젊은 비운동선수인 성인에서 발생한 양측 대퇴 목의 피로골절

(1)

VOL. 18, NO. 2, 2019 Case Report

CLINICAL PAIN

126

https://doi.org/10.35827/cp.2019.18.2.126

접수일: 2019년 7월 1일, 게재승인일: 2019년 9월 24일 책임저자: 이규훈, 서울시 성동구 왕십리로 222-1

󰂕 04763, 한양대학교병원 재활의학과 Tel: 02-2290-9349, Fax: 02-2290-9231 E-mail: [email protected]

젊은 비운동선수인 성인에서 발생한 양측 대퇴 목의 피로골절

한양대학교병원 재활의학과

윤여준ㆍ나용재ㆍ정지원ㆍ이규훈

Bilateral Stress Fracture of Femur Neck, Fatigue Type of Non-Athlete Young Adult

Yeo Joon Yun, M.D., Yong Jae Na, M.D., Ji Won Jung M.D. and Kyu Hoon Lee, M.D., Ph.D.

Department of Rehabilitation Medicine, Hanyang University Seoul Hospital, Seoul, Korea

Bilateral femoral neck stress fractures have been rarely reported. When diagnosed, they are usually limited to athletes or military personnel. A 35-year-old man, previously healthy, visited the emergency department for right inguinal pain. On physical examination, no external wound, tenderness or limitation of motion were found in either lower extremity. Plain radiography showed normal findings but an magnetic resonance image showed a linear fracture in the femoral neck. In this case, bilateral femoral neck stress fractures were found in a young non-athlete adult with no prior medical history of related injuries. Surgery is generally not performed for stress fractures but considering the patient’s early mobilization and the need for quick reintegration into society, surgery was done in this case. (Clinical Pain 2019;18:126-129)

Key Words: Bilateral femoral neck stress fracture, Non-athlete young adult, Magnetic resonance image

INTRODUCTION

Femoral neck stress fractures are uncommon injuries.

Stress fractures can arise as a result of repetitive loading and, in general, there is dose-response relationship between the amount of training and frequency of training.¹ These fractures can progress to non-union and osteonecrosis of the femoral head.² Diagnosis of stress fracture of femoral neck is hard to detected. The clinical symptom is activity related hip pain and the pain is relived when a patient rests.^3,4

Plain radiographs obtained initially are often negative in femoral neck stress fractures. Magnetic resonance imaging (MRI) is considered to be the best choice to diagnosis an incomplete femoral neck stress fracture.^1,2 The key features that appear in an MRI are the fracture line, osseous edema, and hip effusion.

The first report of a fatigue fracture of the femoral neck was documented in 1905.^5-7 Since then, studies of femoral

neck stress fractures were very rare between 1905 and 1977: only 133 cases were reported.² Most of the patients were athletes, military personnel or elderly people. Bilater- al femur neck stress fractures in the non-athlete, young adult population are extremely rare. Here, we report such a case and review the importance of considering a stress fracture for an accurate diagnosis of a patient with inguinal pain.

CASE REPORT

A 35-year-old man, who was previously healthy, visited the emergency department for right inguinal pain. He had no past medical history and medication use. He had not been exercising for more than 10 years. Recently, about three weeks ago he started personal training and worked out hard for two weeks. He did three sets of squats 15 times every two days. Initially without weight, he performed 15 kg for the third and fourth, and 30 kg for the fifth and sixth. He did three sets of burpee exercises and five runs in two weeks. He ran the treadmill without a slope and ran at least five kilometers every day. On the first week he ran at a speed of 7 km/h and on the following week at 11 km/h. He was 175 cm tall and weighed 75 kg.

A week ago, while he was running on a treadmill, he

(2)

윤여준 외 3 인: 젊은 비운동선수인 성인에서 발생한 양측 대퇴 목의 피로골절

CLINICAL PAIN 127 Fig. 3. Marrow change on T1 weighted image (A) and T2 weighted image (B).

Fig. 2. MRI showed linear fracture in the both femoral necks.

Fig. 1. Hip X-ray anteroposterior view.

felt sudden pain on his right inguinal area. The pain lasted for 5 to 10 minutes and disappeared, so he took some rest and completed his daily exercise routine. The next day, the pain was on his right posterolateral hip. Pain was ag- gravated when he did weight bearing and relieved at rest.

The pain was most severe while he was running. He used non-steroidal anti-inflammatory drugs for 5 days but there was no change in pain severity. Two days ago, he visited the orthopedic clinic, and was diagnosed with sub-gluteal bursitis. A triamcinolone injection was done on the right hip sub-gluteal bursa but there was no improvement. So he visited emergency department. On physical examination, there was no external wound, no tenderness on either inguinal area, and no limitation of motion in either lower extremity. The Patrick sign was positive on the right hip joint. There were no physical abnormalities on the left lower extremity. He ambulated with an antalgic gait on the right side. At that time, standard AP radiographs of the pel-

vis showed no gross abnormal findings (Fig. 1). However, the MRI showed linear fractures on both femoral necks with a marrow edema and a small amount of effusion on the right hip joint (Fig. 2, 3).

The results of the laboratory blood test, including a liver profile, thyroid profile, electrolytes and a renal profile was normal. Bone Alkaline Phosphatase was elevated at 26.1 ng/ml. C-telopeptide was also elevated at 0.63 ng/ml. The level of 25 (OH)-Vitamin D was low at 15.1 ng/ml, diagnosed as vitamin D insufficiency. A normal bone mineral density test was administered at the lumbar spine and both femur necks.

