Treating Occult Stress Fractures In Athletes

At Ft. Leonard Wood, Mo., the largest training base in the Army, I see some form of stress fractures from metatarsal stress fractures to femoral neck stress fractures every week.^1-5 They cost the military millions of dollars annually in lost productivity, missed training days and medical separations.²

All types of stress fractures pose diagnostic and treatment challenges. Like athletes, soldiers have a mission to complete and it is hard for them to slow down. From primary care doctors to the emergency room physicians, we all learn to be suspicious for stress fractures when soldiers present with pain without a history of injury. Routine X-rays are almost always negative early on but clinicians still order them. Clinicians are always hesitant early on to slow down trainees and athletes who have normal X-rays. Physicians treat them the Army way: “Drive on and take some Motrin.” They tell them that if it gets worse, they should come back. However, if the activity level remains at a high level, stress fractures can progress to occult fractures.⁶

All stress fractures are avoidable but how do you tell a trainee who is motivated to complete the training to stop, let alone slow down? It is almost as futile as telling a long-distance runner to stop running. They all think they can run through it.   

Athletes from high school to college sustain stress injuries. Stress fractures among high school athletes account for 0.7 to 20 percent of injuries that clinicians see in sports medicine clinics across the country.⁷ There are numerous factors that can contribute to the development of stress injuries. Those factors may include foot type, overuse, poor training, starting a sport out of shape, poor shoegear or simply having a body type (overweight) not suitable for that sport.⁸ Women statistically are far more likely to develop stress injuries than men in sports activities and upon entrance into the military.^4,9-11   

How Occult Stress Fractures Develop

Stress fractures can have either a gradual onset or develop as a sudden occult fracture. The majority of us have all seen the varying degrees of stress reactions and fracture presentations in our practice — whether it is a simple periosteal reaction, a soft tissue swelling to a unicortical fracture or a sclerotic line in the heel — but it is the occult injuries that are often difficult to visualize on X-ray until a full blown occult fracture develops, leading to possible displacement and routinely requiring surgical intervention.

The use of magnetic resonance imaging (MRI) and computed tomography (CT) scans is critical to catch these fractures for diagnosis and preventing propagation of the fracture, or worse, displacement. Magnetic resonance imaging has become critical for assessing bone bruising patterns. The degree of bone marrow changes is highly predictive of outcomes.¹¹

Every week, our orthopedists will see an Army trainee who has either a complete femoral neck stress fracture or a displaced fracture. I routinely see femoral and tibial shaft fractures start out as a simple cortical crack and proceed to a complete bicortical fracture. We have all seen displaced metatarsal shaft and neck fractures. While at Ft. Benning, Ga. with the Ranger School and at Ft. Bragg, N.C. with U.S. Army Special Forces training, I saw displaced metatarsal stress fractures weekly. Often, the soldier would show up with exuberant bone callus and the fracture angulated and/or shortened. Neither situation is fun, whether it’s reducing a displaced fracture with exuberant bone callus or waiting to perform an osteotomy on a malunited fracture. For me, I would rather diagnose these fractures early before they develop signs of transfer metatarsalgia or, worse, transfer lesions.        

Fortunately, occult stress fractures of the tibia, talus, fibula and navicular are very rare in comparison to metatarsal stress fractures. However, like femoral neck stress fractures, all of these occult stress fractures can easily become displaced and require surgical intervention. All of these fractures are considered high-risk type injuries because of the potential for long-term sequelae and/or complications.^8,12 These injuries often present early and when the patients continue to proceed with exercise and training, the fracture gets worse. Just like femoral neck stress fractures, talus and navicular stress reactions are almost always invisible on X-ray. When the fractures are allowed to propagate, often the occult fractures will displace and often can lead to avascular necrosis of that bone. Many of these patients have preexisting foot and ankle deformities. As a result, these trainees and athletes often develop bilateral injuries. These injuries often are career-ending if they are not caught early.   

What You Should Know About Tibial Stress Fractures

Occult fractures of the tibia can occur in any location from the medial malleolus, distal tibia, shaft and proximal tibia.^13-14 The risk of developing a displaced fracture is very high and can turn a simple stress reaction into an emergency.

One case example involved a trainee who developed bilateral distal tibial stress fractures. She had permission to continue to train long after being diagnosed with stress fractures. The patient went from having a simple stress reaction showing a sclerotic line along the distal metaphysis to an occult fracture. The fracture began to collapse into significant varus. Her collapse was significant enough that she not only required open reduction but an opening wedge osteotomy of the fracture as well to realign her collapsed tibia. Other cases involving midshaft tibial stress fractures can require intramedullary nailing. The majority of these stress fractures are transverse in nature.

When Patients Sustain Occult Talus Fractures

Occult fractures of the talus are extremely rare and very difficult to diagnose clinically.^15-17 These patients are often miserable and struggle to bear weight unlike with other stress fractures. Accordingly, one has to have suspicion for a stress fracture when pain is so debilitating. Often, primary care providers will get bone scans early on but MRI is critical for making the diagnosis. Stress fractures of the talar body, neck and head can progress to occult fractures, and are very analogous to femoral neck stress fractures. They often require fixation to prevent propagation of the fracture or displacement. If these patients continue to bear weight, talar neck fractures can essentially become Hawkins II fractures very quickly.     

