Recovery from anterior cruciate ligament (ACL) reconstruction is a long process often complicated by stiffness and limited joint mobility. This persistent loss of range of motion results from the body’s healing response inside the knee joint. The stiffness is caused by the formation of excessive internal scar tissue, which acts as a mechanical restraint to the knee’s ability to fully bend or straighten. Addressing this internal scarring is necessary to regain full function after surgery.
Understanding Post-Surgical Stiffness
The medical term for excessive scar tissue formation within a joint is arthrofibrosis. It represents an overzealous healing response where the body produces too much fibrous material inside the joint capsule and surrounding soft tissues. This process involves the proliferation of fibroblasts, which synthesize extracellular matrix proteins, primarily collagen.
Instead of aligning neatly, these collagen fibers are deposited in a dense, disorganized, and contracted pattern, forming stiff adhesions. These fibrous bands act like internal tethers, physically blocking the smooth gliding motion of the joint surfaces. Arthrofibrosis often develops when there is a prolonged inflammatory state in the knee after trauma or surgery.
The presence of this condition is indicated by persistent symptoms extending beyond the expected recovery timeline. The most noticeable symptom is a painful, mechanical block to knee movement, particularly the inability to achieve full extension or full flexion. This persistent loss of range of motion limits daily activities and suggests that excessive scar tissue is physically impeding the joint.
Non-Surgical Techniques for Breaking Up Scar Tissue
Physical therapy is the primary approach for mechanically breaking down and remodeling the dense collagen fibers that cause stiffness. These interventions focus on applying controlled stress to the scar tissue to encourage its realignment and breakdown into more flexible, functional tissue. Consistency and sustained effort are necessary for these techniques to effectively remodel the internal structures.
Manual Therapy and Tissue Mobilization
A physical therapist may utilize deep tissue massage techniques, such as cross-friction massage, to target restricted areas. This method involves applying firm pressure perpendicular to the scar tissue fibers, often near the incision site. The friction helps mechanically disrupt the disorganized collagen bonds and stimulates localized blood flow, initiating tissue remodeling.
Joint mobilization is another technique performed by a therapist to restore normal movement between the joint surfaces and soft tissues. The therapist applies skilled, passive movements to the joint, which helps free up restricted tissues and improve the mobility of the kneecap and joint capsule. These manual techniques address deep adhesions that may not be accessible through simple stretching alone.
Active and Passive Range of Motion
High-load, low-speed stretching protocols are a cornerstone of non-surgical scar tissue management. These protocols use a sustained, gentle force over an extended period to induce “creep,” where stiff tissues slowly elongate and remodel. An example is the prone hang, where the patient lies face down with the lower leg hanging off a surface, allowing gravity to slowly stretch the knee into full extension.
For knee extension, a small ankle weight can be added to increase the low-level load, and the stretch is typically held for several minutes, often progressing up to 15 minutes per session. Similarly, exercises like heel slides are performed slowly to push the boundary of flexion, holding the deepest point of the bend to apply sustained tension. These sustained stretches are more effective than quick, bouncy movements because they allow the dense collagen to adapt and lengthen.
Modalities
Applying heat to the knee prior to stretching and manual therapy sessions can enhance treatment effectiveness. Heat increases the temperature of the underlying soft tissues, which temporarily improves the elasticity and extensibility of the collagen fibers. This makes the scar tissue more receptive to mechanical stresses, helping achieve greater gains in range of motion.
In some rehabilitation protocols, a Continuous Passive Motion (CPM) machine is employed immediately following surgery to prevent adhesion formation. This motorized device moves the knee through a prescribed range of motion without requiring muscle effort from the patient. While the use of a CPM machine is debated, some studies show it can reduce the likelihood of severe arthrofibrosis requiring later surgical intervention.
When Surgical Intervention is Necessary
If non-surgical treatment fails to restore functional range of motion after several months of intensive physical therapy, surgical intervention may be required. These procedures are reserved as a last resort when conservative methods have plateaued. The two primary surgical methods are Manipulation Under Anesthesia (MUA) and Arthroscopic Lysis of Adhesions (LOA).
Manipulation Under Anesthesia (MUA)
MUA involves the orthopedic surgeon forcefully moving the knee through its full range of motion while the patient is unconscious. This controlled, high-force maneuver is designed to break up the internal scar tissue and adhesions restricting movement. MUA is often the preferred initial surgical choice due to its minimally invasive nature and lower cost compared to an open procedure.
Arthroscopic Lysis of Adhesions (LOA)
LOA is a more direct surgical approach where the surgeon uses a camera and specialized instruments to enter the joint and physically cut away the restrictive bands of scar tissue. This allows for the precise removal of adhesions and is often necessary when the scar tissue is thick, dense, or located in areas like the intercondylar notch. Both surgical options demand an immediate, aggressive post-operative physical therapy regimen to prevent the rapid recurrence of scar tissue, which can quickly negate the surgical gains.