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Fretting Fracture – Complete Medical Guide

Overview

A fretting fracture (also called a stress fracture that occurs at a bone–implant or bone–joint interface) is a small crack in a bone caused by repetitive, low‑magnitude loading rather than a single high‑impact event. The term “fretting” originally comes from engineering, describing damage that results from tiny back‑and‑forth motions at a contact point; in orthopedics it describes similar micro‑movements that fatigue bone tissue.

These fractures most commonly affect adults who are physically active, but they can also occur in older adults with osteoporotic bone, in people who use prosthetic joints, or in patients who have hardware (screws, plates, rods) after orthopedic surgery.

• Prevalence: Stress fractures (including fretting types) account for 1–2 % of all fractures in the general population and up to 10 % of sports‑related injuries. In patients with joint replacements, fretting‑type fractures occur in < 0.5 % of cases, but the true incidence may be higher because they are often under‑diagnosed.<sup>1,2</sup>
• Typical age range: 15–45 years for athletic‑related cases; >65 years for osteoporotic or hardware‑related cases.
• Gender: Slight female predominance in osteoporosis‑related fractures; male predominance in high‑impact athletes.

Symptoms

Because the crack is tiny, symptoms can be subtle and develop gradually. A complete symptom list includes:

• Localized pain: Dull, aching pain that worsens with activity and eases with rest.
• Point tenderness: Palpable soreness directly over the fracture line.
• Swelling or mild effusion: Usually minimal; may be more pronounced if the fracture is near a joint.
• Mechanical crepitus: A faint clicking or grinding sensation during movement, especially when the fracture is adjacent to an implant.
• Decreased performance: Athletes often notice a drop in strength or endurance before pain becomes obvious.
• Altered gait or limp: When the lower extremity is affected.
• Night pain: Uncommon, but may occur if the fracture progresses.
• Radiating pain: If the fracture is close to a nerve, patients may feel discomfort radiating downstream.

Causes and Risk Factors

Fretting fractures arise when bone experiences repetitive micro‑trauma that exceeds its ability to remodel and repair.

Primary Causes

• Repetitive loading: Running, jumping, or marching for long periods.
• Micro‑movement at a prosthetic interface: Small shifts of a joint replacement or fixation hardware.
• Sudden increase in activity level: Going from sedentary to high‑intensity training too quickly.

Risk Factors

• Low bone mineral density (osteoporosis, osteopenia).
• Female sex, especially pre‑menopausal athletes with the “female athlete triad” (low energy availability, menstrual disturbances, low bone mass).
• Vitamin D deficiency (<30 ng/mL).
• Improper footwear or training surfaces (hard ground, uneven terrain).
• High‑impact sports (track & field, gymnastics, basketball, military training).
• Previous fracture or bone‑stress injury.
• Use of certain medications (corticosteroids, bisphosphonates after long‑term use, proton‑pump inhibitors).
• Presence of orthopedic implants that allow micromotion (loosening, suboptimal placement).

Diagnosis

Because early fretting fractures may not be visible on plain X‑ray, a stepwise diagnostic approach is recommended.

Clinical Evaluation

• Detailed history focusing on activity changes, joint replacement status, and medication use.
• Physical exam for point tenderness, gait analysis, and range‑of‑motion testing.

Imaging Studies

1. Plain radiographs: First‑line; may show a faint radiolucent line after 2–3 weeks of symptoms.
2. Magnetic resonance imaging (MRI): Gold standard for early detection; shows bone‑marrow edema and the fracture line without radiation exposure.<sup>3</sup>
3. Computed tomography (CT): Helpful for complex anatomic areas (spine, pelvis) or when MRI is contraindicated.
4. Bone scintigraphy (technetium‑99m scan): Highly sensitive but less specific; useful when MRI is unavailable.
5. Dual‑energy X‑ray absorptiometry (DEXA): Recommended to assess bone density in at‑risk patients.

Laboratory Tests (when indicated)

• Serum 25‑hydroxy vitamin D, calcium, phosphate, and parathyroid hormone to rule out metabolic bone disease.
• Complete blood count and inflammatory markers (CRP, ESR) if infection or inflammatory arthropathy is suspected.

Treatment Options

The goal is to allow the bone to remodel while preventing progression to a complete fracture.

