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Stress fractures in the foot
Foot and Ankle Surgery 1998
4: 3–11
Stress fractures in the foot A. VILADOT AND A. VILADOT JR∗ Hospital San Rafael of Barcelona and Universidad Auto´noma de Barcelona, and ∗Universidad de Barcelona, Barcelona, Spain
Summary Bone stress fractures (SF) occur when force is applied repeatedly, even when that force is inferior to bone resistance. Due to the biomechanics of the foot such occurrences are very frequent in the foot; changes in bone tissue resistance can lead to pathological fractures, especially in cases of osteonecrosis. The pathological anatomy has similar characteristics to that of a normal fracture. Among the, complementary, examinations which are most useful are: radioactive bone scanning, conventional radiography and computerized axial tomography (CAT). This study examines the clinical findings and treatment of SF in the trigonal process of the talus, the calcaneous, Sever’s disease, the navicular bone, the metatarsals and sesamoids–both in genuine SF and in Koehler’s disease. Keywords: Deutschla¨nder disease, Koehler’s disease, pathological fracture, Sever’s disease, stress fracture
Introduction
Biomechanics
In general, a fracture occurs when bone resistance is inferior to the load that it receives; but a stress fracture (SF) appears even if the force applied is inferior to the resistance. An SF is the result of repetitive injury focused on a particular segment of bone, and is not associated with a history of acute trauma, but may occur as a result of overuse: e.g. the long stride of soldiers and athletes; or during such activities as dancing, jumping, and running [1–4]. SFs have been described throughout practically all the skeletal system. But, due to the different biomechanics of the foot, it is logical that they should be especially frequent in this part of the body.
It is possible for an SF to appear in normal bone, but they can also be produced when there is a diminution of the bone’s resistance or other dysfunction. This type of SF is known as a pathological fracture.
Correspondence to: Antonio Viladot, MD, Avenida Diagonal, 467, 08036-Barcelona, Spain 1998 Blackwell Science Ltd
Modifications in bone tissue resistance A diminution of bone strength can appear in osteoporosis, osteonecrosis, infections and tumours. In these cases, the load necessary to provoke a fracture is inferior to that in normal bone. These are the so-called ‘pathological fractures’. In many cases, the fracture appears clinically prior to the causal lesion. The association of repeated trauma with a diminution of the bone strength is especially frequent in osteonecrosis. There are three possibilities for the combination of an SF and osteonecrosis:
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1. The same cause that gives rise to necrosis produces the SF. Overload can produce a direct mechanical alteration or an ischaemia which, separately or together, weaken the bone. 2. The two conditions may coexist in the same bone but have different etiologies and different locations. In the metatarsals one may find necrosis on the head and SF in the diaphysis. 3. SF may be secondary to necrosis if the form and biomechanics of the bone is altered by previous disease, e.g. SF in the navicular bone of adults which follows on from necrosis in childhood. According to Devas [5] an SF can also appear after inflammation; once this has started, local resorption of bone occurs and the blood supply increases, leading to further local weakening of the bone and further resorption. This in turn stimulates new blood vessels to penetrate and rebuild the local structure of the bone. Changes in balance and function also diminish bone resistance. These are of fundamental importance in the foot which must work as a perfectly balanced biomechanical system. Any alteration in the function of one of its parts alters the mechanics of the whole system and an SF may appear. Particularly important in the foot is the imbalance caused by external factors, e.g. badly fitting shoes. Bone tissue is protected by good nutrition and healthy nerve endings. The failure of these and alterations in the joint’s cartilage also contributes to the formation of SFs. Because of this SFs appear with trophic infections of the foot which are of neurological origin.
Pathological anatomy At first the application of force produces an isolated rupture of the trabeculae, a microfracture without loss of bone shape, the presence of which is not indicated by any clinical manifestation. The physiopathological reactions that led to this microfracture (vasodilatation, osteoporosis, etc.) would then provoke a fracture which would become progressively worse [6]. Histologically, an SF presents the same characteristics and evolution as a normal fracture: haematoma, granulation of the tissue, osteoid tissue, periostitis and finally trabeculation. The changes are
Figure 1 Histological image of an SF.
the same as those observed in calluses which form in other types of fractures; however, in the SF there is less haemorrhaging. (Figure 1).
Clinical findings An SF is indicated by the pain that appears after an isolated trauma, frequently after a repeated load has been placed on the affected bone. Hence its frequent occurrence in sport and from walking. Pain is subjective but is also confirmed objectively by palpation of the affected area. Among the, complementary, examinations – in order of importance – the following must be taken into account: 1. Radioactive bone scanning with Tegnecium. This will clearly show hypercaptation which appears before radiological manifestations, even prior to clinical signs, and persists until the complete healing of the infection. 2. Conventional radiograph. In the beginning an SF is not too evident and several projections are necessary to visualize the fracture, and it is only clear when periostitis develops. 3. Planigraphy. Shows the lesion more clearly, in the chosen planes, than a standard radiograph. 4. Computed tomography (CT). Gives similar information to a planigraphy but in a clearer form. 5. Magnetic Resonance Imaging (MRI). Shows up the SF beautifully but does not add any information to the isotope bone scanning and to the CT, which are the chosen exploratory methods. 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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Figure 2 SF in the foot.
