How Much Bone Loss From One Cortisone Injection?

A single cortisone injection produces a small but measurable dip in bone density, with the best-studied example showing about six times the normal annual bone loss at the hip over six months in postmenopausal women. That sounds alarming in isolation, but the picture gets more nuanced when you look at whether that density change actually translates into broken bones. The answer depends on the type of injection, your baseline bone health, and how many shots you end up getting over time.

The Most Direct Evidence on a Single Injection

The clearest data on a single shot comes from a study of postmenopausal women who received one epidural steroid injection for back pain. At six months, hip bone density had dropped by about 0.018 g/cm², which was roughly six times the 0.003 g/cm² decline seen in age-matched women who did not get the injection.¹ In absolute terms, that number is small. A healthy adult femur typically has a bone density somewhere around 0.8 to 1.2 g/cm², so a drop of 0.018 represents roughly a 1.5 to 2 percent loss. But the speed of that loss is what caught researchers’ attention: it compressed what would normally take years of natural aging into just a few months.

What makes these findings tricky to generalize is that the study population was already at higher risk for bone loss. Postmenopausal women lose bone faster than almost any other demographic because of declining estrogen levels. Whether a 30-year-old man or a premenopausal woman would show the same drop after a single epidural injection remains an open question. The research just has not been done in those populations with the same rigor.

Why a Local Injection Affects Bones Elsewhere

It seems counterintuitive that a shot aimed at your knee or spine could weaken bone in your hip. The explanation is systemic absorption. When cortisone is injected into a joint or the epidural space, it does not stay neatly contained. The steroid enters the bloodstream and circulates throughout the body, and reviews of the evidence confirm that both intra-articular and epidural injections can produce body-wide effects lasting weeks.² Those systemic effects include temporary suppression of the adrenal glands, blood sugar spikes, and changes in bone metabolism.³

How much steroid reaches your bloodstream varies enormously from person to person. The same dose can produce very different blood levels in two patients, which helps explain why some people seem to tolerate repeated injections with no trouble while others develop side effects after just one or two.² Body composition, the specific injection site, and the formulation used all play roles. Epidural injections tend to produce more systemic absorption than a single knee injection, partly because of the rich blood supply around the spinal canal.

Once the steroid is circulating, it disrupts the normal cycle of bone maintenance. Corticosteroids suppress the cells that build new bone while ramping up the cells that break it down, tilting the balance toward net bone loss.⁴ Even a brief spike in circulating steroid can temporarily shift this balance, though the body usually recalibrates over the following weeks.

How Quickly the Body Absorbs Different Formulations

Not all cortisone injections are the same, and the formulation matters for how hard it hits your system. Standard crystalline triamcinolone, one of the most commonly used steroids for joint injections, produces a sharp spike in blood levels within about four hours after an intra-articular injection. An extended-release microsphere formulation of the same drug reaches a much lower peak and spreads its release over weeks.⁵ The peak blood level with the standard formulation was more than ten times higher than the extended-release version in a direct comparison.

That difference matters because the systemic effects, including the bone metabolism disruption, are driven by how much steroid is circulating in your blood at any given time. A formulation that keeps more of the drug inside the joint and releases it slowly exposes the rest of your skeleton to far less steroid. If bone loss from injections is a concern for you, this is a reasonable question to raise with your doctor: which formulation are they planning to use, and is a slower-release option appropriate for your situation?

Does Bone Density Loss Actually Mean More Fractures?

Here is where the story gets reassuring for most people. Bone density on a scan and actual fracture risk are related but not the same thing. A large study published in JAMA Network Open followed patients who received corticosteroid injections and found no increased fracture risk across the full dose spectrum, even after adjusting for known fracture risk factors. The adjusted hazard ratio was 1.04, which is essentially flat. That finding held up in patients who already had osteoporosis as well.⁶ When the researchers broke the data into dose quartiles, the fracture rate was not meaningfully different between patients who had received the least cumulative steroid and those who had received the most.

This is an important finding because it suggests the small bone density drops seen in studies like the one in postmenopausal women may not be clinically significant for most patients when it comes to the thing that actually matters: whether you break a bone. The density change is real and measurable, but it may be too small to push most people across the threshold into fracture territory. Age, existing medical conditions, and prior fracture history were the factors that actually predicted fractures in that analysis, not the number or cumulative dose of injections.⁶

That said, the fracture study examined a mixed population, not specifically high-risk groups like postmenopausal women with already-low bone density. If you are starting from a place of borderline bone strength, even a small additional push could matter in ways a population-level average might not capture.

What Changes With Repeat Injections

One injection is one thing. Many injections over months or years are another. A study of postmenopausal women who received an average of about 14 epidural steroid injections, with a cumulative triamcinolone dose around 400 mg, found significantly lower bone density in the femoral neck and total femur compared to women who had received fewer injections. The rates of both osteoporosis and osteopenia were higher in the group that had received more shots.⁷ This is a meaningful dose: 14 injections is well beyond what most patients receive for a single episode of back pain.

The bone loss in these studies was more pronounced at the hip than at the spine. That pattern might seem counterintuitive for someone getting spinal injections, but it likely reflects the fact that the hip contains more of the type of bone (trabecular bone) that is most sensitive to steroid effects, and that degenerative changes in the spine can artificially inflate lumbar density measurements on scans.⁷

An interesting wrinkle in the bone turnover marker data: one study found that markers of bone formation did not change significantly in the first month after a single epidural injection.⁸ Another study, meanwhile, found that a bone formation marker rose between three and six months, possibly reflecting a rebound as the body tried to compensate for earlier suppression.¹ The timing of when you measure matters a great deal when interpreting these blood tests, and a single snapshot can be misleading.

