Is nonunion the same as a bone infection?

No. A nonunion is a fracture that has stopped healing, with no infection present. Refractory osteomyelitis is an infection of bone, and HBOT is FDA-approved as an adjunct for that condition. The two are different diagnoses with different evidence and different coverage rules, so coverage for osteomyelitis does not extend to a non-infected nonunion.

Does insurance cover HBOT for a fracture that won't heal?

Not for a non-infected nonunion. Because this is an off-label use, sessions are paid out-of-pocket, commonly $250-450 each across many sessions. Rates change annually, verify with your facility's billing team. If a clinic implies insurance will pay, confirm it directly with your insurer in writing first.

Hyperbaric Oxygen Therapy for Fracture Nonunion: Early Evidence

Important: In the United States, hyperbaric oxygen therapy is not FDA-approved for non-infected fracture nonunion or delayed union. This is an investigational, off-label use. The strongest review of the evidence found no controlled trials either supporting or refuting it. Insurance will not cover HBOT for this condition. All costs are out-of-pocket.

A fracture that has stopped healing is its own kind of frustration. The cast comes off, the months pass, and the imaging still shows a gap where solid bone should be. By that point many people are facing a second surgery, a bone graft, or a long stretch of restricted activity, and they start looking for anything that might tip the balance without going back under anesthesia. Hyperbaric oxygen is one of the options that comes up in that search. The honest answer is that the rationale is reasonable, the human evidence is thin, and the single best review of it could not say whether it works.

What Nonunion and Delayed Union Mean

A fracture heals through a series of stages that need a working blood supply and a steady oxygen delivery to the break site. When that process stalls, doctors describe it in two ways. Delayed union means the bone is healing more slowly than expected for its type and location. Nonunion means the healing process has effectively stopped, often defined as no progress toward union after about six months, with the bone unlikely to join without intervention.

Several things push a fracture toward nonunion. A poor blood supply at the break, large gaps between the bone ends, instability or too much movement, smoking, diabetes, certain medications, and high-energy injuries that strip away surrounding soft tissue all raise the risk. Karamitros and colleagues (2006) noted that up to roughly 10 percent of the fractures occurring annually in the United States end in delayed union or nonunion, which makes this a common enough problem to draw a lot of marketing attention.

The key point for this page is that the nonunion discussed here is the non-infected kind, sometimes called aseptic nonunion. That distinction matters more than it might first appear, because it is the line between an off-label use and an approved one.

How This Differs From the Approved Bone Conditions

It is easy to assume that because HBOT is FDA-approved for some bone problems, it must be approved here too. It is not, and the difference comes down to infection.

Refractory osteomyelitis is a chronic bone infection that has failed standard antibiotics and surgery. HBOT is a cleared adjunct for that condition because raising oxygen tension helps white blood cells and antibiotics clear bacteria from poorly oxygenated bone. A non-infected nonunion has no infection to clear. The bone is failing to bridge for mechanical or vascular reasons, not because bacteria are living in it.

This distinction has real money attached to it. If a nonunion is also infected, the case can fall under the osteomyelitis indication, and coverage decisions follow that diagnosis. A clean, non-infected nonunion does not. Some clinics blur the two, leaning on the approved osteomyelitis use to imply that any stalled bone qualifies. It does not. The Undersea and Hyperbaric Medical Society lists refractory osteomyelitis among its approved indications. Non-infected fracture nonunion is not on that list.

There is also overlap to be careful about on the trauma side. HBOT is FDA-approved for acute crush injuries, where treatment starts within hours to limit reperfusion damage and salvage tissue. That is a different scenario from a fracture that has already failed to heal months later. Approval for the acute crush setting does not carry over to chronic nonunion.

Why HBOT Is Being Studied

The reasoning behind looking at HBOT for nonunion is straightforward. Bone healing depends on oxygen, and many nonunions sit in tissue with a compromised blood supply. The mechanism behind HBOT is that breathing 100 percent oxygen under increased pressure dissolves far more oxygen into the plasma than breathing room air does, which can reach tissue that a damaged vascular bed struggles to feed.

The proposed effects in stalled bone include supporting the activity of bone-forming cells, raising oxygen at the fracture site, and stimulating angiogenesis, the growth of new blood vessels into the healing zone. These ideas are drawn from how HBOT behaves in laboratory models and in other wound conditions. They are hypotheses about why it might help, not confirmed mechanisms in human nonunion. A plausible rationale on paper is not the same thing as a proven result in patients, and that gap is the whole story here.

