The Anesthetic Isn’t Inert

Why a case of rapid femoral head destruction changed what I put in my syringes

During my first year in practice, a patient was referred to me for an ultrasound-guided hip injection.

He had significant left hip osteoarthritis and had already undergone several image-guided intra-articular injections elsewhere using triamcinolone and bupivacaine.

When I performed an ultrasound exam, something didn’t look right.

His hip anatomy was so distorted that rather than perform another injection, I stopped and obtained updated imaging.

The radiograph was striking.

Much of his femoral head had essentially disappeared.

As I searched for an explanation, I began finding reports of similar cases of rapid femoral head destruction after intra-articular hip injections.

The corticosteroid preparations and other components varied.

In the reports I was finding, bupivacaine was the ingredient that kept showing up.

That did not prove it was responsible. Rapidly destructive hip disease is complicated and can occur without an injection. Osteoarthritis, subchondral insufficiency fracture, osteonecrosis, corticosteroid exposure, and other factors may all contribute.

So I couldn’t say bupivacaine caused what I was seeing.

I still can’t.

But it raised a more practical question:

Was bupivacaine really the best local anesthetic to be putting into joints?

I suspect many of us do not give that question much thought.

We tend to use the anesthetic we were trained to use, and eventually it simply becomes part of our standard injection mixture.

A survey of 674 sports medicine physicians supports that idea. Lidocaine dominated large-joint and bursal injections, bupivacaine remained common, and ropivacaine was rarely used. Physicians who used lidocaine were also significantly less likely to report that their injectate choice was based on literature they had reviewed. Cushman et al., 2021​

Sometimes the anesthetic in the syringe may be there simply because that is what we were taught to put there.

My original question was about bupivacaine.

Once I started looking at the basic science, the question became broader:

Are we choosing the best local anesthetic for the tissue, or simply the one we are accustomed to using?

What happens when cartilage sees local anesthetic?

One of the studies that initially caught my attention directly compared bupivacaine and ropivacaine in human articular cartilage.

Researchers exposed cartilage to saline, 0.5% ropivacaine, or 0.5% bupivacaine for 30 minutes.

Twenty-four hours later, chondrocyte viability within intact cartilage was:

Saline: 95.8%​
​0.5% ropivacaine: 94.4%​
​0.5% bupivacaine: 78.0%

In isolated human chondrocytes, viability was approximately 64% with ropivacaine versus 37% with bupivacaine. Piper & Kim, 2008​

Those numbers should not be interpreted as the amount of cartilage lost after an injection in a living joint.

This was a laboratory experiment, not a clinical outcome trial.

But it tells us something important:

These drugs are not biologically equivalent.

And it isn’t just bupivacaine

A systematic review of 16 studies found chondrotoxicity in 13 of 14 studies evaluating bupivacaine and 5 of 7 evaluating lidocaine.

Ropivacaine was not harmless, but at concentrations of 0.5% or less it was the least chondrotoxic anesthetic studied. Jayaram et al., 2019​

Another review similarly found lidocaine and bupivacaine more chondrotoxic than ropivacaine and mepivacaine. Importantly, none of the included studies demonstrated significant chondrotoxicity with 0.1% or 0.2% ropivacaine. Kreuz et al., 2018​

There is another clinically relevant point.

Osteoarthritic cartilage may be more vulnerable to local-anesthetic toxicity than healthy cartilage, which makes this question particularly relevant in the very joints we are most likely to inject. Kreuz et al., 2018​

So this is not simply a bupivacaine problem.

It may be a local-anesthetic-selection problem.

There is also evidence that combining local anesthetics with corticosteroids may increase chondrotoxicity. Jayaram et al., 2019​

We routinely combine the two and tend to think almost exclusively about the steroid.

The cells may not see the anesthetic as an innocent diluent.

It isn’t just cartilage

We also place local anesthetics around tendons, fascia, bursae, muscle, and peripheral nerves.

In one study, human rotator cuff tenofibroblasts were exposed to different concentrations of ropivacaine, bupivacaine, and lidocaine.

Toxicity increased with both concentration and exposure time.

Of the clinically relevant preparations tested, 0.2% ropivacaine was the least cytotoxic. Sung et al., 2014​

Again, that does not prove that a few milliliters of lidocaine or bupivacaine around a tendon causes clinically meaningful degeneration.

But it reinforces an important principle:

The anesthetic shouldn’t get a free pass simply because it isn’t the medication we consider the “treatment.”

What about orthobiologics?

This may matter even more when the goal is biologic healing.

In vitro, adding lidocaine or bupivacaine to PRP reduced human tenocyte proliferation and viability. Separate work found that bupivacaine impaired platelet viability and function, while lidocaine and ropivacaine were relatively well tolerated under the conditions studied. Carofino et al., 2012 Dregalla et al., 2021​

That does not prove that anesthetic negates a PRP treatment.

But if the goal is to support biology, it makes sense to minimize unnecessary exposure to agents that may work against it.

Does this translate clinically?

This is where we have to be careful.

Most of the toxicity evidence comes from cell culture, tissue explants, and animal studies.

The dramatic clinical cases of local-anesthetic-associated chondrolysis were largely associated with continuous intra-articular pain pumps, which created prolonged exposure very different from a single outpatient injection. Gulihar et al., 2015​

We also do not have clinical outcome trials showing that ropivacaine reduces cartilage degeneration, osteoarthritis progression, or joint replacement compared with lidocaine or bupivacaine.

So the evidence does not justify saying:

“Bupivacaine destroys cartilage.”

Or:

“Lidocaine destroys cartilage.”

But we do not need proof of catastrophic clinical harm before asking whether there is a more biologically favorable choice.

Why I switched

When local anesthetics are compared in MSK-relevant laboratory models, low-concentration ropivacaine consistently sits toward the least cytotoxic end of the spectrum.

That is why I now use ropivacaine rather than bupivacaine for most of my MSK procedures when I want a longer-acting anesthetic.

I typically use 0.2% ropivacaine.

That concentration is intentional.

It does not mean ropivacaine is harmless or that lidocaine has no role. Lidocaine’s rapid onset and shorter duration remain useful for superficial anesthesia and certain diagnostic procedures.

But when anesthetic is going into or immediately adjacent to cartilage, tendon, or other tissue I am trying to preserve, 0.2% ropivacaine is the choice I can currently justify most easily.

Which means the more useful question may not simply be:

Bupivacaine, lidocaine, or ropivacaine?

It may be:

Do I need local anesthetic here at all?

And if I do:

Which agent, at what concentration and volume, accomplishes what I need with the least unnecessary tissue exposure?

The MSK Logic takeaway

The patient whose femoral head seemed to disappear did not prove that bupivacaine caused his joint destruction.

But that case forced me to question something I had previously done without much thought.

The anesthetic sitting next to the “important” medication in the syringe is not biologically neutral.

The drug matters.

The concentration matters.

The exposure matters.

Among commonly used local anesthetics, low-concentration ropivacaine has one of the more favorable tissue-safety profiles in the available laboratory literature.

That doesn’t make it biologically inert.

It means that when I need local anesthetic in or around musculoskeletal tissue, 0.2% ropivacaine is the choice I can currently justify most easily.

The larger lesson may be even more important:

If I’m injecting something directly next to tissue I’m trying to preserve or heal, I want a reason for every ingredient in the syringe.