JBJS | Pathoanatomy of Intra-Articular Fractures of the Calcaneus*

The Journal of Bone & Joint Surgery, Volume 80, Issue 2

Articles | February 01, 1998

Pathoanatomy of Intra-Articular Fractures of the Calcaneus*

ALEXANDER MIRIC, M.D.†; BRENDAN M. PATTERSON, M.D.†, CLEVELAND, OHIO

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Investigation performed at the MetroHealth Medical Center, Case Western Reserve University, Cleveland

The Journal of Bone & Joint Surgery. 1998; 80:207-12

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Abstract

Radiographs of 220 calcaneal fractures (205 patients) were reviewed retrospectively. One hundred and sixty-three fractures were intra-articular; thirty (18 per cent) of the 163 fractures were a tongue-type injury, and 133 (82 per cent) were a joint-depression injury. Plain radiographs and computerized tomography scans in the coronal and axial planes were available for 116 intra-articular fractures (106 patients). These studies were reviewed, and the 116 fractures were grouped according to the Sanders classification of calcaneal fractures and the anterior extension of the primary fracture line was evaluated. Sixty-two primary fracture lines (53 per cent) extended into one articular surface; twenty-three (20 per cent), into two articular surfaces; twenty-three (20 per cent), into a periarticular location; and eight (7 per cent), into a medial or lateral location. Sixty-seven (58 per cent) involved the calcaneocuboid joint, thirty-one (27 per cent) involved the anterior facet of the talocalcaneal joint, and ten (9 per cent) involved the middle facet of the talocalcaneal joint. A distinct anterolateral fragment was identified in 108 fractures (93 per cent). Plain radiographs failed to demonstrate the anterior extension of fifty-one (47 per cent) of the primary fracture lines. The prevalence of involvement of the anterior facet was significantly greater in Sanders type-III fractures (sixteen of thirty-five; 46 per cent) than in the other types (p < 0.01). The prevalence of involvement of the calcaneocuboid joint and the middle facet was evenly distributed among the fracture types.The primary fracture line typically extends anterior to the angle of Gissane, creating a relatively consistent anterolateral fracture fragment. The primary fracture line cannot be reliably seen on plain radiographs and is better visualized on computerized tomographic scans.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Until recently, there has been only minimum interest in the extension of calcaneal fractures anterior to the posterior facet. Numerous descriptions of the anatomy of calcaneal fractures can be found in the literature of the last 150 years. Malgaigne is credited²¹ with the first accurate description of such extension in 1843, while Böhler is thought to have been the first to devise a classification and description based on the mechanism of injury. Many authors have refined Böhler's basic description of the anatomy of calcaneal fractures. Essex-Lopresti introduced the concept of intra-articular and extra-articular fractures and subdivided intra-articular fractures into tongue-type and joint-depression injuries. Many authors^{4,6,15,22,23,29} have contributed to the understanding of this fracture. However, as different as the various classification schemes and approaches to treatment are, all emphasize the central importance of the posterior facet. This perhaps can be attributed to the fact that plain radiographic evaluation of calcaneal articular surfaces highlights the posterior facet.

The advent of computerized tomography prompted a number of authors to pay closer attention to the anatomy of the anterior portion of the calcaneus. There are three articular surfaces anterior to the posterior facet: the surfaces of the anterior and middle facets of the talocalcaneal joint and the surface of the calcaneocuboid joint. It has been reported that alterations in the alignment of the joints may contribute to degenerative osteoarthrosis and pain in the subtalar joint^14,26,27. We are not aware of any study in which investigators attempted to delineate the degree to which the articular surfaces anterior to the posterior facet are involved in calcaneal fractures.

The purposes of the present study were to define the anterior extension of the primary fracture line in calcaneal fractures and to determine the value of computerized tomography and plain radiography in the evaluation of the pathoanatomy of the anterior portion of the calcaneus.

*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

†Department of Orthopaedic Surgery, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, Ohio 44109.

*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

†Department of Orthopaedic Surgery, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, Ohio 44109.