In regard to talar stress fractures, it is critical not to misinterpret the MRI for simple bone bruises. Often, the T2 images are filled with bone marrow edema but the T1 image will show the fracture line clearly. Similar to how one would address Hawkins II-III fractures, using two 4.5 mm screws will suffice. The surgeon can insert the screws percutaneously. Compression is not critical for these fractures as much as simply providing support to resist propagation or displacement of the fracture.

Addressing Occult Fractures Of The Fibula and Navicular

Occult fractures of the fibula are very controversial. Within the military community, we often see fibular stress fractures despite surgeons swearing that the fibula is not a load sharing bone for the ankle. Stress fractures of the fibula seem to occur proximal to the syndesmosis. More often, trainees will have either a severe varus or valgus alignment issue. Why some people develop fibula versus tibia fractures is unknown but we see plenty of stress fractures of the fibula that will progress to bicortical fractures just as we see with metatarsal fracture.^18-19 Luckily, to date, I haven’t seen one displace enough to warrant open reduction.

Occult fractures of the navicular are very rare but they seem to be very popular to discuss. There are more journal citations for navicular stress fractures than I have seen in my career. Grambart had an excellent review of navicular stress fractures for Podiatry Today in the February 2015 issue.²⁰ I am sure we have all seen the vertically oriented mid-body fracture line — so common in textbooks and journal articles — that has gone on to a nonunion.^21-24

Too often, the majority of navicular stress reactions get a diagnosis of widespread navicular bone bruising patterns on T2 imaging but rarely do we see occult fracture lines. For me, I suspect that if we wait long enough, we will see those fracture lines on T1 images. When we see the fracture lines on X-ray, it is usually late in the process.  

In Conclusion

The cases that I have illustrated show a far more different plane of fracture than I think we are all familiar with. Treatment for these fractures tends to be rest and non-weightbearing. Rarely is surgery required for occult fractures like the ones I have discussed. Occult fractures of the remaining bones like the calcaneus, cuboid and cuneiforms are extremely rare. More often, we simply see bone marrow edema on MRI or eventually see a sclerotic line develop. When we do see occult fractures in the calcaneus, they are usually in patients with diabetes or osteoporotic bone.  

Occult stress fractures in the foot and ankle are rare but are far more common in military trainees and long distance/endurance athletes. It is critical to appropriately examine these patients. When necessary, order an MRI instead of a bone scan and bear in mind that intervening surgically when appropriate can expedite recovery and get athletes/soldiers back to work sooner.

Dr. Spitalny is a staff podiatrist at the General Leonard Wood Army Community Hospital in Ft. Leonard Wood, Mo. He is an adjunct faculty member with the Depaul Podiatric Surgical Residency Program in St. Louis. Dr. Spitalny is a Fellow of the American College of Foot and Ankle Surgeons.

References

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7. Changstrom BG, Brou L, Khodaee M, Braund C, Comstock RD. Epidemiology of stress fracture injuries among US high school athletes, 2005-2006 through 2012-2013. Am J Sports Med. 2015;43(1):26-33.
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14. Nunns M, House C, Rice H, Mostazir M, Davey T, Stiles V, Fallowfield J, Allsopp A, Dixon S. Four biomechanical and anthropometric measures predict tibial stress fracture: a prospective study of 1065 Royal Marines. Br J Sports Med. 2016;50(19):1206-10.
15. Sormaala MJ, Niva MH, Kiuru MJ, Mattila VM, Pihlajamäki HK. Outcomes of stress fractures of the talus. Am J Sports Med. 2006;34(11):1809-14.
16. Sormaala MJ, Niva MH, Kiuru MJ, Mattila VM, Pihlajamäki HK. Bone stress injuries of the talus in military recruits. Bone. 2006;39(1):199-204.
17. Kim YS, Lee HM, Kim JP, Moon HS. Fatigue stress fracture of the talar body: an uncommon cause of ankle pain. J Foot Ankle Surg. 2016;55(5):1113-6.
18. Cheng Y, Yang H, Ni L, Song D, Zhang H. Stress fracture of the distal fibula in flatfoot patients: case report. J Clin Exp Med. 2015;8(4):6303-7.
19. Woods M, Kijowski R, Sanford M, Choi J, De Smet A. Magnetic resonance imaging findings in patients with fibular stress injuries. Skeletal Radiol. 2008;37(9):835-41.
20. Grambart S. Getting athletes back in the game after navicular stress fractures. Podiatry Today. 2015; 28(2):65-67.
21. Burne SG, Mahoney CM, Forster BB, Koehle MS, Taunton JE, Khan KM. Tarsal navicular stress injury: long-term outcome and clinicoradiological correlation using both computed tomography and magnetic resonance imaging. Am J Sports Med. 2005;33(12):1875-81.
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For further reading, see “Getting Athletes Back In The Game After Navicular Stress Fractures” in the February 2015 issue of Podiatry Today.