Stress fractures of the fifth metatarsal

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1 Review Article pissn X eissn Stress fractures of the fifth metatarsal Jae-Young Lee, Jin-Wha Chung Department of Orthopedic Surgery, The Catholic University of Korea, Bucheon St. Mary s Hospital, Bucheon, Korea A stress fracture can be defined as a spontaneous fracture due to accumulation of stress on a healthy bone. Stress fractures of the 5th metatarsal usually locate to the proximal 1.5 cm of the metatarsal shaft, a characteristic based on anatomical and biomechanical parameters. Many surgeons agree that the postoperative outcome of 5th metatarsal stress fractures tend to be associated with prolonged healing time, with nonunion, and sometimes with refracture. Acute stress fractures have been treated with immobilization using a non-weight-bearing cast, but the incidence of complications (delayed union or nonunion) after non-surgical treatment makes surgical treatment a more favorable treatment option for competitive athletes, even for young adults. Curettage and bone grafting or intramedullary screw fixation, the standard surgical treatment for the 5th metatarsal stress fractures, has been associated with rapid recovery and early return to physical activities. Malalignment or instability of the foot or ankle must be addressed at the time of surgical treatment. Keywords: Fifth metatarsal; Stress fracture; Metatarsal fracture; Jones fracture INTRODUCTION In stress fractures, a sustained submaximal external force, which is just inadequate to induce an acute fracture, overlays the bone and causes a characteristic hairline fracture that can be seen on radiographs [1]. Stress fractures are often found on tibial, metatarsal, and tarsal bones on which a lot of weight-bearing occurs and in professionals such as athletes, dancers, and military soldiers whose job requires overuse of the lower limbs as well as in the normal population [2]. However, stress fractures are distinct from pathologic fractures that are induced by even trivial force on bones that are pathologically weakened as a result of systemic metabolic or inflammatory diseases or of severe osteoporosis. The base of the 5th metatarsal of the foot is the region in which the stress concentrates biomechanically; thus, for anatomical characteristics the prevalence of stress fractures is higher in the 5th metatarsal compared to those of other sites. For reasons related to blood flow, the time taken to bone union is slow, and complications such as refractures are common. These factors associated with 5th metatarsal fractures make it a condition of clinical significance and one that requires an accurate diagnosis and an appropriate treatment [3]. In 1902, Jones suggested that a base fracture of the 5th metatarsal may also occur as a result of an indirect trauma [4]. A classification system to divide these fractures into groups was devised by Torg et al. [5] in 1984, and many studies have investigated the treatment, classification, and prognosis of base fractures of the 5th metatarsal. ANATOMY AND BIOMECHANICS OF THE 5TH METATARSAL BONE A metatarsal bone consists of a head, a tibia, a shaft, a base, and a tuberosity. The tuberosity protrudes into the posterolateral base of the plantar foot and provides the dorsolateral insertion site for the peroneous brevis tendon. The insertion of the lateral fibrous tissue of the plantar fascia in the direction of the plantar contributes to the stability of the base of the 5th metatarsal bone (Fig. 1). In the 2nd and 3rd metatarsal bones, the base and the cuneiforms form a lattice-shaped joint that build Arthroscopy and Orthopedic Sports Medicine AOSM Received December 1, 2015; Revised December 23, 2015; Accepted December 23, 2015 Correspondence to: Jin-Wha Chung, Department of Orthopedic Surgery, The Catholic University of Korea, Bucheon St. Mary s Hospital, 372 Sosa-ro, Wonmi-gu, Bucheon 14647, Korea. Tel: , Fax: , koreafoot@gmail.com Copyright 2016 Korean Arthroscopy Society and Korean Orthopedic Society for Sports Medicine. All rights reserved. CC This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Arthrosc Orthop Sports Med 2016;3(1):1-5 1

