What is a bone stimulator?

What is a Bone Stimulator?

A bone stimulator is a medical device designed to promote bone healing by applying electrical, electromagnetic, or ultrasound energy to fracture or fusion sites, though current evidence strongly recommends against their use for most fracture healing applications. 1

Types of Bone Stimulators

There are three main categories of bone stimulation devices, each using different mechanisms to theoretically enhance bone healing (osteogenesis): 1

1. Direct Current Stimulation (DCS)

• Involves electrodes implanted surgically within or very close to the desired fusion/healing site 1
• Consists of a sealed electrical source implanted at the time of surgery 1
• May or may not be removed after achieving solid bone union 1
• Completely invasive and requires surgical placement 1

2. Capacitive Coupling Stimulation (CCS)

• Uses two electrodes placed on the skin over the fracture/fusion site 1
• Connected to an external battery-powered device 1
• Requires daily battery changes 1
• Patients encouraged to use up to 24 hours per day 1

3. Pulsed Electromagnetic Field Stimulation (PEMFS)

• Requires coils (usually embedded in a brace) that produce a time-varying magnetic field around the healing area 1
• Patients typically instructed to wear the device 3-8 hours per day 1
• Non-invasive external application 1

4. Low Intensity Pulsed Ultrasound (LIPUS)

• Portable, patient-operated device that emits ultrasound waves 1
• Probe applied directly to skin over fracture site using conducting gel 1
• Used for 15-20 minutes daily for 14-140 days 1
• FDA approved in 1994 for fracture healing and in 2000 for non-unions 1

Current Evidence and Recommendations

Strong Recommendation AGAINST LIPUS for Fracture Healing

The most recent high-quality evidence from the BMJ (2017) provides a strong recommendation against using LIPUS for bone healing in fractures and osteotomies: 1

• Moderate to high certainty evidence shows LIPUS has little or no impact on: 1

  • Time to return to work
  • Time to full weight bearing
  • Pain reduction
  • Number of subsequent operations
  • Time to radiographic healing

• The BMJ panel unanimously agreed that all or nearly all informed patients would elect not to use LIPUS 1

Limited Support for Electrical Stimulation in Spinal Fusion Only

The Journal of Neurosurgery (2005) provides more nuanced guidance specifically for lumbar spinal fusion procedures: 1

• DCS or CCS may be considered as an adjunct to increase fusion rates in high-risk patients undergoing posterolateral lumbar fusion 1
• PEMFS may be considered for patients undergoing lumbar interbody fusion procedures 1
• Important caveat: There is insufficient evidence to recommend these as treatment standards 1

Practical Considerations and Burdens

Cost Issues

• LIPUS devices cost between $1,300-$5,000 per unit 1, 2
• Global revenues for bone stimulators were approximately $400 million in 2004 1
• Health insurance may not cover costs 1
• Does not represent efficient use of healthcare resources given lack of demonstrated benefit 1, 2

Patient Compliance Challenges

• Devices can be cumbersome to travel with 1, 2
• Clinical trials show limited patient compliance with prescribed protocols 1, 2
• Daily use requirements (15-20 minutes for LIPUS, up to 24 hours for CCS, 3-8 hours for PEMFS) create significant burden 1

Clinical Context: When Bone Stimulators Are NOT Indicated

For routine fracture healing, bone stimulators should not be used based on current evidence: 1, 2

• The evidence applies to fresh fractures, stress fractures, non-unions, and osteotomies 1
• No compelling anatomical or physiological reasons exist to suggest LIPUS would be beneficial in these cases 1
• Mechanical stabilization remains the cornerstone of treatment 2
• Autogenous bone grafting is the gold standard for biological enhancement if revision surgery becomes necessary 2

Common Pitfalls to Avoid

• Do not prescribe LIPUS for fracture healing despite FDA approval and previous NICE guidance supporting its use—the most recent high-quality evidence contradicts earlier recommendations 1
• Do not confuse spinal fusion applications with fracture healing—the limited evidence supporting electrical stimulation applies only to high-risk spinal fusion patients, not general fracture care 1, 2
• Do not use bone stimulators as a substitute for adequate surgical fixation—mechanical stability is essential regardless of adjunctive therapies 2
• Avoid using implantable bone stimulators in patients with active deep soft tissue infection or osteomyelitis—this increases postoperative infection rates 3

De-Implementation Considerations

Healthcare organizations currently paying for LIPUS may reasonably choose to stop reimbursements based on best current evidence: 1

• Healthcare administrators may consider de-implementation of LIPUS as a performance indicator in quality improvement initiatives 1
• Further research is unlikely to alter the evidence against LIPUS for fracture healing 1