➢ Percutaneous fixation of Jones fractures with an intramedullary screw is the standard of care for athletes, who experience unacceptably high rates of nonunion, refracture, and delayed return to activities with nonoperative treatment.
➢ Fixation should use the largest solid partially threaded screw, usually 5.5 or 6.5 mm in diameter, that can be inserted without displacing or comminuting the fracture.
➢ Autogenous bone graft should be used to supplement intramedullary fixation in cases of nonunion, refracture, and implant failure.
➢ An understanding of risk factors for refracture and nonunion, including cavus and/or varus foot alignment and nutritional and hormonal deficiency, is critical.
➢ Return to normal walking or sport activities is dependent on clinical and radiographic healing. Computed tomography (CT) can be especially helpful as a confirmatory test in elite athletes, but may not be necessary or cost-effective in non-athletes.
Proximal fifth metatarsal metaphyseal (often termed Jones) fractures are one of the most common forefoot injuries in the general population and occur especially in athletes and patients with deformity resulting in disproportionate loading of the lateral aspect of the foot1. Delayed union can occur because these injuries occur in an area with a tenuous, retrograde blood supply2,3. Additionally, the repetitive shear stresses endured by athletes both cause this injury and contribute to nonunion and refracture. Because elite and competitive athletes experience an unacceptably high rate of complications with nonoperative treatment, primary fixation remains the standard of care in this population4-7. In contrast, acute Jones fractures are typically treated initially in a non-weight-bearing cast in non-athletes. It is critical to identify and to address biomechanical, nutritional, and behavioral factors that can both predispose patients to these injuries and impede a successful outcome. Despite appropriate surgical treatment, nonunion, delayed union, and refracture can still result in many elite athletes.
Fractures of the proximal fifth metatarsal are categorized most commonly on the basis of anatomic location as tuberosity avulsions (zone I), Jones fractures (zone II), or proximal diaphyseal stress fractures (zone III)8. A true Jones fracture is defined as a fracture of the proximal fifth metatarsal metaphysis without extension distal to the fourth-fifth intermetatarsal articulation8. This eponym has generated confusion among orthopaedic surgeons between a true Jones fracture and a proximal diaphyseal stress fracture. Even the first account of this injury in 1902 included these two adjacent fracture patterns9. Similar clinical outcomes have been demonstrated between these two fracture locations. Therefore, it has been proposed that both should be described as Jones fractures and should be treated in the same fashion10. As a result, the distinction between zone-II and III fractures has become largely academic. Although surgeons have anecdotally observed a higher nonunion rate with zone-III fractures, both will be referred to as Jones fractures for the purpose of this review.
Stress fractures can be distinguished from acute fractures by the presence of prodromal pain and cortical thickening or stress reaction on radiographs5. Stress fractures of the fifth metatarsal have been categorized by Torg et al.11. Type-I injuries refer to early stress fractures with periosteal reaction, type-II injuries have a widened fracture line and intramedullary sclerosis, and type-III injuries are established nonunions with complete medullary canal obliteration11.
Mechanisms of Injury and Pathophysiology
Acute Jones fractures are caused by a substantial indirect abduction force applied to the forefoot while the ankle is plantar-flexed9,12,13. However, stress fractures of the proximal fifth metatarsal diaphysis are most commonly associated with a sudden increase in high-impact training (e.g., marathon or military) or a change in shoe wear. Underlying anatomic predisposing factors (e.g., hindfoot varus, cavus foot, genu varum) may contribute to the risk of fracture.
The metadiaphyseal region of the proximal fifth metatarsal is a watershed zone with a retrograde blood supply2,3. The blood supply comes from the metaphyseal arteries at the base of the fifth metatarsal and a nutrient artery that enters at the proximal diaphysis and travels proximally3. A cadaveric study demonstrated that an osteotomy created in the proximal 40 mm of the fifth metatarsal violated the nutrient artery14. Therefore, zone-II and III fractures occurring within this region of the metatarsal have poor healing potential.
Multiple anatomic structures exist that place stress across the metadiaphyseal region of the fifth metatarsal. These include the peroneus brevis, the peroneus tertius, the lateral band of the plantar aponeurosis, the tarsometatarsal ligaments, and the distal adductor. Field athletes wearing tight-fitting cleats and court players withstand substantial repetitive loading at the fifth metatarsal base, both predisposing them to this injury initially and increasing the likelihood of recurrence. National Football League (NFL) players with this injury demonstrated a trend toward decreased post-injury participation, although no measure of return to play was significantly lower15. In a series of eighty-one elite football players, players able to compete for at least one full collegiate season after injury were significantly less likely (p < 0.001) to have a persistent fracture gap (9.7%) compared with those who were not able to compete (60%) and were significantly less likely (p < 0.001) to sustain a refracture (5.6%) compared with those who were not able to compete (46.7%)16.
