Knotted Anchors Research Articles

Poster 111: Biomechanical Analysis of Anteroinferior Bankart Repair Anchor Types: Has Technology Surpassed Surgeon Technique?

Objectives: To limit risk of recurrent dislocation, subsequent injury, and more complex surgeries, it is critical to understand the best techniques to repair a soft-tissue Bankart lesion in the setting of minimal bone loss. To the authors’ knowledge, there is no current biomechanical data comparing tensionable knotless all-suture anchors to knotted all-suture anchors and hardbody knotless anchors in labral repair constructs. Therefore, the purpose of this study was to perform a quantitative biomechanical comparison of three labral fixation devices for soft-tissue Bankart lesions: soft body tensionable knotless anchor (SB knotless), knotted soft body anchor (SB knotted), knotless interference polyetheretherketone (PEEK) hardbody anchor (HB knotless). The authors hypothesized that the three anchor types would exhibit similar biomechanical properties including elongation, failure load, and stiffness but that the SB knotless would display different failure mechanisms from the SB knotted and HB knotless anchors. Methods: Twenty-one glenoid cadavers were randomized to 3 groups: SB knotless (Arthrex 1.8mm FiberTak Knotless All-suture Anchor), SB knotted (Arthrex 1.8mm FiberTak Knotted single loaded All- Suture Anchor), and HB knotless (Arthrex 2.9mm PushLock Knotless PEEK anchor). The humeral head was disarticulated and artificial Bankart lesions were created at the anteroinferior (AI) labrum. Anchors were placed at the 3:30, 4:30, and 5:30 positions, and sutures were passed through 1cm of tissue (Figure 1). Knotted anchors were tied with five square knots. Anchors were tested simultaneously as one construct by pulling the capsular tissue connected to the AI quadrant. Cyclic loading (5-25 N, 100 cycles) was followed by load-to-failure testing (15mm/min). Mechanical testing variables were collected, and failure mechanisms were recorded per individual anchor. Statistical comparisons were made among groups including ANOVA for normally-distributed continuous variables, Kruskal-Wallis for non- parametric continuous variables, and Fisher’s Exact test for categorical variables. Results: There were no significant differences among groups in cadaveric age (p = 0.43), body mass index (p = 0.42), bone mineral density (p = 0.84), laterality (p = 0.26), or sex (p = 0.098). There was no significant difference between groups in cyclic elongation measured from the first to last cycle during cyclic loading (p = 0.40). Ultimate load to failure between SB knotless (309.7 ± 125.6 N), SB knotted (226.40 ± 34.8 N), and HB knotless (256.5 ± 90.5 N) did not significantly differ (p = 0.25) (Table 1). Failure mechanisms significantly differed among groups; mechanisms included anchor pull-out (SB knotless 33.3%; SB knotted 23.8%; HB knotless 28.6%), suture pull-through (SB knotless 66.7%; SB knotted 38.1%; HB knotless 33.3%), and anchor fixation failure, defined as knot failure for knotted anchors or locking mechanism failure for knotless anchors (SB knotless 0%; SB knotted 38.1%; HB knotless 38.1%, p = 0.008) (Figure 2). Conclusions: The SB knotless, SB knotted, and HB knotless labral fixation anchors studied exhibit comparable elongation during cyclic loading, stiffness, and ultimate loads to failure. However, the SB knotless anchor avoids the risk of knot failure and interference failure inherent to SB knotted and HB knotless interference anchors, respectively. This data supports the benefit of SB knotless anchors for anteroinferior labral repair in limiting knot failure seen with knotted anchors and perhaps demonstrating that all- suture anchors may have better locking mechanism quality than their PEEK counterpart. How and if these mechanical properties of the anchors correlate with clinical results for soft-tissue Bankart repair requires further investigation, and likely one with high power from multi- center studies to detect if subtle differences exist. [Table: see text]

