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Lower limb stress fractures in sport: Optimizing management and outcome

Stress fractures are common injuries in athletes and account for 10% of all sport injuries.  Ninety percent of stress fractures are located in the lower extremities. The risk factors related to stress fractures consist of the following: a history of past stress fractures, female sex, training regimen, footwear, training surface, and type of sport with repetitive loading (such as running and jumping). Non-steroidal anti-inflammatory drugs should be avoided in all fractures as they may inhibit callus formation and slow down the initial healing process.

In the management of stress fractures, 7 aspects should be considered:

  • Is the fracture low or high risk?
  • What is the optimal imaging modality?
  • Conservative versus surgical treatment?
  • What technique is chosen if surgical?
  • What optimal rehabilitation schedule if conservative treatment?
  • How fast can sport be resumed?
  • What preventive program is available for this type of fracture?

In all stress fractures, radiographs are the first-line modality and may reveal linear sclerosis and periosteal reaction prior to the development of a frank fracture. In most stress fractures, the radiographs are negative although clinical symptoms are present. When a high-risk stress fracture is considered and radiographs are negative, a bone scan, CT scan or MRI is recommended. MRI is highly sensitive with findings ranging from periosteal edema of bone marrow to intracortical signal abnormality.

Conservative management ranging from non-weightbearing with a cast or Aircast with crutches to limited weightbearing crutch-assisted without pain is usually the optimal treatment when possible, even in high risk fractures.

High risk stress fractures;

A stress fracture is considered high risk because it is located either on the tension side of the bone or in an area of limited vascularity. Therefore, they are at increased risk of fracture propagation, displacement, non-union or delayed union. High risk stress fractures should be referred to orthopedic surgery with immediate cessation of activity as they might need surgical treatment. Those include distal anterior tibial diaphysis, fifth metatarsal base, medial malleolus, lateral femoral neck, tarsal navicular and great toe sesamoid. These fractures require specialized imaging to define and quantify the injury. The location of injury and response to initial conservative treatment will determine whether surgical management is needed.

High risk sport related stress fractures include the following:

 Anterior tibial diaphysis:

In 85% of cases, the radiographs are negative although clinical symptoms are present which should accelerate the request for a bone scan, CT or MRI. Treatment protocols consist of conservative management for 3 to 6 months with crutch-assisted weightbearing until resolution of pain in lower grade injuries and of casting in higher grades of injuries. In case of failure of conservative treatment, then a surgical intervention is recommended. The return times to sports for such injury is usually 7 months for both conservative and surgical management. However, the return to sports rates differed with 71% for conservative management and 96% for surgical management.

An exception is made when a complete fracture line is seen with both cortices involved. In this case, the stress fracture should be managed as an acute fracture. If the fracture is undisplaced, conservative management is recommended. If the fracture is displaced, a surgical intervention with an intra-medullary nail is required. The return times for these injuries then increases to 11.5 months for conservative management and 7 months for surgical management. The return rates remain similar with 67% for conservative and 100% for surgical management. For conservative management, recommended rehabilitation techniques consist of activity cessation, with avoidance of heavy loading of the tibia, limited weightbearing with crutches for 3 to 6 months. For surgical management, rehabilitation involves a progressive weight-bearing program supervised by a physiotherapist starting the first week following surgery with return to full loading activities between 6 and 8 weeks after surgery.

Fifth metatarsal base:

These stress fractures present on radiographs as a sclerotic or radiolucent line at the proximal aspect of the fifth metatarsal. These changes can be absent on radiographs in up to 69% of patients for this type of fracture. Again, MRI is the second line imaging. CT can be used to assess if there is fracture union after conservative treatment. Treatment of these fractures depends on the radiologic “Torg” classification. Conservative treatment is now often favored except in high level athletes and in high repetitive loading sports (running, jumping) where surgery is considered first line. If there is delayed union (Torg 2) or non-union (Torg 3), surgery is also recommended.