Patients with Jones fractures have point tenderness and swelling over the proximal fifth metatarsal. Standing hindfoot and forefoot alignment should be observed to look for hindfoot varus and cavus (forefoot equinus). In patients with varus hindfoot alignment, lateral ankle stability and peroneal strength should be assessed. Other than the proximal fifth metatarsal fracture, the differential diagnosis in patients with tenderness in this area includes fourth or fifth tarsometatarsal joint sprain, cuboid fracture, insertional peroneus brevis tendinitis, and fracture of the os peroneum.
Weight-bearing three-view (anteroposterior, oblique, lateral) radiographs of the foot should be made when possible. Non-weight-bearing views are acceptable in the case of acute fracture. Radiographs are typically adequate to distinguish between acute fracture and nonunion as well as complete and incomplete fracture. The presence of stress hypertrophy suggests an acute-on-chronic situation. In the case of persistent pain without abnormality evident on radiography, a bone scan or magnetic resonance imaging (MRI) can be employed to look for stress reaction. MRI, albeit more expensive, may be helpful because of its ability to simultaneously evaluate surrounding soft-tissue structures. A computed tomography (CT) scan is generally reserved as a confirmatory test for assessment of healing after a known Jones fracture. Especially in cases treated with an intramedullary screw, CT can more clearly delineate whether or not bridging trabeculation is present.
In non-athletes, the initial treatment of acute Jones fractures traditionally involves a period of immobilization in a non-weight-bearing cast or boot. In the general population, 50% of these injuries fail to heal or refracture17. Based on this, operative treatment is appropriate for an active, healthy patient who is educated regarding treatment options. In the case of symptomatic nonunion, operative intervention is indicated.
When treating elite and competitive athletes, nonoperative treatment of Jones fractures is not an acceptable option, as the union rate was only 76% among 198 patients18 and the refracture risk was 38% among twenty-one patients19. However, a recent meta-analysis demonstrated a 96% union rate in 157 operatively treated patients18. Other indications for operative treatment include fracture displacement exceeding 2 to 3 mm, presence of abnormal sclerosis at the fracture site on radiographs (Torg types II and III), and failure to progress toward healing after at least three months10.
One common operative technique for acute Jones and stress fractures in athletes is an antegrade percutaneous intramedullary screw18,20,21. Reports have demonstrated that this method may improve union rates, may expedite return to play, and may reduce refracture rates22-24. An appropriately placed screw is infrequently prominent. However, plate fixation can result in symptomatic implant necessitating removal, and these screw holes become stress risers that increase the risk for refracture. This is especially problematic in athletes wearing tight-fitting cleats or shoes. Despite advances in the operative treatment of Jones fractures, treatment failures can occur.
Athletes with symptomatic nonunion, refracture, or implant failure typically require a revision procedure to achieve osseous union12,18,25. In these cases, the recommended treatment is open autogenous bone-grafting with percutaneous screw fixation. A recurrent fracture that is nondisplaced or minimally displaced can initially be treated with a bone stimulator and boot immobilization. If displaced, refracture site debridement is warranted and adjunct procedures are dependent on the condition of the existing implant. If an appropriate screw is in place without evidence of fatigue or failure, percutaneous treatment can be undertaken with injection of a mixture of bone marrow aspirate and demineralized bone matrix or cancellous bone graft25. Evidence of screw fatigue or failure requires implant removal, revision fixation with a larger-diameter intramedullary screw, and autogenous bone-grafting12,25,26. The efficacy of this treatment algorithm has been demonstrated in elite athletes25. For nonunions, extracorporeal shock wave therapy is an alternative to operative treatment that has been shown to have similar union rates and time to union and fewer complications27.
In addition to the treatment of the fifth metatarsal fracture, hindfoot varus, if present, should be corrected. If the deformity is forefoot-driven and correctible, a first metatarsal dorsiflexion osteotomy is recommended28. If the hindfoot deformity is rigid, a lateralizing calcaneal osteotomy should be considered. A recent Level-III NFL study demonstrated that players with proximal fifth metatarsal fractures had significantly more hindfoot varus (as measured by the coronal plane talar-first metatarsal angle) than a control group without this injury (p = 0.015)15. Conversely, another NFL study showed that no radiographic measurements are predictive of refracture or a persistent fracture gap16.
To maximize the chance of healing, nutritional and hormonal deficiencies must be identified and corrected. Vitamin D deficiency is defined as a 25-hydroxyvitamin D level of <20 ng/mL, whereas vitamin D insufficiency corresponds to a 25-hydroxyvitamin D level between 20 and 32 ng/mL29. One study of 723 patients showed that 43% of patients scheduled to undergo elective orthopaedic procedures were vitamin D-insufficient, with 40% of these being vitamin D-deficient30. Additionally, thyroid hormone abnormalities should be addressed31. Although we do not routinely check vitamin D and thyroid hormone levels in all patients presenting with a Jones fracture, this work-up is recommended in patients with nonunion, refracture, or a history of multiple fractures.