Localization of the sf in the foot Stress fractures have been described in practically all the bones of the foot (Figure 2) by the following authors: talus (Savoca [7]); calcaneous (Hullinger [8]); epiphysis calcaneous (Sever [9]); navicular (Towne et al. [10]); necroid navicular (Mu¨ller [11]); cuneiform (Buchman et al. [12]); cuboid (Silfverskio¨ld [13]); lateral metatarsals (Deutschla¨nder [14]); the posterior portion of the fifth metatarsal (Jones [15]); the first metatarsal (Savoca [7]); sesamoids (Rennander [16]); and the phalangeal epiphysis (Thiemann [17]). These fractures are, from the etiological point of view, classified into three types: 1. Genuine SF (normal bone): occurs in the talus, calcaneous, navicular, and cuboids; and in the tuberosity at the base of the fifth metatarsal. 2. SF caused by biomechanical alterations: occurs in the metatarsals and sesamoids. 3. Pathological SF (necrosis): occurs in the trigone of the talus, the epiphysis calcaneous, navicular (adult), cuneiforms, sesamoids and phalanges. 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
Figure 3 Compression of the trigone in classical ballet dancers.
It is possible for fractures with several etiologies to occur in the same bone.
Stress fractures of the talus trigone These are lesions caused by compression. The posterior talar tubercle or the trigonum – when it exists – are compressed between the tibia and the calcaneous when the foot is plantar flexed. This occurs in sports where the ball is kicked with the dorsum of the foot. The same mechanics occur in classical ballet dancers (Figure 3), who dance ‘sur les pontes’ (on the tips of their toes). This condition is clinically manifested by intense pain which sometimes impedes the practice of sports or dance. It is localized in the posterior aspect of the
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Figure 4 (a) Achilles tendon plantar system; (b) fracture of the calcaneus by compression.
ankle joint, before the Achille’s tendon. Radiology shows an impingement on the trigone between the tibia and calcaneous. In some cases tendinitis occurs on the long flexor hallux. This tendon passes longitudinally through the trigonal zone. The clinical findings are similar to Hallux rigidus or flexus. In the beginning, treatment can be symptomatic (infiltration, physiotherapy, etc.) but in many cases the posterior tubercle must be removed, which usually gives excellent results.
Figure 5 MRI showing SF in the calcaneus.
Stress fractures of the calcaneous There are two types of SF:
Flattening of the tuberosity This is observed in sportsmen who jump from a stationary postion or during gait, when at the stance phase the pressure is placed on the heel. From the biomechanical point of view the cause is not only the impact of the foot on the ground but, at the same time, the contraction of the Achilles-calcaneo-plantar system [8] formed by the triceps surae Achilles tendon, the posterior epiphysis of the calcaneous, fascia and plantar muscles (Figure 4). It can also occur in adults due to osteoporosis or rheumatoid arthritis. Radiologically, the condition is manifested in the form of dense lines that cross the tuberosity of the calcaneous. When the foot is immobilized in plaster the fractures heal easily (Figure 5).
Figure 6 Sever’s disease.
Some authors have interpreted these as stress lesions (Figure 6). We consider them more as alterations of the ossification of such nucleus – that forms the intermediate part of the Achilles-calcaneo-plantar system – than as true pathological formations.
Stress fractures of the navicular bone Two types of fracture are also found in this bone:
Distraction in Sever’s disease [9]
Genuine SF
In the posterior epiphysiary of the growing foot nucleus lines can appear that interrupt its continuity.
These are frequent in sportsmen due to the overload of the navicular which is located in the apex of 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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STRESS FRACTURES IN THE FOOT
(a)
(b) Figure 7 SF of the navicular bone revealed by (a) CT and (b) radioactive bone scanning.
the medial arch of the foot. This fracture was first described by Towne et al. [10] in 1970. It is first manifested as a pain that increases with activity and when the individual is standing on tiptoe. At this stage radiology is often normal. As the condition progresses, one can observe a longitudinal line that divides the navicular [19]. However, isotope bone scans are clearly positive from the beginning (Figure 7). Although in some cases, internal fixation of the navicular is advised, the most recommended treatment is simple immobilization with a plaster bandage, since the fractures consolidate easily. In any case, in sports, it is important use a plantar support for several months to compensate for the biomechanical alteration which has facilitated the occurrence of the fracture.
Pathological fractures This appears in the necroid navicular of the adult. This lesion was described in 1927 by Mu¨ller [11], and in 1929 by Weiss [20]. The first indication is 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
a flattening of the navicular. This is often only discovered by chance through radiological examination as there are no clinical manifestations; pain is most severe in adults when it appears with osteoarthritis of the talo-navicular and naviculacuneiform joints. When it was first discovered, this disease was given the name of ‘double navicular’ and was believed to be a congenital malformation, even though in other patients, osteonecrotic processes were found in the form of cystic cavities. It should be noted that this type of injury, with a typical oblique line going forward and upward, is completely different from the genuine SF observed in athletes (Figure 8). The authors agree with Rochera [21, 22] that this necrosis of the navicular in adults must be related to Koehler’s disease in children [23]. This is a necrosis which occurs in the formative years. The majority of cases end with a normal morphological reconstruction; but in some cases, the bone heals in a flattened shape (in a similar way to that in which Perthe’s disease can provoke a ‘coxa plana’). From the biomechanical point of view, in the normal navicular the axial stress which is transmitted
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(a)
(b)
(c)
Figure 8 (a) Necrosis of the navicular bone in a young child. (b) Flattening of the navicular bone in a young woman. (c) Necroid SF in an adult.
along the medial arch of the foot is transferred between the talus and the navicular through a spheric joint. In the convex part of the joint (the talus), the forces are parallel to the axis of the medial arch. In the navicular affected by this disease the alterations are as follows: (1) narrowing of the bone into the shape of a wedge, with the base in the inferior position; (2) shortening of the medial arch of the foot; and (3) descent of the geometric axis of the navicular, which causes a displacement of the axial forces toward the dorsal side of the foot.
