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This article was reviewed and co-authored by Dr. John Tiberi, M.D.,OS (board-certified orthopaedic surgeon).

Everyone who undergoes a knee replacement will experience some stiffness throughout their recovery. Stiffness is very common. However, if stiffness is a major player that is getting in the way of your recovery, action must be taken.

A manipulation under anesthesia (MUA) is something that is recommended as a last resort to fix knee stiffness and range of motion issues. When dealing with post-op stiffness, physical therapy and continued at-home range of motion rehab exercises usually fix the problem. Regaining motion after knee surgery isn’t passive, so patients who put more into their physical therapy can usually nip stiffness in the bud. In saying this, some patients are the exception to the rule and aggressive physical therapy and “doing all the right things” won’t solve their knee stiffness or help them reach good knee flexion for everyday living.

Dr. John Tiberi adds, “I typically want to see my patients reach 90 degrees in the first 2-4 weeks, but if that was [the final result] they ended up with, I wouldn’t be happy.”

If stiffness is impacting your ability to recover at the pace your care team expects, a manipulation under anesthesia (MUA) may be recommended.

Knee stiffness as a diagnosed complication that requires a MUA is quite rare. Studies we examined suggest that only about 1.3-4% of all patients undergo a MUA after a total or partial knee replacement.

What is a Knee Manipulation Under Anesthesia (MUA)?

A manipulation under anesthesia may be necessary to improve range of motion (extension and flexion) in some patients. The MUA is a second procedure after a knee replacement. During the procedure, your surgeon will break-up the scar tissue, fibrous materials and adhesions that are causing stiffness (essentially cleaning up the area around your knee joint). During this procedure, no incisions are made. Your surgeon will position your leg in several different positions, applying pressure and breaking up the tissue. Your surgeon will be able to see and hear the tissue breaking away. Lastly, the leg will be flexed and extended to its maximum range.

All of this will be performed while you are under anesthesia (likely a general anesthetic, not regional but this varies by surgeon and patient), so you will not feel any pain.

A manipulation under anesthesia (MUA) for knee surgery is most common and effective around the 6-12 week mark after surgery.

Surgeons won’t consider the procedure until a minimum of 6 weeks out from surgery. On the other end, a MUA may be recommended months (even years) after a knee replacement. However, if done years after a replacement, it may not be as effective as a manipulation that took place closer to the 12 week mark.

In a study that recorded knee manipulations under anesthesia over a 6 month period, researchers found that the average MUA took place 13.2 weeks after the initial knee arthroplasty

Benefits of a Knee MUA

benefits of knee MUA

A MUA treats the complication of stiffness, addressing problems with range of motion and flexion. As such, it may be a necessary and very worthwhile secondary procedure for patients who unfortunately, are experiencing the complication of stiffness. Here are the main important benefits of a MUA:

  • Improves knee movements and range of motion. In a controlled study that measured 21 MUA patients, the average arc of motion improved from 60.2° pre-MUA to 91.9° post-MUA.
  • Excellent, immediate results. Almost every patient, had significantly improved range of motion after a MUA. Patients notice a difference immediately or in the days to follow.
  • A proven “plan B” after surgery. If physiotherapy is not improving range of motion, at-home rehab exercises are delivering the results you expect, a MUA is a safe, proven option. Your care team will be well-versed in this procedure.
  • Gets you back on track. If done early enough, your recovery will not be set back greatly. Obviously having this secondary procedure will mean additional recovery time, but in the long-run you can catch up to peers who had their primary replacement around the same time.

Downsides of a Knee MUA

  • Possible Bone breakage. Applying pressure to break-up adhesions around your knee joint requires force. Applying this force without breaking any bones requires a skillful surgeon. If you’re bones are very degraded or too much force is applied, bones could break. Although low risk, it is a risk you should be aware of. The risk increases for those who have osteoporosis, weak bones, are older etc
  • Added risk factors (for some patients especially). Going under anesthesia is very low risk, but is a risk. Anesthesia is taxing on your body and comes with mild-moderate side effects. If you have any secondary conditions (like high blood pressure, diabetes, obesity, a history of alcohol abuse) then anesthesia is more risky. Talk to your doctor about the different types of anesthesia that may be available (regional may be a better option for some patients).

