Knot Strength Varies Widely Among Expert Arthroscopists

No Clear Difference in Clinical Outcomes Between Knotted and Knotless Arthroscopic Bankart Repair: A Systematic Review

PURPOSE

To analyze whether the arthroscopic Bankart repair using a knotless suture anchor has a better functional outcome than the conventional knot-tying Bankart repair.

METHODS

A comprehensive literature search was done in the PubMed, Scopus, Embase, and Cochrane databases in May 2023. Studies comparing the clinical outcome of Bankart repair using knotless and knot-tying techniques were included in the study. In vitro, animal, and Level IV and V studies were excluded. The risk of bias in randomized controlled trials was calculated according to the RoB 2 tool, and for nonrandomized studies, Methodological Index for Non-Randomized Studies criteria were used. Statistical analysis was done using RevMan software.

RESULTS

A total of 9 studies, including 2 randomized controlled trials and 7 nonrandomized comparative studies involving 720 patients, were included in the systematic review. The ROWE score ranged from 81.7 to 94.3 in the knot-tying group and 86 to 96.3 in the knotless group. Visual Analog Scale scores at the final follow-up ranged from 0.1 to 1.7 in the knot-tying group and 0.7 to 2.5 in the knotless group. The rate of redislocation, subluxation, and revision surgery in the knot-tying group ranged from 0% to 14.7%, 16.7% to 29.7%, and 1.6% to 17.6%, respectively, whereas that in the knotless group ranged from 2.4% to 23.8%, 7.4% to 22.2%, and 2.4% to 19%, respectively. The mean external rotation was 54° to 65° in the knot-tying group and 61° to 99° in the knotless group. The mean forward-flexion was 164 to 172 in the knot-tying group and 165 to 174 in the knotless group. Our subjective synthesis does not reveal any difference in the outcome between the 2 groups.

CONCLUSIONS

The available literature does not demonstrate a clear difference in functional outcomes, residual pain, and rate of complications as redislocation, subluxation, and revision surgery between Bankart repairs performed with knotted and knotless anchors.

LEVEL OF EVIDENCE

Level III, systematic review of Level I to III studies.

Technique Variation in the Surgical Treatment of Lateral Ankle Instability

INTRODUCTION

Lateral ankle sprains are the most common type of injury to the ankle and can lead to ankle instability. There are many described techniques for the surgical treatment of lateral ankle instability. The purpose of this study is to quantify the variation in surgeon technique for lateral ankle instability treatment.

METHODS

Surveys were sent to 62 orthopaedic foot and ankle surgeons regarding surgical technique for the treatment of lateral ankle instability. Clinical agreement was defined as greater than 80% agreement to assess the cohesiveness of surgical methods as described by Marx et al. Results. Response rate was 49/62 (79%). There was clinical agreement for not using bone tunnels and not using metal anchors. All other factors lacked clinical agreement. A greater average number of throws and knots (4.2 for each, range 1-6 throws, range 2-12 knots) were used by surgeons that do not believe knots cause pain compared to an average of 3.9 (range, 1-6) throws and 4.0 (range, 2-15) knots by surgeons who do believe knots cause pain. The association that surgeon who believed knots do cause pain and thus used fewer knots and throws was not statistically significant (P > .05). The preferred material by surgeons in our study are as follows: nonabsorbable braided suture (26/49, 53%), suture tape (15/49, 31%), and fiber tape (4/49, 8%). Among surgeons who use absorbable suture (34/49, 69%), there was no significant difference (P > .05) between surgeons who believe knots cause pain (23/34, 68%) and those who do not (11/34, 32%).

DISCUSSION AND CONCLUSION

Among this small sample of orthopaedic foot and ankle surgeons, there is wide variation in surgical technique for lateral ankle instability treatment and little agreement on the clinical standard of care. This disagreement highlights the need for comparative outcome studies in the treatment of ankle instability.

LEVEL OF EVIDENCE

Level III: Retrospective cohort study.

Biomechanical properties of suprapectoral biceps tenodesis with double-anchor knotless luggage tag sutures vs. subpectoral biceps tenodesis with single-anchor whipstitch suture using all-suture anchors

Background

As the use of all-suture anchors continues to increase, limited biomechanical data on the use of these anchors in various configurations for tenodesis of the long head biceps tendon (LHBT) exists. The aim of this study was to compare the biomechanical properties of a 2-anchor luggage tag suprapectoral biceps tenodesis (Sup-BT) vs. a single-anchor whipstitch subpectoral biceps tenodesis (Sub-BT) using all-suture anchors. The hypothesis was that the Sub-BT will have a higher ultimate load to failure and less creep relative to the Sup-BT construct.

Methods

Eighteen fresh frozen cadaveric humeri were used. The specimens were randomly divided into 2 groups of 9; i) The Sup-BT were performed with 2 1.8 mm knotless all-suture anchors using a luggage-tag fixation configuration, ii) The Sub-BT were performed using a single 1.9 mm all-suture anchor and a whipstitch suture configuration with a tied knot. The humeri were tested on a hydraulic MTS machine where the specimens were preloaded at 5 N for 2 minutes and then cyclically loaded from 5 to 50 N for 1000 cycles at 1 Hz while maximum displacement was recorded with a motion system and markers attached to the bone and bicep tendon. The tendon was then tensioned at a rate of 1 mm/s to obtain the ultimate load to failure. CT scans of the specimens were used to calculate the bone mineral density at the site of the anchor/bone interface and video recordings were captured during load to failure to document all modes of failure.

Results

There was no significant difference in the average load to failure of the Sup-BT and Sub-BT groups (197 N ± 45 N (SD), 164 N ± 68 N (SD) respectively; P = .122) or creep under fatigue between the Sup-BT vs. Sub-BT specimens (3.1 mm, SD = 1.5 vs. 2.2 mm, SD = 0.9; P = .162). The bone mineral density was statistically different between the 2 groups (P < .001); however, there were no observed failures at the anchor/bone interface and no correlation between failure load and bone mineral density.