What the Research Shows

The most authoritative look at this question is a Cochrane systematic review by Bennett, Stanford, and Turner (2012). The authors set out to find randomized controlled trials testing HBOT for promoting fracture healing or treating nonunion. They found none that met their inclusion criteria. Their conclusion was blunt: the review could neither support nor refute the use of HBOT for delayed union or established nonunion, and good quality trials were needed to define its role, if any (PMID: 23152225). At the time they noted several trials underway. A finding of no controlled evidence is not a finding that HBOT fails. It means the question has not been answered properly.

Below that level of evidence sit narrative reviews and small case series. Karamitros and colleagues (2006), writing in the journal Injury, reviewed both electrical stimulation and hyperbaric oxygen as options for nonunions that have not responded to conventional surgery, summarizing proposed mechanisms and scattered clinical reports rather than controlled outcomes (PMID: 16581073). A 2025 review of HBOT for bone-related diseases by Feng and colleagues in the International Journal of Molecular Sciences likewise described nonunion work as limited, citing a small number of cases and preclinical models and stating that further research is required to confirm whether HBOT helps (PMID: 39940834).

Read together, the picture is consistent. There is a biological rationale, there are scattered reports of bone healing in treated patients, and there is no controlled trial showing that HBOT changes outcomes for non-infected nonunion. The honest description is preliminary and unproven, not encouraging.

Where It Fits Against Standard Care

Standard management of nonunion is driven by why the bone failed to heal. Surgeons address the mechanical and biological causes directly. Revision fixation with plates, rods, or external frames restores stability. Bone grafting, often using the patient’s own bone, fills gaps and adds healing cells. Removing dead bone, correcting alignment, and stopping smoking all matter. Non-surgical options that have controlled evidence in some settings include low-intensity pulsed ultrasound and electrical or electromagnetic stimulation, though their results are debated.

HBOT, where it is used at all for nonunion, sits outside that standard pathway as an unproven add-on, not a substitute for fixing the underlying mechanical or vascular problem. No one should read the scattered case reports as a reason to delay a surgical plan that an orthopedic surgeon recommends. An orthopedic surgeon, and a hyperbaric physician where one is involved, are the people who can look at your imaging, identify why the bone stopped healing, and weigh whether any added approach is reasonable in your specific case. The decision belongs with your care team, not with a clinic’s website.

Cost and Coverage

Because non-infected nonunion is an off-label use, you pay out-of-pocket. HBOT sessions commonly run $250-450 each, and any protocol would involve many sessions, which puts a course in the several-thousand-dollar range. Rates change annually, so verify current pricing with your facility’s billing team. Do not expect insurance to reimburse HBOT for a clean nonunion. If a clinic suggests it will, ask them to put the coverage claim in writing and confirm it directly with your insurer before you commit. For a fuller walkthrough of how to weigh an unproven use like this one, see the guide on what to consider with off-label HBOT.

FAQ

Is HBOT FDA-approved for fracture nonunion? No. For non-infected nonunion or delayed union it is investigational and off-label, and it is not on the UHMS approved indications list. Insurance will not cover it for this purpose.

Is a nonunion the same as a bone infection? No. A nonunion is a fracture that stopped healing with no infection present. Refractory osteomyelitis is an infection of bone and is an approved HBOT indication. They are separate diagnoses with separate coverage.

What did the Cochrane review conclude? Bennett and colleagues (2012) found no randomized trials meeting their criteria and could neither support nor refute HBOT for nonunion. PMID: 23152225.

Are there any positive reports at all? There are small case series and reviews, plus laboratory models, but no controlled trials. Reviewers describe the evidence as limited and call for proper studies.

How much does it cost? Roughly $250-450 per session across many sessions, all out-of-pocket. Rates change annually, verify with your facility.

References

Bennett, M.H., Stanford, R.E., Turner, R. (2012). Hyperbaric oxygen therapy for promoting fracture healing and treating fracture non-union. Cochrane Database of Systematic Reviews. PMID: 23152225
Karamitros, A.E., Kalentzos, V.N., Soucacos, P.N. (2006). Electric stimulation and hyperbaric oxygen therapy in the treatment of nonunions. Injury. PMID: 16581073
Feng, J. et al. (2025). Hyperbaric Oxygen Therapy for the Treatment of Bone-Related Diseases. International Journal of Molecular Sciences. PMID: 39940834

Medical Disclaimer: This page is for informational purposes only. It does not constitute medical advice, diagnosis, or treatment. Hyperbaric oxygen therapy for non-infected fracture nonunion is investigational and not FDA-approved. Always consult a qualified healthcare provider before pursuing any medical treatment. Individual outcomes vary. This site does not establish a doctor-patient relationship.