When orthopedic injuries involve a torn ligament or tendon, the damaged soft tissue often needs to be reattached securely to the bone to promote healing. The modern solution for achieving this strong, stable connection is a specialized medical device known as a suture anchor. This small implant provides a reliable point of attachment within the bone, allowing the surgeon to precisely position and secure the torn tissue back to its anatomical location.
Defining the Suture Anchor
A suture anchor is an implantable device designed to act as a miniature toggle bolt or screw for the skeletal system. Its primary purpose is to provide a fixed point within the bone, which then allows attached suture material to secure soft tissue. The device is composed of two main elements: the anchor body, inserted directly into the bone, and the attached high-strength suture used to secure the torn tendon or ligament.
The anchor body often features a small hole or loop, called an eyelet, through which the suture is pre-loaded by the manufacturer. Once the anchor is seated, the eyelet ensures a fixed connection between the implant and the suture, preventing slippage. This design allows the surgeon to pull the torn soft tissue tightly against the bone surface, creating the compression necessary to encourage biological healing. The anchor stabilizes the repair site, which is important in joints subjected to frequent movement.
The Mechanics of Fixation
The implantation of a suture anchor begins with the creation of a precise pilot hole in the bone at the desired fixation site. This hole is drilled to a specific depth and diameter, often using a specialized guide to ensure accurate placement and to preserve the surrounding bone stock. The anchor is delivered into this prepared site via an insertion tool, which is removed once the anchor is fully seated, leaving the implant and its attached sutures behind.
Fixation is achieved through several mechanical principles, depending on the anchor’s design. Screw-in anchors feature threads that engage the bone tissue, providing purchase through mechanical interlocking. Non-threaded anchors, often called push-in or barbed anchors, rely on an interference fit or deployable fins that expand or toggle once inside the bone. These mechanisms resist pullout forces by creating a large surface area of contact with the inner bone wall. A contemporary design is the all-suture anchor, which consists of only a small sheath and a suture, requiring a smaller pilot hole. Fixation is achieved when tension on the suture causes the sheath to compress and expand against the bone’s inner cortex.
Materials and Resorbability
Suture anchors are manufactured from biocompatible materials, categorized as either permanent or temporary. Non-resorbable, or permanent, anchors remain in the body indefinitely and are commonly made from metals like titanium or high-performance polymers such as Polyetheretherketone (PEEK). Titanium anchors offer high strength and pullout resistance, while PEEK provides a strong, non-metallic option that minimizes artifacts on postoperative magnetic resonance imaging (MRI) scans.
Bioabsorbable anchors are created from materials that the body’s natural processes break down and replace with native bone over time. These temporary anchors are composed of polymers like Poly-L-lactic acid (PLLA) or polyglycolic acid (PGA), which slowly hydrolyze over a period of months to a few years. Bio-composite anchors combine polymers with osteoconductive ceramics, such as beta-tricalcium phosphate (ß-TCP). This combination encourages new bone ingrowth into the anchor site as the material resorbs, leaving no foreign body behind once the soft tissue has healed.
Common Surgical Applications
Suture anchors are a standard tool across numerous orthopedic procedures, especially those performed using minimally invasive arthroscopic techniques. A primary application is the repair of the rotator cuff in the shoulder, where multiple anchors secure the torn tendon back onto the humeral head. This reattachment restores the tendon’s footprint and ensures sufficient contact pressure for healing.
Anchors are routinely used for labral repairs in the shoulder and hip, stabilizing the rim of cartilage surrounding the joint socket. For example, anchors re-fix the torn labrum to the glenoid bone in Bankart or SLAP tear repairs. Suture anchors are also implemented in ligament repairs in the knee, particularly for reattaching collateral ligaments like the medial collateral ligament (MCL) or lateral collateral ligament (LCL). Beyond major joints, they are employed in foot and ankle surgery, such as reattaching the Achilles tendon to the heel bone or stabilizing lateral ankle ligaments.