Range of Motion Following a Total Knee Replacement Surgery

BalanceMany of us either have experienced or know someone who has experienced chronic knee pain due to arthritis. Arthritic pain occurs because the cartilage on the ends of the bones (that is, the femur and the tibia) in the knee joint, which is responsible for cushioning and lubrication of the joint, wears down due to both injury and time, thus resulting in rubbing of the ends of the bones. Because bones have lots of nerve input, pain occurs when they rub against one another.


Healthcare professionals, including physical therapists and orthopedic surgeons, recommend delaying knee replacement surgery for as long as possible. This can be done by engaging in appropriate exercises, including stretching and strengthening exercises, and using more conservative treatments for pain and inflammation, including oral medication, topical creams, and injections (e.g. cortisone) administered by a physician. However, because arthritis is a progressive condition, it is inevitable that pain will eventually become severe and debilitating, thus necessitating a surgery at some point. Once a total knee replacement surgery is performed, the interior knee joint pain resolves, as the ends of the femur and tibia bones are capped by metal. However, a patient is then left with other complications, including scar tissue formation and soft tissue stiffness, that may lead to range of motion restrictions and, therefore, functional deficits.


Prior to surgery, a person’s knee range of motion often can help predict the level of stiffness that can be expected after surgery. This means that if a person has good knee mobility prior to surgery, then better mobility can be expected after surgery. Conversely, if a person exhibits knee stiffness prior to surgery, it can be expected that mobility may be more difficult to achieve post-operatively. Oftentimes, surgeons recommend that patients engage in physical therapy before surgery to maximize knee range of motion, leg strength, and overall function pre-operatively so as to improve outcomes post-operatively. This engagement in physical therapy has been dubbed “Pre-hab.”


Once a knee replacement surgery has been completed, initiation of mobilization of the knee is extremely important. Some surgeons will prescribe a continuous passive motion (CPM) machine to move a patient’s knee. The leg is strapped into the machine, which is then set to specific degrees of motion and moves the patient’s leg for them. Studies are inconclusive with regards to the efficacy of the use of CPM machines, however. Still, whether a CPM machine is implemented or not, early mobility of the post-operative knee is key.


Although full knee range of motion may not be achieved until several months after surgery, there are some guidelines for improving knee mobility. Full knee straightening (i.e. extension) must be the priority first. This is because for normal weight bearing when standing and walking, full knee straightening is essential. If the knee is even slightly bent during standing and walking, the leg muscles must work harder than usual, which can lead to muscle fatigue and, thus, episodes of knee buckling. Knee bending (i.e. flexion) is important as well, but straightening must occur sooner rather than later. Once full knee straightening is achieved, the focus can shift to knee bending, as it is required for adequate comfort while sitting, squatting, and lunging.


Post-operative complications that can affect knee range of motion include excessive pain and scar tissue formation. While physicians make every attempt to control a patient’s pain as much as possible, each person experiences pain differently, and medications – both oral and topical – must be adjusted to achieve optimal results with regards to pain. While a certain level of scar tissue is needed for proper healing after knee replacement surgery, too much scar tissue can lead to knee mobility restrictions.


Proper stretching techniques and manual therapy (e.g. from a physical therapist), including soft tissue mobilization, joint mobilization, and scar mobilization, can help control excessive scar tissue formation. If scar tissue formation does become a problem, though, surgeons may recommend that a patient undergo a manipulation under anesthesia procedure (i.e. extreme knee ranging with a patient unconscious while under anesthesia) or surgical removal of scar tissue.


In order to avoid complications that can lead to knee mobility restrictions after a joint replacement surgery, it is vital that patients engage in physical therapy as soon as possible. Working with a physical therapist will ensure that you perform appropriate exercises and receive necessary hands-on treatment to maximize knee range of motion as quickly as possible.


Rob Kohutanycz, PT, DPT

Posted in: Knee

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