Doctors have long worried that patients carrying extra weight might not do as well after shoulder replacement surgery. But a new study of 217 patients followed for nearly three years found something surprising: people with higher body weight actually did just as well—and sometimes even better—after their surgery. The researchers looked at shoulder function, pain levels, and movement range in patients with different body weights. The bottom line? Having a higher body mass index (BMI) didn’t prevent people from getting the pain relief and improved movement they hoped for after shoulder surgery.

The Quick Take

  • What they studied: Whether people who weigh more have worse results after shoulder replacement surgery compared to people who weigh less
  • Who participated: 217 patients who had shoulder replacement surgery (either standard or reverse shoulder replacement) and were followed for an average of almost 3 years. Researchers looked at patients with different body weights, including those with a BMI over 40 (considered very high)
  • Key finding: Patients with higher body weight had the same or better improvements in shoulder pain and function after surgery compared to lighter patients. People with BMI over 40 actually showed greater improvement in their pain and function scores, likely because they started with more pain before surgery
  • What it means for you: If you’re considering shoulder replacement surgery and worried that your weight might make the surgery less successful, this research suggests that shouldn’t be a major concern. However, this doesn’t mean weight isn’t important for overall health—it just means it doesn’t seem to prevent good shoulder surgery outcomes

The Research Details

This was a retrospective study, meaning researchers looked back at records of patients who had already had shoulder surgery. They reviewed 217 patients who had either standard shoulder replacement (called anatomic) or reverse shoulder replacement (used when certain shoulder muscles are damaged). All patients had surgery at least 2 years before the study and completed surveys about their shoulder pain and function.

The researchers divided patients into groups based on their BMI (a measurement of body weight relative to height). They compared how well each group did after surgery by looking at three main things: how much their shoulder could move, how much pain they had, and how well their shoulder functioned in daily activities. They also checked other health factors like blood sugar control, cholesterol, and vitamin D levels to see if these affected results.

The study followed patients for an average of 34 months (almost 3 years), which is long enough to see whether surgery benefits lasted over time.

This research matters because many doctors have been uncertain about whether patients with higher body weight should have shoulder surgery, or whether they would benefit as much. By looking at actual patient outcomes over several years, this study provides real-world evidence rather than just theory. The long follow-up period is important because it shows whether improvements lasted, not just whether surgery helped immediately.

This study has some strengths: it included a reasonable number of patients (217), followed them for a long time (average 34 months), and used standardized surveys that doctors trust to measure shoulder function. However, it’s a retrospective study, which means researchers couldn’t control all the factors that might affect results—they just looked at what already happened. The study was done at one hospital system, so results might be different in other places. The researchers did measure several health factors beyond just weight, which strengthens the findings.

What the Results Show

The main finding was that patients with very high BMI (over 40) had the same shoulder movement and function as patients with lower BMI after surgery. When researchers looked at pain and function scores, they found no meaningful differences between weight groups at the final follow-up visit.

Interestingly, patients with BMI over 40 actually showed greater improvements in their pain and function scores compared to lighter patients. This might seem surprising, but it makes sense when you look at the details: these heavier patients started with worse pain and function before surgery, so they had more room to improve. In other words, surgery helped them more dramatically because they started from a worse place.

When researchers looked at other health factors—like blood sugar control, cholesterol levels, albumin (a protein in blood), and vitamin D—none of these independently predicted how well patients would do after surgery. This suggests that weight itself, rather than weight-related health problems, is what matters for shoulder surgery outcomes.

The study also found that patients with higher BMI were more likely to reach what doctors call ‘minimal clinically important difference’—meaning they improved enough that they could really notice the difference in their daily lives. This happened more often in heavier patients, again likely because they had more severe problems before surgery and therefore more potential to improve.

Previous research on this topic has been mixed, with some studies suggesting weight might be a problem and others suggesting it doesn’t matter much. This study adds to the evidence that weight probably isn’t the barrier to good outcomes that doctors once thought. However, most previous studies were smaller or followed patients for shorter periods, so this research provides stronger evidence.

The biggest limitation is that this was a retrospective study—researchers looked backward at what already happened rather than randomly assigning patients to different groups. This means some differences between groups could be due to factors researchers didn’t measure. The study was done at one hospital system, so results might be different elsewhere. The researchers didn’t measure some factors that might matter, like how active patients were before surgery or how well they followed physical therapy instructions after surgery. Finally, all patients had at least 2 years of follow-up, which might mean patients with very bad outcomes were less likely to be included.

The Bottom Line

If you’re considering shoulder replacement surgery and have concerns about your weight, this research suggests weight alone shouldn’t prevent you from having the surgery or make you expect worse results. However, you should still discuss your overall health with your doctor, as weight can affect other health conditions. The evidence here is fairly strong (based on 217 patients followed for years), but it’s specific to shoulder surgery outcomes—not overall health recommendations.

This research is most relevant for people considering shoulder replacement surgery who worry that their weight might make surgery less successful. It’s also important for doctors deciding whether to recommend surgery to heavier patients. This doesn’t apply to people with other types of surgery, as results might be different. People with weight-related health problems (like diabetes or heart disease) should still address those with their doctor, even though weight didn’t affect shoulder surgery outcomes in this study.

Based on this study, patients saw their main improvements within the first 2 years after surgery, and these improvements lasted through the 3-year follow-up. You shouldn’t expect overnight results—shoulder recovery takes months—but you can expect meaningful improvement in pain and function within the first year, regardless of your weight.

Want to Apply This Research?

  • If you’re having shoulder surgery, track your shoulder pain (0-10 scale) and specific activities you can do (like reaching overhead or lifting) weekly for the first 3 months, then monthly. This lets you see your own improvement over time, similar to how the study measured outcomes.
  • Set a goal to gradually increase your shoulder activity as your doctor recommends. Use the app to log specific movements you’re working on (like reaching to a shelf or lifting your arm to shoulder height) and celebrate when you can do these activities with less pain. This creates a positive feedback loop for recovery.
  • Create a long-term tracking system that measures shoulder function at 3 months, 6 months, 1 year, and 2 years after surgery. Include pain levels, range of motion exercises you can complete, and daily activities you can perform. This mirrors the study’s approach and helps you see whether your recovery is on track.

This research discusses shoulder replacement surgery outcomes and should not be interpreted as medical advice. If you’re considering shoulder surgery or have concerns about how your weight might affect surgical outcomes, discuss these findings with your orthopedic surgeon or doctor. Individual results vary based on many factors including overall health, age, and commitment to physical therapy. This study specifically examined shoulder replacement outcomes and may not apply to other types of surgery or medical conditions. Always consult with qualified healthcare providers before making decisions about surgery or treatment.