Femoral Stress Fracture

Original Editors - Matthias Verstraelen as part of the Vrije Universiteit Brussel's Evidence-based Practice project

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Introduction

Femoral stress fractures occur in two different regions.

1. Femoral shaft stress fractures: overuse injuries in which abnormal stresses are placed on trabecular bone of the femoral shaft resulting in microfractures. Most common in young athletic individuals.
2. A Femoral Neck Stress Fracture (FNSF): caused by repetitive loading of the femoral neck that leads to either compression side (inferior-medial neck) or tension side (superior-lateral neck) stress fractures. Most commonly (3-5%) of sports-related stress fractures 9% of lower extremity stress fractures .

Femoral stress fractures can be hard to diagnose. Symptoms are often mild at first, lsimilar to a strained muscle, but can get worsen if activity continues.

Etiology

Occurs through fissure propagation in bone. Repetitive loads, exceeding the threshold of intrinsic bone healing either due to: repetitive stress on normal bone ifatigue fracture); repetitive stress on abnormal bone (insufficiency fracture).

Epidemiology

Femoral neck stress fractures make up approximately 11% of stress injuries in athletes. The patient complains of hip or groin pain which is worse with weight bearing and range of motion especially internal rotation. There are 2 types of femoral neck stress fractures: tension-type (or distraction) fractures and compression-type fractures. Tension-type femoral neck stress fractures involve the superior-lateral aspect of the neck and are at highest risk for complete fracture; thus, these should be detected early. Compression-type fractures are seen in younger athletes and involve the inferior-medial femoral neck. A trial of non-surgical management can be attempted for patients without a visible fracture line on radiographs in compression type injuries. This injury is common in runners.

Stress fractures of the femoral shaft are well documented in the literature, and in one study among military recruits, they represented 22.5% of all stress fractures. Patients typically complain of poorly localised, insidious leg pain often mistaken for muscle injury. An exam is often non-focal, although the “fulcrum test” test can be used by providers to localise the affected pain and suggest the diagnosis. If there is no evidence of a cortical break on imaging, a non-surgical approach can be attempted. 

Clinically Relevant Anatomy

Stress fractures of the femur can occur in the whole bone like the neck, shaft and the condyles.Femoral stress fractures mainly develop on the medial compression side of the femoral shaft, within the proximal and middle thirds of the bone. The highest incidence is seen at the femoral neck.

When the patient doesn’t adapt his or her training, certain stress fractures could lead to complications, even to the point of complete femoral fractures of the head or shaft .

Risk Factors

The risk factors are as follows:

• High-intensity training
• Recreational runners
• Track and field, basketball, soccer, dance
• Women
• Poor nutrition and lifestyle activities
• Lower 25-hydroxyvitamin D
• Female athlete triad
• (history of) smoking
• < 3 times exercising/week
• > 10 alcoholic drinks/week
• Genetic factors
• Change of surfaces (indoor track, frozen field)
• Biomechanical imbalance (leg length, foot arch, forefoot varus, stance of foot and ankle)

Signs and Symptoms

• Local pain and oedema
• Point tenderness on palpation
• Local swelling
• Antalgic gait
• Painful and limited passive and active ROM of hip and/or knee (flexion, internal rotation, extension)
• Pain increases during activity
• Groin pain
• Bone marrow oedema

Outcome Measures

The hop test and tuning fork test could be used as diagnostic test but there is a lack of recent evidence for their validity. Another test is the “fist” test, the therapist create a bilateral pressure on the anterior side of the femur starting at the distal part and moving to the proximal one. The most valid test for the diagnosis is the fulcrum-test, while the therapist pushes to the dorsum of the knee .

Differential Diagnosis

• muscle strain (quadriceps )
• illiopsoas tendinopathy, see relevant section in link .

Diagnostic Procedures

We can use 4 modalities, these techniques can be used in different phases of diagnosis and treatment

• plain radiography,
• bone scan
• MRI (has the highest sensitivity and specificity
• ultrasonography
  

Physical Therapy Management

Conservative Treatment (NOF stress fracture)

If conservative management is chosen, then the patient should be limited weight-bearing with crutches until they are completely free of pain. This normally takes between 6 to 8 weeks but can be up to 14 weeks. During this time, weight-bearing through the injured side can be gradually increased from non-weight-bearing to toe-touch weight bearing to partial weight-bearing, as pain allows.

Upper limb conditioning can be initiated. Hydrotherapy can be undertaken, wearing an inflatable jacket for support. Lower-limb athletic activity should be commenced only when there is clear evidence of fracture union, both radiologically and clinically . Activity is normally commenced in a graduated manner, around 12 weeks, specifically focussing on strengthening and range-of-motion exercises around the hip. Patient should begin with a gentle running programme, which should be increased in intensity over 6 to 8 weeks, ensuring the patient remains pain-free throughout. Return to full sport can normally be achieved between 3 and 6 months after injury, though this can require up to a year if not longer.

Surgical intervention

If NOF surgery was required post-operatively, the patient should remain non- to toe-touch weight-bearing with crutches for 6 weeks, followed by partial weight-bearing with crutches for a further 6 weeks . After this, weight-bearing is permitted as tolerated. Rehabilitation can then follow the above guideline for conservative management.

Ivkovic et al. designed a new treatment algorithm for femoral shaft stress injuries. Four phases have to be fulfilled to start normal training and each phase is evaluated by a hop or fulcrum test. The first phase is called symptomatic, where the patient has to walk with crutches. The second phase is the asymptomatic one where patient are allowed to walk normally and to start swimming and exercises the upper extremity. During the third ‘basic’ phase the patient can perform exercises of lower and upper extremities. During the last ‘resuming phase’, the athlete is allowed to gradually start normal training . No recurrence of injury after treatment and follow-up for 48-96 months .The treatment algorithm is free available in the article from Ivkovic et al.: "Stress fractures of the femoral shaft in athletes: a new treatment algorithm."

A triple-phase bone scan is recommended for an early diagnosis. It is very important to perform an adequate evaluation, patient history, and have a high index of suspicion. This will enable the practitioner to justify having a bone scan performed and thereby decrease the incidence of undiagnosed asymptomatic femoral shaft stress fractures.

An early diagnosis is needed. Often, x-rays are not going to detect these injuries. Therefore, we must go through the appropriate referral channels to have a triple-phase bone scan ordered. One needs to maintain a high level of suspicion, especially if the athlete is experiencing persistent pain that shows no improvement with treatment.

Prevention

To prevent femoral stress fractures, people could modify their training schedules and wear shock-absorbing shoe inserts. Insoles lowers the incidence because the improves biomechanics, less fatigue and limit the impact on the ground. The size of these insoles can range in different types to support the forefoot and/or the toes . Also calcium and vitamin D supplementation could play a role in the prevention but their data are controversial . Leg muscle stretching during warm-up has no significant effect on prevention for femoral stress fractures.