Joint-Level Damage Beyond Bone Density

The bone density conversation focuses on the skeleton as a whole, but there is a separate set of concerns about what happens to the joint that actually receives the injection. These are local effects rather than systemic ones, and they involve cartilage and the bone just beneath it rather than distant bones like the hip or spine.

A trial comparing intra-articular steroid injections to placebo injections in the knee found that the steroid group lost more cartilage volume over two years, though knee pain at the end of the study was not significantly different between groups.⁹ A separate observational study found that the rate of worsening osteoarthritis on X-rays was about three times higher in patients who received intra-articular steroid injections compared to controls. In hip injections specifically, one study found that 17 percent of patients who received steroid injections developed collapse of the joint surface, and a single-institution review found subchondral insufficiency fractures in about 1 percent of hip and knee injections combined.⁹

These local effects are distinct from the systemic bone density question. You could have perfectly normal bone density everywhere else and still develop cartilage thinning or a subchondral fracture in the injected joint. The mechanisms are different: local effects involve direct exposure of the joint tissues to high concentrations of steroid, while systemic bone loss involves the steroid circulating through the bloodstream and affecting the entire skeleton at lower concentrations.

Avascular Necrosis After a Single Injection

One of the rarer but more serious complications is avascular necrosis, where the blood supply to part of a bone dies off, causing the bone to collapse. This is well established as a risk of long-term oral steroid use, but case reports have documented it occurring after a single intra-articular injection, particularly in the hip.¹⁰ The complication is rare enough that it has mostly been described in individual case reports rather than large studies, but it is worth knowing about because the consequences are severe, often requiring surgical intervention.

The mechanism is not fully understood. It may involve a direct toxic effect of the steroid on blood vessels within the bone, or it could be related to fat cell expansion in the bone marrow that compresses the blood supply. Whatever the cause, the risk is another reason clinicians are cautious about hip injections in particular and tend to limit the number of injections to a given joint over any time period.

Who Should Be Most Cautious

If you are a younger adult with normal bone density getting a single cortisone shot for a sports injury or an inflamed joint, the evidence suggests the bone-related risks are minimal. The density dip is small, likely temporary, and does not appear to translate into a meaningful increase in fracture risk for people who are not already vulnerable.

The calculus shifts for certain groups. Postmenopausal women are the most studied and most clearly affected population, with the hip density data described above showing an outsized response to even a single epidural injection.¹ Anyone who already has osteoporosis or osteopenia deserves a more careful conversation about alternatives. People who have a history of steroid exposure from other routes, such as oral prednisone for asthma or autoimmune conditions, are also starting with a disadvantaged skeleton. Long-term corticosteroid therapy changes not just the density but also the internal architecture of bone, altering the fine structural patterns of trabecular bone even when density changes are modest.¹¹ Stacking an injection on top of that baseline is a different proposition than starting from healthy bone.

Other factors that should prompt a more careful discussion include:

Prior fracture: A previous fragility fracture is one of the strongest predictors of future fracture, and it was confirmed as a key risk factor independent of injection history in the JAMA Network Open analysis.
Advanced age: Age was the other dominant risk factor for fractures in the same study, and older adults lose bone density faster in general.
Planned repeat injections: If your treatment plan involves getting injections every few months for chronic pain, the cumulative dose becomes a real consideration even if each individual injection is low risk.
Low body weight: Lower body mass is associated with lower baseline bone density, leaving less buffer before crossing into fragility territory.

Putting the Numbers in Context

It helps to compare the bone density impact of a single cortisone injection against other common exposures. Natural menopause causes bone density loss at the hip of roughly 0.5 to 1 percent per year in the first decade after periods stop. The single-injection study in postmenopausal women showed a loss equivalent to about six times that annual rate over just six months, but then it was measured at that one time point, and it is not clear the loss continued at that pace. For comparison, oral prednisone taken daily for months, the classic bone-damaging steroid scenario, causes bone density losses of 5 to 15 percent in the first year, dwarfing what a single injection does.

The real-world picture also matters. People getting cortisone injections are typically dealing with significant pain that limits their activity. Immobility itself causes bone loss. If a cortisone injection relieves enough pain to get someone walking, exercising, and bearing weight on their skeleton again, the net effect on bone health could theoretically be positive even if the drug itself causes a small direct hit to density. No study has formally tested this trade-off, but it is a factor that gets lost when the bone density numbers are presented in isolation.

When a Bone Density Scan Makes Sense

For the average patient receiving an occasional cortisone injection, routine bone density monitoring specifically because of the injection is not standard practice. The density changes from a single shot are too small and too transient to reliably detect on a standard DEXA scan, which has its own measurement variability of around 1 to 2 percent.

A DEXA scan is reasonable before starting a series of planned injections if you fall into a higher-risk category: postmenopausal, over 65, history of fracture, or concurrent oral steroid use. Having a baseline gives you and your doctor something to compare against if injections continue over the following year. It also helps frame the decision about whether to proceed or try alternative pain management approaches. If your density is already in the osteoporosis range, even a small additional loss carries more weight than if you are starting with robust bones.

For patients getting intra-articular hip injections specifically, periodic imaging of the joint itself is more relevant than whole-body density monitoring. The concern there is the local joint complications, such as cartilage thinning or the rare subchondral fractures, rather than systemic skeletal effects. Your doctor may order an MRI if symptoms change or persist in unexpected ways after an injection.⁹