Rotator cuff surgery is a common orthopedic procedure performed to mend torn tendons in the shoulder, reattaching them to the upper arm bone, known as the humerus. During the repair, a specialized device called a surgical anchor is used to secure the tendon back to its bony attachment site. The number of anchors used in any given surgery is not fixed; instead, it is highly dependent on the surgeon’s chosen technique and the specifics of the patient’s injury. This hardware creates the initial, stable connection necessary for the body’s natural healing process to succeed.
The Role and Types of Surgical Anchors
A surgical anchor is a small implant designed to secure sutures directly into the bone, providing fixation for the torn tendon. The anchor is inserted into the humeral head, and the attached high-strength sutures are then passed through the tendon tissue to pull and hold the tendon against the bone’s surface. This stable reattachment minimizes gap formation and withstands the mechanical stresses of the early post-operative period until biological healing occurs.
Anchors are primarily categorized by their material composition. Bioabsorbable anchors are made from polymer materials, such as poly-L-lactic acid (PLLA) or biocomposites, which slowly dissolve and are replaced by bone over time. Non-absorbable anchors, often made of titanium metal or polyetheretherketone (PEEK), are permanent implants that remain in the bone indefinitely. Fixation mechanisms include threaded, screw-in anchors that engage the bone, and non-threaded or all-suture anchors, which use a smaller insertion hole and rely on an expansion mechanism to achieve fixation.
Clinical Factors That Determine Anchor Usage
The total number of anchors is tailored to the unique characteristics of each patient’s tear. A primary determinant is the size and geometry of the tendon tear; larger or more complex tears require more fixation points to fully cover the bone footprint. For instance, a small, crescent-shaped tear may only require one or two anchors, while a massive tear could necessitate four or more.
The degree of tendon retraction also influences the repair strategy and anchor placement. If the tendon is under high tension when pulled back to the bone, the surgeon may use more anchors to distribute the load and prevent pullout failure. The quality of the patient’s bone, specifically the bone mineral density, also plays a role. Poor or osteoporotic bone may require specialized anchors or a greater number of anchors to achieve adequate pullout strength. The specific location of the tear, such as whether it involves the supraspinatus or infraspinatus tendons, can also influence the number and positioning of the implants.
Surgical Techniques and Associated Anchor Counts
The repair technique chosen by the surgeon is the primary factor determining the final anchor count. The single-row (SR) repair is common for smaller tears, securing the tendon edge directly to the bone using a single line of anchors. This technique typically involves two to three anchors placed along the margin of the tear, aiming for sufficient fixation with minimal hardware.
For larger or more retracted tears, a double-row (DR) repair is often selected. This method creates a wider area of contact between the tendon and the bone, improving fixation strength. The double-row technique involves placing a medial row of anchors closer to the joint and a lateral row further out on the humerus, using a total of four to six anchors. This configuration aims to restore the natural tendon footprint more completely.
A variation is the Transosseous Equivalent (TOE) or Suture Bridge technique. This method also uses a medial and a lateral row of anchors, totaling four to six, but employs a different suture pattern. The sutures from the medial anchors are passed over the tendon and secured to the lateral anchors, creating a broad, compression-like “bridge” over the entire tendon-to-bone interface. This bridging effect maximizes the pressurized contact area, which is theorized to promote better biological healing.
Post-Surgical Healing and Anchor Longevity
The surgical anchor’s immediate function is mechanical, providing the initial stability required to hold the tendon securely against the bone. Over the first few weeks and months following surgery, the biological process of tendon-to-bone healing, called the enthesis, begins. The anchors maintain their hold throughout this period, minimizing motion at the repair site that could disrupt new tissue formation.
The long-term fate of the anchor depends on its material composition. Permanent anchors made of PEEK or metal remain inert in the bone for the patient’s lifetime. Bioabsorbable implants are engineered to slowly lose mechanical strength and break down through hydrolysis. This degradation process takes six to eighteen months, with the polymer material being gradually replaced by native bone tissue. Even after two years, some biocomposite anchors may still be partially visible on imaging, though they have lost most of their original structure.