|Year : 2017 | Volume
| Issue : 1 | Page : 60-63
Simultaneous bilateral femoral neck stress fractures in a young female runner: A case report and review of literature
Department of Orthopedics, Lady Hardinge Medical College, New Delhi, India
|Date of Web Publication||3-Jan-2017|
Dr. Atul Mahajan
G-22, Bali Nagar, New Delhi - 110 015
Fatigue fractures generally appear in normal bone following increased repetitive activity or strenuous exercise, when imbalance occurs between applied force and elastic resistance. Femoral neck fatigue fractures are most common in athletes and young military recruits. They are not as common as stress fractures of the metatarsals or tibia and other bones. This paper reports bilateral stress fractures of the femoral neck in a 14-year-old girl presenting with pain in the anterior aspect of the right thigh of 3 months duration and without evidence of previous injury with low Vitamin D and elevated parathyroid hormone levels. Correction of Vitamin D levels, bed rest, and relief of weight-bearing were indicated as fractures were undisplaced.
حادثة كسر اجهاد لعنق الفخذ ثنائي الجانب لعداءة يافعة: تسجيل حالة ودراسة مرجعية
تظهر كسور الارهاق في العظام الطبيعية عموماً بعد ازدياد وتكرار النشاط أو التمارين المجهدة، حين يظهر عدم التوازن بين القوة المطبقة والمقاومة المرنة. كسر ارهاق عنق الفخذ اكثر شيوعاً عند الرياضين والجنود اليافعين. وهو ليس شائعاً ككسر الاجهاد لعظام مشط القدم او العظم الاعظم والعظام الاخرى. سجلت هذه الورقة حالة لكسر اجهاد ثنائي الجانب لعنق الفخذ لفتاة عمرها 14 عاماً حضرت بألم في الجانب الأمامي في الفخذ الأيمن مدته ثلاثة أشهر وبدون أي أدلة على اصابة سابقة لانخفاض فيتامين د او ارتفاع في مستوى هرمون الغدة جارالدرقية. وصف تصحيح معدل فيتامين د, راحة تامة في الفراش, التخلص من الوزن حيث ان الكسور لم تكن مزاحة.
Keywords: Compression fracture, overuse injury, stress fracture, tension fracture
|How to cite this article:|
Mahajan A. Simultaneous bilateral femoral neck stress fractures in a young female runner: A case report and review of literature. Saudi J Sports Med 2017;17:60-3
|How to cite this URL:|
Mahajan A. Simultaneous bilateral femoral neck stress fractures in a young female runner: A case report and review of literature. Saudi J Sports Med [serial online] 2017 [cited 2019 Oct 24];17:60-3. Available from: http://www.sjosm.org/text.asp?2017/17/1/60/197474
| Introduction|| |
Stress fractures are one of the most common and debilitating overuse injuries seen in athletes and young military recruits. Fractures of femoral neck are not as common as stress fractures of the metatarsals or tibia and other bones. Intense muscular activity is considered to be the main cause of these stress fractures. The risk of sustaining stress fracture is increased if there are low serum 25-hydroxyvitamin D [25(OH) D] concentrations. This paper reports a fatigue fracture of the femoral neck in a 14-year-old girl presenting with pain in the anterior aspect of the right thigh of 3 months duration and without evidence of previous injury but with low serum 25(OH) D levels and elevated parathyroid hormone (PTH) levels.
| Case Report|| |
A 14-year-old healthy female runner who competed regularly in running events presented to our clinic with right hip pain and difficulty in walking of approximately 3 months duration. Pain was not associated with any radiation or sensory change. Because of the pain, the patient had to decrease her training mileage. The pain worsened over 3 months and radiated into groin and anterior thigh. At the time of presentation, the patient presented with sharp and constant groin pain rated 6/10 on a numeric rating scale. It also began to occur with normal ambulation. Nonweight-bearing activities decreased her pain. The patient did report that her lower extremity strength and endurance were significantly decreased because she has not been able to train or compete in her sports. Physical examination showed minimally antalgic gait with slightly decreased stance phase on the right lower extremity. No notable muscle atrophy was seen. On palpation, anterior joint line tenderness was elicited with no palpatory findings elsewhere. The patient reported pain in the right hip on flexing, abducting, and externally rotating hip. Neurological evaluation revealed sensory, motor, and reflex testing to be within normal limits. Vibration testing did not aggravate her symptoms. Gait assessment revealed an antalgic gait pattern. Static palpation of this patient revealed pain in the groin region around the hip flexor insertion.
Anteroposterior and lateral radiographs were obtained which showed nondisplaced fracture through inferior part of femoral neck of right proximal femur [Figure 1]. 25(OH) D levels were found to be low (17 ng/mL: ref range: 25-40 ng/mL). Erythrocyte sedimentation rate, C-reactive protein, thyroid function tests, and parathormone levels were elevated (220 pg/mL; ref range: 15-60 pg/mL). Serum calcium, phosphorus, and alkaline phosphatase levels were found to be normal. Magnetic resonance imaging (MRI) scan of the bilateral hips [Figure 2] and [Figure 3] showed undisplaced fracture across the right femoral neck along with osseous edema showing as small, linear hypointense line (on T1 and short tau inversion recovery) along the femoral neck and similar but incomplete fracture along inferior part of medical side of left femoral neck. Bone mineral density test was done on her using the Lunar Prodigy Advance DEXA System (analysis version 13.40, GE Healthcare, Diegem, Belgium) which showed T-score of −0.3 at femur neck, femur total, and −0.5 at total body signifying low fracture risk.