Conclusion

The ultimate load to failure and creep between a Sup-BT with 2 knotless all-suture anchors using a luggage tag suture configuration was equivalent to a Sub-BT with 1 all-suture anchor using a whipstitched suture configuration and a tied knot. Surgeons can perform either technique confidently knowing that they are biomechanically equivalent in a cadaver model at time zero, and they offer similar strength to other fixation methods cited in the literature.

Endoscopic Proximal Hamstring Tendon Repair With Knotless Suture-Bridge Technique

Symptomatic proximal hamstring tendon tears are typically repaired surgically, with open incision and knot-tying technique. An endoscopic, knotless, suture-bridge repair technique is presented. Potential advantages include knotless simplicity, compression over a broad zone to improve tendon-bone healing, and decreased pain secondary to elimination of knots and the open incision and approach.

Subpectoral Biceps Tenodesis Using an All-Suture Knotless Anchor

The long head of the biceps tendon is a common pain generator in the anterior shoulder and is concomitantly seen with other shoulder pathology including subacromial impingement, as well as rotator cuff and labral tears. This Technical Note describes a mini-open onlay biceps tenodesis technique using all-suture knotless anchor fixation. This technique is easily reproducible, is efficient, and offers the unique benefits of providing a consistent length-tension relation and mitigating the risk of peri-implant reaction and fracture without sacrificing strength of fixation.

Clinical Results of Knot-tying Versus Knotless Suture Anchors in Arthroscopic Anteroinferior Labral Repair

Background Arthroscopic repair of glenohumeral instability is becoming an increasingly common procedure. These repairs can be undertaken using knot-tying and knotless suture anchors; there is currently no clear consensus in the literature about what type of repair is most cost-effective and provides superior outcomes. The purpose of this study is to examine postoperative outcomes of patients undergoing arthroscopic anteroinferior labral repair (AALR) with either knot-tying or knotless anchors. Methods A single institution retrospective observational cohort study of 122 patients undergoing AALR from January 2014 to June 2021 was conducted. Univariate statistics were used to assess differences in demographics, operative characteristics, and postoperative outcomes between repair types; multivariate analysis was used to evaluate risk factors for recurrent instability and reoperation. Results Patients undergoing AALR with knotless anchors had a shorter case duration than those with knot-tying anchors (112.64 vs. 89.86 minutes, p<0.001). There were no significant differences between groups in the size of labral tear, presence of a glenoid bone defect, or Hill-Sachs lesion. After controlling for age, BMI, sex, glenoid bone defect, number of preoperative dislocations, and fixation type, only age (OR=0.896, p=0.010) and female sex (OR=5.341, p=0.008) were independent risk factors for recurrent instability and no factors were independent predictors of reoperation. Conclusion Patients undergoing AALR experienced similar rates of reoperation and recurrent instability regardless of whether a knot-tying or knotless repair was performed. The use of knotless suture anchors may improve cost-effectiveness due to decreased surgical time without diminishing postoperative outcomes.

Tensionable Distal Biceps Tendon Repair With Intramedullary Knotless All-Suture Anchors and FiberLoop w/FiberTag Suture

Distal biceps tendon rupture is commonly repaired via bicortical drilling, extramedullary cortical button placement, and inlay tendon fixation. A retensionable technique with unicortical drilling, intramedullary knotless all-suture anchors placement, and onlay tendon fixation is presented, incorporating up-to-date advances in tendon-bone healing basic science, biceps tendon/radial tuberosity biomechanics, and knotless all-suture implant technology to facilitate radial tuberosity bone preservation, anatomic footprint restoration, improved suture-tendon connection security, and avoidance of drilling and implant-related injury to the posterior interosseous nerve.

Knotless, Retensionable Posterior Meniscal Root Repair With Anterior Cruciate Ligament Repair TightRope and FiberRing Sutures

Posterior meniscal root repair techniques continue to evolve, influenced by rapidly increasing clinical interest, surgical technology advances, and biomechanical insights. A posterior meniscal root repair technique is presented, utilizing a knotless, retensionable suspensory construct developed for anterior cruciate ligament repair but is also well suited for meniscal root repair. Benefits include built-in shuttling sutures, knotless technology, and poststressing retensioning capability to ensure maximal final repair security.

Arthroscopic Fixation of Knee Osteochondritis Dissecans With Interlinked Knotless All-Suture Anchors

Unstable, displaced, and persistently symptomatic osteochondritis dissecans of the knee typically requires surgical treatment. An arthroscopic, knotless fixation method using interlinked all-suture anchors is presented, with potential advantages over other current techniques in fixation over a broad zone, treatment versatility for a wide range of fragment types, retensioning ability after stressing, decreased risk of implant-breakage complications, and avoidance of additional surgery for implant removal.

Arthroscopic Subcoracoid Decompression, Coracoplasty, and Subscapularis Repair for Subscapularis Tears in the Setting of Subcoracoid Impingement

Subscapularis tears have been found to occur in the setting of subcoracoid impingement and are related to the narrowing of the coracohumeral interval. The advancement of arthroscopic techniques has allowed for improved identification and treatment of this historically overlooked pathology. Challenges of arthroscopic subscapularis treatment include nearby neurovascular structures, tendon retraction, and adhesions, which are further complicated by diminished arthroscopic visualization, resulting from the concomitant subcoracoid impingement. The purpose of this Technical Note is to describe our preferred technique for arthroscopic management of subscapularis tears in the setting of subcoracoid impingement that is simple and reproducible, as well as cost-effective and efficient with limited additional morbidity to that of a standard diagnostic shoulder arthroscopy.

How to tie dangerous surgical knots: easily. Can we avoid this?

Objective

Secure knots are essential in all areas of surgical, medical and veterinary practice. Our hypothesis was that technique of formation of each layer of a surgical knot was important to its security.

Design

Equal numbers of knots were tied, by each of three groups, using three techniques, for each of four suture materials; a standard flat reef knot (FRK), knots tied under tension (TK) and knots laid without appropriate hand crossing (NHCK). Each knot technique was performed reproducibly, and tested by distraction with increasing force, till each material broke or the knot separated completely.

Setting

Temporary knot tying laboratory.

Materials

The suture materials were, 2/0 polyglactin 910 (Vicryl), 3/0 polydioxanone, 4/0 poliglecaprone 25 (Monocryl) and 1 nylon (Ethilon).