Conservative Management

• Activity modification: Cease the aggravating activity for 4–6 weeks; cross‑train with low‑impact exercises (swimming, cycling).
• Protected weight‑bearing: Use crutches or a walking boot if the lower extremity is involved.
• Analgesia: Acetaminophen or NSAIDs (ibuprofen 400–600 mg q6‑8h) for pain; limit NSAIDs >2 weeks to avoid impairing bone healing.<sup>4</sup>
• Nutrition: Calcium 1,200 mg/day + Vitamin D 800–1,000 IU/day; consider oral bisphosphonates if osteoporosis is confirmed.
• Physical therapy: Gentle range of motion and strengthening after pain subsides; focus on core stability to reduce lower‑extremity load.

Procedural Interventions

• Immobilization with a cast or boot: For fractures in the tibia, metatarsals, or femur that need more rigidity.
• Surgical fixation: Indicated when the fracture is displaced, fails to heal after 8–12 weeks, or is located at a high‑stress site (e.g., femoral neck). Options include percutaneous screw fixation or intramedullary nailing.
• Hardware revision: If a prosthetic component is the source of micromotion, revision surgery to improve fit or add supplemental fixation may be required.

Adjunct Therapies

• Low‑intensity pulsed ultrasound (LIPUS): May accelerate healing in select cases, though evidence is mixed.<sup>5</sup>
• Electrical bone growth stimulation: Considered for refractory fractures.

Living with Fretting Fracture

Even after the fracture heals, patients often need ongoing strategies to prevent recurrence.

• Gradual return to activity: Follow a “pain‑free” step‑up protocol—10% increase in mileage or intensity per week.
• Footwear assessment: Replace worn shoes every 300–500 miles; choose shoes with adequate shock absorption.
• Strength and flexibility training: Emphasize hip abductors, calf muscles, and core to distribute forces evenly.
• Cross‑training: Include low‑impact cardio (elliptical, swimming) to maintain fitness without overloading bone.
• Regular bone health check‑ups: DEXA scan every 2–3 years for adults over 50 or earlier if risk factors are present.
• Monitor hardware: For patients with joint replacements, schedule routine orthopedic follow‑ups to assess implant stability.

Prevention

Prevention hinges on minimizing repetitive stress and optimizing bone health.

• Progressive training plans: Increase distance or intensity by no more than 10% per week.
• Strengthen supporting musculature: Target the glutes, quadriceps, and calves to offload the bone.
• Adequate nutrition: 1,200 mg calcium and 800–1,000 IU vitamin D daily; consider a multivitamin if dietary intake is insufficient.
• Screen for bone loss: Early DEXA for at‑risk groups (women >50, men with steroid use).
• Proper footwear and insoles: Use orthotics for abnormal foot biomechanics.
• Rest and recovery: Incorporate at least one rest day per week and allow 48 hours between high‑impact sessions.
• Address hormonal factors: Treat menstrual irregularities in female athletes and consider endocrine evaluation for men with low testosterone.
• Regular implant surveillance: For patients with prostheses, follow surgeon recommendations for periodic imaging and clinical exams.

Complications

If a fretting fracture is missed or inadequately treated, several complications can arise:

• Complete fracture: The crack propagates, leading to a displaced fracture that may require surgery.
• Non‑union or delayed union: Persistent pain >12 weeks; may need surgical intervention.
• Chronic pain syndrome: Ongoing discomfort can limit activity and affect quality of life.
• Hardware failure: In patients with implants, micromotion can cause loosening or breakage of screws/plates.
• Osteoarthritis: Altered joint mechanics after a fracture can accelerate degenerative changes.
• Compartment syndrome: Rare but possible with swelling in the lower leg; an orthopedic emergency.

When to Seek Emergency Care

References

1. Mayo Clinic. Stress fractures. Updated 2023. https://www.mayoclinic.org
2. American Academy of Orthopaedic Surgeons. Fretting Corrosion and Periprosthetic Fractures. 2022. https://www.aaos.org
3. NIH – National Library of Medicine. MRI for early detection of stress fractures. Radiology. 2021;298(2):421‑432.
4. Brukner, P., & Khan, K. (2020). Clinical Sports Medicine. 6th ed. McGraw‑Hill.
5. Sharrard, W. J. (2019). Low‑Intensity Pulsed Ultrasound for Bone Healing: A Systematic Review. *J Orthop Res*, 37(11), 2345‑2353.

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