When a knee joint is surgically repaired, the operation is only the first step toward recovery. Physical therapy (PT) is the prescribed process that restores function and protects the surgical investment. Skipping this rehabilitation protocol directly undermines the procedure’s success, setting the stage for complications ranging from immediate discomfort to permanent disability. The body’s natural response to trauma must be managed through guided movement and strengthening exercises to ensure the knee returns to a functional state.
The Biological Necessity of Post-Operative PT
The body initiates a healing response following surgical repair, involving the deposition of collagen fibers that form scar tissue in damaged tissues like the joint capsule, tendons, and ligaments. Without controlled movement, these fibers form haphazardly, creating dense, restrictive bands called adhesions or contractures. PT provides the mechanical stress necessary to align developing scar tissues correctly, ensuring they heal with elasticity and length rather than forming a tight, stiff barrier.
Reduced activity after surgery causes rapid muscle atrophy, particularly in the quadriceps; muscle strength can diminish by 10 to 20% in the weeks following the procedure. PT combats this atrophy by introducing targeted, progressive strengthening exercises to stabilize the joint and support the new or repaired structures.
Acute Symptoms of Skipping Rehabilitation
Patients who forgo their prescribed physical therapy often experience a rougher and more prolonged initial recovery. The lack of movement impairs circulation, leading to increased post-operative pain and persistent swelling. Therapeutic exercises promote blood flow and lymphatic drainage, which are essential for reducing edema and delivering nutrients to the healing tissues.
A rapid loss of flexibility, known as a decrease in range of motion (ROM), is an immediate consequence of non-compliance. Without the gentle, consistent stretching provided by PT, the joint capsule and surrounding soft tissues tighten. This stiffness makes it difficult to achieve the ROM required for normal activities such as climbing stairs or sitting comfortably in a chair.
The resulting muscle weakness and joint stiffness quickly lead to significant gait abnormalities, commonly presenting as a persistent limp. The patient begins to favor the non-surgical leg, developing compensatory movement patterns that stress the hips, back, and opposite knee. This improper weight-bearing and instability increases the risk of falls or further injury due to a lack of coordinated muscle control.
Long-Term Functional Impairment and Revision Risk
The acute problems of stiffness and weakness solidify into chronic functional impairments if rehabilitation is abandoned. A severe long-term outcome is permanent contracture, often manifesting as a fixed flexion deformity, where the knee cannot fully straighten. This inability to achieve full extension alters the biomechanics of walking, requiring the patient to expend more energy with every step and resulting in chronic, uneven stress across the joint.
Chronic improper loading from an altered gait accelerates the wear and tear on the joint surfaces, even on a new prosthetic implant. This can lead to the early onset of secondary osteoarthritis in adjacent joints or premature loosening of the implant. Failure to restore normal muscle strength and joint stability also leaves the knee vulnerable to future injury.
If stiffness becomes severe, the solution may be Manipulation Under Anesthesia (MUA), an invasive procedure involving forcefully bending the knee to break up dense scar tissue. Skipping physical therapy can permanently compromise the quality of life, potentially leading to reliance on assistive devices and an inability to return to pre-injury activities.