As a consequence of this deformity, the total axial force is no longer uniformly distributed; rather, it is increased in the upper part of the joint and decreased in the lower part. These resultant forces can produce a fracture of the navicular in the form of a wedge. Conservative treatment with a plantar support and anti-inflammatory medication is not always successful. In the majority of cases surgical treatment becomes necessary. This consists of remodelling the navicular and performing a talo-navicular-cuneiform arthrodesis. 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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Stress fractures of the metatarsals These are the most frequent of SFs not only in the foot, but the whole skeletal system. The most frequent location of a metatarsal SF is in the second and third metatarsals. However, in recent reports, SF of the first metatarsal is more common than that of the fourth and fifth metatarsals [24]. The radiographical appearance of a first metatarsal SF is different from that of the lesser metatarsal, in that it occurs throughout the diaphyseal bone. Radiographic examination shows the lesion at the base of the first metatarsal [25]. In the central metatarsals the cause of the fracture is the alteration of metatarsal biomechanics. The metatarsal heads form a balanced unit with proportional distribution of weight. Physiologically greater weight is placed on the first ray, which is biomechanically designed to support this effort. When this fails, an overload of the adjoining rays occurs, producing the fracture. The authors have classified this SF in the first ray as part of the insufficiency syndrome [1]. This fracture is presented in an acute form as the typical ‘march fracture’. It appears frequently in soldiers who are obliged to walk with long strides. It can be identified by the sudden onset of intense pain, oedema in the dorsum of the foot and the inability to march. The radiological image shows a fracture at the level of the union between the distal and the middle third of the bone. The maximum stress at the moment of the flexion appears at that point (Figure 9). The fracture can also appear in a chronic form, when the second metatarsal attempts to compensate, leading to an increase in bone resistance in the form of a periostitis that covers the central fissure. This is the so-called Deutchla¨nder’s disease [14]. Among the causes of insufficiency of the first ray are: 1. Congenital shortening of the first metatarsal. 2. metatarsus primus varus. 3. backward displacement of the sesamoids. (These three findings are those which Morton [25] has described as comprising the vestigial metatarsal.) 4. Relaxation of the capsuloligamentous structures. Such relaxation prevents the strong fixation of the first metatarsal to the ground, resulting in an upward 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
Figure 9 SF in the metatarsals seen in Deutchla¨nder’s disease.
or dorsal tilt of the first metatarsal, as in a piano key. 5. Flatfoot. In this condition the supinated position of the forefoot paradoxically keeps the first metatarsal raised and therefore prevents it from providing its normal support. 6. Hallux valgus. Together with the metatarsus adductus, which is the basic deformity, this causes weakening of flexor power and results in a decreased push-off during gait. 7. First ray insufficiency of iatrogenic origin. More than 100 operations have been proposed for the treatment of Hallux valgus. The majority of these are concerned with the aesthetics rather than with the statics of the foot. The many and varied osteotomies produce shortening of the first metatarsal and thus decompensation of the forefoot. The same can be said of resection of the head of the first metatarsal.
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Figure 10 Fractures of the proximal part of the fifth metatarsal.
If the phalangeal bases are removed, in addition to the great inconvenience of removing a large portion of the phalanx, the sesamoids are left loose with the subsequent loss of muscle power.
Figure 11 SF of the fifth metatarsal caused by poor distribution of the crampons on the shoe.
The fracture heals with plaster immobilization but the biomechanics of the foot are not modified. For this reason orthotic or surgical treatment is necessary.
to have a plantar support and, particularly in sport, to make a careful choice of shoes.
Stress fractures of the sesamoids Stress fractures of the proximal part of the fifth metatarsal Three types of fractures are found in this area (Figure 10): [2]: 1. Avulsion of styloid process. This is produced by the contraction of the short peroneous muscle. Ferna´ndez Fayren et al. [26] concluded in a biomechanical study that stress on this area produces an SF. 2. Fracture of the proximal epiphysis. This is the true Jones’s [15] fracture, in which the lesion is produced by a sudden mechanism of flexion of the metatarsal with the foot in supination. 3. Stress fracture secondary to a repetitive stress of the bone, also with the forefoot in a supination and dorsal flexion position. This is sometimes observed in football players and is due to poor distribution of the crampon which leaves the medial portion of the plantar vault unprotected. In this situation the metatarsal rests on the proximal and the distal parts of the crampons without support of its diaphysis, thus causing the fracture (Figure 11). Treatment varies according to authors: internal fixation of the styloids with a screw or, in the majority of cases, a plaster bandage is sufficient. Before normal activities or sport are resumed it is usually necessary
The sesamoids of the first metatarsal are two small bones situated under its head. They form part of the glenoid pad which serves as protection against the force that is exerted on such a joint; the remaining cartilage ensures the smooth motion of the joint. The sesamoids form the junction of the short muscles of the first ray, which transmit force to the base of the phalanx through the phalangeal-sesamoid ligaments; these ligaments constitute a plantar reinforcement of the joint capsule of the metatarsophalangeal joint. It should be remembered that ossification of the sesamoids usually appears between 9 and 10 years of age, so it should normally be observable in radiographs after the age of 12 years. The sesamoids appear as individual centres of ossification that afterwards combine into a single centre. However, the existence of a bipartite or tripartite sesamoid is normal. Absence of ossification of one of the sesamoids may occur; this anomaly is usually bilateral. In order to produce an overload of a sesamoid it is necessary to use traction to keep it in position (traction is obtained when the muscles of the first ray contract) and, at the same time, pressure must be maintained on the first metatarsal over the sesamoid. An SF can show up in form of a bipartition of the bone (not to be confused with the congenital bipartite 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
STRESS FRACTURES IN THE FOOT
Figure 12 SF of the sesamoid bone.
