July 2018

Stress Fractures Of the Foot in Football

High-impact sports expose athletes to greater risk of injury overall. Is there a way to prevent such trauma by applying the lessons of sports science?

By D. Chris Cothern PT, CES, PES

Stress fractures of the foot result from repetitive microtraumas and chronic submaximal loading of tissues. Among football players, the most common are the Jones fracture, a break in the fifth metatarsal between the base and the middle, and the Lisfranc fracture, a fracture or dislocation within the Lisfranc joint complex, which stabilizes the midfoot and is critical for walking. Athletes in high-impact sports that involve running, jumping, or contact with others, such as football, are at higher risk for injury. Diagnostic imaging can play a significant role in getting to a stress fracture diagnosis rather than a misdiagnosis of tendinitis. If not properly diagnosed, these fractures can lead to significant morbidity and can, for some athletes, be career-ending. The key to successful management is proper diagnosis, but given what we have learned in sports science, is there a way to prevent these stress fractures from occurring at all

Stress Fractures in College Athletes

In the most comprehensive evaluation of stress fractures in collegiate athletes to date, Rizzone et al.1 examined data from the National Collegiate Athletic Association Injury Surveillance Program (NCAA-ISP) covering more than 25 sports from 2004–2005 to 2013–2014. A total of 671 stress fractures were reported after 11,778,145 athlete-exposures (AEs), for an overall injury rate of 5.70 per 100,000 AEs.1 Consistent with other studies, women’s cross country (29 per 100,000), women’s outdoor track (22 per 100,000), and women’s gymnastics (26 per 100,000) had the highest stress fracture rates, all with at least 22 per 100,000 AEs. Football had 57 total foot stress fractures: 50 metatarsal and three navicular. Three areas of the foot had stress fractures so rare they were included only in the total number of fractures for all athletes in all sports during the study period: five sesamoid, six cuboid, and seven cuneiform. The rate of foot stress fractures in football was 3.01 per 100,000 AEs. Seventeen of the 25 sports evaluated had higher stress fracture injury rates per 100,000 AE’s than football. Sports with lower rates were men’s and women’s swimming and diving, men’s and women’s ice hockey, men’s tennis, and men’s and women’s baseball and softball. Conversely, women’s gymnastics, men’s and women’s cross-country, , and women’s tennis had higher injury rates than football (see table 1 on page 20).1

With sports science, we are learning that a large acute-to-chronic-workload ratio at the beginning of the season, along with lack of proper bone loading in the offseason, can lead to a higher risk of stress fractures. The rate of stress fractures was 51% higher during preseason than during the regular season in the Rizzone et al study.1 Chronic overload can lead to stress injuries, most commonly due to fatigue rather than actual bone structure issues, yet stress injuries constitute only 2% of total football injuries according to a 2012 study.2 In a 2011 study of 320 college players invited to the 2006 National Football League (NFL) Scouting Combine, 72% of the players had a history of foot and ankle injuries, but only 5% had Jones fractures and 3.4% had Lisfranc sprains.3 Five injuries (lateral ankle sprain, medial ankle sprain, syndesmotic sprain, fibular fracture, MTP/turf toe) were responsible for 81% of the injuries, and these five did not include Jones fracture or Lisfranc dislocation. This study had a selection bias because players who are injured and cannot perform would never be invited to the Combine.

  • Athlete exposure – One athlete participating in one organized practice or competition.
  • Overuse injury – Repeated stresses to an area without adequate rest to occur for structural adaptation.
  • Injury risk – Proportion of athletes who have at least one incident of injury during a fixed period of time. Risk is expressed either as a decimal or a percentage.
  • Injury rate – Number of fractures per 100,000 exposures (per 10,000 in some articles)