Biomechanical Analysis of Anteroinferior Bankart Repair Anchor Types

Background: All-suture anchors and knotless anchors are increasingly used in the repair of anteroinferior labral tears in patients with shoulder instability. Optimal repair constructs may limit recurrent instability. Purpose: To perform a quantitative biomechanical comparison of 3 labral fixation devices for soft tissue Bankart lesions: knotless soft-body tensionable anchor (SB knotless), knotted soft-body anchor (SB knotted), and knotless hard-body PEEK (polyether ether ketone) interference anchor (HB knotless). Study Design: Controlled laboratory study. Methods: A total of 21 glenoid specimens were randomized into 3 groups: SB knotless, SB knotted, and HB knotless. Artificial Bankart lesions were created at the anteroinferior labrum. Anchors were placed at the 3:30, 4:30, and 5:30 clockface positions, and sutures were passed through 1 cm of tissue. Anchors were tested simultaneously as one construct by pulling capsular tissue connected to the anteroinferior quadrant. Cyclic loading (5-25 N, 100 cycles) was followed by load-to-failure testing (15 mm/min). Biomechanical testing variables were collected, and failure mechanisms were recorded per individual anchor. Results: There were no differences in baseline specimen characteristics. There was no difference in elongation during cyclic loading (P = .40). The ultimate load to failure between SB knotless (309.7 ± 125.6 N), SB knotted (226.4 ± 34.8 N), and HB knotless (256.5 ± 90.5 N) did not significantly differ (P = .25). Failure mechanisms differed among groups (P = .008); mechanisms included anchor pullout (SB knotless: 33.3%; SB knotted: 23.8%; HB knotless: 28.6%), suture pull-through (SB knotless: 66.7%; SB knotted: 38.1%; HB knotless: 33.3%), and anchor fixation method failure, defined as knot failure for knotted anchors or locking mechanism failure for knotless anchors (SB knotless: 0.0%; SB knotted: 38.1%; HB knotless: 38.1%).) Conclusion: The SB knotless, SB knotted, and HB knotless labral fixation anchors studied exhibited comparable elongation during cyclic loading, stiffness, and ultimate loads to failure in a cadaveric model. However, the failure mechanisms significantly differed, as SB knotless anchors failed primarily from suture pull-through, while SB knotted and HB knotless anchors were subject to knot failure and locking mechanism failure, respectively. Clinical Relevance: These data support the benefit of SB knotless anchors for anteroinferior labral repair in limiting knot failure typically seen with knotted anchors, perhaps demonstrating that all-suture anchors may have better locking mechanism quality than their PEEK counterparts.

Paper 59: Comparison of Knotless versus Knotted Suture Anchors in the Arthroscopic Management of Adolescent Shoulder Instability

