Stiffness After Knee Replacement Surgery

Risks, Causes, and Current Treatment Options

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A knee replacement surgery is performed to replace the worn-out cartilage of the knee joint. Knee replacement is an excellent procedure for severe knee arthritis. Unfortunately, complications can occur after a knee replacement, even when all goes well at the time of surgery.

One possible complication of a knee replacement is stiffness after the surgery has been performed. People with a stiff knee after knee replacement may experience an inability to fully straighten the leg, to bend the knee back, or both.

Therapist working on a patient's knee
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Assessing Preoperative Risk

When trying to predict the likelihood of stiffness after a knee replacement, the most important variable is the mobility prior to surgery. People who have stiff knees heading into knee replacement surgery, tend to have stiffer knees after knee replacement surgery.

Those who have better mobility prior to surgery are less likely to have stiffness after surgery.

There are steps that can be taken at the time of surgery to help release tight ligaments and tissue around the joint, and remove bony impediments to mobility, but sometimes the flexibility of the tissues is limited to a point that cannot be fully corrected.

Expected Range of Motion

After knee replacement surgery, it is important to work with a physical therapist to achieve the maximal range of motion. Typically, the range of motion will progress quickly during the first three months and can continue to increase for up to two years following surgery.

Normal motion after knee replacement is defined as the ability to get within 5 degrees of a straight knee and the ability to bend the knee back to 90 degrees. Most knee replacements have movement ranging from 0 degrees to 110 degrees or more.

The optimal motion of the replaced knee can be achieved with a combination of stretches, exercises, and gradual resumption of normal activities. Some surgeons will recommend the use of a machine to bend the knee, called a CPM, (despite the lack of evidence to support their use).


In some people, knee motion can be difficult to regain after surgery. Lack of normal motion after knee replacement can be due to one of the several causes, or a combination of causes :

Inadequate Pain Control

Pain control after joint replacement is usually a manageable problem, but in some people, this can be quite difficult. Some patients find the side effects of pain medication intolerable, but a lack of adequate pain control can lead to difficulty working on motion of the newly replaced joint.

It is important to work with your healthcare provider to develop a pain treatment plan that works for you.

Poor Motion Before Surgery

Your motion before surgery can be used to predict your motion after surgery. Patients with stiffness before their surgical procedure are more likely to have stiffness after surgery.

Excessive Scar Formation

Some people seem to make scar tissue more abundantly than others, and there are some situations where scar formation is more abundant. Patients who have undergone prior joint surgery, or are having revision knee replacement, are more likely to have stiffness after surgery.

Malpositioning of the Implants

Surgeons make an effort to balance the knee at the time of surgery. This means finding the proper size and alignment of the knee replacement so that the knee joint is not too tight, and not too loose, and so this balancing is the same with the knee straight and bent.

This is precisely why a knee replacement is a difficult procedure, and the art of perfecting this takes many years. Errors in the positioning of an implant may not be apparent on the operating table and only become evident when the recovery is stalled.

Newer patient-specific knee replacements are tailor-made and may reduce the risk of malpositioning.

Other Surgical Complications

Complications of surgery often lead to other problems. Patients who experience joint replacement infections, complex regional pain syndrome, or other complications, have a higher chance of developing stiffness.


Treatment of stiffness after knee replacement depends on the time since surgery, and the cause of the stiffness. The usual treatments for stiffness are:

Aggressive Physical Therapy

Physical therapy is a useful treatment for a stiff knee, especially within the first three months after knee replacement. Physical therapy can also be considered after this time, but the results are not as good as early physical therapy.

A new type of splint called a dynamic splint has also shown some encouraging results when used in conjunction with physical therapy.

Manipulation Under Anesthesia

A manipulation is a procedure where no incisions are made. The patient is given anesthesia, usually through an IV, and while sleeping, your surgeon forcibly moves the knee to break up scar tissue. This procedure is most beneficial in the six to 12 weeks after surgery.

The primary concern with a manipulation is the risk of bone breakage. This is a real issue given that most recipients are older and at greater risk of osteoporosis. Breakage is also more likely if the manipulation is performed more than a year after the replacement.

Surgical Removal of Scar Tissue

Surgical removal of scar tissue after knee replacement is seldom performed but may be helpful in some rare circumstances. The results of removing scar tissue have not been particularly good at improving motion, and therefore, other treatments are usually considered first.​

Revision Knee Replacement

When all other options fail or the knee replacement parts are irretrievably malpositioned, it may be necessary to perform a revision knee replacement. The bone cuts and the size of the new replacement can be modified to help allow for better knee motion.

Determining the proper treatment of a stiff knee after replacement depends on the cause of the stiffness and the length of time since your replacement. Your healthcare provider can make recommendations for your knee based on your specific situation.

A Word From Verywell

Stiffness after knee replacement surgery can generally be avoided with appropriate pain control, physical therapy, and steps to reduce the likelihood of complications. However, in situations where stiffness occurs, there are steps that can be performed to try to improve the situation.

The early postoperative treatment of knee stiffness is vital as delayed treatment (of six months or more) is far less likely to deliver adequate results. In cases like these, repeat surgery may be the only option.

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Article Sources
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  1. Bong MR, Di cesare PE. Stiffness after total knee arthroplasty. J Am Acad Orthop Surg. 2004;12(3):164-71.

  2. Bong MR, Di cesare PE. Stiffness after total knee arthroplasty. J Am Acad Orthop Surg. 2004;12(3):164-71.

  3. Laskin RS. Joint line position restoration during revision total knee replacement. Clin Orthop Relat Res. 2002;(404):169-71. doi:10.1097/00003086-200211000-00029

Additional Reading
  • Ghani H, Maffulli N, Khanduja V. "Management of stiffness following total knee arthroplasty: a systematic review" Knee. 2012 Dec;19(6):751-9.
  • Scott RD. "Stiffness associated with total knee arthroplasty" Orthopedics. 2009 Sep;32(9).