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Fig. 1 Schematic representation of the coronal view of the posterior facet, illustrating the Sanders classification^16-18 of calcaneal fractures on computerized tomography scans. A = the lateral third of the posterior facet, B = the central third, and C = the medial third.

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Fig. 2-A Lateral radiograph and computerized tomography scan of a fractured calcaneus with an anterolateral fragment. The computerized tomography scan also reveals extension of the fracture line into the calcaneocuboid joint.

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Fig. 2-B Lateral radiograph and computerized tomography scan of a fractured calcaneus with an anterolateral fragment. The computerized tomography scan also reveals extension of the fracture line into the calcaneocuboid joint.

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Fig. 3-A: Lateral radiograph of a fractured calcaneus with no identifiable anterolateral fragment.

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Fig. 3-B: Transverse computerized tomography scan revealing extension of the fracture line through the middle facet.

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Fig. 4 Transverse computerized tomography scan showing extension of a fracture line through the anterior facet.

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Fig. 5-A: Schematic representation of the dorsal view of the calcaneus, demonstrating anterior extension of the primary fracture line into articular locations. The prevalence of extension into each anterior articulation in the present study is indicated.

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Fig. 5-B: Schematic representation of the most common types of periarticular extension of the fracture line.

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TABLE I LOCATION OF ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO THE CHARACTERISTICS OF THE EXTENSION

		Location of Extension
Type of Extension	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
Articular
One surface	62	47	10	5
Two surfaces	23	20	21	5
Non-articular
Periarticular	23	—	—	—
Medial or lateral	8	—	—	—
Total	116	67	31	10

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TABLE I LOCATION OF ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO THE CHARACTERISTICS OF THE EXTENSION

		Location of Extension
Type of Extension	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
Articular
One surface	62	47	10	5
Two surfaces	23	20	21	5
Non-articular
Periarticular	23	—	—	—
Medial or lateral	8	—	—	—
Total	116	67	31	10

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TABLE II LOCATION OF THE ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO SANDERS TYPE^16—18

*The difference in prevalence from the other types of fractures is significant (p < 0.01). †The number of extensions does not add up to the number of fractures because twenty-three primary fracture lines extended into two articular surfaces and thirty-one were non-articular.

		Location of Extension
Type of Fracture	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
I	5	2	0	0
II	70	37 (53%)	14 (20%)	6 (9%)
III	35	22 (63%)	16 (46%)*	3 (9%)
IV	6	6	1	1
Total†	116	67 (58%)	31 (27%)	10 (9%)

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TABLE II LOCATION OF THE ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO SANDERS TYPE^16—18

		Location of Extension
Type of Fracture	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
I	5	2	0	0
II	70	37 (53%)	14 (20%)	6 (9%)
III	35	22 (63%)	16 (46%)*	3 (9%)
IV	6	6	1	1
Total†	116	67 (58%)	31 (27%)	10 (9%)

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

The records of all patients who were seen with a calcaneal fracture at MetroHealth Medical Center, a level-I trauma center in Cleveland, Ohio, from May 1988 to May 1995, were retrospectively reviewed. Two hundred and seventy-eight patients were identified through an inpatient hospital database, and radiographs were available for 205 (220 fractures). Fifty-seven extra-articular fractures (26 per cent) were excluded from the study population, leaving 163 intra-articular fractures: thirty (18 per cent) of these were tongue-type fractures and 133 (82 per cent) were joint-depression fractures. Computerized tomography scans and adequate plain radiographs—that is, anteroposterior and lateral radiographs of the foot and a Harris axial radiograph of the calcaneus—were available for 116 fractures. Broden radiographs were also available for many fractures, although they were not a prerequisite for inclusion in the study. The computerized tomography scans were made parallel to the sole of the foot (axial) and perpendicular to the posterior facet (coronal) in two-millimeter increments.