Choice of Fixation
Multiple studies exist describing different types of screws in the treatment of Jones fractures. We prefer solid partially threaded screws (5.5 and 6.5 mm), and newer site-specific screw systems have lower rates of adverse events and implant failure than conventional screws21. The largest diameter screw that can be inserted without displacing or comminuting the fracture should be used. Cannulated screws should not be used as they have lower fatigue strength than solid screws32 and are more likely to result in refracture and nonunion12. Although less likely to cause soft-tissue irritation33, we do not recommend headless screws because removal, if necessary, is more challenging. Although tapered variable-pitch screws have similar bending stiffness, they are inferior to partially threaded screws in terms of fracture site compression, pull-out strength, and fracture site angulation34.
Operative treatment of acute fractures is typically performed in an outpatient setting under regional or general anesthesia. The patient is placed supine with a bump beneath the ipsilateral hip with the heel at the end of the bed to facilitate fluoroscopy (Fig. 1). Frequent orthogonal fluoroscopic views are critical to ensure an accurate starting point, screw position, and maintenance of reduction. Fluoroscopy is also beneficial to verify appropriate screw length and to visualize compression across the fracture site.
A percutaneous incision 1.5 to 2 cm in length is made approximately 2 to 3 cm proximal to the base of the fifth metatarsal (Fig. 2). Subcutaneous dissection is performed to expose the proximal fifth metatarsal. Care must be taken to protect the sural nerve and peroneus brevis tendon during exposure, drilling, and screw insertion. A protective tissue guide is used to introduce a cannulated guide pin against the fifth metatarsal base adjacent to the cuboid articulation. Fluoroscopy is used to confirm the starting point on the dorsal and medial aspect of the bone. Once the position and angle of the guide pin are deemed satisfactory, the guide pin is advanced carefully into the shaft and across the fracture.
An understanding of the anatomy of the fifth metatarsal is essential, as the bone is often curved at the shaft, distal to the metaphysis. The guide pin should advance freely as confirmed on multiple views without entering the medial cortex of the proximal shaft. With use of a soft-tissue protector (Fig. 3), a 3.2 or 3.5-mm cannulated drill is inserted over the guidewire through the proximal cortex, into the canal, and across the fracture site. Once the canal has been entered proximally, the guidewire and cannulated drill are exchanged for a solid drill, which should be advanced on reverse to ream the canal and to decrease the risk of cortical violation (Fig. 4). Next, the guidewire is reinserted and a 4.5-mm cannulated tap is introduced. The size of the tap can be increased in 1-mm increments until sufficient torque is achieved. There is a substantial amount of variation in the shape and size of the medullary canal among patients. In our experience, although the anatomy of most athletes can accommodate a 5.5-mm screw, a 6.5-mm screw is usually necessary to adequately stabilize the fracture.
After the screw diameter has been established, the screw length is determined by measuring a screw radiographically alongside the metatarsal (Fig. 5). The ideal screw length is such that all threads are just distal to the fracture site. Because the metatarsal is curved, a screw that extends beyond the midshaft may result in distraction of the fracture, particularly at the lateral cortex, leading to varus angulation. Screw length is usually between 40 and 55 mm. The guidewire is removed and the solid screw is inserted. The screw should have excellent purchase, and sufficient torque occurs when the lateral aspect of the foot appears to rotate with the screwdriver. One must take care to avoid overtightening, as this can cause the screw head to violate the subchondral bone.
It is necessary to verify acceptable screw position, length, and fracture site compression on multiple fluoroscopic views. Bone-grafting is not required during the index procedure unless the fracture distracts during screw insertion. Wound closure is performed with interrupted 3-0 nylon suture alone, and a well-padded splint is applied.
Refractures and Nonunions After Operative Fixation
In patients with nonunion and those requiring revision procedures, retained implants must be exchanged for a new intramedullary screw and biologic augmentation should be added. The ipsilateral iliac crest should also be prepared and draped. The previous incision on the foot is typically adequate for screw removal and insertion. The operative approach to the base of the fifth metatarsal is identical to that previously described for the index procedure. A more extensile incision is necessary for removal of a plate-screw construct. In the event of a broken screw (Fig. 6), the proximal portion can be removed in standard fashion and the distal portion must be removed through the nonunion or refracture site with a screw removal set.
