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Bone Stress Injury or Stress Fracture is very common in athletes (M Fredericson, 2006), and most of it comprises sports-related injuries. When bone fails to handle the repetitive loading, bone stress injury occurs. Another name of the condition is “Stress Fracture”. These injuries start from inflammation of the periosteum and progress to stress fracture, causing fracture lines to appear in the bone.

To understand bone stress injuries, we must know about skeletal homeostasis, which occurs in everyone even if you are not exercising. Under this process, the human body continuously breaks down and rebuild the bones. As we know, bones are the storehouse for calcium which is essential for important bodily functions like blood clotting, muscle contraction, heart rhythm and function of the enzyme. In a normal individual, rebuilding of bone occurs at a higher rate than it is broken down.

Loading also plays a key role in bone remodelling. Our bones experiences stress through external loads (ground reaction force) and internal loads (force caused by muscle contraction). Such stress results in load-induced microtrauma. If in an individual all the body systems are working in an ideal state, loading results in good bone remodelling and growth, leading to strong bones capable of bearing higher loads. However, if your body is not functioning in an orderly manner, you can experience bone stress injury.

Here are few conditions that should be in order to prevent bone stress injury:

a.  Sufficient energy – This means eating adequate calories to support your training and to make your body function properly. Sometimes runners and athletes do not realize how many calories they need in order to support their training. In order to lose weight, they sometimes cut down the calories, which results in low energy levels that lead to reduced bone strength and a high risk of a bone stress fracture. Having low energy for even five days is said to affect bone resorption in a negative manner (Papageorgiou M, 2018). Low energy is the main root cause of various physiological dysfunction.

b. Hormonal balance – Hormonal imbalance is also associated with low energy levels. Reduced hormone levels are associated with a negative effect on other metabolic hormones like IGF-1, Leptin, and peptides, which are essential for bone health (Goolsby MA, 2017). Females who have amenorrhea or have less than nine menstration cycles in a year have a tendency to develop decreased bone mineral density with decreased bone strength and a high risk of bone stress injury (Ackerman KE, 2015). This may be due to the reduced circulation of hormones in the body. The relationship of irregular menstruation, low availability of energy and poor bone health is known as the female athlete triad.

 

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The condition is no different for males. They experience the condition called hypogonadism, where there is a deficiency of the male reproductive hormone testosterone. The symptoms are not as obvious in males as in females, and blood work is important to make the proper diagnosis.

c. Vitamin D and calcium levels – To maintain bone health, it is important for the runner to take the right amount of Vitamin D and calcium. A low level of calcium and Vitamin D results in a high risk of bone stress injury (Goolsby MA, 2017).

d. Load progression – When too much load is applied to the bone, which is not accustomed to such load, then bone stress injury may happen (Warden SJ,2014). Bones need time to acclimate to the higher loads. So gradual training is necessary. Loading too soon may increase your risk of bone stress injury.

e. Proper rest – Bone tissue needs time to repair itself. Training promotes bone remodelling, but too many training sessions without any rest can break down the bone at a faster rate than it is rebuilt.

f. Adequate sleeping hours – Sleep deprivation may also increase the risk of bone stress injury as it alters the balance between bone remodelling and resorption (Staab JS, 2019).

Common locations where bone stress injury occur:

Medial tibia, fibula, the shaft of the femur, metatarsal bones and calcaneus are some of the common sites for bone stress injury. However, bone stress injury may also affect the pelvis, femoral neck, lumbar spine, navicular and anterior tibia (Song SH, 2020).

Symptoms of bone stress injury:

Common symptoms of bone stress injury are:

 a. Pain during palpation

b. Pain at night or during rest

c. Swelling

d. Pain during activation of muscles attached to the bone

e. Pain while running

f.  Limping due to pain

As bone stress injury takes a lot of time away from sports and sometimes daily activities, early detection is very important. Apart from early detection, proper rehabilitation is also very essential as there can be decreased bone remodelling, endocrine dysfunction and energy deficiency.

