Femoral Stress Fracture

Original Editors - Matthias Verstraelen as part of the Vrije Universiteit Brussel's Evidence-based Practice project Top Contributors - Lucinda hampton, Matthias Verstraelen, Kim Jackson, Redisha Jakibanjar, Daniele Barilla, Adam Vallely Farrell, Admin, Alexandra Stead, Daphne Jackson, Wanda van Niekerk, Evan Thomas, Naomi O'Reilly, WikiSysop, Elise Audiens, Vidya Acharya, Claire Knott, Laura Ritchie and Mohit Chand

Introduction

Bone scan

Introduction

Femoral stress fractures occur in two distinct anatomical regions:

1. Femoral Shaft Stress Fracture (FSSF): An overuse injury characterised by abnormal stresses placed on cancellous bone of the femoral shaft, resulting in microfractures. Most commonly observed in young athletic populations.
2. Femoral Neck Stress Fracture (FNSF): Caused by repetitive loading of the femoral neck, leading to either compression-side (inferior-medial neck) or tension-side (superior-lateral neck) stress fractures. These injuries predominantly affect young athletes and military personnel.

Femoral stress fractures can present diagnostic challenges, particularly in their early stages. Initial symptoms may be subtle and often mimic muscular strains. Without appropriate activity modification, progression to complete femoral fracture of the head or shaft may occur, potentially resulting in significant complications.

Aetiology

Femoral stress fractures develop through fissure propagation in bone tissue. The injury occurs when repetitive mechanical loads exceed the threshold of intrinsic bone healing capacity. This can manifest as either fatigue fractures (repetitive stress on normal bone) or insufficiency fractures (repetitive stress on pathologically weakened bone). Stress fractures result from an imbalance between osteoclast and osteoblast activity, leading to microdamage accumulation that exceeds the bone's capacity for physiological remodelling.

Epidemiology

Femoral Neck Stress Fractures (FNSF)

FNSF account for approximately 11% of stress injuries in athletic populations. Two distinct types exist:

• Tension-type FNSF: Involve the superior-lateral aspect of the femoral neck and carry the highest risk for progression to complete fracture, necessitating early detection and intervention.
• Compression-type FNSF: More common in younger athletes, affecting the inferior-medial femoral neck.

Femoral Shaft Stress Fractures (FSSF)

FSSF are well-documented in the literature, representing 22.5% of all stress fractures amongst military recruits in published studies.

Risk Factors

CT: Femoral-neck-stress-fracture

The following risk factors have been identified in current literature:

Training and Activity-Related

• High-intensity training regimens
• Participation in high-impact sports (track and field, basketball, football, dance)
• Rapid increases in training volume or intensity
• Training frequency <3 times weekly
• Changes in training surfaces (indoor track, frozen field)

Demographic and Physiological

• Female sex
• Female Athlete Triad components
• Nutritional deficiencies
• Lower 25-hydroxyvitamin D levels
• History of tobacco use
• Excessive alcohol consumption (>10 units weekly)

Biomechanical

• Leg length discrepancy
• Abnormal foot arch
• Forefoot varus
• Altered stance of foot and ankle

Metabolic and Genetic

• Genetic predisposition
• Low bone mineral density
• Corticosteroid use
• Bisphosphonate therapy

Clinical Presentation

Signs and Symptoms

• Localised pain and oedema
• Point tenderness on palpation
• Localised swelling
• Antalgic gait pattern
• Painful and limited passive and active range of motion of hip and/or knee (particularly flexion, internal rotation, extension)
• Pain that increases with activity
• Groin pain
• Bone marrow oedema on advanced imaging

Clinical Tests and Outcome Measures

1. Fulcrum Test: The most valid clinical test for diagnosis. The clinician applies dorsal pressure to the knee whilst the patient's thigh is positioned over the edge of the examination table.
2. Fist Test: The clinician creates bilateral pressure on the anterior aspect of the femur, progressing from distal to proximal.
3. Hop Test and Tuning Fork Test: Historical diagnostic tests with limited recent evidence supporting their validity.

