Ability to Retension Knotless Suture Anchors: A Biomechanical Analysis of Simulated Bankart Lesions

Abstract

Background: Knotless suture anchors are gaining popularity in arthroscopic glenohumeral labral repairs. The ability to retension knotless designs after initial anchor placement has been reported; however, no studies have quantified this claim or investigated the biomechanical consequence of retensioning. Purpose/Hypothesis: To determine whether knotless and knotted suture anchors have biomechanical or anatomic differences with regard to labral repairs and to determine whether retensioning of knotless suture anchors affects capsular tension, labral height, and capsular shift. We hypothesized that retensioning of knotless anchors would result in improved capsular tension compared with conventional knotted suture anchors. Study Design: Controlled laboratory study. Methods: A total of 18 fresh-frozen cadaveric shoulders with a mean age of 56 years were dissected to the capsule and disarticulated at the humeral capsular insertion. The scapula was potted and placed in a custom shoulder simulator to tension the capsule via braided sutures localized to the anteroinferior glenohumeral ligament. Specimens were randomized into 3 groups: (1) Knotted (KT), (2) Knotless with end retensioning (KLend), and (3) Knotless with stepwise retensioning (KLstepwise). All repairs were completed using all-suture anchors placed at the 5-, 4-, and 3-o’clock positions. KLstepwise was used to simulate an intraoperative technique. Resultant mean capsular tension under 5 mm of displacement (subfailure loading) was measured for each anchor placement and retensioning step. Labral height and capsular shift were measured using a MicroScribe digitizer. Results: The intact, defect, 1-anchor, 2-anchor, and 3-anchor tensions were not significantly different between the KT and KLend groups. For the latter, retensioning of all knotless anchors increased capsular tension by 2.1 N compared with its 3-anchor state, although this was not statistically significant ( P = .081). The KLstepwise group explored an alternative method to retension the capsule using knotless anchors, with similar final capsular tensions compared with the other groups. All repairs had similar improvements in capsulolabral height and superior capsular shift. Conclusion: Knotted and knotless suture anchors provided similar overall restorations in anteroinferior glenohumeral ligament tension. However, knotless devices were capable of small but statistically insignificant improvements in capsular tension with retensioning. Clinical Relevance: Retensioning of knotless anchors allows the surgeon to tighten regions of the glenohumeral capsule that remain lax after repair.

Knotless Tensionable Anchors: Versatility, Tips, and Tricks

“…Using a smaller diameter anchor decreases the bony footprint required for fixation, increasing the opportunity for multiple points of fixation within the existing surface area of bone−soft-tissue interface. This implant has not only proven to be a good resource, achieving satisfactory results at short-term outcomes in Bankart repair, 16 it has also proven other benefits from its versatility, such as technical improvements with its retensioning ability, 17 and its novel implementation as an alternative for posterior meniscal root repair. 18 In conclusion, the use of a knotless tensionable anchor is a versatile, precise, and reproducible tool to address different scenarios in arthroscopy surgery.…”

Biomechanical Analysis of Anteroinferior Bankart Repair Anchor Types

“…However, another study on Bankart lesions by Nho et al, 31 evaluating 15 cadaveric shoulders in 2010, found that the load required to produce 2 mm of gapping was significantly less for knotless anchors (35.0 6 12.5 vs 66.5 6 21.7 N, respectively; P = .02), which was also found by Sileo et al 39 in 2009. It is also possible that with time, the technology of both knotless and knotted anchors has improved and become consistent and more equivalent, as more recent studies in 2011, 35 2020, 20 and 2022 24 have each detected no biomechanical differences. The present study found similar ultimate loads to failure, stiffness, and cyclic elongation among the tested anchors, along with other biomechanical properties.…”

“…23 Moreover, many studies have found minimal differences between the 2 constructs. 20,24,35 There are also mixed data on newer all-suture anchors, which have been investigated in rotator cuff repair, biceps tenodesis, and labral repair around the shoulder. 3,4,15,20,29 Also, 2 recent studies have evaluated the insertion position, depth, and angle for all-suture anchors in the glenoid to provide superior stability and fixation of labral repair, 21,36 and another has shown minimal biomechanical differences between knotless and knotted all-suture anchors.…”