This patient was diagnosed as having a bilateral femoral fatigue fracture and was admitted to an orthopedic general ward. A closed reduction was performed on both femurs.

A closed reduction and internal fixation with three cannu- lated screws and one washer were done for both femoral

(3)

VOL. 18, NO. 2, 2019

CLINICAL PAIN

128

Fig. 4. Postoperative X-ray state of both femur necks (A) and 8 weeks follow up X-ray (B).

fatigue fractures. After the surgery he was discharged. He ambulated with a wheel chair at discharge. Four weeks later, he visited the outpatient clinic for follow up. He was using crutches, and his gait was partial weight bearing.

Eight weeks later, he can now ambulate by himself without using crutches and is full weight bearing. A post-operative and eight weeks follow up X-ray are shown in Fig. 4.

DISCUSSION

In this case, a young non-athlete adult was diagnosed with a bilateral femur neck stress fracture. The first symptom he complained of was right inguinal pain. Femoral fractures are rarely considered when young adults complain of right inguinal pain. Futhermore, the patient had no pre- vious history of trauma. It is very difficult to diagnose a femur neck stress fracture with only clinical symptoms. As we can see in this case, femoral neck stress fractures often show normal X-ray findings initially, and this makes it more difficult to diagnose. The most common symptom that patients complain of is a dull ache in the hip region.⁵ It is not a characteristic symptom, so imaging tests are es- sential to diagnosis accurately. The plain radiographic ap- pearance of spontaneous fractures depends on the time elapsed since the injury.⁵ Like in our case, in early exami- nations the degree of trabecular fractures may be in- sufficient on radiographic findings. MRI is usually considered as the best choice for the diagnosis of incomplete femoral neck stress fracture. The key features on the initial MRI were osseous edema, the presence of fracture line and hip effusion. Misdiagnosis or delayed diagnosis of femoral neck fatigue fracture can lead to displacement of an initially non-displaced fracture.⁴ Fatigue fractures of the fem-

oral neck have potential to become disabling injuries if the diagnosis is missed or delayed.

There are several risk factors associated with femur neck stress fractures. Intrinsic risk factors are composed of nutritional factors and biochemical factors. Calcium levels and vitamin D levels are important in nutritional factor.⁸ In biochemical factors, muscle mass and bone mass density are important factor. Most of external factors are associated with overtraining such as sudden increases of exercise intensity or poor warming up before training. In our case, patient showed low level of vitamin D which indicated vitamin D insufficiency. Also, patient started high intensity exercise suddenly. These factors may have caused the bilateral femoral neck fractures in the case.

In our case, the exact diagnosis took two weeks, which included a misdiagnosis as sub-gluteal bursitis for 5 days.

There were several reasons for the late diagnosis. The first reason is that the patient was a non-military, non-athlete, young adult, who had not exercised for the past 10 years.

To the best of our knowledge, bilateral femoral neck stress fractures in young, non-athlete, adults have rarely reported before. For this reason, when an young adult who exercises recently suffers from inguinal pain, we must consider a femoral fatigue fracture as a differential diagnosis, even when the patient is not an athlete. The second reason is due to the normal findings on plain film. As we can see in the case above, when there is a fatigue fracture, an MRI is a valuable tool because plain film can show normal sign in early stage. However, there have not been many cases of femur neck fatigue fractures, and since the clinical findings are not specific, MRI should be considered as cost-ef- fectiveness at an early stage.

In general, a stress fracture is not a surgical condition.

(4)

윤여준 외 3 인: 젊은 비운동선수인 성인에서 발생한 양측 대퇴 목의 피로골절

CLINICAL PAIN 129 The vast majority of stress fractures heal within 8 weeks

through conservative treatment.⁸ Non-weight bearing crutches and activity restriction are recommended. But in this case, considering the patient’s need for early mobilization and re-integration to society, surgery was done. Further studies should investigate whether early surgery for early mobilization is beneficial for young adults.

REFERENCES

1. Steele CE, Cochran G, Renninger C, Deafenbaugh B, Kuhn KM. Femoral Neck Stress Fracture: MRI Risk Factors for progression. J Bone Joint Surg 2018; 10: 1496-1502 2. Weistroffer JK, Muldoon MP, Duncan DD, Fletcher EH,

Padgett DE. Femoral neck stress fracture: outcome analysis at minimum five-year follow-up. J Orthop Trauma 2003;

17: 334-337

3. Paul MM, John GC, Thomas JB. Relation between age, femoral neck cortical stability, and hip fracture risk. The Lancet 2005; 366: 129-135

4. Clough TM. Femoral neck stress fracture: the importance of clinical suspicion and early review. Br J Sports Med 2002; 36: 308-309

5. Dorne HL, Lander PH. Spontaneous stress fractures of the femroal neck. Am J Roentgenol 1985; 144: 343-347 6. Slocum KA, Gorman JD, Puckett ML, Jones SB. Resol-

ution of abnormal MR signal intensity in patients with stress fractures of the femoral neck. Am J Roentgenol 1997; 168: 1295-1299

7. Shin AY, Gillingham BL. Fatigue Fractures of the Femoral Neck in Athletes. J Am Acad Orthop Surg 1997; 5: 293- 302

8. Leamor K, Lindsey EE, Kenneth EG. Diagnosis, treatment, and rehabilitation of stress fractures in the lower extremity in runners. J Sports Med 2015; 6: 87-95