Differential Diagnosis

Femoral neck stress fractures should be differentiated from:

• Early osteoarthritis of the hip
• Hip labral tears
• Chondral defects of the hip
• Rectus femoris strain
• Avascular necrosis of the femoral head

Diagnostic Imaging

Four imaging modalities are utilised in diagnosis and treatment monitoring:

1. Plain Radiography: Initial screening tool, though early stress fractures may not be visible
2. Bone Scintigraphy: Sensitive for detecting bone stress, though less specific than MRI
3. Magnetic Resonance Imaging (MRI): Demonstrates the highest sensitivity and specificity for stress fracture diagnosis and classification
4. Ultrasonography: Adjunctive imaging modality

Physiotherapy Management

Femoral Neck Stress Fractures (FNSF)

Conservative Treatment

Patients should maintain limited weight-bearing status with crutches until completely pain-free, typically requiring 6-8 weeks, though duration may extend to 14 weeks. Weight-bearing should be progressed gradually from non-weight-bearing to toe-touch weight-bearing to partial weight-bearing, as pain permits.

Rehabilitation Protocol:

Initial Phase (Weeks 0-6)

• Protected weight-bearing with assistive devices
• Upper limb conditioning
• Hydrotherapy with flotation support
• Pain management strategies

Intermediate Phase (Weeks 6-12)

• Progressive weight-bearing as tolerated
• Hip range of motion exercises
• Strengthening exercises targeting hip musculature
• Continuation of non-weight-bearing cardiovascular training

Advanced Phase (Weeks 12-24)

• Gradual return to running programme over 6-8 weeks
• Sport-specific rehabilitation
• Ensure pain-free progression throughout
• Return to full sport typically achieved between 3-6 months post-injury, though may require up to 12 months in some cases

Surgical Management

Post-operative rehabilitation follows a structured approach:

• Weeks 0-6: Non-weight-bearing to toe-touch weight-bearing with crutches
• Weeks 6-12: Partial weight-bearing with crutches
• Week 12 onwards: Weight-bearing as tolerated
• Subsequent rehabilitation follows conservative management guidelines

Femoral Shaft Stress Fractures (FSSF)

Conservative Management

Indications: Most femoral shaft stress fractures without cortical breach or displacement

Treatment Protocol:

• Rest and activity modification
• Protected weight-bearing until fracture healing confirmed
• Incorporation of cross-training into running programmes
• Progressive loading as radiographic healing demonstrates

Surgical Management

Indications:

• Prophylactic fixation in high-risk populations
• Patients with low bone mass or age >60 years
• Fracture completion or displacement
• Method: Locked intramedullary reconstruction nail

Post-Operative Rehabilitation:

Early Phase (Weeks 0-6)

• Non-weight-bearing to toe-touch weight-bearing with crutches
• Pain and swelling management
• Upper limb and core conditioning exercises
• Hydrotherapy once surgical wound is healed
• Ankle and foot range of motion exercises to prevent distal complications

Intermediate Phase (Weeks 6-12)

• Progressive partial weight-bearing as tolerated, guided by pain and radiographic healing
• Hip and knee range of motion exercises
• Progressive hip abductor, extensor, and quadriceps strengthening
• Non-weight-bearing cardiovascular conditioning (cycling, swimming)

Advanced Phase (Week 12 Onwards)

• Full weight-bearing as confirmed by radiographic evidence of healing
• Gradual return to impact loading and running programme
• Sport-specific conditioning and neuromuscular training
• Return to sport typically achieved at 4-6 months post-operatively, guided by pain-free status and imaging confirmation of healing

Clinical Considerations

Early diagnosis is paramount to optimal outcomes. Triple-phase bone scintigraphy may be warranted when clinical suspicion remains high despite normal radiographic findings. Maintaining a high index of suspicion, particularly in athletes presenting with persistent pain unresponsive to conservative treatment, is essential to prevent progression to complete fracture.

Prevention Strategies

Evidence-based prevention strategies include:

1. Training Modification
   • Gradual progression of training volume and intensity
   • Adequate rest and recovery periods
   • Periodisation of training loads
2. Footwear and Orthotics
   • Shock-absorbing shoe inserts
   • Custom orthotics when indicated to address biomechanical deficiencies
   • Appropriate footwear for sport and training surface
3. Nutritional Optimisation
   • Adequate calcium and vitamin D intake
   • Correction of nutritional deficiencies
   • Management of Female Athlete Triad when identified
4. Biomechanical Assessment
   • Gait analysis
   • Identification and management of biomechanical abnormalities
   • Strength and conditioning programmes

Note: Current evidence does not support leg muscle stretching during warm-up as an effective prevention strategy for femoral stress fractures.