Objectives:Shoulder instability among adolescent athletes remains a complex challenge with high recurrence rates. Knotted suture anchors have provided consistently reliable biomechanical and clinical results. In recent years, the advent of the knotless suture anchor technology has come with proposed advantages of minimizing technical difficulty and knot migration, as well as reducing subsequent intra-articular cartilage irritation and damage. While several studies have analyzed the utility of knotless suture anchors in the adult population, to our knowledge, there has not been a direct comparison within this more at risk for surgical failure adolescent population. The purpose of this study was to compare the effect of knotted versus knotless suture anchor use on postoperative outcomes of arthroscopic shoulder instability surgery in the adolescent athlete.Methods:A multicenter comparative cohort was conducted of patients that underwent primary arthroscopic shoulder labral repair with suture anchor implants for shoulder instability between June 2015 and November 2017. Additional inclusion criteria included patient age <20 years and minimum follow up duration of 3.5 years. Data collected included demographics, number and type of suture anchor (knotted or knotless), number of instability events, type of instability, and presence of bony Bankart lesions. All included patients had <20% glenoid bone loss at the time of surgery. Type of instability was also recorded and was classified as either: anterior, posterior, or multidirectional (MDI). The primary outcome measure was surgical failure, which was defined as any recurrent instability event post-surgery. Incidence of secondary surgery (including revision or need for additional procedure), surgical times, and return to sport (RTS) data were also recorded. Patient-reported outcomes were evaluated using the Pediatric and Adolescent Shoulder Survey (PASS), SANE (Single Assessment Numeric Evaluation) scores, and the Quick version of Disabilities of the Arm, Shoulder and Hand (QuickDASH) survey.Results:Eighty-eight shoulders (54 male, 34 female) from 84 patients met inclusion criteria and were analyzed. 43 received knotless anchors and 45 received knotted anchors. Mean follow-up duration was 4.5 years (range, 3.5-6 years) for the knotless cohort and 4.8 years (range, 3.7-5.8 years) for the knotted cohort. Demographics and type of instability by suture anchor type is shown in Table 1. Surgical failure rate was significantly lower in the knotless cohort (knotless, 16%; knotted, 53%; P<.001). Patients with knotless suture anchors reported significantly higher mean PASS scores (knotless, 90.2; knotted, 81.3; P=.002). There was no difference in both RTS rates (knotless, 86%; knotted, 68%; P=.055) and incidence of repeat surgery between cohorts (knotless, 9%; knotted, 13%; P=.551).Surgical times, SANE scores, and QuickDASH scores were available for approximately three-quarters of shoulders (total, 65; knotless, 36; knotted, 29) in the cohort. Mean surgical time was approximately 18 minutes shorter for knotless anchors (knotless, 84.4 minutes; knotted, 102.7 minutes; P<.001). SANE scores were significantly higher in the knotless group (knotless, 88.8; knotted, 74.3; P=0.004). QuickDASH scores, of which a lower score is considered a better outcome, were not different (knotless, 5.7; knotted, 11.4; P=.063).Conclusions:Our initial intent was to demonstrate that knotless anchors would be just as successful as labral repairs with knotted anchors, but our results indicate several promising advantages, including: better patient reported outcome measures (PASS and SANE scores), reduced surgical times, and lower failure rates at a mean 4.5 years. There were some non-significant differences in the two cohorts regarding the type of instability that likely contributed to the differences in the number of anchors utilized. Future studies with larger sample sizes may serve to confirm our observed benefits associated with knotless anchors. In summary, the utilization of knotless suture anchor constructs for the repair of labral tears in adolescent shoulder instability may be safely considered with potentially improved outcomes over knotted anchors.Table 1.Demographic characteristics of included patients

Knotless PEEK and double-loaded biodegradable suture anchors ensure comparable clinical outcomes in the arthroscopic treatment of traumatic anterior shoulder instability: a prospective randomized study

PurposeTo compare the clinical outcome of arthroscopic capsulolabral repair for traumatic anterior shoulder instability with PEEK knotless and knotted biodegradable suture anchors.MethodsArthroscopic stabilization was performed in 78 patients with recurrent traumatic anterior shoulder instability. They were divided into 2 groups of 39 patients each, according to suture anchors used: knotless PEEK anchors in group 1, and biodegradable anchors in group 2. Exclusion criteria were: instability without dislocation, posterior or multidirectional instability, glenoid bone loss > 20%, off-track lesions, concomitant rotator cuff tears and previous surgery. The primary outcome was the Disabilities of the Arm, Shoulder and Hand (DASH) self-administered questionnaire. Secondary outcomes were: Work-DASH, Sport-DASH, Rowe score, recurrent instability and subsequent surgery. The following independent variables were considered: age, gender, dominance, generalized ligamentous hyperlaxity, duration of symptoms, age at first dislocation, number of dislocations, type of work, type of sport, sports activity level, capsule-labral injury pattern, SLAP lesion and number of anchors. Differences between groups for numerical variables were analyzed by use of the Student’s t-test or Mann–Whitney U-test. Fisher’s exact test was used for analysis of categorical variables. Significance was set at p < 0.05.ResultsSeven patients (9%) were lost at follow-up, 5 from group 1 and 2 from group 2. Follow-up ranged from 36 to 60 months (median: 44; IQR: 13). Comparison between groups did not show significant differences for each independent variable considered. No differences could be found either for DASH (n.s.) or Rowe (p = n.s.) scores between the two groups. Overall recurrence rate was 7%. Three re-dislocations were reported in group 1 and two in group 2 (n.s.). Only one patient in each group underwent re-operation.ConclusionsThe study showed no significant differences in clinical outcomes after arthroscopic treatment of traumatic anterior shoulder instability using PEEK knotless or biodegradable knotted anchors at mid-term follow-up.Level of evidenceI.