Medial malleolus:

Radiographs can be negative in 55% of cases. For undisplaced fractures, they can be treated conservatively in low level athletes although a good evaluation has to be done as these fractures tend to contribute to long term ankle instability. These injuries must be followed by strengthening, range of motion and proprioception training with a physiotherapist to prevent ankle instability.

Lateral (tension side) femoral neck:

Theses stress fractures occur most commonly in marathon and long distance runners. They are not seen on radiographs in up to 80% of cases. This stress fracture is treated with urgent surgical fixation to prevent fracture displacement and associated risk of avascular necrosis (AVN) of the femoral head. A minimum of 2 years clinical and radiographic follow-up should be done to ensure that delayed post-treatment AVN does not occur.

Navicular:

These stress fractures present most commonly in sprint runners. In high level athletes, surgical management may result in faster return to sport time but some randomized control studies are still needed to confirm this.

Sesamoids (great toe):

These stress fractures occur most commonly in sports such as dancing, gymnastics and sprinting; all involving forced dorsiflexion of the great toe. Medial sesamoid fracture is more common than lateral sesamoid as load occurs on the medial aspect of the toe with gait. Conservative treatment is the first line approach. However, if the patient remains symptomatic after 3 to 6 months, surgery should be considered because of a high rate of delayed union, non-union and fragmentation.

Low risk stress fractures:

Low risk fractures are treated with rest and exercise limitation because of the low risk of fracture propagation, non-union or delayed union. These include posteromedial tibial diaphysis, metatarsal shafts, distal fibula, medial femoral neck, femoral shaft and calcaneus.

In the majority of low risk stress fractures, a bone scan or radiographs are sufficient and the x-ray can be repeated instead of ordering a CT scan or MRI. In the case of medial femoral neck, femoral shaft or calcaneus fracture suspicion, an MRI should be requested because of the possibility of surgical management or to exclude other diagnoses.

Medial femoral neck:

If a fracture line is more than 50% of the femoral neck width or is displaced, a surgery is required to stabilize the fracture.

Femoral shaft:

Displaced fractures, delayed union and non-union require surgical consultation.

Calcaneus:

MRI can help to eliminate differential diagnoses such as plantar fasciitis, Achilles tendinosis and retrocalcaneal bursitis. These stress fractures are also difficult to detect on radiographs and may require surgical intervention if there is subtle displacement.

Metatarsal shafts fractures:

Among metatarsals, the second is the most common affected, followed by the third and fourth metatarsals. These fractures are usually treated conservatively with activity limitation for 6 to 8 weeks with an Aircast boot, short leg cast or fore-foot offloading shoe. Progressive return to exercise as pain allows can then be started.

In conclusion, it is important to remember that negative plain radiographic findings should not be considered alone but in conjunction with clinical findings. In the case of negative imaging with positive clinical findings, if there is a suspicion of high-risk stress fracture, additional imaging (bone scan, CT, or MRI) must be requested and conservative treatment implemented immediately for optimal treatment. If a low risk stress fracture is suspected, additional bone scan and serial plain radiographs are sufficient with conservative treatment, except in the case of femoral fractures suspicion.

In all stress fractures, independent of whether management is conservative or surgical, full level sport should not be started until there is clear evidence of clinical and radiological union and pain free ambulation.

Marie-Ève Roy, MD, CCFP
Sports and Exercise Medicine Fellow, University of Ottawa

Advisor: Dr. Taryn Taylor, BKin, MSC, MD, CCFP (SEM), Dip Sport Med

 

References:

Robertson GA, Wood AM. Lower limb stress fractures in sport: Optimising their management and outcome. World J Orthop. 2017 Mar 18;8(3):242-255.

Saunier J, Chapurlat R. Stress fracture in athletes. Joint Bone Spine. 2018

May;85(3):307-310.

Matcuk GR Jr, Mahanty SR, Skalski MR, Patel DB, White EA, Gottsegen CJ. Stress fractures: pathophysiology, clinical presentation, imaging features, and treatment options. Emerg Radiol. 2016 Aug;23(4):365-75

 

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