sesamoid–isotope bone scanning is negative in this case), or in form of multiple fragments that are difficult to differentiate clinically and radiologically from a bone necrosis (Figure 12). Sesamoid lesions appear frequently in sprinters and dancers, especially in Spanish dance (tap dance) and modern dance (claque). The cavus foot with a plantar flexed first metatarsal also predisposes one to this fracture. Treatment can procede either by orthotic methods or, if the problem is a cavus foot, by a proximal osteotomy of the first metatarsal, to make it more horizontal. In cases of advanced destruction of the bone a partial resection is indicated. A curettage is performed from the dorsal approaching the plantar aspect of the bone, leaving the plantar cortical intact. This improves the metatarsal support and the action of the short muscles of the foot.
References 1 Viladot A. Patologı´a de Antepie. Barcelona: Toray, 1984. 2 Puigdellivol J, Lopez MI, Viladot A Jr et al. Fracturas de stress de la base del quinto metatarsiano en futbolistas. Paper presented at the Twenty-second Symposium of the International Traumatologie and Orthopaedics, FREMAP, Madrid, 23–25 November 1995.
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3 Sammarco JG, Miller EH. Forefoot conditions in dancers. Foot Ankle 1982; 3: 85–98. 4 Milgram C, Giladi M. Stress fractures in military recruits. A prospective study showing an unusually high incidence. J Bone Joint Surg 1985; 67B: 732–735. 5 Devas M. Stress Fractures. New York: Churchill Livingstone Longman Inc., 1975. 6 Mijares JA. Fisiopatologı´a de las fracturas por sobrecarga, Concepto de fractura por fatiga y fractura por insuficiencia. Rev Ort y Traum 1979; 1: 87–92. 7 Savoca CJ. Stress fractures. Radiol 1971; 100: 519–524. 8 Hullinger CW. Insufficiency fracture of the calcaneus similar to march fracture of metatarsal. J Bone Joint Surg. 1944; 26A: 751–758. 9 Sever JW. Apophysitis of the os calcis. NY Med J 1912; 95: 1025–1028. 10 Towne LC, Blazina ME, Cozen LN. Fatigue fracture of the tarsal navicular. Bone Joint Surg 1970; 52A: 376–380. 11 Mu¨ller W. Uber eine eigenartige doppelseitige Vera¨nderung des os naviculare pedis beim Erwachsenen. Dtsch Zschr Chir 1927; 201: 84–89. 12 Buchman DN, Roeser WM, Holmes Jr et al. Cuboid Stress fractures: a report of two cases. Foot Ankle, 1993; 9: 525–528. 13 Silfverskio¨ld N. En fall von post-traumatiche neknose in calcaneus und cuboideum in adie. Lokall malazie erinnecuden verand runzen. Acta Radiol 1926; 7: 473–475. ¨ ber eine eifenartife Mittelfusserkrankung. 14 Deutschla¨nder C. U Z Chir 1921; 39: 1422–1426. 15 Jones R. Fracture of the fifth metatarsal bone. Ann Surg 1902; 35: 697–700. 16 Renander A. Two cases of typical osteochondropathy of the medial sesamoid hook of the first metatarsal. Acta Radiol 1925; 3: 521–525. 17 Thiemann H. Juvenile Epiphysen Sto¨rungen. Fortschr Ro¨entgen 1909; 14: 79–80. 18 Viladot A. Anatomie, physiologie et physiopathologie du system suro-achilleo-calcaneo-plantaire. Med Chir Pied 1985; 4: 69–76. 19 Viladot A Jr. Fracturas de stress del escafoides tarsiano a proposito de seis casos. Rev Ortop Traum 1992; 2: 181–185. ¨ ber die maladie des os navicularis pedis. Fortschr 20 Weiss K. U Geb Roentgenstr Nuklearmed Enganzungsband 1929; 40: 63–70. 21 Viladot A, Rochera R. Necrosis of the navicular bones. Bull Hospital Joint Dis Orthop Inst 1987; 47: 2:285–288. 22 Viladot A, Viladot A Jr Osteochondroses Aseptic necrosis in Jahss M. In: Disorders of the Foot. Philadelphia: W B Saunders, 1991; 617–638. 23 Ko¨hler A, Zimmer EA, Roentgenologia Barcelona et al. Stress fractures of the first metatarsal. AM J Roentgend 1978; 130: 679–681. 24 Lucas MJ, Baxter DE. Stress fracture of the first metatarsal. Foot Ankle 1977; 18: 373–374. 25 Morton D. The human foot. New York: Columbia University Press, 1948. 26 Ferna´ndez Fayren Roca J, Foure F. Stress fractures of the fifth metatarsal. Acta Orthopaedica Belgica, 1980; 46: 5:630–636.