Participants

Three groups comprised, a senior surgeon, a resident surgeon and three medical students.

Outcome measures

Proportion of each knot type that slipped, degree of slippage and length of suture held in loop secured by each knot type.

Results

20% of FRK tied with all suture materials slipped; all knots tied with the other two techniques, with all materials, slipped, TK (100%) and NHCK (100%). The quantitative degree of slip was significantly less for FRK (mean 6.3%–, 95% CI 2.2% to 10.4%) than for TK (mean 312%, 95% CI 280.0% to 344.0%) and NHCK (mean 113.0%, –95% CI 94.3% to 131.0%).

The mean length of suture in loops held within (FRK mean 25.1 mm 95% CI 24.2 to 26.0 mm) was significantly greater than mean lengths held by the other techniques (TK mean 17.0 mm, 95% CI 16.3 to 17.7 mm), (NHCK mean 16.3 mm, 95% CI 15.9 to 16.7 mm). The latter two types of knot may have tightened more than anticipated, in comparison to FRK, with potential undue tissue tension.

Conclusion

Meticulous technique of knot tying is essential for secure knots, appropriate tissue tension and the security of anastomoses and haemostasis effected.

Comparison of mechanical properties between Nice knot, Modified Nice knot, and surgeon's knot

BACKGROUND

The success of surgical repairs rely on the effectiveness and integrity of the surgical knots used to secure the repair. The purpose of this study is to examine and compare the performance of the Nice knot, the modified Nice knot, and a commonly used combination of surgeons' and square knots with respect to cyclic loading and load-to-failure usiflueng a high-strength suture composed of ultra-high molecular weight polyethylene in the hands of experienced surgeons.

METHODS

Two experienced surgeons threw 3 different knot types 9 times, consisting of the Nice knot, modified Nice knot, and a surgeon's knot utilizing Ultrabraid #2 sutures. Each knot was subject to cyclic loading and load to failure testing.

FINDINGS

Both surgeons had similar displacement data for the surgeon's knot, while the identity of the surgeon impacted displacement for the Nice knot (p = 0.03) and the modified Nice knot (p = 0.0002). The load to failure for the modified Nice knot (p < 0.001) and the Nice knot (p = 0.001) were significantly impacted by the surgeon tying the knot, while the surgeon's knot was not. Specimens failed where the sutures passed through the loop at the "base" of the knot.

INTERPRETATIONS

The strength and integrity of complex surgical knots are variable between surgeons. While the proposed Modified Nice Knot has a theoretical advantage because the half hitches reinforce the primary knot, in load to failure testing both the Modified Nice Knot and the Nice Knot failed where the suture passed through the loop in the primary knot.

Biomechanical Testing of Suture Anchor Versus Transosseous Tunnel Technique for Quadriceps Tendon Repair Yields Similar Outcomes: A Systematic Review

PURPOSE

To systematically review the literature to evaluate the biomechanical properties of the suture anchor (SA) versus transosseous tunnel (TO) techniques for quadriceps tendon (QT) repair.

METHODS

A systematic review was performed by searching PubMed, the Cochrane Library, and Embase using PRISMA guidelines to identify studies that evaluated the biomechanical properties of SA and TO techniques for repair of a ruptured QT. The search phrase used was "quadriceps tendon repair biomechanics". Evaluated properties included ultimate load to failure (N), displacement (mm), stiffness (N/mm), and mode of failure.

RESULTS

Five studies met inclusion criteria, including a total of 72 specimens undergoing QT repair via the SA technique and 42 via the TO technique. Three of 4 studies found QTs repaired with SA to have significantly less elongation upon initial cyclic loading when compared to QTs repaired with the TO technique (P < .05). Three of 5 studies found QTs repaired with SA to have significantly less elongation upon final cyclic loading when compared to QTs repaired with the TO technique (P < .05). The pooled analysis from 4 studies reporting on initial displacement showed a statistically significant difference in favor of the SA group compared to the TO group (P = .03). The pooled analysis from studies reporting on secondary displacement and ultimate load to failure showed no significant difference between the SA and TO groups (P > .05). The most common mode of failure in both groups was suture slippage.

CONCLUSION

On the basis of the included cadaveric studies, QTs repaired via the SA technique have less initial displacement upon cyclic testing when compared to QTs repaired via the TO technique. However, final displacement and ultimate load to failure outcomes did not reveal differences between the two fixation strategies. Knot slippage remains a common failure method for both strategies.

Mechanical Comparison of High-Strength Tape Suture Versus High-Strength Round Suture

Purpose

To compare knot and loop characteristics of commonly used high-strength tapes and high-strength round sutures.

Methods

Twenty tied 30-mm loops were prepared for using suture-knot combinations of 4 common arthroscopic knots or a hand-tied surgeon’s knot and 7 sutures. Two tapes (BroadBand, SutureTape) and three no. 2 sutures (MaxBraid, FiberWire, DynaCord) were compared. Two additional larger tape sutures (FiberTape, PermaTape) not commonly tied arthroscopically were included in the hand-tied group. Each suture-knot combination was evaluated for loop integrity (single load to a specified elongation), knot security (plastic loop deformation with cyclic testing), loop security, and knot volume. Data were compared using analysis of variance followed by Tukey-Kramer post hoc tests.

Results

BroadBand and SutureTape demonstrated superior loop integrity compared to most no. 2 suture-knot combinations. FiberTape (430.48 ± 89.00 N) and PermaTape (545.16 ± 95.09 N) required significantly greater force to undergo 3 mm of displacement than all other hand-tied sutures (P < .001). All suture-knot configurations demonstrated significant plastic deformation (cyclic elongation) over 1000 cycles (P < 0.001). DynaCord displayed the best loop security except when paired with the Duncan loop. Overall, BroadBand and SutureTape had lower knot volumes compared to all other sutures.

Conclusion

This study exhibits the ability of narrow tape sutures to provide reliable tissue apposition and fixation in multiple suture-knot configurations, while decreasing the potential adverse effects accompanying knot prominence. Generally, BroadBand and SutureTape demonstrated an ideal balance of mechanical characteristics to achieve the optimal suture-knot construct among those tested. Dynacord displayed superior loop security and performed best among round sutures. PermaTape and FiberTape showed greater loop integrity, albeit to the detriment of loop security and knot volume.

