1. Ultrasonic osteogenesis stimulator

   1. Aetna considers the use of an ultrasonic osteogenesis stimulator (e.g., the Sonic Accelerated Fracture Healing System (SAFHS)) medically necessary DME to accelerate healing of fresh fractures, fusions, or delayed unions at either of the following high-risk sites:

      1. Fresh fractures, fusions, or delayed unions of the shaft (diaphysis) of the tibia that are open or segmental; or

      2. Fresh fractures, fusions, or delayed unions of the scaphoid (carpal navicular).
         
         This system uses pulsed ultrasound to speed healing. Fractures on these sites are difficult to heal because of poor vascular supply. 

   2. Aetna considers an ultrasonic osteogenesis stimulator medically necessary for non-unions, failed arthrodesis, and congenital pseudarthrosis (pseudoarthrosis) of the appendicular skeleton if there has been no progression of healing for three or more months despite appropriate fracture care.
   3. Aetna considers an ultrasonic osteogenesis stimulator experimental and investigational for fractures, failed fusions, or non-unions of the axial skeleton (skull and vertebrae) because the effectiveness of SAFHS in these fractures has not been determined.

   4. Aetna considers an ultrasonic osteogenesis stimulator experimental and investigational for all other indications, including stress fractures, pathological fractures due to malignancy (unless the neoplasm is in remission), avascular necrosis of the femoral head, and Charcot arthropathy because the medical literature does not support its use for these indications.

2. Electrical stimulation

   Aetna considers a direct current electrical bone-growth stimulator medically necessary for any of the following indications:

   1. Non-unions, failed fusions, and congenital pseudarthrosis where there is no evidence of progression of healing for three or more months despite appropriate fracture care, or
   2. Delayed unions of fractures or failed arthrodesis at high risk sites (i.e., open or segmental tibial fractures, carpal navicular fractures), or

   3. Members who are at high risk for spinal fusion failure when any of the following criteria is met:

      1. One or more failed fusions, or
      2. Grade II or worse spondylolisthesis, or
      3. A multiple level fusion entailing 3 or more vertebrae (e.g., L3 to L5, L4 to S1, etc.), or

      4. Other risk factors for fusion failure are present, including gross obesity, degenerative osteoarthritis, current smoking, previous fusion surgery, or gross instability; or
         

   4. Any other condition where it is determined by Aetna, upon medical review, that electrical stimulation is likely to avoid the need for open reduction and bone graft.

Aetna considers direct current stimulation experimental and investigational for all other indications, including the treatment of Charcot foot, avascular necrosis of the hip and fractures of the scapula or pelvis, spondylolysis, Charcot arthropathy, and lunate fractures (not an all inclusive list) because of a lack of adequate evidence of its effectiveness for these conditions.

Ultrasonic Osteogenesis Stimulators for Fresh Fractures

When applied over a fracture site, the Sonic Accelerated Fracture Healing System (SAFHS) device produces an ultrasonic wave, which delivers mechanical pressure to the bone tissue at the fracture site. Although the mechanism by which the low intensity pulsed ultrasound device accelerates bone healing is uncertain, it is thought to promote bone formation in a manner comparable to bone responses to mechanical stress.

In October 1994, the Food and Drug Administration (FDA) approved the Sonic Accelerated Fracture Healing System (SAFHS), manufactured by Exogen, Inc. (West Caldwell, NJ), to accelerate the healing of new bone fractures in the tibial diaphysis and Colles' fractures of the distal radius in adults. The FDA approval of the device was based in part on its review of two multicenter randomized controlled trials of the device on tibial diaphyseal fractures and distal radius (Colles') fractures.

SAFHS low intensity pulsed ultrasound has been demonstrated to significantly accelerate the time to clinical healing of fractures of the tibial diaphysis. Although SAFHS low intensity pulsed ultrasound has been demonstrated to accelerate the time to radiologic healing of fresh closed Colles' (wrist) fractures, it has not been shown to significantly reduce the time to clinical healing of these fractures.

SAFHS is most likely to result in clinically significant benefits when applied to fresh fractures with poor vascularity that are slow to heal and at high risk of non-union. Tibial fractures that are open or segmental are notorious for prolonged healing and a high incidence of delayed union and non-union. Fractures of the scaphoid (carpal navicular) are uncommon, but when they occur, they are at high risk of delayed union and non-union. Hence, use of SAFHS may be particularly helpful in patients with these fractures.