4: 3–11
Stress fractures in the foot A. VILADOT AND A. VILADOT JR∗ Hospital San Rafael of Barcelona and Universidad Auto´noma de Barcelona, and ∗Universidad de Barcelona, Barcelona, Spain
Summary Bone stress fractures (SF) occur when force is applied repeatedly, even when that force is inferior to bone resistance. Due to the biomechanics of the foot such occurrences are very frequent in the foot; changes in bone tissue resistance can lead to pathological fractures, especially in cases of osteonecrosis. The pathological anatomy has similar characteristics to that of a normal fracture. Among the, complementary, examinations which are most useful are: radioactive bone scanning, conventional radiography and computerized axial tomography (CAT). This study examines the clinical findings and treatment of SF in the trigonal process of the talus, the calcaneous, Sever’s disease, the navicular bone, the metatarsals and sesamoids–both in genuine SF and in Koehler’s disease. Keywords: Deutschla¨nder disease, Koehler’s disease, pathological fracture, Sever’s disease, stress fracture
Introduction
Biomechanics
In general, a fracture occurs when bone resistance is inferior to the load that it receives; but a stress fracture (SF) appears even if the force applied is inferior to the resistance. An SF is the result of repetitive injury focused on a particular segment of bone, and is not associated with a history of acute trauma, but may occur as a result of overuse: e.g. the long stride of soldiers and athletes; or during such activities as dancing, jumping, and running [1–4]. SFs have been described throughout practically all the skeletal system. But, due to the different biomechanics of the foot, it is logical that they should be especially frequent in this part of the body.
It is possible for an SF to appear in normal bone, but they can also be produced when there is a diminution of the bone’s resistance or other dysfunction. This type of SF is known as a pathological fracture.
Correspondence to: Antonio Viladot, MD, Avenida Diagonal, 467, 08036-Barcelona, Spain 1998 Blackwell Science Ltd
Modifications in bone tissue resistance A diminution of bone strength can appear in osteoporosis, osteonecrosis, infections and tumours. In these cases, the load necessary to provoke a fracture is inferior to that in normal bone. These are the so-called ‘pathological fractures’. In many cases, the fracture appears clinically prior to the causal lesion. The association of repeated trauma with a diminution of the bone strength is especially frequent in osteonecrosis. There are three possibilities for the combination of an SF and osteonecrosis:
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1. The same cause that gives rise to necrosis produces the SF. Overload can produce a direct mechanical alteration or an ischaemia which, separately or together, weaken the bone. 2. The two conditions may coexist in the same bone but have different etiologies and different locations. In the metatarsals one may find necrosis on the head and SF in the diaphysis. 3. SF may be secondary to necrosis if the form and biomechanics of the bone is altered by previous disease, e.g. SF in the navicular bone of adults which follows on from necrosis in childhood. According to Devas [5] an SF can also appear after inflammation; once this has started, local resorption of bone occurs and the blood supply increases, leading to further local weakening of the bone and further resorption. This in turn stimulates new blood vessels to penetrate and rebuild the local structure of the bone. Changes in balance and function also diminish bone resistance. These are of fundamental importance in the foot which must work as a perfectly balanced biomechanical system. Any alteration in the function of one of its parts alters the mechanics of the whole system and an SF may appear. Particularly important in the foot is the imbalance caused by external factors, e.g. badly fitting shoes. Bone tissue is protected by good nutrition and healthy nerve endings. The failure of these and alterations in the joint’s cartilage also contributes to the formation of SFs. Because of this SFs appear with trophic infections of the foot which are of neurological origin.
Pathological anatomy At first the application of force produces an isolated rupture of the trabeculae, a microfracture without loss of bone shape, the presence of which is not indicated by any clinical manifestation. The physiopathological reactions that led to this microfracture (vasodilatation, osteoporosis, etc.) would then provoke a fracture which would become progressively worse [6]. Histologically, an SF presents the same characteristics and evolution as a normal fracture: haematoma, granulation of the tissue, osteoid tissue, periostitis and finally trabeculation. The changes are
Figure 1 Histological image of an SF.
the same as those observed in calluses which form in other types of fractures; however, in the SF there is less haemorrhaging. (Figure 1).
Clinical findings An SF is indicated by the pain that appears after an isolated trauma, frequently after a repeated load has been placed on the affected bone. Hence its frequent occurrence in sport and from walking. Pain is subjective but is also confirmed objectively by palpation of the affected area. Among the, complementary, examinations – in order of importance – the following must be taken into account: 1. Radioactive bone scanning with Tegnecium. This will clearly show hypercaptation which appears before radiological manifestations, even prior to clinical signs, and persists until the complete healing of the infection. 2. Conventional radiograph. In the beginning an SF is not too evident and several projections are necessary to visualize the fracture, and it is only clear when periostitis develops. 3. Planigraphy. Shows the lesion more clearly, in the chosen planes, than a standard radiograph. 4. Computed tomography (CT). Gives similar information to a planigraphy but in a clearer form. 5. Magnetic Resonance Imaging (MRI). Shows up the SF beautifully but does not add any information to the isotope bone scanning and to the CT, which are the chosen exploratory methods. 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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Figure 2 SF in the foot.