Clinical Relevance

When securing a rotator cuff repair construct with a knot, one should have a basic understanding of the mechanical properties of the suture and knot being used to provide the best possible repair. This study will provide information about the mechanical characteristics of commonly used high-strength tape suture knots and loops to help determine what knot type may provide the best overall construct.

Are Suture Tape Knots as Secure as Standard Suture? A Biomechanical Study

Background

Few studies have investigated the biomechanical performance of flat-braided suture tapes versus round-braided sutures after being knotted.

Purpose

To compare the loop security and knot strength of a standard round-braided suture with 3 commercially available flat-braided suture tapes using 2 types of arthroscopic knots.

Study Design

Controlled laboratory study.

Methods

One standard suture (SS) and 3 suture tapes (T1, T2, and T3) were tied with the surgeon's knot (SK) and the Tennessee slider (TS), 25 times each, by a single surgeon. Each combination of knots and sutures underwent a preload, cyclic loading, and load to failure. Outcomes were loop security (defined by loop stretch after a 5-N preload), load at clinical failure (3 mm of displacement), and load at ultimate failure (suture rupture or knot slippage). Two-way analysis of variance was used for analysis.

Results

Overall, the SK group had greater overall loop security than that of the TS group (0.4 ± 0.3 vs 0.5 ± 0.3 mm of stretch, respectively; P = .020). The clinical failure load varied by suture type (P < .001) but not knot type (P = .106). For both knot types, the SS had the lowest mean ± SD clinical failure load (SK, 171 ± 49 N; TS, 176 ± 37 N), which was significantly less than that of T2 (247 ± 85 N; P < .001) and T3 (251 ± 96 N; P < .001) for the SK type and T2 (231 ± 67 N; P = .023) for the TS type. T2 sutures had the greatest ultimate failure load for both knot types (SK, 418 ± 45 N; TS, 461 ± 57 N), which was significantly greater than SS, T1, and T3 (P < .001 for all). The TS knot had greater overall ultimate failure load than the SK (375 ± 64 vs 350 ± 66 N; P < .001).

Conclusion

Not all suture tape knots had the same biomechanical properties, although knot security and strength appeared to be adequate for all suture tapes as well as for SS. There was no evidence that suture tape knots are lower profile than SS knots.

Clinical Relevance

Surgeons should not use suture tape based only on the assumption that it has superior biomechanical properties to a standard round-braided suture.

Excellent Functional Outcomes and Low Complication Rates Following Knotless Arthroscopic Bankart Repair: A Systematic Review of Clinical and Biomechanical Studies

PURPOSE

To provide a comprehensive review of the current clinical and biomechanical evidence for the use of knotless suture anchors during arthroscopic Bankart repair.

METHODS

A comprehensive search of 5 electronic databases from inception to July 2020 was performed for clinical and biomechanical studies in English evaluating outcomes following arthroscopic Bankart repair using knotless suture anchors. Two independent reviewers assessed articles for inclusion. Risk of bias was assessed using the Methodological Index for Non-Randomized Studies (MINORs) criteria. Clinical outcomes of interest and key findings from biomechanical studies were summarized.

RESULTS

Ten clinical studies (430 knotless repairs), including 4 cohort studies directly comparing knotless (N = 117) to knot-tying repairs (N = 192), were deemed eligible. Four biomechanical studies were also identified. Heterogeneity and the lack of randomized studies precluded data pooling and quantitative meta-analysis. Rates of redislocation ranged from 2.2% to 14.7% and 1.5% to 23.8% for knot-tying and knotless repair, respectively. Both knot-tying and knotless repair demonstrated excellent postoperative functional outcome, as assessed by visual analog scale, Constant-Murley, Rowe, and QuickDASH scores, with 80% to 94% of patients returning to sports participation. Biomechanical studies showed similar stiffness and load to failure between knot-tying and knotless repairs, with the most common mode of failure being retear at the suture-soft tissue interface.

CONCLUSIONS

Current level II to IV clinical and biomechanical evidence supports knotless arthroscopic Bankart repair as an effective procedure with excellent functional outcomes and low rates of complication and reoperation.

LEVEL OF EVIDENCE

Level IV, systematic review of level II to IV studies.

Orthopaedic Resident Arthroscopic Knot-Tying Skills Are Improved Using a Training Program and Knot-Tying Workstation

Purpose

To quantify an orthopaedic trainee’s ability to tie arthroscopic knots before and after a short cadaveric-based arthroscopy training period using a commercially available knot-tying workstation.

Methods

During a weeklong cadaveric arthroscopic training camp, 15 third- and fourth-year orthopaedic residents were evaluated using a commercially available benchtop knot-tying workstation. At the beginning of the week (baseline), each participant was asked to tie 3 knots of his or her choice backed up by 3 half-hitches using nonabsorbable suture. Successful knots fit the sizer and elongated less than 3 mm after application of a 15-lb load. Afterward, residents watched a video demonstrating a sample knot and were encouraged to practice over the ensuing days. At the end of the week (post-training), residents were asked to tie 3 knots. The time to completion and success of each knot were recorded. To compare baseline and post-training knot success, t tests and χ² analysis were performed.

Results

During baseline testing, residents successfully tied 26.7% of their knots (12 of 45 knots) in 352 ± 116 seconds (mean ± standard deviation). During post-training testing, residents successfully tied 66.7% of knots (30 of 45 knots, P = .00014) in 294 ± 63 seconds (P = .023), showing significant improvement in the time and ability to tie arthroscopic knots.

Conclusions

With a short cadaveric-based training period, orthopaedic trainees showed a significant improvement in their ability to tie arthroscopic knots on a commercially available benchtop knot-tying workstation. Given the initial low percentage of successfully tied knots and the limited opportunities for trainees to improve, trainees should be encouraged to practice and improve their skills.

Clinical Relevance

With training, residents can improve arthroscopic knot-tying abilities, which may allow them to successfully perform this critical task in the operating room.

Reported Technical Aspects of Type II SLAP Lesion Repairs in Athletes

Purpose

To systematically review the available literature to further describe and report the available data on SLAP repair techniques and the association with outcomes.

