Range of motion (ROM) refers to the full extent of movement a knee joint can achieve, measured in degrees from complete straightening (extension) to maximum bend (flexion). Regaining this movement is the primary, immediate goal following any knee surgery, such as total knee replacement or ligament repair. The ability to fully extend the leg, reaching zero degrees, is particularly important for normal walking mechanics. Failure to achieve adequate ROM quickly allows the joint capsule and surrounding soft tissues to contract, leading to long-term functional limitation.
Phase-Specific Techniques for Increasing Knee Movement
Regaining movement begins with passive and assisted techniques immediately following surgery, focusing on gentle, controlled motion. An early and persistent focus on achieving full extension is necessary because loss of extension is more debilitating to walking than a slight loss of flexion. For extension, the heel prop exercise is widely used: the patient lies on their back with the heel resting on a rolled towel or firm object, allowing gravity to gently push the knee down toward the bed or floor. This position should be held for several minutes at a time, often between five and fifteen minutes, and repeated multiple times daily.
Another effective extension technique is the prone hang, performed by lying face-down on a firm surface with the affected knee positioned just past the edge of the bed. The lower leg hangs freely, using the weight of the leg to encourage straightening, which can be done for a minute or more at a time. Actively engaging the quadriceps muscle, known as a quad set, is also a foundational exercise that helps restore the muscle’s ability to fully contract and hold the knee straight. The patient tightens the thigh muscle, pressing the back of the knee down against the surface, and holds this contraction for a few seconds before relaxing.
As the initial post-operative pain subsides, the focus shifts to increasing knee flexion, or bending, starting with assisted exercises. The heel slide is a foundational exercise, performed while lying on the back, where the heel is slowly slid toward the buttocks, bending the knee as far as possible. Assistance can be provided by looping a towel or strap around the foot and gently pulling it, or by using the non-surgical leg to push the surgical leg further into a bend. This assisted movement is a form of passive range of motion, using external force rather than muscle power alone.
In the intermediate phase, movement progresses to active techniques and light resistance. Using a stationary bicycle is often introduced because it allows for controlled, repetitive, and low-impact movement through the available range. Initially, the seat height is adjusted to prevent excessive knee bend, and the patient may start by pedaling backward before moving to forward pedaling. Seated knee flexion exercises, where the patient sits and uses their non-surgical foot to support the ankle of the operative leg, allow the patient to gently push the surgical leg into a deeper bend. These techniques progress the knee from passive movement to active motion.
Controlling Pain and Swelling to Support Mobility
Swelling and pain are the primary physical barriers that restrict movement and prevent the knee from achieving its full range of motion. The body’s natural inflammatory response to surgery causes fluid to accumulate, which increases pressure within the joint and surrounding tissues, leading to stiffness. Effectively managing this inflammation is a necessary prerequisite for successful and productive movement sessions.
Non-pharmacological methods are important for reducing swelling, most notably the principles of Rest, Ice, Compression, and Elevation (RICE). Consistent application of ice packs for about 15 to 20 minutes several times a day constricts blood vessels, directly reducing inflammation and providing a temporary numbing effect. Elevating the leg above the level of the heart encourages fluid to drain away from the surgical site, minimizing fluid build-up.
Wearing a compression garment or bandage helps to physically restrict the amount of swelling that can occur in the soft tissues around the joint. Furthermore, timing pain medication, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or prescribed analgesics, to be active approximately 30 minutes before an exercise session can significantly improve the quality and intensity of the movement. Reducing the discomfort allows the patient to push gently into the stretching phase, which is necessary for regaining tissue length.
Typical Timeline and Milestones for Recovery
Setting realistic expectations for knee recovery involves understanding the general benchmarks for restoring movement. In the first week after surgery, the immediate goal is to establish a strong foundation, often targeting at least 90 degrees of flexion, which is enough movement for basic activities like sitting and walking. Simultaneously, achieving full knee extension, or zero degrees, is a persistent and high-priority goal from day one.
As recovery progresses into weeks two and three, the goal for knee flexion typically increases to 100 degrees, while maintaining full extension remains paramount. This early period is often referred to as a “window of opportunity” because the tissues are most amenable to stretching and regaining length before significant scar tissue fully matures. Consistent daily effort during this time is particularly effective in preventing long-term stiffness.
By weeks four to six, patients should aim to be approaching or achieving between 110 and 120 degrees of flexion, which is considered a functional benchmark for most daily activities. While most substantial range of motion gains occur within the first three months, the knee will continue to improve in strength and endurance for up to a year after the procedure. Consistent adherence to the exercise program allows the joint to settle into its new functional range.
Interventions for Persistent Stiffness
In some cases, despite diligent rehabilitation efforts, a significant plateau in range of motion can occur, often due to a condition known as arthrofibrosis, which is the excessive formation of scar tissue inside the joint. This dense, fibrous tissue acts as a physical barrier, preventing the knee from bending or straightening fully. When standard physical therapy fails to produce measurable progress over several weeks, more aggressive, medically supervised interventions may be necessary.
Advanced Physical Therapy
Advanced physical therapy techniques can include specialized joint mobilization performed by a therapist or the use of dynamic splinting, which applies a prolonged, low-load stretch to the joint over several hours a day.
Manipulation Under Anesthesia (MUA)
If non-surgical methods prove ineffective, the surgeon may recommend a procedure called Manipulation Under Anesthesia (MUA). During an MUA, the patient is placed under general anesthesia, and the surgeon manually moves the knee through a full range of motion to physically break up the internal scar tissue adhesions. This intervention is typically most effective when performed within the first few months following the initial surgery, before the scar tissue becomes too mature and rigid.