A MUA is not the sole cure for larger complications that could be caused by a technical surgical error. A MUA alone may not cure all stiffness.

Avoiding a Manipulation After Knee Surgery

A lot of factors that are out of your control, mixed with some bad luck, help determine who will experience knee stiffness and require a manipulation. However, there are some things that you, someone who is preparing for and recovering from a knee replacement, can do.

Here’s how to avoid a manipulation (MUA) after a knee replacement.

Engage in a PreHab Program.

PreHab before a knee replacement essentially means, “to actively try and improve your mind and body for surgery, with the aim of having a better outcome and recovery”. Those who follow a guided PreHab program, like PeerWell, will have improved flexion, extension, and muscle strength surrounding their joint on surgery day. The best indication of knee range of motion and stiffness after surgery is what your range of motion was like before surgery. Those who are stiffest after their replacement generally had the poorest range of motion, flexion and extension going into surgery.

Follow Best Recovery Practices: Exercise, Ice, Elevate.

After a knee replacement it is absolutely crucial to be “working” your knee. This means regular physical therapy complimented by an at-home rehab program. This at-home rehab program will guide you through supplementary knee exercises, movements and cardio to best improve your motion. There is a science to your recovery, so it’s best to follow your doctor’s orders and that of a knee replacement rehab program (like PeerWell). Overdoing it on your knee can also cause swelling which can lead to stiffness. Under doing it can “lock up” your knee and cause severe stiffness.

In addition to following the best exercises at the right frequency, you must remember to ice your knee several times a day. You should be icing daily for several weeks after surgery (90 days is suggested). Pair icing with elevation to cut down swelling, pain, and stiffness.

Best Icing Practices for the First Weeks After a Knee Replacement

  • Elevate and ice for 15-20 minutes at a time.
  • Wrap ice in a tea towel, t-shirt, or thin cloth. DO NOT apply directly to your skin.
  • Repeat icing at least 3-4 times a day.

Read all about the best icing practices after knee replacement surgery to stay on top of your game.

Other Tips to Improve Post-Op Stiffness

  • Keep working at it. It can be frustrating (and painful) to have post-op knee stiffness, but the more you work and it and pay attention to your body, the better.
  • Get enough rest. If you are mentally and physically exhausted, your body is not able to recovery the way it should. If you’re having trouble sleeping after a replacement, here are some tips to get to sleep and to sleep more soundly.
  • Try a passive motion machine or cryotherapy. There have been some positive testimonials about these alternative treatments, Before trying, consult with your care team to see if they recommend either for you. Everyone is different and every surgery case is different so your surgeon may have good reason to say no!
  • Dynamic Splint. If range of motion is under par, your surgeon may suggest a dynamic splint. The splint improves range of motion by creating prolonged stretching. flexion or extension. This splint can be controlled by the patient to deliver a constant, forceful stretch or bend to the knee. Splints are designed to improve knee flexion and extension.

John Tiberi, M.D.,OS is a board-certified orthopaedic surgeon who specializes in minimally-invasive hip and knee replacement surgery and reconstructions. He attended medical school at the Harbor-UCLA Medical Center in Torrance, California. Dr. Tiberi completed his fellowship at Massachusetts General Hospital and Harvard Medical School in Boston, Massachusetts. He is a published orthopedic in journals such as The Journal of Arthroplasty, Journal of Bone Joint Surgery (JBJS), and Clinical Orthopaedics and Related Research. Dr. Tiberi is the winner of Dana M. Street Orthopaedic Research Award.

In pain? Preparing for surgery? PeerWell Health helps you fast forward to better with 1:1 doctor visits, physical therapy, and a custom at-home program for your condition. 

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