All of the fractures that had been studied with computerized tomography were grouped according to the Sanders classification for intra-articular calcaneal fractures^16-18, a four-part system based on the coronal and axial scan sections at the widest portion of the posterior facet of the talus (Fig. 1). Type I indicates a non-displaced articular fracture; type II, a two-part fracture of the posterior facet; type III, a three-part articular fracture; and type IV, a four-part or highly comminuted articular fracture. The letters A, B, and C are used to define a fracture line in the lateral, central, or medial third of the posterior facet.

For the purposes of this study, when multiple fracture lines extended through the posterior facet, the one that produced the most articular displacement was defined as the primary fracture line. All fractures were classified by one of us (A. M.). Comminuted or complex fractures were classified by consensus of the two of us.

A chi-square test was used to evaluate the relationship between the type of fracture, according to the Sanders classification^16-18, and the extension of the articular fracture. P values were two-sided with an alpha of 0.05. A 2 x 2 contingency table was designed with use of type-III fractures versus non-type-III fractures and the presence of extension into the anterior facet versus no extension into the anterior facet.

Results

Introduction | Materials and Methods | Results | Discussion | References

Five (4 per cent) of the 116 fractures were type I, seventy (60 per cent) were type II, thirty-five (30 per cent) were type III, and six (5 per cent) were type IV. The most commonly diagnosed fracture type was IIA (fifty-one fractures; 44 per cent). Sixty-two (53 per cent) of the primary fracture lines extended anteriorly into one anterior articular surface, and twenty-three (20 per cent) split anterior to the angle of Gissane and extended into two anterior articular surfaces. Thus, eighty-five primary fracture lines (73 per cent) extended anteriorly through a total of 108 articular surfaces (Table I). Sixty-seven (58 per cent) of the primary fracture lines involved the calcaneocuboid joint (Figs. 2-A and 2-B), ten (9 per cent) involved the middle facet of the talocalcaneal joint (Figs. 3-A and 3-B), and thirty-one (27 per cent) involved the anterior facet of the talocalcaneal joint (Figs. 4 and 5-A) (Table I). Highly comminuted fractures include fracture lines oriented in the coronal plane (Fig. 5-B).

Of the remaining thirty-one primary fracture lines, twenty-three (20 per cent) extended to a periarticular area immediately lateral or medial to the calcaneocuboid joint. The other eight (7 per cent) extended to the medial wall of the calcaneus proximal to the middle facet or to the lateral wall of the calcaneus immediately anterior to the posterior facet (Fig. 5-B) (Table I).

A distinct anterolateral fracture fragment was identified on the computerized tomography scans of 108 fractures (93 per cent) (Figs. 2-A and 2-B)—that is, all of the fractures except the eight that extended to the medial or lateral wall. The plain radiographs of those 108 fractures were reviewed again, by an investigator who was blinded to the findings on the computerized tomography scans, in an effort to determine the sensitivity of plain radiographs with regard to visualizing this fragment. The plain radiographs demonstrated the anterior extension of forty-seven (70 per cent) of the sixty-seven primary fracture lines that extended into the calcaneocuboid joint and the anterior extension of only ten (24 per cent) of the forty-one primary fracture lines that extended into the anterior or middle facet. Plain radiographs failed to identify the anterior extension of the primary fracture line in fifty-one (47 per cent) of the 108 fractures for which an anterolateral fragment was identified.

There was a significantly greater prevalence of involvement of the anterior facet among type-III fractures (sixteen of thirty-five, 46 per cent) than among the other types (p < 0.01). Involvement of the calcaneocuboid joint and the middle facet was distributed relatively evenly among all fracture types (Table II).

Discussion

Introduction | Materials and Methods | Results | Discussion | References

The anatomy of a normal, uninjured calcaneus is complex because of the undulating facets that articulate with the talus and cuboid. The intricate relationships between the talocalcaneal and calcaneocuboid articulations are the basis for the complex kinematics of subtalar motion that make normal gait possible. A clear understanding of the pathoanatomy of calcaneal fractures and its impact on function of the lower extremity is essential if one is to begin to understand the controversies surrounding the treatment of calcaneal fractures.

