Sports Sciences Feature: Fifth Metatarsal Stress Fractures
Duke's Reggie Love has already missed one month after breaking the fifth metatarsal in his right foot.

Duke's Reggie Love has already missed one month after breaking the fifth metatarsal in his right foot.

Feb. 1, 2005

ACC Sports Sciences Main Page

Robin M. Queen, Ph.D.
Coordinator of Sports Biomechanics
Michael W. Krzyzewski Human Performance Lab
Duke University

Basketball is a sport that is played by many people on a variety of levels from pickup games in parks and gyms, to high schools, colleges, and professional leagues across the world. Over the past few years we have seen an increase in the number of players opting to skip college and instead enter the NBA directly from high school. In addition, we have seen the development of a women's professional basketball league (WNBA) in the United States.

In 1998 it was estimated that as many as 450 million people play basketball world wide at all levels of the game, which accounts for approximately 11 percent of the world's population. Recently the CDC reported that there are an estimated 977,000 basketball injuries each year in the United States alone. The need for injury prevention measures at all levels of the game is becoming increasingly apparent as the number of players and injuries continues to rise. Most basketball injuries are minor and result in either no loss of time from practice or games, or result in the athletes being out of competition for only a short period of time. Most of these injuries happen at the foot or the ankle, with ankle sprains or strains accounting for approximately 53% of the loss of time from games.

In addition to ankle injuries, stress fractures of the lower extremity are extremely common in athletes and are usually classified as overuse injuries. Sites of involvement include the tarsal, navicular, tibia, fibula, and the metatarsals. Fifth metatarsal stress fracture, specifically, can significantly compromise an athlete's ability to perform, which translates into loss of practice time, game play, and can even result in the loss of an entire season of play for complicated cases.

The diagnosis of metatarsal stress fracture is often made clinically when the athlete complains of bony pain usually accompanied with specific soft tissue swelling. Radiographic assessment is used to confirm the diagnosis. Because the x-ray evidence of a stress fracture can lag as much as two weeks behind the onset of the break in the bone, a bone scan or MRI can be used to confirm the diagnosis earlier. In addition, bone scan or MRI may be used to determine if an athlete with symptoms is at risk for a stress fracture prior to the actual fracture.

Two Major Types of Fifth Metatarsal Fractures

Avulsion Fractures:

  • Most common fracture, result from forced inversion while the foot and ankle are in plantar flexion. Sometimes called a dancer's fracture since it's seen in dancers.
  • Usually will heal with conservative treatment: walking boot, weight bearing as tolerated, and strengthening exercises once symptoms have subsided, 3-6 weeks
  • Union of the fracture on x-ray: approximately 8 weeks after the injury.

    Proximal Shaft Fractures:

  • Acute "Jones" Fractures
    Type I: Early, conservative treatment
    Type II: delayed union, conservative treatment
    Type II: non-union, surgical fixation
  • Stress Fractures
    Type I: Early, conservative treatment
    Type II: delayed union, conservative treatment
    Type II: non-union, surgical fixation

    Mechanism of Injury
    All of the proximal shaft fractures of the fifth metatarsal occur at the metaphyseal-diaphyseal junction which is away from the end of the bone where the avulsion fracture occurs. Both the acute "Jones" fractures as well as the stress fractures have a similar injury mechanism, however, in the acute fracture there is no evidence of intramedullary sclerosis or bony stress, whereas evidence of sclerosis is present on imaging in the case of a stress fracture. During the injury the athlete's foot is planted, with the heel off the ground (plantar flexion) and a lateral force is being applied to the forefoot. Such positioning can occur during a plant and pivot maneuver, when landing on one foot from a jump as is done following a lay-up, or when landing on another player's foot when landing from a jump.

    Treatment
    Both Type I (Jones Fracture) and Type II fractures can be treated conservatively with non-weight bearing in a cast or walking boot for six to eight weeks with a progression to ambulation. In some Type II cases the period of non-weight bearing has to be extended until union has been achieved. To go on crutches without bearing weight for several weeks is difficult regardless if you are an athlete. A substantial number of these fractures if nonoperatively managed will not heal or the healing will be delayed. Therefore, conservative treatment of these fractures is not recommended for most athletes. Instead surgical fixation is recommended for competitive athletes in an attempt to improve fracture healing, decrease recovery time, and shorten the time away from athletic activity.

    Type III fractures are classified as being non-union fractures that require surgical intervention. The nonunion of these fractures is due in large part to the poor blood supply to the metaphyseal-diaphyseal junction. In the athletic population, the preferred treatment of metatarsal shaft fracture is intramedullary screw fixation because operative treatment provides more predictable healing with healing rates of up to 100% reported in the literature. Athletes should be followed closely during rehabilitation and radiographs should be repeated approximately every two weeks until union is achieved. (For Rehab: See Dave Englehardt's article) It is important to note that re-fracture of the proximal fifth metatarsal following surgical fixation has been reported in the literature to be anywhere from 5% to 40% depending on the study.

    Prevention of Fifth Metatarsal Stress Fractures
    The study of fifth metatarsal stress fracture prevention from a biomechanical perspective is fairly new. The mechanism of injury is still not well understood and there is a lack of information related to the incidence of such fractures in the basketball population as well as other sports. Research is currently being conducted at Duke University in an attempt to determine the number of players who have sustained a fifth metatarsal stress fracture over the past five years. In addition to determining the number of injuries this research is attempting to determine which sports see the highest incidence of these stress fractures as well as what surfaces the athletes are playing on when the injury occurs. Through a better understanding of the at-risk athletic population researchers will be able to better tailor studies to those at-risk sports and movements.

    In addition to determining the incidence of fifth metatarsal stress fractures, a recent preseason imaging study demonstrated the importance of diagnosing stress reactions prior to complete fracture. In this study, conducted at Duke University, one player was identified through MRI imaging as having stress symptoms and as a result was treated prior to complete fracture. This athlete was then able to play through the entire season without sustaining a fracture, using a custom orthotic device.

    Future Research
    In conjunction with determining the incidence of fifth metatarsal stress fractures attention needs to be given to determining if different athletes within the same sport are more susceptible to fifth metatarsal stress fractures based on foot type or other intrinsic factors. Through gaining a better understanding of the injury mechanism and an understanding of the at-risk player, researchers will be able to develop better injury prevention strategies. The long term goal of this research is to be able to prevent fifth metatarsal stress fractures through alterations in shoe wear or playing surface design.