After implant removal, the fracture or nonunion site is identified fluoroscopically with use of a radiopaque instrument. A 1 to 2-cm incision is made over this location for open debridement and bone-grafting (Fig. 7). The incision length varies depending on the bone-graft material used. For demineralized bone matrix mixed with bone marrow aspirate, the incision is shorter (<1 cm) compared with that used for cancellous autograft. The sural nerve must be protected throughout the procedure. In revision cases with scar formation, it may need to be mobilized for safe, tension-free retraction. The fracture is exposed by elevating the periosteum dorsally and plantarly. Debridement is achieved with a curet and a small-diameter Kirschner wire or drill.
For refracture and implant failure, the same technique is used for screw selection and insertion. In the case of nonunion with canal sclerosis, a 3.2-mm drill-bit is slowly advanced across the fracture site, alternating between the forward and reverse modes, ensuring that the cortical bone is not violated. The inserted partially threaded screw should have all threads immediately distal to the fracture site; however, if a cortical window was required for screw removal, a longer screw is required for stabilization. This is the only case in which sufficient screw length trumps screw diameter, as the curve of the metatarsal may not accommodate a larger-diameter screw.
Prior to screw insertion, bone graft is harvested and inserted. If cancellous autogenous bone graft is desired, we favor harvest from the ipsilateral iliac crest, which has a high number of osteoblastic progenitor cells35. Additionally, we prefer to avoid bone graft harvest from the weight-bearing bones of the lower extremity to avoid creating a stress riser, particularly in elite athletes. We typically harvest cancellous autograft with use of an 8-mm power trephine via a minimally invasive technique. The graft is then placed into the canal adjacent to the fracture and is used to fill any defects at the fracture site. Alternatively, bone marrow aspirate from the iliac crest combined with demineralized bone matrix can be used in place of cancellous autograft when there is minimal bone defect following debridement25. This decision can best be made following debridement. Bone marrow aspirate and demineralized bone matrix can be injected into the subperiosteal space at the fracture site and into the medullary canal on both sides of the fracture (Fig. 8). Once grafting is satisfactory, the desired solid screw is advanced under fluoroscopy to ensure satisfactory alignment and compression.
Postoperative Protocol and Return to Play
After Acute Fracture
We adhere to an aggressive rehabilitation protocol for elite athletes. Postoperatively, patients are kept non-weight-bearing for two weeks to allow healing of the skin incision. Following suture removal, patients can begin weight-bearing in a short walker boot. A bone stimulator can be used to expedite healing. Once the fracture site is minimally tender, radiographic data demonstrate bridging trabeculation, and the patient is able to bear weight without pain (usually at four to six weeks), he or she can transition to a running shoe and can begin a running progression protocol followed by sport-specific integration. A clamshell orthosis or turf toe plate is used during rehabilitation to decrease stress on the metatarsal base. A full-length orthosis with a lateral hindfoot post extending proximally to the cuboid is used when the athlete returns to play, at an average of eight to ten weeks after the operation. If there is any question about sufficient healing, a CT scan with three-dimensional reconstructions can be performed to better delineate union from nonunion. CT provides a more reliable assessment of union than radiography, as demonstrated in the arthrodesis literature36.
After Revision Procedures
Advancement of weight-bearing is more conservative in the revision setting. Patients typically remain non-weight-bearing in a cast or splint for four weeks, followed by the initiation of weight-bearing in a short walker boot. A longer period of non-weight-bearing (six to eight weeks) is advised if a trough had to be created for screw removal. Once there is clinical and radiographic evidence of healing (usually at eight weeks), patients are transitioned into running sneakers with a custom orthosis. If there is any question regarding adequate healing, a CT scan should be obtained. This is particularly beneficial in athletes in mid-season when time is of the essence. Once complete radiographic healing is visualized, running can be initiated on an anti-gravity treadmill or in a pool. Assuming that they remain pain-free, athletes can then progress gradually to sprinting, jumping, cutting, and position-specific drills.
Existing evidence, although predominantly based on retrospective case series, favors the use of partially threaded intramedullary screws for treatment of acute fractures, stress fractures, and nonunions, particularly in athletes. We agree that the distinction between a true Jones fracture and a proximal diaphyseal stress fracture is purely academic as their treatment and prognoses are the same10,15. Although it may be a reasonable initial option in non-athletes, conservative treatment is associated with unacceptably high rates of refracture, nonunion, and delayed return to play in elite athletes. Return to play prior to complete radiographic union increases the risk of refracture. Therefore, CT scanning can be beneficial in the athletic population as a confirmatory test when radiographs are indeterminate.
Source of Funding: This study did not utilize any external sources of funding.
Investigation performed at the OrthoCarolina Foot & Ankle Institute, Charlotte, North Carolina
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. In addition, one or more of the authors has a patent or patents, planned, pending, or issued, that is broadly relevant to the work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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