Arthroscopic Labral Repair Using Knotless Suture Anchors in the Setting of a 270° Labral Tear of the Shoulder

Extensive glenoid labral tears, whether the result of repetitive instability or first-time dislocation, compromise the mechanical stability of the glenohumeral joint due to disruption of the anterior, inferior, posterior, and/or superior portions of the labrum. These lesions often result in recurrent multiplanar instability and pain that is nonresponsive to conservative management and difficult to diagnose due to variability in clinical presentation and advanced imaging findings. Arthroscopic repair techniques to address symptomatic shoulder instability have showed positive patient-reported outcomes, low failure rates, and high return-to-sport rates. The evolution of knotless suture anchors offers a fixation method that has proven to be functionally equivalent to knotted suture anchors while avoiding the risks of knotted anchors (knot loosening, knot migration, articular abrasion) and allowing easier placement and decreased operative time. The purpose of this technique is to describe our preferred method to treat a 270° labral tear through arthroscopic knotless anchor repair and demonstrate the expanded application of this technique for extensive glenoid labral pathology.

Biomechanical analysis of arthroscopically assisted latissimus dorsi transfer fixation for irreparable posterosuperior rotator cuff tears-Knotless versus knotted anchors.

We compared the construct stability of traditional knotted techniques with modern knotless anchor systems used in arthroscopically assisted latissimus dorsi transfers (aLDTs) for irreparable posterosuperior rotator cuff tears. Eighteen cadaveric shoulders were age- and gender-matched to the following three groups: knotted group (two knotted anchors); knotless group (two knotless anchors); and triple anchor group (two knotless anchors; one all-suture anchor at the apex of the humeral head). All tendons were cyclically loaded in line of the aLDT over 400 cycles followed by a load to failure test. Outcome measures were the ultimate load to failure, elongation, construct stiffness, and failure modes. The triple anchor group revealed the highest ultimate load to failure (431 ± 78 N) compared with the knotted (326 ± 52 N; p = .022) and knotless (353 ± 105 N; p = .129) groups. Total elongation and construct stiffness were not significantly different comparing all three groups. The failure modes were: anchor pull-out in all specimen of the knotted group; three (50%) anchor pull-out and three suture pull-out in the knotless group (p = .046); four (67%) anchor pull-out, one (17%) suture pull-out and one tendon pull-out in the triple anchor group. Biomechanical analyses of knotless fixation techniques for aLDTs show similar construct stability and elongation compared with the traditional, knotted techniques. Bone fixation seems to be improved with the knotless anchor systems. In our practice, we continue to use the knotless fixation technique for aLDT and in the situation of weak, osteoporotic bone, we add a third (all-suture) anchor to improve construct stability.

Complications and Return to Activity After Arthroscopic Repair of Isolated Type II SLAP Lesions: A Systematic Review Comparing Knotted Versus Knotless Suture Anchors.

Background:Superior labral anterior to posterior (SLAP) tears are one of the most common injuries to the shoulder, with the type II variant representing the most frequently encountered subtype.Purpose:To systematically review the literature to better understand outcomes after arthroscopic repair of isolated type II SLAP lesions using knotted versus knotless anchors based on implant number, implant location, patient position, and portal position.Study Design:Systematic review; Level of evidence, 4.Methods:A systematic review investigating all studies in the literature between January 2000 and June 2019 reporting on patients undergoing arthroscopic repair for isolated type II SLAP lesions using knotted versus knotless suture anchors was performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the PubMed, BIOSIS Previews, SPORTDiscus, PEDro, and Embase databases.Results:A total of 234 patients undergoing isolated arthroscopic repair of type II SLAP lesions using suture anchors were identified, with 76% (179/234) treated using knotted anchors versus 24% (55/234) treated using knotless anchors. Complications were reported in 12% of patients treated using knotted anchors versus no patients treated using knotless anchors (P = .008). The incidence of complications for knotted anchor repair was not significantly affected by patient position (P = .22) or portal position (P = .19). Using multiple regression analysis, we found no significant association with the incidence of complications when analyzing for anchor design (R 2 = 0.02; P = .06) or anchor position (R 2 = 0.02; P = .92). No significant difference in return-to-activity timing was appreciated based on anchor type (P = .28), patient position (P = .98), or portal position (P = .97) in patients treated using knotted anchors.Conclusion:Patients treated using knotted anchors were significantly more likely to experience a postoperative complication compared with patients treated using knotless anchors after arthroscopic repair of isolated type II SLAP lesions. Despite the increased incidence of a postoperative complication after knotted anchor fixation compared with knotless anchor fixation, multiple regression analysis showed that anchor design and anchor position were not significantly predictive of the incidence of complications. Given the increasing popularity of knotless anchor fixation, further study on the long-term outcomes after knotless repair for isolated type II SLAP lesions is warranted.