Localization of the sf in the foot Stress fractures have been described in practically all the bones of the foot (Figure 2) by the following authors: talus (Savoca [7]); calcaneous (Hullinger [8]); epiphysis calcaneous (Sever [9]); navicular (Towne et al. [10]); necroid navicular (Mu¨ller [11]); cuneiform (Buchman et al. [12]); cuboid (Silfverskio¨ld [13]); lateral metatarsals (Deutschla¨nder [14]); the posterior portion of the fifth metatarsal (Jones [15]); the first metatarsal (Savoca [7]); sesamoids (Rennander [16]); and the phalangeal epiphysis (Thiemann [17]). These fractures are, from the etiological point of view, classified into three types: 1. Genuine SF (normal bone): occurs in the talus, calcaneous, navicular, and cuboids; and in the tuberosity at the base of the fifth metatarsal. 2. SF caused by biomechanical alterations: occurs in the metatarsals and sesamoids. 3. Pathological SF (necrosis): occurs in the trigone of the talus, the epiphysis calcaneous, navicular (adult), cuneiforms, sesamoids and phalanges. 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
Figure 3 Compression of the trigone in classical ballet dancers.
It is possible for fractures with several etiologies to occur in the same bone.
Stress fractures of the talus trigone These are lesions caused by compression. The posterior talar tubercle or the trigonum – when it exists – are compressed between the tibia and the calcaneous when the foot is plantar flexed. This occurs in sports where the ball is kicked with the dorsum of the foot. The same mechanics occur in classical ballet dancers (Figure 3), who dance ‘sur les pontes’ (on the tips of their toes). This condition is clinically manifested by intense pain which sometimes impedes the practice of sports or dance. It is localized in the posterior aspect of the
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Figure 4 (a) Achilles tendon plantar system; (b) fracture of the calcaneus by compression.
ankle joint, before the Achille’s tendon. Radiology shows an impingement on the trigone between the tibia and calcaneous. In some cases tendinitis occurs on the long flexor hallux. This tendon passes longitudinally through the trigonal zone. The clinical findings are similar to Hallux rigidus or flexus. In the beginning, treatment can be symptomatic (infiltration, physiotherapy, etc.) but in many cases the posterior tubercle must be removed, which usually gives excellent results.
Figure 5 MRI showing SF in the calcaneus.
Stress fractures of the calcaneous There are two types of SF:
Flattening of the tuberosity This is observed in sportsmen who jump from a stationary postion or during gait, when at the stance phase the pressure is placed on the heel. From the biomechanical point of view the cause is not only the impact of the foot on the ground but, at the same time, the contraction of the Achilles-calcaneo-plantar system [8] formed by the triceps surae Achilles tendon, the posterior epiphysis of the calcaneous, fascia and plantar muscles (Figure 4). It can also occur in adults due to osteoporosis or rheumatoid arthritis. Radiologically, the condition is manifested in the form of dense lines that cross the tuberosity of the calcaneous. When the foot is immobilized in plaster the fractures heal easily (Figure 5).
Figure 6 Sever’s disease.
Some authors have interpreted these as stress lesions (Figure 6). We consider them more as alterations of the ossification of such nucleus – that forms the intermediate part of the Achilles-calcaneo-plantar system – than as true pathological formations.
Stress fractures of the navicular bone Two types of fracture are also found in this bone:
Distraction in Sever’s disease [9]
Genuine SF
In the posterior epiphysiary of the growing foot nucleus lines can appear that interrupt its continuity.
These are frequent in sportsmen due to the overload of the navicular which is located in the apex of 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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(a)
(b) Figure 7 SF of the navicular bone revealed by (a) CT and (b) radioactive bone scanning.
the medial arch of the foot. This fracture was first described by Towne et al. [10] in 1970. It is first manifested as a pain that increases with activity and when the individual is standing on tiptoe. At this stage radiology is often normal. As the condition progresses, one can observe a longitudinal line that divides the navicular [19]. However, isotope bone scans are clearly positive from the beginning (Figure 7). Although in some cases, internal fixation of the navicular is advised, the most recommended treatment is simple immobilization with a plaster bandage, since the fractures consolidate easily. In any case, in sports, it is important use a plantar support for several months to compensate for the biomechanical alteration which has facilitated the occurrence of the fracture.
Pathological fractures This appears in the necroid navicular of the adult. This lesion was described in 1927 by Mu¨ller [11], and in 1929 by Weiss [20]. The first indication is 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
a flattening of the navicular. This is often only discovered by chance through radiological examination as there are no clinical manifestations; pain is most severe in adults when it appears with osteoarthritis of the talo-navicular and naviculacuneiform joints. When it was first discovered, this disease was given the name of ‘double navicular’ and was believed to be a congenital malformation, even though in other patients, osteonecrotic processes were found in the form of cystic cavities. It should be noted that this type of injury, with a typical oblique line going forward and upward, is completely different from the genuine SF observed in athletes (Figure 8). The authors agree with Rochera [21, 22] that this necrosis of the navicular in adults must be related to Koehler’s disease in children [23]. This is a necrosis which occurs in the formative years. The majority of cases end with a normal morphological reconstruction; but in some cases, the bone heals in a flattened shape (in a similar way to that in which Perthe’s disease can provoke a ‘coxa plana’). From the biomechanical point of view, in the normal navicular the axial stress which is transmitted
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(a)
(b)
(c)
Figure 8 (a) Necrosis of the navicular bone in a young child. (b) Flattening of the navicular bone in a young woman. (c) Necroid SF in an adult.
along the medial arch of the foot is transferred between the talus and the navicular through a spheric joint. In the convex part of the joint (the talus), the forces are parallel to the axis of the medial arch. In the navicular affected by this disease the alterations are as follows: (1) narrowing of the bone into the shape of a wedge, with the base in the inferior position; (2) shortening of the medial arch of the foot; and (3) descent of the geometric axis of the navicular, which causes a displacement of the axial forces toward the dorsal side of the foot.