Now we will discuss the rehabilitation process in bone stress injury:

1. Early Rehabilitation

• Detect the potential contributing factors

• Prescribe activity modification and initial training guidelines

2. Mid-stage Rehabilitation

• Gradual loading in respect to the speed of healing

3. Returning to sports

• When and how? 

1. Early Rehabilitation

The initial goal is to focus on the expectation of the athlete related to the time duration in which he wants to return to the sport. During this phase, the therapist makes some weight-bearing restrictions while guiding modifications for the daily activities.

Another thing that your therapist will ensure is the proper rest of the affected part. Whether you are experiencing pain during or after activity will indicate if the bone is excessively loaded or not. The main aim of the therapist is to make sure that the athlete remains free of pain throughout the rehab. If walking is painful, you will be advised to used crutches for partial weight-bearing. The initial period after bone stress injury is a good time to examine the contributing factors and addressing them.

It is very important to find the reason for the spike in training load, which may be due to a change in the running shoes or the lack of recovery due to insufficient rest. By acquiring the knowledge regarding the running progressions, resting habits, change in training etc., your therapist may design a balanced running program design.

Recommendations on the activities that promote healing depends on the site of the injury, its severity and the presence of pain. Your therapist may suggest activities that may not overload the injured bone-like biking, swimming, resistance training etc.

 

2. Mid-stage Rehabilitation

Recovery from Bone stress injury mainly needs prevention of the aggravating activities and appropriate loading. Loading on the bone should be such that it doesn’t trigger the bone stress injury symptoms during or after activity. When symptoms improve, the rehab focuses on the pain-free loading progression. Strength training of athlete’s muscles, ligaments and joints is a must in order to return to the sports. However, specific training of the muscles associated with the injured site also promotes bone healing and improves its capacity of loading.

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3. Returning to sports

Before returning to the sports, the following criteria should be met:

a.  The athlete is symptom-free and the site of injury is healed completely.

b. All the activities are pain-free.

c.  Adequate muscle strength is present to allow the athlete to initiate sports training.

Your physical therapist may identify the ways to reduce the bone loading so as to decrease the chances of a bone stress injury in the future. This will include modification of gait, changes in the shoes etc. Increasing step-rate by 7.5-10% can reduce the vertical loading rate along with the work done by the knee and hip during running (Willy, 2016).

Conclusion:

Early diagnose of bone stress injury is a must for optimal outcomes. Having a balance between bone capacity and the training load can prevent bone stress injury. Rehabilitation of the patient with bone stress injury should be customized and should focus on identification of the risk factors and symptom-free returning to the sport with no future chance of recurrence.

Contact the rehabilitation team of Progressive Care to get a proper diagnosis and treatment of your bone stress injury.

References:

1. Fredericson M, Jennings F, Beaulieu C, and Matheson G. Stress fractures in athletes. Top Magn Reson Imaging. 2006; 17(5):309-25.

2. Papageorgiou M, Dolan E, Elliott-Sale KJ, Sale C. Reduced energy availability: implications for bone health in physically active populations. Eur J Nutr. 2018;57(3):847–859.

3. Goolsby MA, Boniquit N. Bone Health in Athletes. Sports Health. 2017;9(2):108–117.

4. Ackerman KE, Cano Sokoloff N, DE Nardo Maffazioli G, Clarke HM, Lee H, Misra M. Fractures in Relation to Menstrual Status and Bone Parameters in Young Athletes. Med Sci Sports Exerc. 2015;47(8):1577–158.

5. Goolsby MA, Boniquit N. Bone Health in Athletes. Sports Health. 2017;9(2):108–117.

6. Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014;44(10):749–765.

7. Staab JS, Smith TJ, Wilson M, Montain S, Gaffney-Stomberg, E. Bone turnover is altered during 72 h of sleep restriction: a controlled laboratory study. Endocrine. 2019;65: 192–199.

8. Song SH, Koo JH.   Bone Stress Injuries in Runners: a Review for Raising Interest in Stress Fractures in Korea.  J Korean Med Sci. 2020;35(8):e38.

9. Willy, RW, Buchenic L, Rogacki K, Ackerman J, Schmidt A, and Willson JD. In‐field gait retraining and monitoring. Scand J Med Sci Sports. 2016;26:197-205. 

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