Knotless anchors offer better prevention of meniscal excursion than knotted anchors: An experimental study of the bovine knee.

Due to the biomechanical importance of the meniscal root ligament, several surgical techniques have been defined in order to treat meniscal root tear. Different application techniques have different levels of difficulty. We aimed to find a stronger and simpler repair technique. Sixteen bovine knee joints were prepared. The posterior root of the medial meniscus was dissected and repaired with one of two different techniques. The knees in group 1 ("knotted group") were repaired with the knotted suture anchor technique, and the knees in group 2 ("knotless group") were repaired using the knotless suture anchor technique. The strength of the repairs was tested biomechanically. Cyclic loading tests were done. On the 0-20 N one-cycle test, the knotted anchor group's equivalent stiffness average was 5.28 N/mm, and the knotless anchor group's equivalent stiffness average was 5.48 N/mm. The 5-20 N two-cycle test results were 8.29 N/mm for the knotted group and 8.66 N/mm for the knotless group. On the 5-20 N 100-cycle test, the equivalent stiffness averages were 8.59 N/mm for the knotted group and 10.18 N/mm for the knotless group. Elongation was 5.83 mm for the knotted group and 4.86 mm for the knotless group. After performing load-to-failure tests, the failure forces were recorded as 237.83 N for the knotted group and 204.90 N for the knotless group. The failure test elongation values were 26.83 mm for the knotted group and 18.70 mm for the knotless group. The failure energies were 3.87 J for the knotted group and 1.83 J for the knotless group. Except for elongation until failure (p=0.009), there were no significant differences between the two groups tested (p>0.05). The average elongation was significantly less in group 2, showing that the knotless anchor had an advantage, with less meniscal excursion compared to the sutured anchor. Knotless anchors have a mechanical advantage over knotted anchors for preventing meniscal excursion. When thought together with technical simplicity during arthroscopic surgery, knotless anchors could be used safely for the fixation of the meniscal root ligament.

Biomechanical comparison of knotless vs. knotted suture anchors in the acetabular rim with respect to bone density

BackgroundAcetabular labral tears are managed with suture anchors providing good clinical outcomes. Knotless anchors are easier to use and have a quicker insertion time compared to knotted anchors. The purpose of this study was to compare the biomechanical behavior of two different anchor designs (knotted vs. knotless) in ultimate load testing in correlation with bone density in the acetabular rim. MethodsEighteen knotted Bio-FASTak and seventeen knotless PushLock anchors (both: Arthrex Inc., Naples, FL, USA) were inserted in the rims of two human acetabula, with known bone density distribution. The anchors were subjected to load-to-failure tests. Anchors were additionally tested in solid polyurethane foam with defined densities. FindingsThe Bio-FASTak group showed higher survival rates at 1, 2, and 3 mm displacement and was able to withstand significantly higher loads at 3 mm displacement (p = 0.031). There was no statistically significant difference in stiffness (p = 0.087), yield- (p = 0.190), and ultimate load (p = 0.222) between the two groups. Only the PushLock group showed correlation between bone volume over total volume (BV/TV) and stiffness (R = 0.750, p = 0.086) and between BV/TV and yield load (R = 0.838, p = 0.037). Experiments on solid polyurethane foam confirmed the correlation between the mechanical properties and tissue density for the same anchor. InterpretationPushLock shows similar biomechanical properties to the Bio-FASTak, but eliminates knot tying and potentially abrasive knots. In addition, biomechanical properties of the PushLock are governed by local bone density.