Methods

A systematic review of literature was performed on manuscripts describing type II SLAP repairs in athletes. Selection criteria included studies reporting exclusively type II SLAP tears without concomitant pathology, minimum 2-year postoperative follow-up, use of anchor fixation, and return to previous level of play data available. We extracted patient outcome as well as surgical construct details from each article. Average outcomes and return to play rates were calculated and substratified further by athlete type. Return to play rates were compared by repair constructs with the Student t test.

Results

Initial search resulted in 107 articles. After exclusion criteria were applied, 17 articles were included in the final analysis. Overall, 84% of patients had good-to-excellent results. Of all athletes, 66% returned to previous level of play. There was significant variation in reported technique in terms of anchor number, location, material, suture type, and knotless versus knotted constructs. No significant difference was reported in outcomes in comparison of suture type (P-value .96) or knotted versus knotless constructs (P-value .91). Given the significant variability in reporting, no statistical analysis was felt able to be performed on anchor location and number.

Conclusions

Repair of type II SLAP tears in athletes is a difficult problem to treat with overall low return to play despite a high rate of “good” outcomes when assessed by outcome measures. Significant variability exists in surgical technique, as well as reporting of surgical technique, potentially limiting the ability to define the best or most effective technique for SLAP repair.

Level of Evidence

IV, systematic review of level III and level IV studies.

Differences of tensile strength in knot tying technique between orthopaedic surgical instructors and trainees

BACKGROUND

Knot tying technique is an extremely important basic skill for all surgeons. Clinically, knot slippage or suture breakage will lead to wound complications. Although some previous studies described the knot-tying technique of medical students or trainees, little information had been reported on the knot-tying technique of instructors. The objective of the preset study was to assess surgeons' manual knot tying techniques and to investigate the differences of tensile strength in knot tying technique between surgical instructors and trainees.

METHODS

A total of 48 orthopaedic surgeons (postgraduate year: PGY 2-18) participated. Surgeons were requested to tie surgical knots manually using same suture material. They were divided into two groups based on each career; instructors and trainees. Although four open conventional knots with four throws were chosen and done with self-selected methods, knot tying practice to have the appropriate square knots was done as education only for trainees before the actual trial. The knots were placed over a 30 cm long custom made smooth polished surface with two cylindrical rods. All knots were tested for tensile strength using a tensiometer. The surgical loops were loaded until the knot slipped or the suture broke. The tensile strength of each individual knot was defined as the force (N) required to result in knot failure. Simultaneously, knot failure was evaluated based on knot slippage or suture rupture. In terms of tensile strength or knot failure, statistical comparison was performed between groups using two-tailed Mann-Whitney U test or Fisher exact probability test, respectively.

RESULTS

Twenty-four instructors (PGY6-PGY18) and 24 trainees (PGY2-PGY5) were enrolled. Tensile strength was significantly greater in trainees (83.0 ± 27.7 N) than in instructors (49.9 ± 34.4 N, P = 0.0246). The ratio of slippage was significantly larger in instructors than in trainees (P < 0.001). Knot slippage (31.8 ± 17.7 N) was significantly worse than suture rupture (89.9 ± 22.2 N, P < 0.001) in tensile strength.

CONCLUSIONS

Mean tensile strength of knots done by trainees after practice was judged to be greater than that done by instructors in the present study. Clinically, knot slippage can lead to wound dehiscence, compared to suture rupture.

The effect of pulsed lavage irrigation on suture knot security

PURPOSE

The purpose of this study was to determine the effect of low-pressure and pulsed lavage irrigation on suture knot security.

METHODS

Ninety-tied suture loops were measured for baseline circumference and then subjected to no irrigation, bulb syringe irrigation, or pulsed lavage irrigation. The sutures were placed under a load and then measured for final circumference. A larger circumference difference indicated poorer knot security.

RESULTS

There was a statistically significant difference in the knot security between all three groups (p < 0.001). Pulsed lavage resulted in the greatest circumference increase (0.52 ± 0.19 mm), followed by bulb syringe (0.24 ± 0.18 mm), and lastly no irrigation (0.08 ± 0.00 mm). None of the groups had any catastrophic failures. No knots met the predetermined criteria for knot failure.

CONCLUSION

Pulsed lavage irrigation resulted in a statistically significant decrease in suture knot security as compared to bulb syringe irrigation and no irrigation. None of the groups met the currently accepted criteria for clinical suture failure, which has a relatively arbitrary value. While the available literature does not discuss increases in loop circumference for specific orthopedic applications, this small difference suggests that pulse lavage is unlikely to have a clinically significant impact on the suture integrity for most orthopedic procedures.

Arthroscopic Knotless Rotator Cuff Repair With Decellularized Dermal Allograft Augmentation: The "Canopy" Technique

Repairability and clinical outcomes of full-thickness rotator cuff tears rely on tendon mobility, tissue quality, and subsequent tension on a repair. While repair of rotator cuff tears tend to yield excellent clinical results, poor tissue quality has been an important factor that has hampered successful outcomes. This Technical Note describes a double-row rotator cuff repair using a SpeedBridge configuration with dermal allograft "canopy" augmentation to bolster the repairable but thinned rotator cuff tissue. This technique employs a unique graft fixation strategy to simplify the procedure. This approach could provide surgeons with a great option when faced with mobile but thinned rotator cuff tissue.

