A Guide To Intramedullary Fixation Of Jones Fractures

A true Jones fracture is a transverse fracture at the metaphyseal-diaphyseal junction, 1.5 cm from the base of the fifth metatarsal. We typically group proximal fifth metatarsal fractures into three zones as described by Lawrence and colleagues.¹ Within this classification system, zone 2 fractures are fractures at the metaphyseal-diaphyseal junction or Jones fractures. Most commonly, the fracture originates at the cuboid-fourth metatarsal articulation and extends laterally across the fifth metatarsal. Given the poor vascularity at this site, healing of these fractures is quite variable and difficult.

Jones fractures are most common in patients with a cavovarus alignment due to overloading of the lateral column and repetitive stress in the area. Similarly, in patients with metatarsus adductus, authors have reported a higher incidence of Jones fractures with the literature suggesting up to a 2.4-fold greater incidence of Jones fractures.² Physicians frequently misdiagnose these fractures as avulsion fractures.

The most common mechanism of injury for Jones fractures in athletes is forefoot adduction with inversion of the foot as the resultant forces cause a break in the fifth metatarsal. This occurs frequently with pivot shifting in football or when the heel is off the ground in basketball.

Imaging includes three standard views of the foot including dorsoplantar, lateral and medial oblique views. Advanced imaging modalities such as computed tomography (CT) or magnetic resonance imaging (MRI) are not routine for acute Jones fractures. However, one may consider CT or MRI in instances of delayed or non-union.

The Jones fracture has a high non-union rate that is reportedly as high as 50 percent in some studies.³ The area in which the fracture occurs is an area of poor blood supply within the fifth metatarsal found in a watershed area between two blood supplies. In addition to fractures occurring in a relatively avascular zone, tendon attachments in the area can cause diastasis of the fracture fragment and motion at the site of healing.

What You Should Know About Current Management Of Jones Fractures

The current accepted management for Jones fractures includes both non-operative treatment and surgical management. Conservative treatment involves non-weightbearing with immobilization for up to five months.

One would typically reserve surgical treatment for elite athletes or inpatients who refuse conservative management.³ There is a reported 50 percent re-fracture or non-union rate without surgical management.³ Surgical repair, however, is not without complications and can include damage to the sural nerve and peroneus brevis tendon.

Surgical intervention for Jones fractures may include intramedullary fixation or the use of a hook plate. Current literature suggests that intramedullary fixation greatly reduces the risk of non-union and allows for faster rates of union and return to sport.⁴ In one study, surgical intervention allowed for return to sport, on average, at 8.7 weeks in NFL players (range eight to 10 weeks) with a low re-fracture rate.⁵ One would typically reserve hook plates for patients with comminuted fractures, poor bone quality or a significant amount of cortical blowout due to previous surgical intervention. Cadaveric studies have demonstrated that intramedullary screw fixation is superior to the hook plate in preventing bending stiffness and fracture site rotation.⁶

A Closer Look At The Authors’ Treatment Protocol

At our institution, we place patients with Jones fractures under general anesthesia and apply a thigh tourniquet. Then, utilizing a bean bag, we place the patient in the lateral decubitus position. This allows for adequate visualization and access to the lateral aspect of the foot.

Mark the borders of the fifth metatarsal and position the guide wire “high and inside” on the fifth metatarsal base. Confirm the guide wire position with fluoroscopy. When inserting the intramedullary guide wire, use power instrumentation until the wire engages the proximal cortex and one can easily mallet the wire down the medullary canal. Then utilize fluoroscopic guidance and obtain multiple views in order to confirm that positioning of the guide wire is satisfactory.

