How Long After Knee Surgery Can You Smoke?

Most orthopedic surgeons recommend waiting at least four to six weeks after knee surgery before smoking again, and many prefer you stay smoke-free even longer. But the honest answer is more uncomfortable than a neat timeline: the biology of healing does not care about a calendar cutoff. Smoking slows wound repair, raises infection risk, weakens new bone growth, and doubles the odds of certain serious complications after knee procedures. The longer you abstain, the better your knee does, and a growing number of surgeons now frame the question differently altogether, treating surgery as an opportunity to quit for good rather than to pause temporarily.

What Smoking Actually Does to a Healing Knee

Two components of cigarette smoke cause the most damage after surgery. Nicotine constricts blood vessels, reducing the flow of oxygen-rich blood to the surgical site. That matters because oxygen is the fuel for collagen production, new blood vessel formation, and the cellular cleanup that prevents infection. Carbon monoxide, the other major culprit, binds to hemoglobin roughly 200 times more strongly than oxygen does, further starving the tissues around your incision and inside your joint.¹ Together, these effects create a kind of oxygen drought right when your body needs it most.

This is not a theoretical concern. In orthopedic procedures involving hardware like screws, plates, or joint replacements, adequate blood flow is what lets bone grow into and around the implant. Nicotine also makes platelets stickier, which can clog the tiny blood vessels feeding the surgical area. The result is tissue that heals more slowly, scars more poorly, and is far more vulnerable to bacteria.

Infection and Wound Complications

The numbers on infection risk are striking. A systematic review and meta-analysis of primary total joint arthroplasty studies found that tobacco users had about twice the odds of developing a periprosthetic joint infection compared to non-users, along with roughly 80 percent higher odds of wound complications like discharge, separation of the incision, or hematoma.² These are pooled numbers across many studies, so they represent a fairly reliable picture of what tobacco does to surgical outcomes.

The pattern holds for revision surgeries too. Among patients undergoing a second total knee replacement, smokers had about double the rate of deep infections and wound complications compared to nonsmokers.³ A separate study in orthopedic surgery with implant materials found that smoking was a significant risk factor for deep surgical-site infections and for wound problems during the hospital stay itself.⁴ When your incision gets infected after a knee replacement, the fix is often another surgery, sometimes involving removal of the implant, weeks of intravenous antibiotics, and a second procedure to put a new one in. That is a months-long ordeal that dwarfs any discomfort from nicotine withdrawal.

Blood Clots After Knee Surgery

Blood clots are already one of the bigger risks after any knee procedure, especially replacement and arthroscopy. Your leg is immobilized, blood pools in the deep veins, and the surgery itself triggers clotting responses. Smoking adds fuel to that fire. A meta-analysis of studies on venous thromboembolism after knee arthroscopy found that a smoking history independently raised the odds of developing a blood clot by about 35 percent.⁵ That is on top of whatever baseline risk the surgery itself creates. For total knee arthroplasty, the picture is even starker: smokers showed sharply elevated odds of deep vein thrombosis, pulmonary embolism, and cardiac events including heart attack and stroke in a large database analysis.⁶

A blood clot that breaks loose and travels to the lungs, known as a pulmonary embolism, can be fatal. This is the complication that makes surgeons most anxious about smoking in the early postoperative period, when you are least mobile and your clotting system is already in overdrive.

Long-Term Implant Survival

If your knee surgery involved a joint replacement, the consequences of continued smoking extend well beyond the initial healing window. A prospective cohort study found that current tobacco users had nearly 80 percent higher hazard of needing an implant revision and more than double the hazard of deep infection compared to non-users.⁷ Another study tracking patients for up to about four years after total knee replacement reported that smokers had an overall implant survivorship of 90 percent, compared to 99 percent in nonsmokers.⁸ Losing 9 percentage points of survivorship within just a few years is a significant difference when you consider that a knee replacement is supposed to last 15 to 20 years or more.

A meta-analysis of cohort studies confirmed the trend, finding that smokers had higher rates of surgical complications, pneumonia, and revision surgery after total knee arthroplasty.⁹ The upshot: even if your incision heals fine and you avoid infection in the short term, smoking quietly undermines the bond between bone and implant over time, making early failure more likely.

What About ACL Reconstruction and Ligament Repairs?

Knee surgery is not always a joint replacement. For ligament repairs, particularly ACL reconstruction, smoking carries a different but equally serious risk: graft failure. One study found that smokers had roughly triple the odds of needing a second ACL reconstruction compared to nonsmokers, with a failure rate of about 9 percent versus 3 percent.¹⁰ The risk was even more pronounced in patients under 25, where the failure rate gap widened further.

A separate study examining ACL graft quality using MRI showed that smokers had an overall rupture rate of about 13 percent compared to roughly 5 percent in nonsmokers, and their grafts showed signs of less complete tissue maturation, suggesting the replacement ligament never fully incorporated the way it should.¹¹ For younger, active patients especially, this is the finding that should give pause. A torn graft means another surgery, another long recovery, and reduced long-term knee function.

Smoking and Postoperative Pain

There is a less obvious but very real connection between smoking and how much pain medication you need after surgery. A study of hip and knee arthroplasty patients found that smokers required roughly 90 percent more narcotic pain medication in the postoperative period compared to nonsmokers.¹² The reasons are partly biological (smokers tend to have altered pain sensitivity and tolerance) and partly behavioral, but the practical result is the same: more opioids, more side effects from those opioids, and a harder recovery overall.