2 Peroneus brevis Peroneus tertius Metaphyseal arteries Nutrient artery Lateral band of plantar fascia Fig. 1. An adduction force on the fifth metatarsal bone is counterbalanced by a stress force that induces a stress fracture. Between the counteracting forces of the 5th metatarsal bone, the rigid fascial and tendinous anchors act as a fulcrum. "Avascular zone" Fig. 2. Blood supply to the fifth metatarsal is provided by a single nutrient artery to the shaft and by the epiphyseal and the metaphyseal arteries to the base and to the tuberosity. a stable anatomical structure. In the 4th and 5th metatarsal bones, the base does not contribute to the stability of the joints in this way. For this anatomical basis, during the rehabilitation after treatment of the latter two metatarsal fractures, adduction and abduction exercises in the axial plane are restricted and around 10 o of flexion motion is permitted in the sagittal plane [6]. Of the metatarsals, the distal portion of the 5th metatarsal has the most mobility, thus movement is permitted relatively freely. Conversely, the base of the 5th metatarsal, as the section that receives the most support from the ligaments and tendons, acts as a lever during metatarsal movement, and therefore is the region where stress accumulates excessively. The accumulation of stress leads to stress fractures at the proximal 5th metatarsal, especially because of stress that accumulates with repeated adduction of the foot. By evaluating the fracture site radiographically, we can deduce by way of the fracture line that the fracture began at the lateral plantar foot and extended toward the medial dorsal foot. Biomechanical causes of stress on and, therefore, of stress fractures of the base of the 5th metatarsal during weight-bearing gait include a larger than normal curvature of the distal shaft of the 5th metatarsal, inversion of the tibia, and cavus foot-induced excessive abduction force on the base of the 5th metatarsal [7]. The risk of stress fractures can also increase if patients already have an inversion deformity of the hindfoot. This is because an inverted hindfoot leads to a sustained locking of the metatarsals during the stance phase of a gait in the background of an already low subtalar joint mobility; the metatarsal locking compromises the flexibility of the foot and increases chances of fractures because the foot cannot effectively absorb the shock against ground force. The vasculature distinctive to the base of the 5th metatarsal is one of the factors that prevent successful fracture healing. Shereff et al. [8] found that whilst vascular supply to the shaft of the 5th metatarsal is provided through one nutrient artery, that to the base of the 5th metarsal is provided through more than one metadiaphyseal arteries. Because stress fractures of the proximal 5th metatarsal occur near the medial cortical hole through which the nutrient vasculature feeds through, upon fracture this site is separated from the source of blood vessels leading to formation of an avascular fracture site; this has been reported to be one of the important anatomical reasons for the high rate of nonunion or delayed union in 5th metatarsal fractures (Fig. 2) [8]. DIAGNOSIS AND CLASSIFICATION OF STRESS FRACTURES OF THE FIFTH METATARSALS Early stress fractures are distinctively associated with a precursory symptom of intermittent pain, rather than acute pain. This mild, intermittent pain is mistakenly taken for soft tissue injuries that gradually increase in intensity. Often, this precursory pain suddenly exacerbates with a piercing sensation during exercise or during gait. Patients with 5th metatarsal fractures have a history of a change in habit such as taking up a new sports or an increase in the intensity or in the amount of sports activity and rarely have a history of trauma. The fractures at the proximal 5th metatarsal can be divided into 3 types according to anatomical position. Zone 1 fractures are avulsion fractures that occur at the most proximal metatarsal bone, the tuberosity. They occur as 2

$Jae-Young Lee, Jin-Wha Chung. Stress fractures of the fifth metatarsal a result the insertion of the peroneous brevis tendon and plantar facia.$ $Fractures of the latter two zones, for reasons related to anatomical and biomechanical factors, are associated with a high incidence of delayed union, of nonunion, or of refractures.$ $Because patients symptoms and their history of trauma tend to be ambiguous, it is difficult to differentiate Jones fractures from stress fractures that arise at the same site [9].$ $But even when a fracture line cannot be discriminated initially, hypertrophy of the cortical bone that occurs between 2 and 4 weeks of the fracture causes the fracture line to become A B prominent.$ $Conversely, nuclear medicine test or magnetic resonance imaging may assist early diagnosis of the stress fractures. Torg et al.$

3 Jae-Young Lee, Jin-Wha Chung. Stress fractures of the fifth metatarsal a result the insertion of the peroneous brevis tendon and plantar facia. Zone 2 fractures occur in the metaphysiodiaphyseal junction, and zone 3 fractures occur within 1.5 cm of the proximal shaft of the 5th metatarsal (Fig. 3). Fractures of the latter two zones, for reasons related to anatomical and biomechanical factors, are associated with a high incidence of delayed union, of nonunion, or of refractures. Zone 2 fracture are also known as Jones fracture and are usually limited to acute fractures. Because patients symptoms and their history of trauma tend to be ambiguous, it is difficult to differentiate Jones fractures from stress fractures that arise at the same site [9]. The stress fractures of the 5th metatarsal, as in other metatarsal stress fractures, present with a clear fracture line at the initial stage on plain radiography. But even when a fracture line cannot be discriminated initially, hypertrophy of the cortical bone that occurs between 2 and 4 weeks of the fracture causes the fracture line to become A B prominent. Thus, when stress fractures are suspected and an early plain radiography is not suggestive of them, imaging should be repeated across a few weeks until they can be seen. Conversely, nuclear medicine test or magnetic resonance imaging may assist early diagnosis of the stress fractures. Torg et al. [5] established a classification system that divided the base fractures of the 5th metatarsal into 3 stages: a type 1, acute injury; a type 2, delayed union; and a type 3, nonunion (Fig. 4). Type 1 fractures are acute fractures without expansion of the fracture line or without intramedullary sclerosis but with trivial hypertrophy of the cortical bone. Type 2 fractures are those with delayed union, mild intramedullary sclerosis, and expansion of the fracture line or hypertrophy of the cortical bone. Type 3 fractures are those with an expanded fracture line, hypertrophy of the cortical bone, and sclerosis of the intramedulla that has progressed to a breakage of the bone. C Fig. 3. Anatomical classification of the fifth metatarsal fractures: a tuberosity fracture (A), a Jones fracture (B), and a diaphyseal stress fracture (C). Fig. 4. Torg classification of 5th metatarsal fractures: acute fracture (I), delayed union (II), and nonunion (III). 3