Ultrasonic bone growth stimulation has also been studied for accelerating healing of stress fractures. In a prospective, randomized, double-blind clinical trial, Rue, et al. (2004) ascertained if pulsed ultrasound reduces tibial stress fracture healing time. A total of 26 midshipmen (43 tibial stress fractures) were randomized to receive pulsed ultrasound or placebo treatment. Twenty-minute daily treatments continued until patients were asymptomatic with signs of healing on plain radiographs. The groups were not significantly different in demographics, delay from symptom onset to diagnosis, missed treatment days, total number of treatments, or time to return to duty. Findings of this study demonstrated that pulsed ultrasound did not significantly reduce the healing time for tibial stress fractures. Furthermore, Zura and colleagues (2007) surveyed the attitudes of members of the Orthopaedic Trauma Association (OTA) concerning the use and effectiveness of bone growth stimulators. A questionnaire regarding bone growth stimulators was sent to the active members of the OTA. Descriptive statistics was performed using frequencies and percentages. All analyses were performed using Stata for Linux, version 8.0 (Intercooled Stata, Stata Corporation; College Station, TX). A response rate of 43 % was obtained. Respondents indicated that they only occasionally used bone stimulators for the treatment of acute fractures and stress fractures. A majority of respondents have utilized stimulators for the treatment of delayed unions and non-unions. The authors concluded that many members of the OTA utilize bone stimulators for delayed unions and non-unions, but not routinely for the treatment of acute fractures or stress fractures.

Ultrasound Osteogenesis Stimulators for Nonunions

SAFHS low intensity pulsed ultrasound was approved by the FDA in February 2000 for the treatment of established non-unions, excluding the skull and vertebrae. The FDA approval of the device was based on a review of retrospective studies of 79 patients with non-unions treated with SAFHS. Patients with pathologic fractures due to malignancy were excluded from these studies. Of the 74 completed cases, 86% healed both radiographically and clinically and 14% were failures of SAFHS treatment. The mean time to a healed fracture was 5½ months.

Other evidence of the effectiveness of SAFHS for non-unions include a registry of prescription use of SAFHS for non-unions in the United States, which showed a heal rate of 82% of 429 completed cases, and a retrospective study of non-unions which showed a heal rate of 90% of 30 completed cases.

Electrical Stimulation for Spinal Fusion

Spinal fusion is a general term which describes the surgical results of a procedure designed to eliminate motion across a spinal segment.  All fusions involve the placement of a bone graft across the spinal segment with or without a wide variety of internal fixators and techniques for postoperative immobilization.

There are three general indications for spinal fusion: 1) to restore the integrity of the spine, to replace bone deficits, i.e. in fracture, tumor, infection; 2) to maintain the correction of spinal deformity or prevent the progression of deformity, i.e. scoliosis; 3) to produce an arthrodesis to suppress painful instability.  See CPB 743 -- Spinal Surgery: Laminectomy and Fusion.  The correction of painful instabilities probably the most common and controversial indication for fusion.  The controversy centers around the treatment of low back pain and whether laminectomy and discectomy should be accompanied by a fusion.  This is in turn related to whether instability itself is contributing to the low back pain or whether the surgical procedure, for example, discectomy and laminectomy, will produce an iatrogenic instability.  Because of the potential for failed fusion, electrical stimulation techniques have been investigated as a method to improve the chances for a successful fusion.

Two general types of electrical stimulation devices are available for spinal fusion.  An implantable device (e.g., SpF-2) uses direct current to stimulate osteogenesis.  The implantable device consists of a battery pack which provides direct current over four cathodes.  The device is implanted during the fusion procedure; the cathodes are implanted at the fusion site while the battery pack is implanted just beneath the dorsal fascia or in the soft tissue above the iliac crest.  An external device (e.g., Spinal Stim) uses pulsating electromagnetic energy to induce weak electrical currents in the underlying tissue.  The external electrical stimulation device consists of the magnetic coils incorporated into a corset like device which the patient wears 8 to 10 hours per day, usually while sleeping.  The external device can either be used immediately after surgery, or only when fusion failure becomes apparent.

There have been several clinical studies on either device.  In a randomized prospective controlled trial of the implanted electrical stimulation device in difficult spinal fusion patients, subjects were randomized to undergo a spinal fusion procedure either with or without simultaneous implantation of an electrical stimulation device.  At 18 month post surgery, successful fusion was achieved in 54% of the control group and 81% of the treatment group (Kane, 1988).

In a randomized double blind prospective study of an external electrical stimulation device, 195 patients were randomized to receive either a functioning or nonfunctioning brace following surgery (Mooney, 1990).  A total of 40% of patients were non-compliant.  In those compliant patients who received an active brace, the fusion success rate was 92.2% versus a success rate of 67.9% of the compliant patients in the control group.