Posterior Glenohumeral Instability: Diagnosis and Management

Posterior glenohumeral instability can manifest as posterior shoulder pain and dysfunction, particularly among athletes. Repetitive, posteriorly-directed axial loads, as commonly encountered by contact athletes (American football linemen, rugby players), result in microtrauma that can induce posteroinferior labral tears. Alternatively, SLAP tears commonly seen in throwing athletes may propagate in a posteroinferior direction (i.e., a type VIII SLAP tear), owing to a complex pathologic cascade involving glenohumeral capsular contracture and imbalances among the dynamic stabilizing muscles of both the glenohumeral joint and shoulder girdle. The diagnosis of posterior glenohumeral instability is elucidated by a thorough history and physical examination. Posterior shoulder pain is oftentimes insidious in onset. The throwing athlete with posterior glenohumeral instability may complain of diminished control, accuracy, and generalized shoulder discomfort. A number of provocative physical examination maneuvers have been described (Kim test, Jerk test), which load the humeral head against the labral lesion and recreate patients' symptoms. Magnetic resonance imaging and magnetic resonance arthrography can be of value in demonstrating avulsions of the labrum from the posteroinferior glenoid, and computed tomography is useful for quantifying the location and amount of attritional glenoid bone loss, although in contradistinction to anterior glenohumeral instability, clearly defined thresholds that would otherwise guide treatment have not been established. In the absence of substantial bone loss, arthroscopic posterior capsulolabral repair remains the gold standard for the surgical management of symptoms refractory to nonoperative treatment, and excellent clinical outcomes have generally been reported. However, high rates of return to play at the previous level of participation, particularly among throwing athletes, have been less consistently observed. Risk factors for the need for revision stabilization include surgery on the dominant extremity, female sex, and capsulolabral repairs involving either anchorless techniques or the use of less than 4 anchors.

Posterior Labral Injury and Glenohumeral Instability in Overhead Athletes: Current Concepts for Diagnosis and Management

Posterior glenohumeral instability in overhead athletes presents a unique set of challenges for both diagnosis and treatment. Although a great deal of attention has been focused on the management of injuries to the biceps-labrum complex and rotator cuff in throwers, comparatively less has been written about posterior glenohumeral instability within this unique cohort. Historically, posterior instability has been observed secondary to either acute trauma or repetitive microtrauma, usually among collision athletes, weight lifters, and rowers. However, posterior glenohumeral instability resulting from pathology of the posterior capsulolabral tissues in throwers is a different entity, and the clinical assessment begins with an accurate differentiation between adaptive capsular laxity and labral injury with pathologic instability. Some posterior capsule labrum tears confirmed on arthroscopy will require nothing more than débridement. However, for more extensive lesions, surgical treatment must balance the necessity to repair torn capsulolabral tissues with the tendency to over constrain the shoulder. The literature provides mixed results regarding the likelihood of overhead athletes with posterior glenohumeral instability and labral injury treated surgically returning to their preinjury level of sport performance.

Biomechanical Comparison of Knotless All-Suture Anchors and Knotted All-Suture Anchors in Type II SLAP Lesions: A Cadaveric Study

PURPOSE

To compare the biomechanical performance of knotless versus knotted all-suture anchors for the repair of type II SLAP lesions with a simulated peel-back mechanism.

METHODS

Twenty paired cadaveric shoulders were used. A standardized type II SLAP repair was performed using knotless (group A) or knotted (group B) all-suture anchors. The long head of the biceps (LHB) tendon was loaded in a posterior direction to simulate the peel-back mechanism. Cyclic loading was performed followed by load-to-failure testing. Stiffness, load at 1 and 2 mm of displacement, load to repair failure, load to ultimate failure, and failure modes were assessed.

RESULTS

The mean load to repair failure was similar in groups A (179.99 ± 58.42 N) and B (167.83 ± 44.27 N, P = .530). The mean load to ultimate failure was 230 ± 95.93 N in group A and 229.48 ± 78.45 N in group B and did not differ significantly (P = .958). Stiffness (P = .980), as well as load at 1 mm (P = .721) and 2 mm (P = .849) of displacement, did not differ significantly between groups. In 16 of the 20 specimens (7 in group A and 9 in group B), ultimate failure occurred at the proximal LHB tendon. Failed occurred through slippage of the labrum in 1 specimen in each group and through anchor pullout in 2 specimens in group A.

CONCLUSIONS

Knotless and knotted all-suture anchors displayed high initial fixation strength with no significant differences between groups in type II SLAP lesions. Ultimate failure occurred predominantly as tears of the proximal LHB tendon.

CLINICAL RELEVANCE

All-suture anchors have a smaller diameter than solid anchors, can be inserted through curved guides, preserve bone stock, and facilitate postoperative imaging. There is a paucity of literature investigating the biomechanical capacities of knotless versus knotted all-suture anchors in type II SLAP repair.

Prospective Analysis of Arthroscopic Hip Anatomic Labral Repair Utilizing Knotless Suture Anchor Technology: The Controlled-Tension Anatomic Technique at Minimum 2-Year Follow-up

BACKGROUND

Labral tears are the most common abnormalities in patients undergoing hip arthroscopic surgery. Appropriate management is crucial, as it has been shown that better overall outcomes can be achieved with labral restoration.

PURPOSE

To report the patient-reported outcomes (PROs) at minimum 2-year follow-up of patients who underwent hip arthroscopic surgery for labral tear repair using the knotless controlled-tension anatomic technique in the setting of femoroacetabular impingement syndrome (FAIS).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Data were prospectively collected for patients who underwent hip arthroscopic surgery for FAIS for labral tear repair using the knotless controlled-tension anatomic technique. Patients were excluded if they had prior hip conditions, prior ipsilateral surgery, Tönnis grade >1, a lateral center-edge angle (LCEA) <25°, or workers' compensation claims. Preoperative and postoperative scores at minimum 2-year follow-up were recorded for the modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sport-Specific Subscale (HOS-SSS), International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain. The proportion of patients who achieved the minimal clinically important difference (MCID) or patient acceptable symptomatic state (PASS) for the mHHS, HOS-SSS, and iHOT-12 were also reported.

RESULTS

A total of 309 hips were included. The mean patient age was 36.2 years (range, 12.8-75.9 years). The mean preoperative LCEA and alpha angle were 31.9° and 57.1°, respectively. A significant improvement on the mHHS (62.6 ± 15.7 preoperatively vs 86.9 ± 16.2 at 2-year follow-up), NAHS (63.1 ± 16.7 vs 86.1 ± 16.7), and HOS-SSS (39.8 ± 22.0 vs 74.2 ± 27.3) was found (P < .001 for all). A significant decrease was shown for VAS scores (P < .001). Also, 78.6% and 82.2% of patients achieved the MCID and PASS for the mHHS, respectively; 60.8% and 69.9% of patients met the MCID and PASS for the HOS-SSS, respectively; and the MCID for the iHOT-12 was met by 77.3% of patients.