4 TREATMENT As a rule, type 1 fractures classified through the Torg classification system are treated conservatively unless they are sustained by young athletes. Torg et al. [5] found that for acute stress fractures without displacement cast immobilization alone under non weight-bearing conditions has shown to result in bone union in 93% of patients by the 7th week. But Stewart [4] and Dameron [10] found that in those who did not receive surgical treatment, the rate of nonunion and delayed union was high. Similarly, DeLee et al. [11] and Kavanaugh et al. [12] recommended that because conservative treatment of type 1 fractures in young athletes necessitate a long time for union and for rehabilitation, a surgical treatment is recommended, especially if the patient desires an early return to sports. For the treatment of type 2 stress fractures, surgical treatment is recommended to prevent nonunion. Of the many surgical treatments, the one described by DeLee et al. [11] which uses compression screws for intramedullary screw fixation is most commonly used. Other treatment methods include bone grafting, intramedullary screw fixation with concomitant bone grafting, and tension band wiring [1]. Intramedullary screw fixation Intramedullary screw fixation is the conventional method for the treatment of stress fractures of the 5th metatarsal. Several studies have shown favorable outcomes for metatarsal stress fractures after using this approach. An study by DeLee et al. [11] has shown good clinical outcomes of percutaneous screw fixation for metatarsal fractures in 10 patients. Josefsson et al. [13] found that after using the same method they achieved bone union in all 27 patients without complications. In accordance to these previous findings, subsequent studies have shown good clinical outcomes after intramedullary screw fixation, but several postoperative complications have been reported. Complications such as a mis-inserted screw during a subcutaneous insertion, breakage of the opposite cortical bone, soft tissue irritation, screw head-induced metatarsalgia, peroneous brevis tendon tear, and stimulation of the sural nerve have been shown to be associated with intramedullary screw fixation [14,15]. Nowadays, the selftapping screw fixation does not require pre-tapping in principle, but for type 2 or 3 stress fractures pre-tapping has been recommended to remove intramedullary sclerosis and to promote re-establishment of blood flow [16]; this approach may lessen the occurrence of complications. Tension band wiring Tension band wiring has been introduced as an alternative to the intramedullary screw fixation for base fractures of the 5th metatarsal. A modified tension band wiring that uses 2 screws and wires has also been developed [17]. Inlay bone graft Bone graft for union is a conventional alternative to internal fixation. It has the advantage of not requiring an additional removal surgery of screws but requires a secondary incision. Specifically, compared to the intramedullary compression screw fixation, bone grafts have the disadvantage that a relatively longer duration, of more than 3 months, is needed for bone union. Surgical difficulties related to bone grafting include insufficient removal of the sclerotic bone and graft compatibility. Conservative accessory treatments Conservative treatments such as extracorporeal shock therapy and platelet-rich-plasma injection therapy have been reported to successfully complement the core treatment for 5th metatarsal fractures. Such supplementary treatments are useful when patients are nonresponsive to standard treatments, when complications such as nonunion or delayed union exist, or when patients refuse to receive surgical treatment [18]. REHABILITATION AND RETURN-TO-SPORTS Competitive athletes desiring to return-to-sports at the earliest possible date tend to downplay their level of pain at the postoperative follow-up. Because they hurry their return-to-sports before a complete recovery, they tend to incur complications such as refractures and nonunion more easily than those who comply to rehabilitation faithfully [1,19]. It has been shown that most patients who present with complications had disregarded the postoperative rehabilitation protocol and had returned to sports prematurely. Especially in athletes, the point at which the patient returns to sports, which should be only once a clinical and a radiological union is achieved, should be clearly defined through a collaborative decision made between the coaching staff and the patient. Yet even a bone union that is achieved through screw insertion does not guarantee prevention of refractures at the 4

