Treating Stress Failure Injuries In Young Athletes

By Patrick Agnew, DPM

Is the term “overuse injuries” really appropriate? After all, many so-called “overuse” injuries of the lower extremity are unilateral. In most cases, the right foot is used just as much as the left foot so the term becomes illogical. Perhaps stress failure phenomena would be a more accurate description of these injuries. Some examples of mechanisms leading to stress failure problems include repetitive motion, repetitive loading and repetitive impact. Your patients might encounter repetitive motion injuries in endurance sports like swimming or sports such as cross-country running or basketball. Athletic injuries are often blamed on training, technique or equipment errors. I would add biological errors to the mix. Training errors occur when a child goes too far, too fast, too heavy or too soon. Technique errors often occur in the absence of good coaching. An example might be when an athlete’s improper kicking in swimming breaststroke leads to knee derangement. Equipment errors, such as worn out shoes, can lead to repetitive impact injuries. Unfortunately, biological errors are all too often discovered after the fact. For example, a child who sustains a repetitive loading injury to the second metatarsal head may later be recognized as one who overpronates. If a practitioner had recognized the injury early on, he or she could have used an orthotic to stop the overpronation from destabilizing the first ray and allowing overloading of the second ray. However, stress failure injuries are tough to detect as they often have an insidious onset. This is because the repetitive nature of the damage builds gradually to the point that the “straw that breaks the camel’s back” may occur. Prodromal signs and symptoms of an impending stress failure might include vague or mild discomfort, similarly mild edema, erythema, ecchymosis and eventually a loss of use of the involved anatomy. These are the same signs and symptoms associated with acute trauma but they are more gradually developing with stress failure injuries. Some examples of stress failure in children might be categorized by tissue type. These certainly could include failure of bone, soft tissues or skin. A Primer On The Intricacies Of Bone Failure Failure of bone in children is controversial subject. The actual etiology of injuries is often unclear. These injuries are characterized by what appears to be a failure of vasculature to a bone or part of a bone, which results in death of bone cells and often culminates in failure of bone structure. Also be aware that the terminology is awkward. Naming the injury is often complex and terms such as avascular necrosis, osteonecrosis, osteocondritis, infarction and infraction are sometimes used interchangeably. The proposal of a convention on this controversy is beyond the scope of this article. The signs and symptoms of this type of injury are those listed above. You’ll usually see these symptoms focused in a predictable area such as the second metatarsal head, the navicular, the base of the fifth metatarsal, the heel, etc. A typical bone failure patient may be a teenage gymnast or cheerleader who has experienced a recent increase in activity level. The activity has overloaded an area such as the second metatarsal head. Other predisposing factors might include a short first metatarsal, a degree of equinos, overpronation, a cavus foot type and/or inappropriate footwear. Radiographs of the affected area may reveal deformation of the metatarsal head but this would presumably indicate late recognition. For example, you may see that a child’s dorsal planar foot radiograph demonstrates delayed growth of the third metatarsal from a stress failure injury. Treating these type of injuries involves resting the injured part for a sufficient time, both to alleviate symptoms and to allow redevelopment of adequate strength in the bone to prevent failure. If failure (deformation) has already occurred, complex individualized treatment is likely to be necessary. Be aware that failing to identify these injuries early and prevent subsequent deformation of the affected bone can have far reaching consequences. The resulting changes in joint surfaces may result in early and often severe degenerative joint disease. The controversy regarding stress failure of bone in children overflows into the discussion of stress failure of soft tissue. Repeated stress failure injuries of bone may indicate a collagen disease like osteogenisis imperfecta. You must also consider the possibility of physical abuse and carefully look for the characteristic signs. If you see evidence of physicial abuse, there is an array of resources you can turn to in these situations. Pertinent Pearls For Treating Soft Tissue Failure As far as soft tissue failure goes, the prototypical example is calcaneal apophysitis. This may be interchangeably considered with avascular necrosis of the calcaneal secondary ossification center. The suffix “-itis” may not belong in many of these descriptors because the actual injuries may involve attenuation, excessive compression and other forms of repetitive impact, loading and or movement. Apophysosis might therefore be a more accurate description of the injury. The typical patient with this injury would likely be a “tween” (10-year-old) competitive athlete who may be overweight. Predisposing factors might include equinos, inappropriate footwear and/or high body weight. Treatment may include temporarily accommodating the equinos with a heel lift. This can be gradually reduced in thickness over a period of several weeks. Applying ice to the painful area after activity may be both analgesic and antiinflammatory. You may recommend a temporary alteration in activity but keep in mind that this recommendation is often poorly tolerated. Also be aware that night splinting with the ankle in a dorsiflex position may prevent contraction of the attached soft tissues. The tendo Achilles and the plantar fascia form a dead eye mechanism. This results in excess stress on each if either is too short. Casting is sometimes necessary to allow healing, prevent contraction of the surrounding soft tissue and enforce rest. Flexibility exercises may help to reduce the risk of relapses. The term stretching should be avoided since muscles, ligaments and tendons really only stretch a small amount before they tear. Relaxing the