Letournel proposed the concept of a constant separation line to describe the orientation and location of a very common pattern of osseous injury of the calcaneus. This constant separation line runs longitudinally along the sagittal axis of the calcaneus from the posterior facet to the calcaneocuboid joint or the anterior facet, or both. The orientation of the fracture line in this manner agrees with the concepts postulated by Palmer as well as Essex-Lopresti on the basis of their clinical work and is further supported by the experimental studies of Carr et al.⁶. These views of fracture pathoanatomy are in contradistinction to the concepts proposed by Warrick and Bremner as well as Stephenson²³, who suggested that the fracture line was oriented closer to the coronal plane and effectively split the calcaneus into anterior and posterior segments. The present study supports the concepts of a relatively constant fracture line that passes through the sagittal axis of the calcaneus and frequently extends into its anterior aspect.

The calcaneus fractures along lines that are frequently consistent among injuries. Joint-depression and tongue-type fractures represent a spectrum of injury of the calcaneus. These two patterns share a relatively constant fracture line that courses in the sagittal plane of the calcaneus. With a joint-depression injury, a transverse fracture in the coronal plane of the calcaneus develops between the posterior facet and the insertion of the Achilles tendon. The location of the transverse fracture forces the posterior facet inferiorly. The medial portion of the posterior facet may remain in continuity with the anterior and middle facets, the amount of so-called blowout of the lateral wall is variable, and the comminution anterior to the angle of Gissane is generally mild. In the tongue-type pattern of injury, the sagittal fracture line is similar to that in the joint-depression pattern, but the coronal failure occurs posterior to the tuberosity. The posterior facet rotates inferiorly, fragmentation of the lateral wall may be mild, and comminution anterior to the angle of Gissane can often be extensive. An anterolateral fragment and sagittal orientation of the fracture line are found in both patterns.

The advent of computerized tomography has improved imaging of the anatomy of calcaneal fractures, especially in the region anterior to the posterior facet of the talocalcaneal joint^7,9,17. However, despite the ability to define the anterior extension of the primary fracture line adequately, many authors have continued to emphasize the posterior facet^{3,7,12,18,24,25}. Recent studies have started to address the importance of the articulations of the anterior and middle facets^{5,6,10,19,20,28}. It is our contention that both anterior and posterior subtalar articulations need to be considered during treatment, especially if it is operative.

In the operative treatment of calcaneal fractures, restoration of the joint surface does not ensure a good outcome but poor articular alignment is associated with post-traumatic degeneration of the joint^14,26,27. Anatomical studies have suggested that the congruence of the anterior subtalar surfaces may be very important. Experiments on cadaveric specimens by Wagner et al. indicated that the mean contact pressure at the anterior and middle facets is approximately 50 per cent greater than that at the posterior facet²⁸. Contact pressures were also shown to change significantly with as little as two millimeters of malalignment of the talar neck²⁰. Failure to restore the anterior and middle facets of the calcaneus anterior to the neck of the talus may produce a similar effect.

The inability to demonstrate superior outcomes after operative treatment may be related to the inability to assess the quality of the articular reduction. Sanders et al. suggested that there may be no benefit to operative treatment of highly comminuted fractures, as the articular damage is severe and the ability to restore the surface of the joint is limited¹⁸. Langdon et al. raised the possibility that poor results may be due to "inadequate reduction and fixation of the calcaneum anterior to the angle of Gissane." Carr emphasized the importance of reduction of the calcaneocuboid joint as well as the need to consider the anterior anatomy in the treatment of these fractures⁵. Restoration of the height of the posterior facet is an important step in the restoration of the subtalar joint. The relationship of the posterior facet with the anterior and middle facets must also be reestablished to restore the articular anatomy of the calcaneus.

