MUA (Manipulation Under Anesthesia) After Total Knee Replacement
Manipulation under anesthesia is a technique after total knee arthroplasty (TKA) or knee revision surgery to treat stiffness and poor motion range. Stiffness and decreased motion range after TKA affects about 6 to 7 percent of patients.1 MUA is a non-surgical procedure performed in a hospital with general or spinal anesthesia patient. Some internal tissues of the body are exposed to the air during a total knee replacement, causing essential lubricating fluids to evaporate within the tissues of the body. If after surgery, the fluids are not rapidly replenished, affected muscles that normally glide over each other can bind and form adhesions that can cause pain and greatly limit the ability to move the affected joint.
Physiotherapy and therapeutic massage / manipulation techniques can often work out light adhesions. However, if adhesions are large, orthopedic manipulation under anesthesia may be required for treatment to free the joint. The incidence of orthopedic MUA-requiring adhesions and scar tissue is low, occurring in 3.9–4.6 percent of total knee replacements.
The procedure
Because the reflexes and sensitivity to pain of a patient are absent under anesthesia, manipulation using specific maneuvers breaks down fibrous adhesions around the joint and surrounding tissue. The patient is placed on their back during MUA after knee replacement and the hip is flexed to 90 degrees. Stable progressive pressure is applied with the leg held close to the knee joint until the surgeon can hear and feel the adhesions breaking away.
The knee is held for 20 to 30 seconds in this position. It is then flexed and extended several times to the maximum position.3 Upon completion of the procedure, the patient is usually released to go home the same day although some surgeons prefer to keep the patient overnight in order to ensure adequate pain management. Postoperatively, it is recommended that active assisted physical therapy maintain the joint flexing and delay the formation of new adhesions. Some patients may use a continuous passive motion machine (CPM) to keep the joint flexing.
Some people experience extensive pain after MUA, but many find the average and manageable level of pain with knee icing and pain medication prescribed by the doctor. Some knee area swelling may result in poor bending at first–which may be unsettling as it may feel like the procedure was unsuccessful. The stiffness usually subsides within a few weeks of pain management, icing and elevation, and greater range of movement is experienced. If the pain level is manageable, people who have jobs with low physical demands may be able to return to work a few days after the procedure.
Risks involved
Although extremely rare, MUA complications are often associated with the force used to manipulate the knee that results in bone fracture or rupture of the wound. Applying enough force to break adhesions without breaking bones is a skill and prudent surgeons will be cautious about this risk to their patients. Other considerations that may prevent an individual from undergoing MUA include: osteoporosis or other disorder of bone weakening, heart disease, advanced age, circulatory disease, and acute arthritis.
The outcomes
Most people experience an increase in motion range after MUA, although some muscle soreness is temporarily added. There should be a significant change in cases involving muscle adhesions and shortened tissues, either immediately or within a few weeks of the procedure. After MUA care, the most important thing is to set up a program that allows the patient to learn how to maintain function and range of motion, regain strength and prevent future pain and disability.