CONCLUSION

In the setting of FAIS and labral tears, patients who underwent hip arthroscopic surgery for labral tear repair using the knotless controlled-tension anatomic technique demonstrated significant improvement in several validated PRO measures, the VAS pain score, and patient satisfaction at a minimum 2 years of follow-up. Based on this evidence, labral tear repair using the knotless controlled-tension anatomic technique seems to be a safe option.

Sliding or Nonsliding Arthroscopic Knots for Shoulder Surgery: A Systematic Review

Background

Knot tying is a crucial component of successful arthroscopic shoulder surgery. It is currently unknown whether sliding or nonsliding techniques result in superior clinical outcomes.

Purpose

To assess the clinical outcomes of arthroscopic sliding knot (SK)- versus nonsliding knot (NSK)-tying techniques during arthroscopic shoulder surgery, including rotator cuff repair, Bankart repair, and superior labral anterior-posterior (SLAP) repair.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic search of the PubMed, Embase, and Cochrane Library databases was performed using PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. All English-language literature published between 2000 and 2018 reporting clinical outcomes utilizing SK- or NSK-tying techniques during rotator cuff repair, Bankart repair, and SLAP repair with a minimum 24-month follow-up was reviewed by 2 independent reviewers. Information on type of surgery, knot used, failure rate, patient satisfaction, and patient-reported outcomes was collected. Patient-reported outcome measures included the Constant-Murley score, Rowe score, and visual analog scale for pain. Study quality was evaluated using the modified Coleman Methodology Score.

Results

Overall, 9 studies (6 level 3 and 3 level 4) with a total of 671 patients (mean age, 52.8 years [range, 16-86 years]; 65.7% male; 206 SK and 465 NSK) were included. There were 4 studies that reported on Bankart repair in 148 patients (63 SK and 85 NSK), 3 on SLAP repair in 59 patients (59 SK), and 2 on rotator cuff repair in 464 patients (84 SK and 380 NSK). Also, 6 studies compared knot-tying with knotless techniques (3 Bankart repair studies and 3 SLAP repair studies), while the studies reporting the outcomes of SLAP repair evaluated SK-tying techniques only. The failure rate for Bankart repair was 3.2% (2/63) for SKs and 4.7% (4/85) for NSKs. The failure rate for rotator cuff repair was 2.4% (2/84) for SKs and 6.3% (24/380) for NSKs. The failure rate for SLAP repair was 11.9% (7/59). Because of inconsistencies in outcomes and procedures, no quantitative analysis was possible. The mean modified Coleman Methodology Score for all studies was 65.1 ± 8.77, indicating adequate methodology.

Conclusion

The literature on clinical outcomes using SKs or NSKs for shoulder procedures is limited to level 4 evidence. Future studies should be prospective and focus on comparing the use of SKs and NSKs for shoulder procedures to elucidate which arthroscopic knot results in superior clinical outcomes.

Is suture comparable to wire for cerclage fixation? A biomechanical analysis

BACKGROUND

Cerclage wire is the current standard for circumferential bone fixation. Advances in technology have improved modern sutures, allowing for expanded utility and broader application. The present study compared the strength and durability of cerclage fixation between modern suture materials and monofilament wire.

METHODS

The Surgeon's Knot, the Nice Knot and the Modified Nice Knot, were each tied using three separate suture materials: no. 2 FiberWire (Arthrex, Naples, FL, USA), no. 2 Ultrabraid (Smith & Nephew, Andover, MA, USA) and no. 5 Ethibond (Johnson & Johnson, Somerville, NJ, USA). These sutures were compared with monofilament wire. Sutures were secured around a fixed diameter using three additional half hitches, whereas a 1.2-mm (18 gauge) stainless steel monofilament wire was used for comparison. One fellow and one orthopaedic surgery resident each tied five trials with every knot/material combination. Samples were subjected to cyclic loading and quasi-static load testing. Respectively, cyclic displacement over time and load to failure were analyzed. Clinical failure (3 mm of cyclic displacement) and absolute failure (opening of the knot or material failure) were the outcomes of interest.

RESULTS

During cyclic loading, Ethibond displaced significantly less over time compared to monofilament wire (p < 0.003), whereas FiberWire showed no significant difference. Ultrabraid also behaved similar to wire, except displacing significantly more than wire only with the Surgeon's Knot (p = 0.02). During load to failure, Ethibond and FiberWire failed at significantly greater loads than monofilament wire (p < 0.001), whereas Ultrabraid performed similar to wire. Knot types did not appear to impact the results.

CONCLUSIONS

High-performance sutures achieve superior results in biomechanical testing under cyclic and quasi-static load compared to monofilament wire, suggesting that they provide an alternative to wire for cerclage fixation with select clinical application. Biomechanical security of suture cerclage is dependent on suture material, although it is not altered significantly by choice of knot. An ex-vivo study with clinical application would further reinforce whether suture cerclage offers a valid alternative to wire cerclage.

Footprint coverage comparison between knotted and knotless techniques in a single-row rotator cuff repair: biomechanical analysis

Abstract

Background

The objective of this biomechanical study is to compare two variations of single-row knotless techniques (Knotless repair and Rip-stop Knotless repair) against a single-row double-loaded anchor (DL) repair, focused on evaluating contact pressure and contact area amongst three different single-row techniques for rotator cuff repairs.

Methods

A total of 24 fresh frozen human shoulders were tested. Specimens were randomly assigned into one of the three single-row (SR) repair groups: A Knotted single-row double-loaded anchor (DL) repair, a Knotless (K) repair, or a Knotless Rip-Stop (KRS) repair. The footprint was measured after complete detachment of the supraspinatus tendon from the greater tuberosity, introducing pressure sensors between bony footprint and detached rotator cuff, and finally reconstructing it. All specimens were mounted onto a servohydraulic test system to analyze contact variables at 0° and 30° of abduction with 0 N, 30 N and 50 N of tension.