When performing intramedullary fixation of a Jones fracture, screw diameter is of the utmost importance. The smallest diameter screw that one may use in the fifth metatarsal while obtaining purchase of the inner cortices is 4.5 mm.⁷ By selecting the largest diameter screw that the fifth metatarsal can accommodate, surgeons can achieve maximum purchase of the inner cortices. One can assess this intraoperatively by using the tap to determine which size screw will engage the inner cortices. Granata and colleagues, in a study of 149 patients, attributed failure of intramedullary fixation of Jones fractures in an elite athletic population to inadequate screw diameter or the use of a cannulated screw.⁸ Surgeons should obtain final images following the insertion of the screw to ensure appropriate length and positioning of the hardware.  

In Conclusion

The risks of surgical intervention for Jones fractures far outweigh the benefits of reducing the risk of nonunion and allowing faster return to play for athletes. In an acute repair, augmenting with bone graft is not indicated. In patients with nonunion or delayed union, surgeons may consider the use of autologous or allogenic bone graft.⁹ Screw diameter selection is imperative and screws must not be less than 4.5 mm in diameter. Intraoperatively, one may use the tap to establish inner cortical diameter and appropriate screw width.

When treating Jones fractures, podiatrists should consider the patient’s underlying foot structure and pathomechanics though one does not typically address correction of adduction deformities in the acute setting. When considering return to sport in the athletic population, achieving radiographic union is critical.¹⁰

Dr. Theodoulou is an Attending Surgeon at Cambridge Health Alliance and an Instructor of Surgery at Harvard Medical School. He is the Section Editor of Forefoot Reconstruction for the Journal of Foot and Ankle Surgery. Dr. Theodoulou is the President-Elect of the Massachusetts Podiatric Medical Society.

Dr. Pascarella is a third-year resident at Cambridge Health Alliance in Cambridge, Mass.

References

1. Lawrence SJ, Botte MJ. Jones fractures and related fractures of the proximal fifth metatarsal. Foot Ankle. 1993; 14(6):358–65.
2. Fleischer AE, Stack R, Klein EE, Baker JR, Weil L Jr, Weil LS Sr. Forefoot adduction is a risk factor for Jones fracture. J Foot Ankle Surg. 2017;56(5):917-921.
3. Le M, Anderson R. Zone II and III fifth metatarsal fractures in athletes. Curr Rev Musculoskelet Med. 2017;10(1):86-93
4. Yates J, Feeley I, Sasikumar S, et al. Jones fracture of the fifth metatarsal: Is operative intervention justified? A systematic review of the literature and meta-analysis of results. Foot (Edinb). 2015; 25(4):251–7.
5. Lareau CR, Hsu AR, Anderson RB. Return to play in National Football League players after operative Jones fracture treatment. Foot Ankle Int. 2016;37(1):8-16.
6. Huh J, Glisson RR, Matsumoto T, Easley ME. Biomechanical comparison of intramedullary screw versus low-profile plate fixation of a Jones fracture. Foot Ankle Int. 2016;37(4):411-8.
7. Scott RT, Hyer CF, DeMill SL. Screw fixation diameter for fifth metatarsal Jones fracture: a cadaveric study. J Foot Ankle Surg. 2015;54(2):227–229.
8. Granata JD, Berlet GC, Philbin TM, Jones G, Kaeding CC, Peterson KS. Failed surgical management of acute proximal fifth metatarsal (Jones) fractures: a retrospective case series and literature review. Foot Ankle Spec. 2015;8(6):454-9.
9. Seidenstricker CL, Blahous EG, Bouché RT, Saxena A. Plate fixation with autogenous calcaneal dowel grafting proximal fourth and fifth metatarsal fractures: technique and case series. J Foot Ankle Surg. 2017;56(5):975-981.
10. Roche AJ, Calder JD. Treatment and return to sport following a Jones fracture of the fifth metatarsal: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2013;21(6):1307–1315.

Editor’s note: For further reading, see “Keys To Treating Proximal Fifth Metatarsal Fractures” in the February 2016 issue of Podiatry Today, “Rethinking Our Approach To Jones Fractures To Facilitate Shorter Post-Op Recovery” in the December 2011 issue or “Current Concepts In Treating Fifth Metatarsal Fractures” in the May 2010 issue.