In a retrospective, case-controlled, pilot study, Welch and colleagues (2004) examined the safety and effectiveness of an implantable direct current bone growth stimulator (IDCBGS) as an adjunct to cervical arthrodesis in patients at high risk for non-union after undergoing cervical fusion in region from the occiput to C3. A total of 20 patients underwent para-axial cervical arthrodesis  for the correction of instability. All were at high risk for non-union due to advanced age, rheumatoid arthritis, prior failed fusion attempts, infection, or immunosuppressive drug use. An IDCBGS was used to augment the surgical procedure. The mean follow-up period was 19 months, and 16 patients were available for follow-up. Radiographical evidence of fusion was demonstrated in 15 of 16 patients (94 %). After surgery, all patients demonstrated clinical stabilization, a resolution of symptoms in combination with an improvement in neurological status, or both. The mean elapsed time before fusion occurred was 4.6 months. No neurological complications related to cathode or generator placement were observed. The use of the stimulator as an adjunct to instrument- or non-instrument-assisted surgical fusion of the para-axial region in these high-risk patients appeared both safe and effective. The authors concluded that further investigation is needed to define the possible role and clinical utility of the IDCBGS in selected patients requiring cervical fusion, particularly those at high risk for non-union.

Electrical Stimulation for Nonunion

In nonunion, or interrupted bone healing, the normal process of calcification fails to take place.  The fracture gap remains occupied by cartilage and/or fibrous tissue and vascular penetration cannot proceed.  Factors predisposing to nonunion include infection, extensive comminution, inadequate blood supply, a large fracture gap, damage to surrounding muscles, and torsional or bending stresses.

Under a definition adopted by the Food and Drug Administration (FDA), a nonunion is established when at least nine months have elapsed since injury and the fracture site shows no visibly progressive signs of healing for a minimum of three months.  Others have suggested that nonunion may be suspected as early as three months after fracture if fracture healing has failed to progress during that time.  It has been estimated that approximately 5 percent of all long bone fractures will result in nonunion.

Electrical stimulation devices use low-energy electromagnetic fields to promote healing by creating weak electrical currents across the fracture site.  Weak electrical currents have been found to stimulate bone formation and calcification.  Physicians are not certain why it works, but many speculate that the currents stimulate osteocytes (bone cells) and may change the structure of the cell wall, enhancing bone union.

In 1979, the FDA approved electrical stimulation therapy devices for treatment of nonunion, congenital pseudarthrosis, and failed fusion.  A number of prospective studies, including controlled clinical trials, have demonstrated the effectiveness of electrical stimulation in nonunions of long bones.  These studies have primarily examined the effectiveness of electrical stimulation therapy in the treatment of nonunions of the tibia and femur.  The studies have defined healing endpoints both radiographically (as evidenced by cortical bridging on x-ray) and clinically (no pain or motion at fracture site).  There is evidence that electrical stimulation therapy is also effective in healing nonunions of other bones of the appendicular skeleton.

Electrical stimulation therapy has not, however, been adequately evaluated for treatment of nonunions of the flat bones, such as the pelvis, scapula, and skull.  Nor has electrical stimulation therapy been well evaluated for treatment of fractures of the ribs or sternum.

Electrical stimulation has been used as an adjunct or alternative to bone graft surgery in the treatment of nonunions.  In bone graft surgery, a section of bone taken from another skeletal site is used to bridge the ununited gap.  The major advantage of noninvasive electrical stimulation over bone graft surgery is that it minimizes the risk of infection and avoids the trauma of surgery. Electrical stimulation therapy has also been shown to be an alternative to bone graft surgery in the conservative management of congenital pseudarthrosis, the absence at birth of the mid-portion of bone, and has been approved by the FDA for that purpose.

Three types of electrical stimulators were approved by the FDA in 1979 for treatment of nonunions and congenital pseudarthrosis:  invasive, semiinvasive, and noninvasive. An invasive electrical stimulator that uses constant direct current is implanted at the nonunion site.  The major advantage of implantation is that the electrical therapy is provided constantly without the patient having to take an active role, so that compliance is not an issue.  The major disadvantage is that it requires two operations, one to implant the electrical device and one to remove the device.

A semiinvasive system which uses percutaneous cathodes that provide constant direct current is not currently in production.

Noninvasive electrical stimulator systems use inductive coupling or capacitive coupling .  With inductive coupling, pulsed electromagnetic fields (PEMFs) are delivered by a pair of external magnetic coils placed parallel to each other on top of the cast at the nonunion site.  Treatment times vary from 10 to 16 hours per day.  Because precise placement of the coils is necessary, the patient must remain relatively immobile during treatment.