As a consequence of this deformity, the total axial force is no longer uniformly distributed; rather, it is increased in the upper part of the joint and decreased in the lower part. These resultant forces can produce a fracture of the navicular in the form of a wedge. Conservative treatment with a plantar support and anti-inflammatory medication is not always successful. In the majority of cases surgical treatment becomes necessary. This consists of remodelling the navicular and performing a talo-navicular-cuneiform arthrodesis. 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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Stress fractures of the metatarsals These are the most frequent of SFs not only in the foot, but the whole skeletal system. The most frequent location of a metatarsal SF is in the second and third metatarsals. However, in recent reports, SF of the first metatarsal is more common than that of the fourth and fifth metatarsals [24]. The radiographical appearance of a first metatarsal SF is different from that of the lesser metatarsal, in that it occurs throughout the diaphyseal bone. Radiographic examination shows the lesion at the base of the first metatarsal [25]. In the central metatarsals the cause of the fracture is the alteration of metatarsal biomechanics. The metatarsal heads form a balanced unit with proportional distribution of weight. Physiologically greater weight is placed on the first ray, which is biomechanically designed to support this effort. When this fails, an overload of the adjoining rays occurs, producing the fracture. The authors have classified this SF in the first ray as part of the insufficiency syndrome [1]. This fracture is presented in an acute form as the typical ‘march fracture’. It appears frequently in soldiers who are obliged to walk with long strides. It can be identified by the sudden onset of intense pain, oedema in the dorsum of the foot and the inability to march. The radiological image shows a fracture at the level of the union between the distal and the middle third of the bone. The maximum stress at the moment of the flexion appears at that point (Figure 9). The fracture can also appear in a chronic form, when the second metatarsal attempts to compensate, leading to an increase in bone resistance in the form of a periostitis that covers the central fissure. This is the so-called Deutchla¨nder’s disease [14]. Among the causes of insufficiency of the first ray are: 1. Congenital shortening of the first metatarsal. 2. metatarsus primus varus. 3. backward displacement of the sesamoids. (These three findings are those which Morton [25] has described as comprising the vestigial metatarsal.) 4. Relaxation of the capsuloligamentous structures. Such relaxation prevents the strong fixation of the first metatarsal to the ground, resulting in an upward 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
Figure 9 SF in the metatarsals seen in Deutchla¨nder’s disease.
or dorsal tilt of the first metatarsal, as in a piano key. 5. Flatfoot. In this condition the supinated position of the forefoot paradoxically keeps the first metatarsal raised and therefore prevents it from providing its normal support. 6. Hallux valgus. Together with the metatarsus adductus, which is the basic deformity, this causes weakening of flexor power and results in a decreased push-off during gait. 7. First ray insufficiency of iatrogenic origin. More than 100 operations have been proposed for the treatment of Hallux valgus. The majority of these are concerned with the aesthetics rather than with the statics of the foot. The many and varied osteotomies produce shortening of the first metatarsal and thus decompensation of the forefoot. The same can be said of resection of the head of the first metatarsal.
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Figure 10 Fractures of the proximal part of the fifth metatarsal.
If the phalangeal bases are removed, in addition to the great inconvenience of removing a large portion of the phalanx, the sesamoids are left loose with the subsequent loss of muscle power.
Figure 11 SF of the fifth metatarsal caused by poor distribution of the crampons on the shoe.
The fracture heals with plaster immobilization but the biomechanics of the foot are not modified. For this reason orthotic or surgical treatment is necessary.
to have a plantar support and, particularly in sport, to make a careful choice of shoes.
Stress fractures of the sesamoids Stress fractures of the proximal part of the fifth metatarsal Three types of fractures are found in this area (Figure 10): [2]: 1. Avulsion of styloid process. This is produced by the contraction of the short peroneous muscle. Ferna´ndez Fayren et al. [26] concluded in a biomechanical study that stress on this area produces an SF. 2. Fracture of the proximal epiphysis. This is the true Jones’s [15] fracture, in which the lesion is produced by a sudden mechanism of flexion of the metatarsal with the foot in supination. 3. Stress fracture secondary to a repetitive stress of the bone, also with the forefoot in a supination and dorsal flexion position. This is sometimes observed in football players and is due to poor distribution of the crampon which leaves the medial portion of the plantar vault unprotected. In this situation the metatarsal rests on the proximal and the distal parts of the crampons without support of its diaphysis, thus causing the fracture (Figure 11). Treatment varies according to authors: internal fixation of the styloids with a screw or, in the majority of cases, a plaster bandage is sufficient. Before normal activities or sport are resumed it is usually necessary
The sesamoids of the first metatarsal are two small bones situated under its head. They form part of the glenoid pad which serves as protection against the force that is exerted on such a joint; the remaining cartilage ensures the smooth motion of the joint. The sesamoids form the junction of the short muscles of the first ray, which transmit force to the base of the phalanx through the phalangeal-sesamoid ligaments; these ligaments constitute a plantar reinforcement of the joint capsule of the metatarsophalangeal joint. It should be remembered that ossification of the sesamoids usually appears between 9 and 10 years of age, so it should normally be observable in radiographs after the age of 12 years. The sesamoids appear as individual centres of ossification that afterwards combine into a single centre. However, the existence of a bipartite or tripartite sesamoid is normal. Absence of ossification of one of the sesamoids may occur; this anomaly is usually bilateral. In order to produce an overload of a sesamoid it is necessary to use traction to keep it in position (traction is obtained when the muscles of the first ray contract) and, at the same time, pressure must be maintained on the first metatarsal over the sesamoid. An SF can show up in form of a bipartition of the bone (not to be confused with the congenital bipartite 1998 Blackwell Science Ltd, Foot and Ankle Surgery, 4, 3–11
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Figure 12 SF of the sesamoid bone.
