A total knee arthroplasty (TKA), commonly known as knee replacement surgery, is a procedure where the damaged surfaces of the knee joint are replaced with prosthetic components. While the surgery addresses the underlying structural problem, the success of the outcome relies heavily on the patient’s commitment to rehabilitation through exercise. Movement is not merely beneficial; it is a mandatory part of recovery that ensures the new joint integrates correctly and functions as intended. The “best” exercise changes significantly as a patient moves through the different stages of healing, transitioning from simple motion to rebuilding muscle and finally to maintaining lifelong fitness.
The Immediate Focus: Restoring Range of Motion
The first stage of recovery, typically spanning the initial few weeks, centers on restoring the knee’s ability to fully extend and bend. The primary concern is to prevent the formation of dense scar tissue that could permanently restrict mobility, a complication known as arthrofibrosis. Early, gentle movement is introduced almost immediately after surgery, often starting in the hospital.
Ankle pumps, which involve repeatedly moving the foot up and down, are performed hourly to promote blood flow and reduce the risk of deep vein thrombosis (DVT). Another foundational movement is the quadriceps set, where the patient tightens the thigh muscle to press the back of the knee down against the bed. This helps the quadriceps muscle “re-learn” how to contract and work toward achieving full extension.
The heel slide is the core exercise for regaining flexion, requiring the patient to slide the heel toward the buttocks while lying down to gently bend the knee. Consistent performance of these exercises is necessary to meet the range of motion goals set by the physical therapist. These early movements are slow and controlled, setting the groundwork for the next phase of recovery.
Building Strength and Stability
The intermediate phase, generally spanning from approximately three to sixteen weeks post-surgery, shifts the focus from simple movement to actively rebuilding the muscle mass surrounding the joint. Muscle atrophy is common after TKA, making the quadriceps and surrounding hip muscles significantly weaker. Strengthening these muscles is necessary to stabilize the joint and restore functional independence.
Exercises in this stage introduce active resistance and partial weight-bearing. The straight leg raise, performed with the knee kept completely straight, is a foundational exercise to rebuild quad and hip flexor strength without placing undue stress on the joint. As strength improves, light resistance, such as ankle weights or resistance bands, is incorporated to challenge the muscles further.
Functional movements that mimic daily activities are introduced, including mini-squats and step-ups. Mini-squats, where the patient only bends the knees slightly, help restore the ability to sit down and stand up from a chair. Step-ups rebuild the strength and coordination needed for navigating stairs and uneven terrain. Balance exercises, such as single-leg standing with support, are also incorporated to improve stability and decrease the risk of falls.
Long-Term Low-Impact Activities
Once therapeutic recovery is complete, typically around three to six months post-surgery, the best exercise shifts to activities that support long-term joint health and cardiovascular fitness. The goal is to maintain muscle strength and achieve a high quality of life without jeopardizing the implant’s longevity. Low-impact options are strongly recommended because they reduce the shear forces and repetitive impact that can accelerate the wear of the prosthetic components.
Stationary cycling is highly recommended, as it provides an excellent cardiovascular workout and helps maintain the knee’s range of motion through a smooth, circular, non-impact movement. The seat should be adjusted to ensure the knee is only slightly bent at the bottom of the pedal stroke. Swimming and water-based exercise, such as water walking or aerobics, are also ideal because the water’s buoyancy reduces the weight-bearing load on the knee, allowing for full range of motion against mild resistance.
Brisk walking is another highly effective long-term activity, provided it is performed on level surfaces. Using a treadmill or elliptical machine is an excellent way to gain cardiovascular benefits while maintaining control over the walking surface and impact level. These activities allow for sustained physical activity necessary for overall health.
Crucial Movements to Avoid
To protect the new knee joint and ensure the longevity of the implant, certain activities are strongly discouraged, often permanently. Any high-impact activity that subjects the joint to excessive force, such as running, jogging, or jumping, should be avoided. The force exerted on the knee during running can be up to three times a person’s body weight, which can prematurely wear down the plastic component of the prosthesis.
Sports involving sudden stops, starts, pivoting, or twisting motions, like basketball, soccer, and singles tennis, pose a significant risk of dislocation or damage to the implant and are generally prohibited. Activities that require deep knee bending, such as deep squats or lunges, should also be avoided because they place high pressure on the joint surfaces and can compromise the integrity of the implant. While light kneeling may be possible after a full recovery, it is discouraged as a repetitive activity to prevent excessive friction and wear on the kneecap components.