With capacitive coupling, two electrodes are applied to the skin through windows cut through the cast, and are placed on either side of the nonunion site.  Because the system comes with a portable battery pack and no precise placement of the electrodes is necessary, the patient can remain relatively mobile.

Available evidence suggests that each of these systems gives comparable success rates of 80 to 90 percent in properly selected patients.  There are no known side effects to treatment with electrical stimulation.

More recently, the FDA approved the OrthoLogic 1000, a noninvasive electrical stimulation device, for the treatment of nonunions (OrthoLogic Corp., Phoenix, AZ).  The OrthoLogic differs from standard noninvasive electrical stimulation therapy in that it uses both static and pulsating magnetic fields.  In addition, the OrthoLogic uses magnetic fields that are of lower energy (peak amplitude 400 milligauss) than standard PEMFs (peak amplitude greater than 20 gauss). The chief advantage of the OrthoLogic device is that it needs to be worn only 30 minutes per day, compared to 10 hours per day with standard pulsed electromagnetic field therapy.

In nonunions and congenital pseudarthrosis treated with electrical stimulation therapy, progression of healing should be monitored both clinically and radiologically.  On x-ray, progression of healing is evidenced by the appearance of consolidated bone stress lines gradually bridging the fracture gap until continuity of the cortices occurs.  When cortical continuity is established and no motion exists at the treatment site, pulsed electromagnetic field therapy may be discontinued, generally within 3 to 6 months, and rarely more than 9 months after electrical stimulation therapy is initiated.

Electrical stimulation devices may be used in fractures where fixation devices, such as rods or pins, are already in place, if the fixation devices are non-magnetic.

Electrical stimulation therapy is effective in uniting previously open fractures as well as closed fractures.  Electrical stimulation therapy has also been found to be effective in healing nonunions that have persisted for many years.  Surgical intervention is necessary before electrical stimulation therapy where there is malalignment of the fractured bone.

Electrical stimulation therapy is generally not indicated where the fracture gaps are greater than 1 centimeter or where they are greater than half the diameter of the bone at the level of the nonunion.  This is because larger gaps do not contain enough responsive osteocytes to form bone when stimulated by electricity.

Electrical stimulation therapy is also generally not indicated where there is a synovial pseudarthrosis, or ''false joint'' -- a nonunion that has developed a membrane-lined fluid-filled cavity between the fracture fragments.  Poor results with electrical therapy occur unless the lining of the false joint is removed.  Nonunions with a large gap or synovial pseudarthrosis are thought to be better treated with bone grafting and internal fixation before electrical stimulation.

Electrical stimulation therapy is also contraindicated in persons with pacemakers.

The effects of electrical stimulation therapy on epiphyseal growth plates are not known, so that use of electrical stimulation therapy in children, who lack skeletal maturity, should be closely monitored.

Electrical stimulation has been investigated as a treatment for Charcot arthropathy.Hockenbury and associates (2007) reviewed the results of arthrodesis of the Charcot hindfoot when an implantable bone growth stimulator was added to the procedure. Arthrodesis of the Charcot hindfoot has a high non-union and complication rate. A total of 10 patients (aged 50 to 69 years) with Charcot neuroarthropathy of the ankle, hindfoot, or both had arthrodesis with use of rigid internal fixation and an implantable bone growth stimulator were included in the study. There were 6 tibio-talo-calcaneal, 2 pantalar, and 2 tibio-calcaneal arthrodeses. An intra= medullary nail was used in 9 patients and a blade plate was used in 1 patient. All but 1 patient was diabetic. Four of the 10 patients had pre-operative osteomyelitis or post-operative infection. Another patient had purulent drainage, although cultures were negative. Four patients had a pre-operative ulceration. Five patients had a 2-stage procedure for debridement of infected bone, removal of hardware, and placement of antibiotic beads. Autogenous bone graft from the distal fibula or proximal tibia was used in all patients. One patient with a pre-operative osteomyelitis developed a stable ankle pseudarthrosis. The other 9 patients fused at an average of 3.7 months after surgery for a fusion rate of 90 %. There were 2 major complications and 8 minor complications. There were no amputations. All patients were ambulatory in a double upright brace or shoes for diabetic patients and were free of ulceration at the time of follow-up. Average American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score improved from 21 pre-operatively to 59 post-operatively. The authors concluded that the adjunctive use of an implantable bone growth stimulator in conjunction with rigid internal fixation, autogenous bone grafting, and sound operative technique may enhance the outcome and fusion rate in patients undergoing arthrodesis for Charcot neuroarthropathy of the ankle and hindfoot. The findings of this study need to be validated by well-designed studies.