BROKEN FOOT
5th METATARSAL FRACTURE, aka JONES FRACTURE
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related talks: broken foot (talus fracture, another type); broken foot (lisfranc fracture); broken heel bone; broken ankle (classic type); low ankle sprain; high ankle sprain
What is a Jones Fracture (5th Metatarsal Fracture)?
A Jones Fracture, aka a 5th metatarsal fracture, is a type of broken foot. More specifically, the break occurs along the middle and outside portion of the foot. Its a very common type of broken foot.
It got the name "Jones fracture" for the doctor (Dr. Jones) who first wrote about the fracture after sustaining the injury while dancing.
To better understand the injury lets quickly review our the anatomy of our foot. So your foot has a lot of bones, 29 total. Your toes each have 3 small bones (except the big toe which only has 2) and as you go toward your ankle the bones get bigger and bigger. The 'forefoot' has 5 bones (called metatarsals) which connect the toes to the 'midfoot'. The 5th metatarsal connects your pinky toe to the rest of your foot, and this is the bone we talk about here. Its also a very important bone of the foot because its very mobile an so our muscles can make small adjustments to help maintain balance.
So what makes the 5th metatarsal bone so special that it gets so much attention from Dr. Jones and other orthopedic doctors? This bone doesnt heal like the other metatarsal bones, its a problem child, and so it often requires special treatment. Its like saying: The squeaky wheel gets the grease.
So heres the situation: A broken bone heals with nutrients and growth factors delivered to the bone via our bloodstream. Our body can only fill in the crack with new bone when these nutrients are delivered (in the same way that you can only build a house if the supplies are delivered). If the blood supply to a bone is also injured when the bone breaks, then the bone cannot heal because it cannot get the nutrients it needs. Even though our bones look like rocks, they are more like trees that only stay strong when they have healthy roots. If trees dont get enough water, they will shrivel up and die... bones act the same way.
The 5th metatarsal has a bad blood supply in certain regions and therefore it has trouble healing. There are "Three Zones of Injury" where a break can occur. In Zone 1, at the tip of the bone, the break occurs in an area of great blood supply. In Zone 2 (a break at the joint between this bone and the 4th metatarsal) and in Zone 3 (a break in the middle of the bone) there is poor blood supply and problematic healing.
Diagnosing a Jones Fracture (5th Metatarsal Fracture):
People with this injury typically report twisting their foot while playing sports or tripping on an uneven sidewalk, and they immediately feel pain along the outside of their foot. The foot is tender to touch along the outside of the mid-foot and often people cannot bear weight on the foot due to pain.
Doctors are suspicious for a break and will order x-rays to diagnose this injury. The x-rays will not only show the broken bone, but will show where the break occurs (which is important for deciding the best treatment, see below).
Also the x-rays can show if the injury is new - there is a clean break; or if the injury is the result of a chronic stress fracture - there is a break surrounded by abnormally thickened bone. A stress fracture means the bone has been breaking slowly over many weeks due to the accumulation of too much stress. The abnormal thickened bone is our body's attempt to build up extra bone to withstand this stress. A final twist of the foot that causes a break through this area of stress is like the straw that broke the camels back (its usually a very minimal injury that produces an injury that would never occur in healthier bone).
Treating a Jones Fracture (5th Metatarsal Fracture):
Treatment depends on where the break occurs.
Remember that good healing requires good blood supply, and this little foot bone can be really temperamental. So areas of this bone with good blood supply will heal great and areas with poor blood supply require a lot of attention.
Zone 1 injuries typically heal without issues, so the foot just needs to be protected while it heals. A medical boot (called a CAM boot) or a hard-soled shoe limits stress across the injured bone while it heals. With the foot protected in a boot or hard-sole shoe, people are allowed to walk on the foot as much as they can tolerate.
Zone 2 and Zone 3 injuries occur in the area with poor blood flow (referred to as a "watershed" region). It takes a long time for the breaks to heal (if at all), so the injury needs to be treated carefully. People are advised to keep all weight off that foot while it heals in a hard cast for 6-8 weeks. A follow up x-ray, around 4 weeks after injury should show signs that the bone is healing. If its not healing at this time (called a 'nonunion' because the break fails to unite) then many doctors will recommend surgery. The procedure uses a single screw to hold the two bone fragments close together so its heal. Surgery almost always gets the bone to heal.
Waiting two months for this little foot bone to heal can be a season-ender for most athletes. For this reason many elite athletes will elect to get surgery right away to speed up the healing process. Surgery allows them to begin training sooner and getting back to sports sooner.
References
1) Dameron TB Jr. Fractures of the Proximal Fifth Metatarsal: Selecting the Best Treatment Option. JAAOS 1995; 3: 110-114. full article. review.
2) Shahid MK et al. Aircast walking boot and below-knee walking cast for avulsion fracutres of the base of the fifth metatarsal: a comparative cohort study. Foot Ankle Int 2013; 34: 75-9. full article. nonop rx zone 1 injury.
3) Porter DA et al. Fifth metatarsal Jones fracture fixation with a 4.5-mm cannulated stainless steel screw in the competitive and recreational athlete: a clinical and radiography evaluation. Am J Sports Med 2005; 33: 726-33. full article. 100% union with orif.
4) Portland et al. Acute management of Jones fractures. Foot Ankle Int 2003; 24: 829-833. full article. type 1 6 wks to heal, type 2 8 wks.
5) Larson CM et al. Intramedullary screw fixation of Jones fractures. Analysis of failure. Am J Sports Med 2002; 30: 55-60. full article. orif failure if premature reutrn to play. asx but not full healing on xray had risk.
6) Jones R. Fracture of the base of the fifth metatarsal bone by indirect violence. Ann Surg 1902; 35: 697-700. full article. original report.
7) Smith JW et al. The intraosseous blood supply of the fifth metatarsal: implications for proximal fracture healing. Foot Ankle 1992; 13: 143-52. full article. blood supply reviewed.