All-Suture Anchors in Rotator Cuff Repair

Introduction

• All-suture (soft) anchors were initially developed for labral repairs and have now gained widespread popularity in rotator cuff repair.

• Their increasing use is driven by advantages such as:

  • Smaller anchor size

  • Reduced bone footprint occupation

  • Ability to place more fixation points

  • Ease of insertion

  • Ease of revision surgery

• Clinical and biomechanical studies demonstrate that soft anchors perform equivalently to hard-body anchors.

• Perianchor cyst formation can occur with both soft and hard anchors.

• A near-vertical angle of insertion is ideal for soft anchor placement.

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Evolution of Suture Anchors

• First generation: Metal anchors

  • Durable but associated with imaging artifacts and difficulty during revision surgery

• Second generation: Polyether ether ketone or poly lactic acid anchors

  • Improved imaging compatibility

  • Bioabsorbable or inert materials

• Third generation: All-suture (soft) anchors

  • Minimal bone footprint

  • Excellent bone preservation

  • Easier revision options

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Design Characteristics of Soft Anchors

• Manufactured from:

  • Ultra-high molecular weight polyethylene

  • Braided polyester

• Structural components:

  • Repair sutures enclosed within a textile sheath

  • The sheath expands and anchors within bone

• Deployment mechanism:

  • Pulling the sutures causes the anchor to expand into Y-shaped, V-shaped, or spherical configurations

• Common sizes:

  • Labral repair: 1.3 to 1.8 millimeters

  • Rotator cuff repair: 1.8 to 3.2 millimeters

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Rationale for Using Soft Anchors in Rotator Cuff Repair

• Reduced violation of the tendon footprint, creating a better biological healing environment

• Ability to place more fixation points in a given area, improving:

  • Tendon-bone contact

  • Repair stability

• Faster insertion, especially with self-punching anchor designs

• Simplified revision surgery:

  • Hard anchors can be placed without removing existing soft anchors

• Less bone damage following anchor pullout compared to hard anchors

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Biomechanical Evidence

Labral Repair Models

• Studies demonstrate equivalent load-to-failure values between soft and hard anchors.

• Mazzocca and colleagues found no difference in failure strength between:

  • 2.4-millimeter hard-body anchors

  • 1.4-millimeter soft anchors

Rotator Cuff Repair Models

• Soft anchors measuring 1.5 millimeters demonstrated failure strengths exceeding 250 newtons, which is sufficient for rotator cuff repair.

• Multiple comparative studies show no significant difference in load-to-failure between soft and hard anchors.

• The Q-Fix soft anchor by Smith & Nephew demonstrated:

  • Similar tensile strength

  • Comparable gap formation when compared with hard anchors

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Double-Row Repair Biomechanics

• Studies by Goschka and Bernardoni showed that:

  • Soft anchors in the medial row combined with hard anchors in the lateral row produce biomechanical performance comparable to traditional constructs

• Hoffman and colleagues demonstrated that:

  • Three medial soft anchors produced contact pressures comparable to two medial hard anchors

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Perianchor Cyst Formation

Experimental and Clinical Evidence

• Early animal studies, such as those by Pfeiffer and colleagues, showed cavity formation around all-suture anchors, possibly due to micromotion.

• Perianchor cyst formation has since been observed with:

  • Soft anchors

  • Bioabsorbable anchors

  • Polyether ether ketone anchors

• Clinical studies:

  • Ro and colleagues reported cyst formation in 8.8 percent of soft anchors compared with 16.7 percent of bioabsorbable anchors

  • Kim and colleagues reported no cyst formation with soft anchors at a follow-up of fourteen months

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Factors Influencing Perianchor Cyst Formation

• Timing of magnetic resonance imaging:

  • Early imaging (around seven months) may demonstrate more fluid or cyst-like changes

  • These changes often decrease over time

• Angle of anchor insertion:

  • More horizontal insertion angles (approximately sixty-two degrees) are associated with increased cyst formation

  • More vertical insertion angles (approximately sixty-eight degrees or greater) reduce cyst risk

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Clinical Outcomes

• Overall clinical outcomes with soft anchors are excellent:

  • High healing rates (approximately seventy-one percent in published series)

  • Significant improvement in pain scores

  • Low retear rates (approximately one to two percent in several studies)

• Anchor settling toward the subchondral bone may occur:

  • This phenomenon has not shown clinical significance to date

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Importance of Angle of Insertion

• The traditional “deadman theory” proposed by Burkhart recommended insertion angles less than forty-five degrees for optimal pullout strength.

• More recent evidence supports a more vertical insertion angle, closer to ninety degrees, especially for soft anchors.

• Benefits of vertical insertion include:

  • Improved pullout strength

  • Reduced cortical bone damage (minimizing the “windshield-wiper effect”)

  • Lower rates of perianchor cyst formation

  • Reduced retear rates

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Key Recommendations

• Aim for a near-vertical anchor insertion angle to improve fixation strength and reduce cyst formation

• Soft anchors are particularly well suited for medial-row fixation in double-row rotator cuff repairs

• Bone density should be considered:

  • Anchors may settle deeper in high-density bone

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Limitations of Current Evidence

• Limited availability of long-term clinical outcome studies

• Significant variability in soft anchor design, meaning not all anchors perform identically

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Conclusion

• Soft anchors are biomechanically and clinically non-inferior to hard-body anchors.

• Key advantages include:

  • Preservation of bone stock

  • Ease of revision surgery

  • Ability to place multiple fixation points

• Current evidence suggests that concerns regarding perianchor cyst formation are largely not clinically significant.

• Surgical technique, particularly anchor insertion angle, plays a critical role in optimizing outcomes.