References

Introduction | Materials and Methods | Results | Discussion | References

Böhler, L.: Diagnosis, pathology, and treatment of fractures of the os calcis. J. Bone and Joint Surg.,13: 75-89, Jan. 1931.1375 1931

Broden, B.: Roentgen examination of the subtaloid joint in fractures of the calcaneus. Acta Radiol.,31: 85-91, 1949.3185 1949 [PubMed]

Buckley, R. E., and Meek, R. N.: Comparison of open versus closed reduction of intraarticular calcaneal fractures: a matched cohort in workmen. J. Orthop. Trauma,6: 216-222, 1992.6216 1992 [PubMed]

Burdeaux, B. D.: Reduction of calcaneal fractures by the McReynolds medial approach technique and its experimental basis. Clin. Orthop.,177: 87-103, 1983.17787 1983 [PubMed]

Carr, J. B.: Surgical treatment of the intra-articular calcaneus fracture. Orthop. Clin. North America,25: 665-675, 1994.25665 1994

Carr, J. B.; Hamilton, J. J.; and Bear, L. S.: Experimental intra-articular calcaneal fractures: anatomic basis for a new classification. Foot and Ankle,10: 81-87, 1989.1081 1989 [PubMed]

Crosby, L. A., and Fitzgibbons, T.: Computerized tomography scanning of acute intra-articular fractures of the calcaneus: a new classification system. J. Bone and Joint Surg.,72-A: 852-859, July 1990.72-A852 1990

Essex-Lopresti, P.: The mechanism, reduction technique, and results in fractures of the os calcis. British J. Surg.,39: 395-419, 1952.39395 1952

Gilmer, P. W.; Herzenberg, J.; Frank, J. L.; Silverman, P.; Martinez, S.; and Goldner, J. L.: Computerized tomographic analysis of acute calcaneal fractures. Foot and Ankle,6: 184-193, 1986.6184 1986 [PubMed]

Langdon, I. J.; Kerr, P. S.; and Atkins, R. M.: Fractures of the calcaneum: the anterolateral fragment. J. Bone and Joint Surg.,76-B(2): 303-305, 1994.76-B(2)303 1994

Letournel, E.: Open reduction and internal fixation of calcaneus fractures. In Techniques in Orthopaedics—Topics in Orthopaedic Trauma, p. 173. Edited by P. G. Spiegel. Baltimore, University Park Press, 1984.

Leung, K. S.; Chan, W. S.; Shen, W. Y.; Pak, P. P.; So, W. S.; and Leung, P. C.: Operative treatment of intraarticular fractures of the os calcis—the role of rigid internal fixation and primary bone grafting: preliminary results. J. Orthop. Trauma,3: 232-240, 1989.3232 1989 [PubMed]

Palmer, I.: The mechanism and treatment of fractures of the calcaneus. Open reduction with the use of cancellous grafts. J. Bone and Joint Surg.,30-A: 2-8, Jan. 1948.30-A2 1948

Ramsey, P. L., and Hamilton, W.: Changes in tibiotalar area of contact caused by lateral talar shift. J. Bone and Joint Surg.,58-A: 356-357, April 1976.58-A356 1976

Ross, S. D. K., and Sowerby, M. R. R.: The operative treatment of fractures of the os calcis. Clin. Orthop.,199: 132-143, 1985.199132 1985 [PubMed]

Sanders, R.: Intra-articular fractures of the calcaneus: present state of the art. J. Orthop. Trauma,6: 252-265, 1992.6252 1992 [PubMed]

Sanders, R.; Hansen, S. T., Jr.; and McReynolds, I. S.: Trauma to the calcaneus and its tendon. In Disorders of the Foot and Ankle: Medical and Surgical Management, edited by M. H. Jahss. Ed. 2, vol. 3, pp. 2326-2354. Philadelphia, W. B. Saunders, 1991.