sesamoid–isotope bone scanning is negative in this case), or in form of multiple fragments that are difficult to differentiate clinically and radiologically from a bone necrosis (Figure 12). Sesamoid lesions appear frequently in sprinters and dancers, especially in Spanish dance (tap dance) and modern dance (claque). The cavus foot with a plantar flexed first metatarsal also predisposes one to this fracture. Treatment can procede either by orthotic methods or, if the problem is a cavus foot, by a proximal osteotomy of the first metatarsal, to make it more horizontal. In cases of advanced destruction of the bone a partial resection is indicated. A curettage is performed from the dorsal approaching the plantar aspect of the bone, leaving the plantar cortical intact. This improves the metatarsal support and the action of the short muscles of the foot.
References 1 Viladot A. Patologı´a de Antepie. Barcelona: Toray, 1984. 2 Puigdellivol J, Lopez MI, Viladot A Jr et al. Fracturas de stress de la base del quinto metatarsiano en futbolistas. Paper presented at the Twenty-second Symposium of the International Traumatologie and Orthopaedics, FREMAP, Madrid, 23–25 November 1995.
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3 Sammarco JG, Miller EH. Forefoot conditions in dancers. Foot Ankle 1982; 3: 85–98. 4 Milgram C, Giladi M. Stress fractures in military recruits. A prospective study showing an unusually high incidence. J Bone Joint Surg 1985; 67B: 732–735. 5 Devas M. Stress Fractures. New York: Churchill Livingstone Longman Inc., 1975. 6 Mijares JA. Fisiopatologı´a de las fracturas por sobrecarga, Concepto de fractura por fatiga y fractura por insuficiencia. Rev Ort y Traum 1979; 1: 87–92. 7 Savoca CJ. Stress fractures. Radiol 1971; 100: 519–524. 8 Hullinger CW. Insufficiency fracture of the calcaneus similar to march fracture of metatarsal. J Bone Joint Surg. 1944; 26A: 751–758. 9 Sever JW. Apophysitis of the os calcis. NY Med J 1912; 95: 1025–1028. 10 Towne LC, Blazina ME, Cozen LN. Fatigue fracture of the tarsal navicular. Bone Joint Surg 1970; 52A: 376–380. 11 Mu¨ller W. Uber eine eigenartige doppelseitige Vera¨nderung des os naviculare pedis beim Erwachsenen. Dtsch Zschr Chir 1927; 201: 84–89. 12 Buchman DN, Roeser WM, Holmes Jr et al. Cuboid Stress fractures: a report of two cases. Foot Ankle, 1993; 9: 525–528. 13 Silfverskio¨ld N. En fall von post-traumatiche neknose in calcaneus und cuboideum in adie. Lokall malazie erinnecuden verand runzen. Acta Radiol 1926; 7: 473–475. ¨ ber eine eifenartife Mittelfusserkrankung. 14 Deutschla¨nder C. U Z Chir 1921; 39: 1422–1426. 15 Jones R. Fracture of the fifth metatarsal bone. Ann Surg 1902; 35: 697–700. 16 Renander A. Two cases of typical osteochondropathy of the medial sesamoid hook of the first metatarsal. Acta Radiol 1925; 3: 521–525. 17 Thiemann H. Juvenile Epiphysen Sto¨rungen. Fortschr Ro¨entgen 1909; 14: 79–80. 18 Viladot A. Anatomie, physiologie et physiopathologie du system suro-achilleo-calcaneo-plantaire. Med Chir Pied 1985; 4: 69–76. 19 Viladot A Jr. Fracturas de stress del escafoides tarsiano a proposito de seis casos. Rev Ortop Traum 1992; 2: 181–185. ¨ ber die maladie des os navicularis pedis. Fortschr 20 Weiss K. U Geb Roentgenstr Nuklearmed Enganzungsband 1929; 40: 63–70. 21 Viladot A, Rochera R. Necrosis of the navicular bones. Bull Hospital Joint Dis Orthop Inst 1987; 47: 2:285–288. 22 Viladot A, Viladot A Jr Osteochondroses Aseptic necrosis in Jahss M. In: Disorders of the Foot. Philadelphia: W B Saunders, 1991; 617–638. 23 Ko¨hler A, Zimmer EA, Roentgenologia Barcelona et al. Stress fractures of the first metatarsal. AM J Roentgend 1978; 130: 679–681. 24 Lucas MJ, Baxter DE. Stress fracture of the first metatarsal. Foot Ankle 1977; 18: 373–374. 25 Morton D. The human foot. New York: Columbia University Press, 1948. 26 Ferna´ndez Fayren Roca J, Foure F. Stress fractures of the fifth metatarsal. Acta Orthopaedica Belgica, 1980; 46: 5:630–636.