Foot/Ankle Injuries in Men’s Collegiate Football

In a 2015 study, Lievers and Adamic examined injury data obtained from 60 of the 616 NCAA teams for five football seasons (2004–2009) with over 2,222,155 AEs.4 There were a total of 3326 foot and ankle injuries, with 2523 involving the ankle and 803 involving the foot, leading to an ankle and foot injury rate of 14.97 per 10,000 AEs (see table 2). Foot fracture rate was .52 per 10,000 AEs. Foot injuries more frequently resulted in failure to return to play (98 athletes; 12.2%) with Jones fracture resulting in the highest median time loss. Midfoot sprains have been rare in the NFL with only 15 reported in a 15-year period.5

Risk Factors or Possible Causes

New research has therapists and trainers looking at past lower extremity injuries anew. Is it possible that compensatory movements were developed then, leading to a lack of proper muscle activation patterns today that may be putting more force on the feet and leading to injuries? Traditional causes or risk factors for stress fractures include pronated or supinated feet (which helps performance), flatter foot landing when jumping, muscle fatigue, hypermobile joints, lack of flexibility, previous injury, muscle imbalances, nutritional issues such as lack of milk or calcium, sleep deprivation, weak toe grip, and poor warm-up, among others.6–10 Studies show many noncontact injuries can be related to muscle fatigue or exercise intensity. According to Weist et al., continued training after muscle fatigue changes loading patterns of the foot based on force plate studies and is postulated to be a factor in stress-related injuries.11 A study of 2379 football players from 2001 to 2009 shows that players who excessively exercise are at a higher risk for stress fractures, validating the earlier findings.2,12 The good news is modern sports science’s use of athletic monitoring of acute:chronic workload ratios along with deceleration metrics should provide injury reduction in these cases.13

Specific Foot Injuries: Lisfranc Dislocation

A Lisfranc injury can involve any combination of fracture, joint dislocation, and/or injury to the stabilizing joint ligaments of the midfoot. Causes of Lisfranc injuries are believed to be multifactorial: artificial surface, lighter and more flexible shoes, and bigger, faster, and stronger players. Noncontact twisting moves, such as when a defensive end engages with an offensive lineman, are a common cause of Lisfranc injuries. Other causes include stepping onto another player’s foot and when a cleat does not release from the field. The average recovery is six to 12 months, and patients can have discomfort for over a year afterward. However, each Lisfranc injury is so different—a player can tear one ligament or five, and bone displacement varies—that a definite timeline is likely unattainable.14 In the NFL, there were an average of 18.9 Lisfranc injuries from 2006 to 2014.15 Although rare, Lisfranc dislocations can be devastating: in the previously discussed college football study on foot and ankle injuries, they accounted for the second highest percentage of career-ending injuries (67%).4 Another study of collected data from the NFL Combine from 2009–2015 on all participating players sustaining a Lisfranc injury before entering the NFL found only 41 (1.8%) out of 2162 players had a history of a Lisfranc injury that resulted in a mean 2.9±4.9 missed games during their collegiate football careers.15

“A Lisfranc is often mislabeled as a midfoot sprain. So a sprain is basically a ligament injury in any part of the body, but in this situation, it’s the midfoot. In most cases of athletes, it’s not necessarily a bone injury, but a ligament injury. The ligaments of a midfoot joint rupture and the joints nearby become unstable and shift out of place…. You can have some small bony emulsions or chips injuries occur if the ligaments do pull off. Then these joints become unstable and when they become unstable, guys can’t push off. They’ll have these symptoms and then they’ll have a tremendous amount of midfoot pain and swelling. In order to push off or power through the foot, you have to have a stable midfoot.”

