet being displaced superior to the posterior talar process, which was then reduced into anatomic position. Open reduction internal fixation was performed and the patient went on to successful healing (Figure 6).
Multiple classification systems for calcaneus fractures have been proposed in the literature. Essex-Lopresti1 described calcaneus fractures as divided into 2 groups: joint depression type and tongue type fractures. Both fracture types in his classification have a primary fracture line dividing the calcaneus into an anterolateral fragment and a posteromedial fragment at the angle of Gissane. Joint depression type fractures have a secondary fracture line that separates the articular fragment from the tuberosity, whereas in a tongue type fracture the articular fragment and tuberosity remain attached.1 Sanders2 classified calcaneus fractures based on the number of fractures seen on a coronal plane CT scan of the posterior facet. The principal fragments are lateral, central, medial, and the sustentaculum. Fractures are classified as types I through IV, with subclassifications using A, B and/or C depending on which fracture lines are present in a particular fracture.2 There have also been classifications described by Soeur and Remy,3 Zwipp et al,4 Crosby and Fitzgibbons,5 Miric and Paterson,6 and others. None of these classification schemes address calcaneal fracture-dislocations specifically. Böhler’s angle normal ranges have been studied in several population based studies.7-10 These have shown a mean Böhler’s angle of 30° to 36.4° in adults, with an upper limit of normal Böhler’s angle (defined as 2 SD above the mean) of 42° to 44.8°. The patients described in this article presented with a Böhler’s angle of 42° and 44°, respectively. These are at or above the high end of the previously reported normal ranges in these population studies. Joint-elevation calcaneus fractures are exceedingly rare injuries. We retrospectively reviewed all calcaneus fractures that presented to 2 level I trauma centers that share a combined trauma database and found only 2 cases over a 5 year period, from June 30, 2006 to June 20, 2011. A total of 578
Downloaded from fas.sagepub.com at UNIV OF PITTSBURGH on November 17, 2015
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Figure 5. Case 2: Computed tomography scan showing articular comminution.
Figure 6. Case 2: Postoperative x-ray with restoration of calcaneal anatomy.
calcaneus fractures were documented during that time period with 97 fractures being extra-articular and 13 fractures involving skeletally immature patients. A total of 468 calcaneus fractures were intra-articular in nature. We estimate the incidence of this variant to be less than 0.2% of intra-articular calcaneus fractures; 6 other calcaneal fracturedislocations were identified but they exhibited lateral posterior facet dislocation and not direct superior elevation (further discussed later in the text). However, given that these fractures may present with a normal
appearing Böhler’s angle on plain imaging, additional CT imaging of such patients may not have been performed such that the incidence is possibly higher than what we could determine on retrospective review. Surgeons should be aware of this variant, which to our knowledge has not been previously described, because of the possibility of missed diagnosis or inappropriate treatment secondary to underestimation of injury severity. This may be the case given the relative normal appearance of the calcaneus on lateral plain radiographs. In both our
cases however, although the calcaneus fracture appeared relatively nondisplaced on plain radiographs, Böhler’s angle measured higher than the typical range considered normal as described in the literature because of the elevation of the posterior facet. Therefore, we recommend surgeons have a lower threshold to obtain CT imaging of any obvious calcaneus fracture that exhibits an increased Böhler’s angle. Böhler’s angle has been used to assist in diagnosis,11 as well as evaluating the injury severity.12 It has also been correlated to outcomes.13 Kim et al reported on the double density sign (dual radiodensities noted from superior dislocation of the fracture fragment) variant in fracturedislocations of the calcaneus.14 Originally described by Sanders,2 they similarly reported an increased initial Böhler’s angle with subsequent CT demonstrating fracture dislocation subfibularly. Schepers et al15 reported on clinical outcomes from 17 cases of calcaneal fracture-dislocations, the largest series in the literature. While they reported 16 out of 17 cases demonstrating the double density sign, they did not specifically report on Böhler’s angle. In contrast to this report, they reported fracturedislocations as occurring from the posterolateral fragment dislocating laterally to the talus resulting in locked dislocation between the lateral talus and fibula. The joint-elevation fracture is likely a variant of injuries as previously characterized. The precise mechanism that causes joint-elevation fractures as opposed to joint depression, tongue type or previously reported lateral subfibular fracture-dislocations is unclear. Previous reports of calcaneal fracture dislocations have suggested rupture of the lateral calcaneofibular ligament or associated distal fibula fracture.16 We doubt that differences in foot or ankle position at the time of axial load lead to this injury, as the rarity of this injury would preclude this as a hypothesis. Athavale et al17 looked at the internal
Downloaded from fas.sagepub.com at UNIV OF PITTSBURGH on November 17, 2015
vol. 8 / no. 2
Foot & Ankle Specialist
architecture of the various compression and tension trabeculae and hypothesized that relative areas of hypodensity, as well as differences in lamellar density and structure, lead to the development of the primary and secondary fracture lines commonly seen. We hypothesize that differences in lamellar density may account for this rare variation. Increased lamellar density at the superior portion of the posterior facet in some individuals may cause creation of the secondary fracture below this area of hyperdensity which results in elevation of the posterior facet. An intact lateral calcaneofibular ligament without associated fibular fracture may cause superior displacement of the posterior facet as opposed to laterally as previously described.