Higher opioid use also extends hospital stays and increases costs. Smokers undergoing total knee arthroplasty stayed in the hospital an average of about half a day longer and incurred over $1,000 more in hospital charges than nonsmokers.⁶

Vaping and E-Cigarettes Are Not a Loophole

If you are thinking about switching to e-cigarettes or a vape pen after surgery instead of smoking traditional cigarettes, the current evidence is not encouraging. The nicotine delivered by vaping triggers the same vasoconstriction and platelet effects that make cigarette smoking harmful to healing. A systematic review of vaping’s impact on surgical wound healing concluded that e-cigarettes should be treated like tobacco cigarettes, and that vaping should be stopped during the perioperative period.¹³ A review specifically focused on total joint arthroplasty reached the same conclusion, noting that vaping causes oxidative stress and dysfunction in blood vessel linings that predispose patients to infections and delayed healing.¹⁴

The data are newer and thinner for e-cigarettes than for traditional cigarettes, but what exists points clearly in one direction. A propensity-matched study of total knee arthroplasty patients who used non-tobacco nicotine products found significantly higher rates of infection, blood clots, pulmonary embolism, and prosthetic joint infection within 90 days of surgery, along with higher revision rates at three years.¹⁵ Vaping may expose you to fewer of the thousands of chemicals in cigarette smoke, but the nicotine itself is doing real damage to your surgical recovery.

What About Cannabis?

Cannabis smoking after knee surgery is a question that comes up more often as legalization expands. The evidence here is genuinely mixed, and researchers are still sorting it out. One small matched-cohort study of lower-extremity arthroplasty patients who used cannabis found no significant differences in complication rates, revision rates, hospital stay, or postoperative pain compared to non-users.¹⁶

However, a larger database study found that cannabis use alone modestly raised the odds of periprosthetic joint infection after total knee arthroplasty, and that combining cannabis with tobacco had a synergistic effect, pushing infection odds to more than three times baseline.¹⁷ The practical takeaway: if you use both tobacco and cannabis, the combination is considerably worse than either alone. And any form of inhaled smoke delivers carbon monoxide and particulate matter that interfere with wound healing regardless of the plant involved. If you use cannabis for pain management after surgery, edibles or other non-smoked forms are a safer bet during recovery.

Nicotine Replacement Therapy During Recovery

The question of nicotine patches, gums, and lozenges is more nuanced than the vaping question. These products deliver nicotine without the combustion byproducts like carbon monoxide and the thousands of other toxins in smoke. Animal studies show that nicotine alone still slows bone healing, reduces new bone formation, and weakens the bond between bone and titanium implants, especially at higher doses. But at lower doses, nicotine showed some anti-inflammatory properties that partially offset the damage.¹⁸

Despite these caveats, most orthopedic guidelines support using nicotine replacement therapy in the perioperative period as a lesser evil, because the alternative is a patient who cannot quit and smokes full cigarettes instead. A review in the Journal of the American Academy of Orthopaedic Surgeons noted that smoking cessation protocols incorporating patches, gum, lozenges, inhalers, sprays, or medications like bupropion and varenicline could provide substantial benefits for musculoskeletal and general health.¹⁹ The bottom line on NRT: it is not harmless, but it is far less harmful than smoking, and if it keeps you from lighting up during recovery, the tradeoff is worth it for most patients.

Why Surgeons Test Your Blood Before Surgery

Many orthopedic practices now require a cotinine test before scheduling knee replacement surgery. Cotinine is a breakdown product of nicotine that lingers in the blood for days, making it hard to fake abstinence. One study found that among patients who claimed they had quit smoking, 15 percent still tested positive for cotinine.²⁰ Among patients undergoing primary total knee arthroplasty specifically, the gap between what patients reported and what cotinine tests showed was even wider, reaching about a third of cases.²¹

This is not about shaming patients. Surgeons test because the complication data are so clear that operating on an actively smoking patient means knowingly accepting a much higher risk of serious problems. Some surgeons will delay or decline to perform elective knee replacement until the patient demonstrates a period of abstinence, typically four to eight weeks at minimum. The testing protocol also has a side benefit: it apparently motivates people to actually quit. When patients know they will be tested, cessation rates climb.

Surgery as a Turning Point

The research on perioperative cessation programs is encouraging but also sobering about relapse. In one program that provided counseling and nicotine replacement before joint arthroplasty, 70 percent of enrolled patients successfully passed a carbon monoxide breath test and became eligible for surgery. Among those who had surgery, about two-thirds were still smoke-free six months later.²² A randomized trial of a cessation program started about four weeks before surgery found that roughly a third of patients in the intervention group were still abstinent a year later, compared to about 15 percent of controls.²³

But the relapse numbers tell the other side. A longer-term follow-up of patients who quit smoking for elective lower-extremity orthopedic surgery found that at an average of about four and a half years later, only about half identified as nonsmokers. More than half of those who relapsed had managed to stay smoke-free for at least three months around the time of surgery before eventually returning to cigarettes.²⁴ The postoperative period, with its pain, boredom, limited mobility, and stress, is a minefield for relapse triggers. Having a plan in place before surgery, ideally one that includes medication, counseling, or both, gives you the best chance of making a surgical quit stick.

Secondhand Smoke Exposure During Recovery

Even if you manage to quit, living with a smoker or spending time in smoky environments during recovery is not trivial. Laboratory research on fibroblasts, the cells responsible for building the connective tissue that repairs wounds, found that exposure to doses of smoke similar to what secondhand smoke produces in tissues caused changes that could slow wound repair. The cells became less able to migrate into the wound area, and their survival signals shifted in ways that promote excess scarring and fibrosis.²⁵ This is cell-culture work, not a clinical trial on patients, so the direct translation to your knee recovery is uncertain. But it is a reasonable basis for asking household members to smoke outdoors during your recovery, and for avoiding smoky bars or enclosed spaces in those first weeks.