Robert Anderson, MD, co-chairman of the NFL’s Foot and Ankle Committee.16

Jones Fracture

Despite being rare, Jones fractures resulted in the highest median time loss at 42 days.4 Studies are beginning to show that past lower extremity injuries and muscle imbalances can increase the risk, such as Saita et al.’s 2017 study that related a decrease in hip internal rotation to increased risk of Jones fracture.17 That athletes with a decrease in hip internal rotation and ankle dorsiflexion are at increased risk for many injuries had already been established. Between 1988 and 2002, 4758 elite college football players participated in the NFL Combine, with 86 Jones fractures identified for a rate of only 1.8%.18 Conversely, there were 17 Jones fractures in the NFL from 1996 to 2001. A study of 25 NFL players who had a Jones fracture between 2004 and 2014 revealed wide receivers, linebackers, and tight ends with the highest rate, with 12% needing a repeat surgical procedure.19 One could argue that foot injuries are rare but also possibly more likely to prevent athletes from a Combine invitation or future play in the NFL. This could lower the numbers listed in some articles such as Kaplan’s study that focused only on those invited to the Combine.3 A 2016 Lower Extremity Review article used the bigger, faster, stronger argument, citing frequent starts and stops and hard cuts since players such as Julio Jones and Dez Bryant have had Jones fractures.20 But frequent starts and stops have always been required in the NFL. Have receivers really become that much bigger, faster, and stronger to be mentioned as a possible cause of the increase in foot injuries since mass and acceleration are increasing which leads to more force? Cleats that have become lighter, more flexible, and narrower are a possible contributor along with artificial turf. Does excessive load lead to more foot injuries? GPS technology has been proven to provide insight about a change in running form with fatigue; this should produce a red flag to decrease activity while in practice.21 NFL team doctors have noted the lack of research in Jones fractures in American football players as well as the use of GPS technology, but research on European soccer players using GPS technology has proven there can be early signs or symptoms.

Navicular Fracture

Another rare injury in college football athletes, navicular fractures are very serious as athletes who sustain these are twice as likely to remain undrafted and less than half as likely to be able to compete in at least two NFL seasons.22 There were only 14 (0.6%) overt navicular fractures out of the 2285 invited NFL Combine players between 2009 and 2015, with only three of these being stress fractures.20 Again, those who may have injuries that prevented an invite to the NFL Combine were not included. Rival teams could use this information to steer parents away from a college with a history of foot injuries, which result in the highest loss of playing time and have the greatest potential for ending careers.

Footwear Research and New Technology

There are many more studies on cleats or “boots” for soccer than there are for American football cleats. Many studies focus on the playing surface, such as injury rates from 2000 to 2009 being higher for ACL sprains and eversion ankle sprains in NFL games played on FieldTurf than on natural grass.23 While we know that footwear traction’s link to injury risk is a result of increases in rotational traction, there are other causes.24 Research in this area is lacking and does not address preventive measures, possibly due to the more important focus on concussion. Indeed, one commentator described the NFL’s current foot injury research as focused on narrow improvements rather than holistic and systemic factors.20 PPL Biomechanics, an Irish company focused on soccer, recommends circular molded studs on firm ground and hybrid cleats on soft ground with six-stud placement for optimal injury prevention. Studies have shown bladed cleats produced a greater risk of fifth metatarsal stress fracture with increased forefoot loading during a jump-landing task.25 As with sports science, there is little sharing of anecdotal success. NFL medical staff does say bigger, faster, and stronger players along with lighter and less stable shoes and playing surface could contribute to foot injuries. Cleat customization, as the US Naval Academy learned, may be one answer (see page 28).

Conclusion

While identifying risk factors has long been the norm for sports injury research when attempting to prevent foot injuries, a systems-based process appears to be the future with a focus similar to Fergus Connolly’s holistic psychological, physical, technical, and tactical approach.26 Systems thinking is concerned with the interrelationships between parts and their relationships to a functioning whole, which is often understood within the context of an even greater whole.27 So, it’s not only bigger and faster players, but custom cleats with custom orthotics and a data-driven training plan. Injuries in sports will continue to happen regardless of the best training and sports science available. But if there are ways to decrease the risk of their occurrence, it seems prudent to use any and all measures and to look at the athlete from a holistic view. With sports science tools properly utilized, soft tissue, noncontact, and fatigue-based injuries are on the decline. While these injuries continue to be rare overall, they can have a devastating impact on a player’s current and future career. After all, it does not matter how fast you are if you are not on the field.

Chris Cothern PT, CES, PES, is owner of AthletePlus Physical Therapy & Spine which sees active individuals of all ages at their clinics in the Greater Fayetteville, Arkansas area.

REFERENCES
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