Summary These cases illustrate a rare variant of calcaneus fracture-dislocation, where the Böhler’s angle is at or above the upper limit of normal. We call this the “jointelevation” calcaneus fracture. Orthopaedic surgeons should be aware of this previously undescribed variant in order to avoid inappropriate treatment or misdiagnosis.
References 1. Essex-Lopresti P. The mechanism, reduction technique, and results in fractures of the os calcis. Br J Surg. 1952;39:395-419. 2. Sanders R. Displaced intra-articular fractures of the calcaneus. J Bone Joint Surg Am. 2000;82:225-250. 3. Soeur R, Remy R. Fractures of the calcaneus with displacement of the thalamic portion. J Bone Joint Surg Br. 1975;57:413-421. 4. Zwipp H, Tscherne H, Thermann H, Weber T. Osteosyntheses of displaced intraarticular fractures of the calcaneus. Results in 123 cases. Clin Orthop Relat Res. 1993;(290):76-86. 5. Crosby LA, Fitzgibbons T. Computerized tomography scanning of acute intraarticular fractures of the calcaneus. A new classification system. J Bone Joint Surg Am. 1990;72:852-859. 6. Miric A, Patterson BM. Pathoanatomy of intra-articular fractures of the calcaneus. J Bone Joint Surg Am. 1998;80:207-212. 7. Willmott H, Stanton J, Southgate C. Böhler’s angle—What is normal in the uninjured British population? Foot Ankle Surg. 2012;18:187-189. 8. Khoshhal KI, Ibrahim AF, Al-Nakshabandi NA, Zamzam MM, Al-Boukai AA, Zamzami MM. Böhler’s and Gissane’s angles of the calcaneus in the Saudi population. Saudi Med J. 2004;25: 1967-1970. 9. Seyahi A, Uludag˘ S, Koyuncu LO, Atalar AC, Demirhan M. The calcaneal angles
in the Turkish population. Acta Orthop Traumatol Turc. 2009;43:406-411. 10. Chen MY, Bohrer SP, Kelley TF. Boehler’s angle: a reappraisal. Ann Emerg Med. 1991;20:122-124. 11. Isaacs JD, Baba M, Huang P, et al. The diagnostic accuracy of Böhler’s angle in fractures of the calcaneus. J Emerg Med. 2013;45:879-884. 12. Su Y, Chen W, Zhang T, Wu X, Wu Z, Zhang Y. Böhler’s angle’s role in assessing the injury severity and functional outcome of internal fixation for displaced intraarticular calcaneal fractures: a retrospective study. BMC Surg. 2013;13:40. 13. Loucks C, Buckley R. Böhler’s angle: correlation with outcome in displaced intra-articular calcaneal fractures. J Orthop Trauma. 1999;13:554-558. 14. Kim DH, Berkowitz MJ. Double density sign variant in fracture-dislocation of the calcaneus: clinical tip. Foot Ankle Int. 2012;33:524-525. 15. Schepers T, Backes M, Schep NW, Carel Goslings J, Luitse JS. Functional outcome following a locked fracture-dislocation of the calcaneus. Int Orthop. 2013;37: 1833-1838. 16. Court-Brown CM, Boot DA, Kellam JF. Fracture dislocation of the calcaneus. A report of two cases. Clin Orthop Relat Res. 1986;(213):201-206. 17. Athavale SA, Joshi SD, Joshi SS. Internal architecture of calcaneus: correlations with mechanics and pathoanatomy of calcaneal fractures. Surg Radiol Anat. 2010;32:115-122.
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