Following a major procedure like an ACL repair or a total knee replacement, stiffness and reduced mobility are common. This complication, where the knee does not regain its full range of motion, is often caused by the development of internal scar tissue, a condition medically termed arthrofibrosis. Understanding scar tissue formation and the available methods for addressing it is important for regaining full function and managing recovery effectively.
Understanding Scar Tissue Formation
Scar tissue is the body’s natural response to trauma and is a necessary part of the healing process after surgery or injury. When the knee joint is operated on, the body initiates a repair process that involves laying down fibrous connective tissue, primarily composed of collagen, to close the surgical site and repair internal structures.
When this process becomes excessive, an overgrowth of this collagen-rich tissue occurs inside and around the joint capsule, resulting in arthrofibrosis. This buildup of fibrous adhesions causes the joint capsule to thicken and contract, physically restricting the knee’s ability to bend (flexion) and straighten (extension). Symptoms include persistent stiffness, a painful mechanical block to movement, and a loss of range of motion that does not improve with standard rehabilitation.
Self-Managed Movement and Manual Techniques
Taking a proactive role through consistent, gentle movement is the most immediate way to influence scar tissue formation. The goal of self-managed movement is to stretch newly forming collagen fibers and encourage alignment that permits full joint mobility. This must be done consistently, often multiple times throughout the day, as directed by a physical therapist.
Low-impact exercises designed to increase range of motion are foundational. The heel slide is a common exercise performed while lying on your back, where you actively pull your heel toward your buttocks to work on flexion, sometimes using a strap or towel for gentle overpressure. To address extension, the prone hang involves lying face down with the foot of the surgical leg hanging off the edge of a bed or couch, allowing gravity to gently pull the knee into a straightened position.
Manual techniques can be applied directly to the incision site once the wound is completely healed and dry. Cross-friction massage, or scar massage, involves applying firm pressure directly on the scar and moving the skin side-to-side, perpendicular to the incision line. The pressure should be enough to move the skin over the underlying tissue without the finger sliding, helping to prevent adhesions between skin layers. Spending a few minutes on the entire incision can help desensitize the area and promote mobility of the underlying tissues.
Professional Physical Therapy Interventions
When home-based exercises are not enough to restore full range of motion, a physical therapist can employ specialized techniques to address deeper, more resistant scar tissue. These professional interventions are designed to apply targeted forces that are difficult or impossible to reproduce on your own.
Deep tissue mobilization and joint manipulation are manual, hands-on techniques performed by the therapist to restore flexibility to the joint capsule and surrounding soft tissues. The therapist applies gentle, controlled movements to the joint to help reduce tension, enhance blood flow, and stretch the restricted tissues contributing to stiffness. This process helps break down internal scar tissue and adhesions.
Instrument-Assisted Soft Tissue Mobilization (IASTM) uses specialized stainless steel tools to apply specific pressure and shear forces to the affected area. These instruments allow the therapist to detect and treat fascial restrictions and scar tissue more effectively than hands alone, potentially stimulating connective tissue remodeling. These advanced approaches, combined with specialized stretching protocols, are often necessary when traditional exercises fail to achieve the desired functional outcome.
Advanced Medical and Surgical Options
In cases where persistent stiffness and limited range of motion do not respond to intensive physical therapy, the physician may recommend more advanced medical and surgical procedures. These interventions are reserved for persistent arthrofibrosis that significantly impairs function.
A common medical approach is the use of steroid injections, administered directly into the joint to reduce localized inflammation and pain, creating a more favorable environment for physical therapy. For mature and dense scar tissue, a procedure called Manipulation Under Anesthesia (MUA) may be performed. The patient is placed under general anesthesia, and the surgeon forcefully moves the knee through its full range of motion, physically breaking the internal adhesions and scar bands.
If MUA is unsuccessful or the scar tissue is extensive, the surgeon may perform an Arthroscopic Lysis of Adhesions (ALA). This is a minimally invasive surgery where a camera (arthroscope) and specialized instruments are inserted into the joint to visually identify and surgically cut (lyse) the fibrous adhesions. ALA is often combined with MUA to maximize the breakdown and removal of scar tissue.