5 time of screw removal; therefore, removal of the screw in currently active professional athletes is recommended to be delayed until their sports career is completed [20]. CONCLUSION The conventional approach to treat stress fractures of the proximal 5th metatarsal, especially acute fractures, is that of conservative measures such as non weightbearing cast immobilization. But in athletes or in young patients in whom complications such as delayed union or a nonunion of the fractures are a chief concern, returnto-activity is expedited by treating the fractures surgically rather than conservatively. Intramedullary fixation using compression screws, curettage, and bone grafting are methods of surgical treatment most widely used for stress fractures of the 5th metatarsal. CONFLICT OF INTEREST No potential conflict of interest relevant to this article was reported. REFERENCES 1. Weinfeld SB, Haddad SL, Myerson MS. Metatarsal stress fractures. Clin Sports Med 1997;16: Milgrom C, Giladi M, Stein M, et al. Stress fractures in military recruits. A prospective study showing an unusually high incidence. J Bone Joint Surg Br 1985;67: Drez D Jr, Young JC, Johnston RD, Parker WD. Metatarsal stress fractures. Am J Sports Med 1980;8: Stewart IM. Jones s fracture: fracture of base of fifth metatarsal. Clin Orthop 1960;16: Torg JS, Balduini FC, Zelko RR, Pavlov H, Peff TC, Das M. Fractures of the base of the fifth metatarsal distal to the tuberosity. Classification and guidelines for non-surgical and surgical management. J Bone Joint Surg Am 1984;66: Ouzounian TJ, Shereff MJ. In vitro determination of midfoot motion. Foot Ankle 1989;10: Donahue SW, Sharkey NA. Strains in the metatarsals during the stance phase of gait: implications for stress fractures. J Bone Joint Surg Am 1999;81: Shereff MJ, Yang QM, Kummer FJ, Frey CC, Greenidge N. Vascular anatomy of the fifth metatarsal. Foot Ankle 1991;11: Lawrence SJ, Botte MJ. Jones fractures and related fractures of the proximal fifth metatarsal. Foot Ankle 1993;14: Dameron TB Jr. Fractures and anatomical variations of the proximal portion of the fifth metatarsal. J Bone Joint Surg Am 1975; 57: DeLee JC, Evans JP, Julian J. Stress fracture of the fifth metatarsal. Am J Sports Med 1983;11: Kavanaugh JH, Brower TD, Mann RV. The Jones fracture revisited. J Bone Joint Surg Am 1978;60: Josefsson PO, Karlsson M, Redlund-Johnell I, Wendeberg B. Jones fracture. Surgical versus nonsurgical treatment. Clin Orthop Relat Res 1994;(299): Kelly IP, Glisson RR, Fink C, Easley ME, Nunley JA. Intramedullary screw fixation of Jones fractures. Foot Ankle Int 2001;22: Larson CM, Almekinders LC, Taft TN, Garrett WE. Intramedullary screw fixation of Jones fractures. Analysis of failure. Am J Sports Med 2002;30: Porter DA, Duncan M, Meyer SJ. Fifth metatarsal Jones fracture fixation with a 4.5-mm cannulated stainless steel screw in the competitive and recreational athlete: a clinical and radiographic evaluation. Am J Sports Med 2005;33: Lee KT, Park YU, Young KW, Kim JS, Kim JB. Surgical results of 5th metatarsal stress fracture using modified tension band wiring. Knee Surg Sports Traumatol Arthrosc 2011;19: Acker JH, Drez D Jr. Nonoperative treatment of stress fractures of the proximal shaft of the fifth metatarsal (Jones fracture). Foot Ankle 1986;7: Milgrom C, Finestone A, Shlamkovitch N, et al. Prevention of over use injuries of the foot by improved shoe shock attenuation. A randomized prospective study. Clin Orthop Relat Res 1992; (281): Wright RW, Fischer DA, Shively RA, Heidt RS Jr, Nuber GW. Refracture of proximal fifth metatarsal (Jones) fracture after intramedullary screw fixation in athletes. Am J Sports Med 2000;28:

Kyung Tai Lee, M.D., Ki Won Young, M.D., Young Uk Park, M.D. +, Hyuk Jegal, M.D., Jin Su Kim, M.D.

Kyung Tai Lee, M.D., Ki Won Young, M.D.*, Young Uk Park, M.D. +, Hyuk Jegal, M.D., Jin Su Kim, M.D.* KT Lee s Foot and Ankle Hospital, Seoul, Korea Foot and Ankle Clinic, Eulji Medical Center, Seoul, Korea*