The rotator cuff is a group of four muscles and their tendons that surround the shoulder joint, providing stability and allowing for movement. When one of these tendons tears, it often separates from its attachment point on the upper arm bone, the humerus. Rotator cuff surgery is a procedure designed to reattach this torn soft tissue back to the bone to promote healing and restore function. This repair requires specialized fixation devices, known as surgical anchors, which securely hold the tendon in place during the months-long healing process.
The Function of Surgical Anchors
Surgical anchors provide the high-strength fixation required to hold the detached tendon against the bone. Their primary mechanical purpose is to maintain a secure connection between the soft tendon tissue and the bone. This device is typically a small, screw-like structure or a plug inserted directly into the bone.
Once the anchor is seated, high-strength sutures pre-loaded into the device are passed through the torn edge of the rotator cuff tendon. The surgeon ties these sutures down, pulling the tendon tightly against the bone surface. This fixation creates the necessary environment for biological healing, allowing new tissue to grow and bridge the gap between the tendon and the bone. The strength of this construct resists the natural pull of the muscle while the patient begins the rehabilitation process.
Clinical Factors Influencing Anchor Quantity
The number of anchors used in a rotator cuff repair is customized based on the unique characteristics of the patient’s injury. The primary variable dictating anchor quantity is the size and geometry of the tendon tear. A small tear may require only one or two anchors to secure the edges, while a massive, retracted tear spanning multiple tendons necessitates a greater number to cover the entire defect.
The quality and density of the patient’s bone is another factor influencing anchor choice and quantity. Poor bone density (osteoporosis) can limit the holding power of each anchor, sometimes requiring the surgeon to place more anchors or use a different type of device to achieve adequate pull-out strength. If the tendon has pulled back significantly, a more extensive repair involving more anchors is needed to distribute tension across a wider area and minimize the risk of premature tearing.
The typical number of anchors used in a standard rotator cuff repair generally falls within a range of two to six, though the final count is determined during the intraoperative assessment. The goal is to achieve a stable, anatomically correct repair tailored to the severity of the injury.
Single-Row Versus Double-Row Repair Techniques
The decision between a single-row and a double-row repair technique is the most significant factor determining the final anchor count, based on the tear’s size and tendon tissue quality. The single-row technique is a traditional approach, placing anchors in a single line along the outer edge of the humerus. This technique typically uses a lower number of anchors, often two or three, and is preferred for smaller tears or those where the tendon is not significantly retracted.
The double-row technique employs a greater number of anchors arranged in two parallel lines across the bony footprint. This configuration commonly uses four to six anchors, divided between a medial row (closer to the joint) and a lateral row.
The double-row repair is favored for larger or massive tears because it creates a wider contact area, effectively restoring the tendon’s natural attachment site, or “footprint,” more completely. Biomechanical studies have shown that this two-row construct offers improved strength and a decreased risk of the tendon pulling away from the bone in the early healing phase.
Anchor Materials and Resorption
Surgical anchors are manufactured from two primary material types: non-absorbable and absorbable. Non-absorbable anchors are made from permanent materials, such as medical-grade titanium or Polyetheretherketone (PEEK). These anchors remain permanently in the bone after the tendon has healed, providing a lifelong fixation point.
The alternative is the absorbable, or bio-resorbable, anchor, typically composed of polymers like poly-L-lactic acid (PLLA) or biocomposite materials. These materials are engineered to gradually break down within the body over months to years. As the anchor dissolves, it is replaced by the patient’s own bone, which grows into the space the anchor once occupied.
Surgeons choose absorbable anchors to leave less foreign material behind. While permanent anchors offer proven fixation strength, the bio-resorbable option is popular as it removes the potential for hardware-related issues, such as imaging artifacts or interference with future procedures.