|Figure 1: Anteroposterior radiograph of pelvis with bilateral hips showing undisplaced fracture across right femoral neck|
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|Figure 2: Magnetic resonance imaging showing complete but undisplaced fracture across right femoral neck and incomplete femoral neck fracture inferiorly on the left side|
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|Figure 3: Magnetic resonance imaging in axial cross‑section showing complete but undisplaced fracture of right femoral neck and incomplete fracture left femoral neck|
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Conservative treatment was instituted and the patient was restricted to complete bed rest and 6 weeks after, the patient was allowed walking on crutches without weight-bearing. Six weeks later, she was clinically asymptomatic and the fracture line was no longer visible on the radiographs [Figure 4]. The patient was allowed to walk on crutches with weight-bearing after 3 months and had an uneventful recovery.
|Figure 4: Anteroposterior radiograph of pelvis with bilateral hips done 3 months later showing complete healing of fracture line with no displacement|
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| Discussion|| |
As per Maitra and Johnson, femoral neck fractures comprise 5%-10% of all stress fractures.  Stress fractures of the hip are found in long distance runners, military recruits, and elderly patients. In children, osteogenesis imperfecta and myelomeningocele are associated with an increased risk of femoral neck insufficiency fractures. Stress fractures occur because the body's normal response is unable to compensate the damage caused by repetitive, cyclic, and physiologically abnormal stresses. 
Stress fractures can be commonly found in various female subgroups. One of the highest proportions of stress fracture incidence rates in women is found in military personnel.  Another common group of women who have the tendency to develop stress fractures are endurance athletes who perform repetitive weight-bearing sports such as distance running.  Stress fractures can also frequently occur in adolescent athletes with amenorrhea, eating disorders, and osteopenia, otherwise known as the female athlete triad. , There is a greater incidence among women, owing to a wider pelvis, genu valgus, lower muscle mass per body weight than men, and exercise-induced endocrine anomalies. 
Several locations in the lower extremity have a predisposition toward developing stress fractures including the tibia, metatarsals, and fibula. Owing to the aforementioned subgroups and frequently reported sites of injury, clinicians will frequently screen athletes in these groups and add a differential diagnosis of stress fracture. However, it is still possible for healthy athletes to sustain stress injuries or fractures that can easily be overlooked.
Under conditions of intense mechanical loading, such as occurs during basic military training and intense marathon runs, microfractures develop and lead to targeted remodeling to repair the microfractures. , In this situation, optimal levels of circulating calcium are needed to provide substrate for repair of microdamage and to inhibit an increase of nontargeted remodeling to maintain serum calcium concentration.
High levels of physical activity in the presence of low (or even moderately plentiful) calcium intake can cause additional stress on the skeleton because of the need to offset the substantial cutaneous calcium loss in the sweat. Under conditions of heavy sweating and insufficient calcium intake, calcium is drawn from the bone reservoir under the influence of elevated levels of PTH. In fact, acute bouts of exercise increase PTH levels proportional to exercise intensity. , The cutaneous calcium losses during heavy physical activity can be substantial and the resultant secondary hyperparathyroidism can be weaken the skeleton even over short periods. In that regard, Thorsen et al.  reported that young women showed increased bone turnover, decreased serum-ionized calcium, and increased serum PTH after a single bout of moderate endurance exercise. This calcium stress may act to limit skeletal adaptation and repair mechanisms in both military recruits and athletes during strenuous activity.
Stress fractures in the femoral neck often are missed. This injury should be suspected if there is a history of increased or modified physical activity or an underlying metabolic alteration.
It is typical for a clinician to manage an athletic patient with conservative therapy before sending them for advanced imaging. Therefore, the misdiagnosis and subsequent mismanagement of an athlete with groin pain may easily occur, compounded by the complexity of the anatomical structures in the hip. Delay in diagnosis and treatment may result in undesired complications and lost time from sports participation. It is important to have imaging evidence in combination with physical examination findings to appropriately manage these problematic patients. Accurate diagnosis of femoral neck stress fractures requires the following: (a) Gradual onset of inguinal or inguinocrural pain which may radiate to the knee after infrequent, repeated physical exercise accompanied by limping, and subsiding at rest; (b) pain with range of motion assessment; (c) normal laboratory results; (d) additional tests (radiology, bone scintigraphy, MRI).
In the 1 st week following the onset of pain, radiographs are usually normal. X-rays may be normal or may show either focal sclerosis (the most frequent finding) or a clear cortical disruption with displacement. Three weeks after the onset of symptoms, radiological signs of bone healing may be apparent (periosteal reaction). Only at 4-6 weeks, does callus formation become visible. Bone scintigraphy can show findings (increased radioisotope uptake) 2 or more weeks before X-ray studies. The MRI shows areas of low-signal density on T1-weighted images and high-signal density on T2-weighted sequences. A black line continuous with the cortex may be distinguished in the high-signal area. According to Devas,  tension stress fractures are located in the superior cortex of the femoral neck and carry a risk of displacement leading to severe complications. They are most frequent in older subjects. Compression fractures appear as a fracture line or callus formation in the inferior femoral neck and rarely cause displacement. These are most frequent in young patients. The majority of patients respond to appropriate treatment, which tends to be conservative. Bed rest and unloaded walking or plaster casts are options to be considered for nondisplaced fractures. Surgical treatment is indicated if an opening appears in the fracture, if there is cortical involvement, if bed rest is not possible, or if the patient is uncooperative. For tension fractures, which affect the superior cortex of the femoral neck, internal fixation with cannulated screws is recommended before displacement appears.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]