muscles to optimize flexibility is the objective. “Sprains” in growing children should always raise your suspicion. In younger children, the soft tissues such as ligaments are stronger than the bones’ growth centers. Injury to bone growth areas may have far reaching consequences including accelerated, arrested and/or angulated growth. Prognostic classification systems may help you to prepare the family for subsequent complications. Repetitive injuries to the nerves are particularly worrisome in children. The poor capacity of nerves to heal may result in a long life with pain and/or disability. A Review Of Options For Treating Skin Stress Failures Stress failure of the skin in children may present as blistering. Blisters may be caused by excessive friction, excessive moisture and usually a combination of both. Common predisposing factors might include new footwear, a change in ambient humidity and/or a new activity such as the beginning of a sport season. You’ll usually find prodromal signs and symptoms, which may include pain and erythema. Early recognition of these symptoms may allow preventative intervention. Applying mole skin before a blister occurs might allow a young athlete to stay in competition. Treatment might include changing the footwear, changing the humidity or changing the activity. Changing the humidity is often the simplest and most tolerable approach. The use of an antiperspirant spray every morning and particularly before the activity can reduce the moisture level on the skin, preventing further blistering. Changing the footwear may be the next most tolerable recommendation. Blister preventing socks are widely available. These often combine a wicking, low friction layer against the skin with a padding absorptive outer layer. Admittedly, shoes for children have become extremely high-priced and asking the child or the parent to discontinue the use of a new shoe could lead the patient to ignore your advice. Changing the activity also may be unpalatable if any more than a minor alteration in training is necessary. Dreams of athletic scholarships die hard. Acute treatment of blisters is controversial. I usually recommend leaving unruptured blisters intact. However, if blisters have been present long enough to harbor infection, incision and drainage is necessary. Signs and symptoms of this may include increasing surrounding erythema, lymphangitis, lymphadenopathy, purulent blister contents, local or systemic fever and increasing pain. Blisters that occur on surfaces that will likely lead to rupture may be de-roofed to allow an aseptic approach and wound care. Repeated, frequent and severe blistering may be a result of topical allergies, autoimmune diseases, connective tissue diseases or microbial infection. If the history does not match the presentation, be suspicious. Be sure to obtain family, social and medical histories as they are indispensable in these cases. What Is The Diagnosis? In most of these injuries, imaging is usually superfluous. This is particularly true if patients or their families seek treatment early enough. However, any failure of initial therapy or an unusual presentation must be taken seriously because neoplasm and infection can present with the same initial signs and symptoms. At secondary stages, the typical appearance of stress failure diseased bone may be whiter. Be aware that later stages may present deformation of the bone. Serology may be useful if you’re considering either of the aforementioned possibilities. Knowing the unique characteristics of the serum of children is essential. An elevated erythrocyte sedimentation rate may lead one to consider inflammatory and/or infectious etiology. Elevated alkyline phosphatase levels may be normal at certain stages of development and grave at others. Predisposing systemic diseases may lead you to a broader differential diagnosis. A child with diabetes may complain of neuropathic pain, mimicking or co-morbid with tarsal tunnel syndrome from repetitive loading or impact activities. A child with sickle cell anemia may complain of bone pain consistent with stress fracture, which might really be from hematogenous osteomyelitis. A stress fracture in an unexpected bone area may be a pathological fracture related to malignancy. How To Handle Activity Alteration Recommendations The subject of activity alteration requires a little more discussion. Simply telling a child or his or her family to “rest” or discontinue the patient’s chosen activity will probably not achieve the desired outcome. Even adults are usually reluctant to change a favorite recreation or competitive activity. Children are equally or even less likely to cooperate with these recommendations. If this advice is necessary, very specific recommendations may increase the likelihood of success. Variables in exercise may include frequency, duration, intensity, speed, distance, etc. Recommending a change in frequency may be particularly poorly tolerated in endurance sports. It is generally held that three to five days a week of training for at least 20 minutes is necessary to maintain cardiovascular fitness. The activity must result in achieving a pulse rate within a calculated target zone for the exercise period. The target zone is usually broad enough to permit significant variation of intensity. Your patient may achieve this goal by temporarily changing the other variables such as speed, distance and intensity. Reducing a patient to 50 percent levels and increasing by small (i.e. 10 percent) increments after symptoms improve are reproducible recommendations. In patients who are younger or noncompliant, enforced “rest” may require casting. Final Words As with most discussions of pediatric foot and ankle disorders, you must recognize that a child is not a small adult. You may find unique diagnosis, treatments, presentations and outcomes in this group. Never ignore the duration of the consequences of pediatric foot and ankle disorders and the associated liability of the provider. Fortunately, many resources are available to assist the interested health care provider, including excellent text in Foot and Ankle Pediatrics and organizations such as the American College of Foot and Ankle Pediatrics. Dr. Agnew is the Director of the Eastern Virginia Medical School Podiatric Surgery Residency. He has a private practice in Virginia Beach, Virginia.

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