Knee replacement surgery is a standard procedure performed to relieve severe pain and restore mobility in a damaged knee joint. The recovery process is highly dependent on physical rehabilitation. Physical therapy is the most influential factor determining the success and longevity of the new joint. Understanding when this process begins is a primary concern for patients preparing for the operation. The recovery journey starts much sooner than most people anticipate.
The Immediate Timeline: Starting Physical Therapy
Physical therapy typically begins almost immediately following knee replacement surgery, often within 12 to 24 hours. Many modern recovery protocols aim for the first session to happen on the same day as the operation. Immediate mobilization is standard practice designed to initiate the healing process.
The first session is usually brief, focusing on safety and initial movement. A physical therapist works with the patient while they are still in the recovery unit or hospital room. This early movement is part of accelerated recovery pathways common in orthopedic care.
The exact timing depends on the type of anesthesia and the surgeon’s specific protocol. The goal is consistent: to get the patient moving as soon as their post-operative condition allows. This early start sets the expectation for the patient’s active role in their recovery.
Critical Goals of Early Rehabilitation
Early physical therapy is driven by several physiological objectives. A primary concern is the prevention of Deep Vein Thrombosis (DVT), or blood clots, which are a risk after major lower extremity surgery. Moving the calf and ankle muscles improves blood circulation, which helps reduce the chance of clot formation.
Another goal is to prevent excessive scar tissue formation, known as arthrofibrosis. If the knee remains immobile, scar tissue can limit the ability to bend and straighten the leg long-term. Early, controlled movement guides the healing process and maintains the flexibility of soft tissues around the new implant.
Restoring full range of motion (ROM) is a key objective. It is important to regain full knee extension—the ability to straighten the leg completely—in the first few days. Lack of full extension early on can lead to a gait abnormality or limp that is difficult to correct later.
Initial exercises activate the quadriceps muscle. The quadriceps often become weak due to pre-operative pain and surgical trauma. Activating this muscle group is necessary to provide stability and support for the new joint.
Controlling post-operative swelling and pain is also a major focus. Gentle, controlled exercises help pump fluid away from the surgical site. This reduction in swelling leads to better pain management and a greater willingness to participate in therapy.
Initial Exercises and Mobility Milestones
Common Early Exercises
The exercises performed in the hospital are low-impact and focus on joint movement and muscle activation.
- Quadriceps sets: Tightening the thigh muscle to push the back of the knee down toward the bed. This helps achieve knee extension.
- Ankle pumps: Repeatedly moving the foot up and down to improve circulation in the lower leg and guard against blood clots.
- Heel slides: Bending the knee by sliding the heel along the bed toward the buttocks.
- Continuous Passive Motion (CPM) machine: Used by some facilities, this machine slowly and continuously bends and straightens the knee without active muscle work from the patient to encourage range of motion.
Mobility Milestones
The first major milestone is achieved during the initial therapy session when the patient is helped out of bed. The therapist assists the patient in standing and taking a few steps using a walker or crutches. Ambulation confirms that the patient can safely bear weight on the new joint. Before discharge, patients must demonstrate the ability to safely transfer in and out of bed and walk a short distance with an assistive device. They must also be able to navigate a few steps, a practical requirement for returning home.
Transitioning to Long-Term Recovery and Outpatient Care
The hospital stay following knee replacement is typically short, often lasting one to three days. Once discharged, the patient moves into the next phase of recovery, shifting the focus from basic mobility to rebuilding strength and endurance.
Patients have two options for continued rehabilitation: home health physical therapy or outpatient physical therapy. Home health involves a therapist visiting the patient at home, common in the first couple of weeks for those with limited mobility. Outpatient therapy, where the patient travels to a clinic, typically begins once the patient can safely leave the home.
The exercises progress from simple range-of-motion work to functional activities. The therapist introduces balance training and exercises that mimic daily life, such as stepping, climbing stairs, and standing up from a chair without relying on armrests. Light resistance bands or stationary cycling are used to build muscle strength around the knee.
Physical therapy usually continues for six to twelve weeks, depending on the individual’s recovery rate and specific functional goals. However, the patient must continue a structured home exercise program for several months after therapy ends to achieve maximum long-term function.