Surgeons who give their knee replacement patients a periarticular injection rather than a femoral nerve block find that their patients require less physical therapy and less time in the hospital to recover. A doctor performs a nerve block, which temporally disrupts a patient’s muscle control, by inserting a needle near the hip joint to deliver anesthesia.
Save $1, 615 per Patient With Periarticular Injections

According to Stephen Feller, writing for Home Health News, researchers at the Greater Lansing Medical Center and Michigan State University found that anesthetics injected around the surgical site, rather than to an entire limb allow patients to recover more quickly because they retain control of their muscles.
Customarily, after knee replacement surgery, doctors encourage patients to bear weight on the new knee within 12 to 24 hours and to start physical therapy. Those patients who have had femoral nerve bocks may not get functional nerves for about 24 hours, delaying physical therapy.
Brandon Horn, M.D., a surgeon at McLaren Greater Lansing Medical Center, said in a press release about the study, “Periarticular injections, unlike femoral nerve blocks, allow patients to maintain control of the quadriceps muscles enabling the quadriceps to fully engage helps patients to get up and begin walking independently faster. There’s also a preventative component at work, since femoral nerve blocks are also associated with a high incidence of postoperative falls.”
For the study, researchers examined the records of 16 patients who had had bilateral knee replacement surgeries. In the first surgery doctors had given them a femoral nerve block. At the second the patients received a periarticular injection. The result? Those who received the injection required fewer physical therapy sessions and spent less time in the hospital than did those who received the nerve block.
Horn commented, “To treat knee replacement patients with a nerve block, you’re looking at about $400 in additional costs for the procedure alone compared to that of the analgesic injection. Adding in the cost of additional physical therapy needed and extended hospital stay, the injection can save around $1, 615 per patient.”

Discussion
This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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