Arthroscopic Treatment of Anterior Shoulder Dislocation Using Knotted and Knotless Anchors

The shoulder is the joint that most commonly suffers dislocation, and anterior instability is the most frequent form. The overall incidence of first-time dislocations requiring closed reduction is 23.1 per 100,000 people/year, with a higher incidence in males and Caucasians. Individuals with a younger age at first dislocation show a higher rate of recurrence.

Arthroscopic repair is the gold standard for the treatment of recurrent shoulder dislocation, with similar outcomes to open repair. The technique is less aggressive because the tendon of the subscapularis does not need to be addressed, leading to shorter hospital stays, less scarring, earlier return to normal activities, and a greater postoperative range of motion.

In this technique, the glenoid labrum-ligament complex (GLLC) is repaired using bone anchors that can be metallic, absorbable, or flexible. Biomechanical studies have shown that these three types of anchors are similar in terms of cyclic loading resistance and bone fixation. Absorbable anchors are most frequently used because metallic anchors can cause postoperative imaging interference in MRI study, can migrate and became loose or break, which can damage the articular cartilage. Flexible anchors when submitted to cyclic stress can produce cystic cavities in bone tissue attachment 21, and probably can lead to a failure of glenoid labrum-ligament complex suture.

The most commonly used technique is the attachment of GLLC with knotted anchors. Studies have shown to perform an arthroscopic knot is challenging and can be technically difficult. The knot volume can produce friction during the shoulder movement, leading joint discomfort and cartilage damage. The quality of the soft tissue healing depend on the knot quality too. The dislocation recurrence rate with this technique ranges from 4% to 19%.

In 2001, Thal introduced the concept of tissue fixation using knotless anchors and its applicability for GLLC lesions. Although this new technique had solved the difficulty of tying knots, the results regarding the GLLC suture shown more gap formation between this complex and the glenoid bone, delayed anchor loosening and postoperative arthropathy. The recurrence rate is high associated with perianchor radiolucency.The recurrence rate with this technique is as high as 23.8%.

Some researchers have published studies using knotless anchors and have compared this technique to the use of knotted anchors, demonstrating similar reconstruction of labral height and functional outcomes, while the recurrence rate is still contradictory. To date, there are no prospective randomized controlled clinical trial comparing these two techniques of GLLC repairs.

Our researchers aims to compare clinical outcomes and imaging evaluation of patients undergoing GLLC repair arthroscopically with the use of absorbable knotless and knotted anchors.

Inclusion criteria

• Skeletal maturity;
• Anterior glenohumeral instability;
• Previous labral lesion without bone defects or with defects that affect no more than 20% of the anteroposterior diameter of the glenoid, as shown by MRI;
• Instability severity index score (ISIS) < 4;

Non-Inclusion Criteria

• Epilepsy;
• Associated rotator cuff tear;
• Proximal humeral fracture;
• Multidirectional or posterior instability by clinical evaluation;
• Generalized ligamentous laxity by clinical evaluation;

Exclusion criteria

• Irreparable injury to the anterior capsule or injury to the humeral insertion of the inferior glenohumeral ligament;
• Glenoid bone defect greater than 20% of the anteroposterior diameter measured by arthroscopy;
• Rotator cuff tear found on arthroscopy;
• Abandonment of the rehabilitation program and follow-up before the first evaluation of outcomes