Sanders, R.; Fortin, P.; DiPasquale, T.; and Walling, A.: Operative treatment in 120 displaced intraarticular calcaneal fractures. Results using a prognostic computed tomography scan classification. Clin. Orthop.,290: 87-95, 1993.29087 1993 [PubMed]

Sangeorzan, B. J.; Ananthakrishnan, D.; and Tencer, A. F.: Contact characteristics of the subtalar joint after a simulated calcaneus fracture. J. Orthop. Trauma,9: 251-258, 1995.9251 1995 [PubMed]

Sangeorzan, B. J.; Wagner, U. A.; Harrington, R. M.; and Tencer, A. F.: Contact characteristics of the subtalar joint: the effect of talar neck misalignment. J. Orthop. Res.,10: 544-551, 1992.10544 1992 [PubMed]

Simpson, L. A.; Schulak, D. J.; and Spiegel, P. G.: Intraarticular fractures of the calcaneus: a review. Contemp. Orthop.,6(4): 19-29, 1983.6(4)19 1983

Soeur, R., and Remy, R.: Fractures of the calcaneus with displacement of the thalamic portion. J. Bone and Joint Surg.,57-B(4): 413-421, 1975.57-B(4)413 1975

Stephenson, J. R.: Displaced fractures of the os calcis involving the subtalar joint: the key role of the superomedial fragment. Foot and Ankle,4: 91-101, 1983.491 1983 [PubMed]

Stephenson, J. R.: Surgical treatment of displaced intraarticular fractures of the calcaneus. A combined lateral and medial approach. Clin. Orthop.,290: 68-75, 1993.29068 1993 [PubMed]

Thordarson, D. B., and Krieger, L. E.: Operative vs nonoperative treatment of intraarticular fractures of the calcaneus: a prospective randomized trial. Foot and Ankle Internat.,17: 2-9, 1996.172 1996

Trias, A.: Effect of persistent pressure on the articular cartilage. An experimental study. J. Bone and Joint Surg.,43-B(2): 376-386, 1961.43-B(2)376 1961

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Wagner, U. A.; Sangeorzan, B. J.; Harrington, R. M.; and Tencer, A. F.: Contact characteristics of the subtalar joint: load distribution between the anterior and posterior facets. J. Orthop. Res.,10: 535-543, 1992.10535 1992 [PubMed]

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Fig. 3-A: Lateral radiograph of a fractured calcaneus with no identifiable anterolateral fragment.

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Fig. 3-B: Transverse computerized tomography scan revealing extension of the fracture line through the middle facet.

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Fig. 4 Transverse computerized tomography scan showing extension of a fracture line through the anterior facet.

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Fig. 5-B: Schematic representation of the most common types of periarticular extension of the fracture line.

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TABLE I LOCATION OF ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO THE CHARACTERISTICS OF THE EXTENSION

		Location of Extension
Type of Extension	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
Articular
One surface	62	47	10	5
Two surfaces	23	20	21	5
Non-articular
Periarticular	23	—	—	—
Medial or lateral	8	—	—	—
Total	116	67	31	10

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TABLE I LOCATION OF ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO THE CHARACTERISTICS OF THE EXTENSION

		Location of Extension
Type of Extension	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
Articular
One surface	62	47	10	5
Two surfaces	23	20	21	5
Non-articular
Periarticular	23	—	—	—
Medial or lateral	8	—	—	—
Total	116	67	31	10

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TABLE II LOCATION OF THE ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO SANDERS TYPE^16—18

		Location of Extension
Type of Fracture	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
I	5	2	0	0
II	70	37 (53%)	14 (20%)	6 (9%)
III	35	22 (63%)	16 (46%)*	3 (9%)
IV	6	6	1	1
Total†	116	67 (58%)	31 (27%)	10 (9%)

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TABLE II LOCATION OF THE ANTERIOR EXTENSION OF THE PRIMARY FRACTURE LINE ACCORDING TO SANDERS TYPE^16—18

		Location of Extension
Type of Fracture	No. of Fractures	Calcaneo- cuboid Joint	Anterior Facet	Middle Facet
I	5	2	0	0
II	70	37 (53%)	14 (20%)	6 (9%)
III	35	22 (63%)	16 (46%)*	3 (9%)
IV	6	6	1	1
Total†	116	67 (58%)	31 (27%)	10 (9%)