Results

Groups did not differ significantly in their footprint sizes: DL group 359.75 ± 58.37 mm², K group 386.5 ± 102.13 mm², KRS group 415.87 ± 93.80 mm² (p = 0.84); nor in bone mineral density: DL group 0.25 ± 0.14 g/cm², K group 0.32 ± 0.19 g/cm², KRS group 0.32 ± 0.13 g/cm², (p = 0.75) or average age. The highest mean pressurized contact area measured for the K repair was 248.1 ± 50.9 mm², which equals a reconstruction of 67.1 ± 19.3% at 0° abduction and a 50 N supraspinatus load. This reconstructed area was significantly greater compared with the DL repair 152.8 ± 73.1 mm², reconstructing 42.0 ± 18.5% on average when under the same conditions (p = 0.04). The mean contact pressure did not significantly differ amongst groups (p = 1.0): DL group 30.8 ± 17.4 psi, K group 30.9 ± 17.4 psi and KRS group 30.0 ± 10.9 psi. Neither the 30° abduction angle nor the supraspinatus load had a significant influence on the contact pressure in our study.

Conclusion

Both single-row knotless techniques resulted in significantly higher footprint reconstruction, providing larger contact area and a more uniform pressure distribution when compared with the single-row Knotted techniques. The mean contact pressure did not differ among groups significantly. These knotless techniques may be an alternative if the surgeon decides to perform a single-row rotator cuff repair.

Level of evidence

Basic Science Study, Biomechanics.

Arthroscopic Knotless Remplissage for the Treatment of Hill-Sachs Lesions Using the PASTA Bridge Configuration

Recurrent glenohumeral dislocations can produce Hill-Sachs lesions-bony defects on the humeral head resulting from the humerus hitting the glenoid during dislocations. Some of these lesions can engage on the glenoid during motion, producing instability and potentially affecting the success of a labral repair. The remplissage was developed to address these Hill-Sachs lesions and improve stability. French for "filling," the goal of the remplissage is to fill the Hill-Sachs lesion with the infraspinatus tendon, preventing the margins of the lesion from engaging with the glenoid. Analogous to restoring the rotator cuff footprint during repair, a primary goal of the remplissage is to have the infraspinatus cover the Hill-Sachs lesion. The partial articular supraspinatus tendon avulsion (PASTA) bridge was originally developed for partial-thickness rotator cuff repair in situ, but additional uses have been found in other settings. The PASTA bridge uses a medial row horizontal mattress with a lateral anchor to create a linked construct to effectively distribute force and provide adequate coverage of the lesion. Knotless anchor technology used in this procedure prevents the need for arthroscopic knot tying and potentially damaging knot stacks. This Technical Note describes a remplissage technique using the PASTA bridge configuration to address Hill-Sachs lesions associated with recurrent glenohumeral instability.

Use of a Safety Clamp When Performing Arthroscopic Knot Tying Preserves the Suture When It Is Placed Under Excessive Tension

The purpose of this study was to compare the location of the suture breakage between tying by hand vs with a safety clamp, needle driver. FiberWire No. 2 and 2-0 (Arthrex, Naples, Florida) were fastened onto the hook attachment of the digital force gauge. Sutures were placed under excessive strain using a hand tying technique vs a safety clamp, or instrument tying. Peak forces at which the sutures failed under tension along with locations of the suture breakage, measured from the site of the knot, were recorded. For FiberWire No. 2, the mean load to failure was 142.60±2.33 N for hand tying and 78.79±1.97 N for the safety clamp (P<.0001). For FiberWire 2-0, the mean load to failure was 62.98±4.90 N for hand tying and 34.43±2.46 N for the safety clamp (P<.0001). For FiberWire No. 2, the mean location of suture breakage was 0 cm, at the site of the knot, for hand tying and at the clamping point (10.45±0.34 cm from the knot) for the safety clamp (P<.0001). For FiberWire 2-0, the mean location of suture breakage was 0 cm, at the site of the knot, for hand tying and at the clamping point (10.47±0.22 cm from the knot) for the safety clamp (P<.0001). Use of a safety clamp while mastering arthroscopic suture technique preserves the suture knot when placed under excessive tension. [Orthopedics. 2019; 42(1):e25-e28.].

Reattachment of the flexor and extensor tendons at the epicondyle in elbow instability: a biomechanical comparison of techniques

Background

Elbow dislocation represents a common injury, especially in the younger population. If treated surgically, the reattached tendons require a high amount of primary stability to allow for an early rehabilitation to avoid postoperative stiffness. The purpose of this study was to assess the biomechanical properties of a single and a double row technique for reattachment of the common extensor and common flexor muscles origin. We hypothesized that the double row technique would provide greater stability in terms of pullout forces than the single row technique.

Methods

Twelve cadaveric specimens were randomized into two groups of fixation methods for the common extensor tendon or the common flexor tendon at the elbow (1): a single row technique using two knotted 3.0 mm suture anchors, and (2) a double row technique using an additional knotless 3.5 mm anchor. The repairs were cyclically loaded over 500 cycles at 1 Hz from 10 N to a maximum of 100 N (extensors) or 150 N (flexors), and then pulled to failure. Stiffness and maximum load at failure and mode of failure were recorded and calculated.

Results

No significant differences in stiffness were observed between the two techniques for both the extensor and flexor reattachment (P = 0.701 and P = 0.306, respectively). The mean maximum load at failure indicated that the double row construct was significantly stronger than the single row construct. This was found to be true for both the extensor and flexor reattachment (213.6; SD 78.7 N versus 384.1; SD 105.6 N, P = 0.010 and 203.7; SD 65.8 N versus 318.0; SD 64.6 N, P = 0.013, respectively).

Conclusions

The double row technique provides significant greater stability to the reattached common flexor or extensor origin to the medial or lateral epicondyle. Thus, it should be considered in the development of improved repair techniques for stabilizers of the elbow.

Study design

Controlled laboratory study.

Remplissage Using Interconnected Knotless Anchors: Superior Biomechanical Properties to a Knotted Technique?

PURPOSE

To evaluate the biomechanical fixation strength and gap formation of 2 different remplissage fixation methods (double pulley knotted construct and interconnected knotless repair construct) in cadaver specimens.

METHODS

Seven matched pairs of human cadaveric shoulders were used for testing (mean age, 56 ± 10 years). A shoulder from each matched pair was randomly selected to receive a Hill-Sachs remplissage using either a knotted (No. 2 FiberWire double pulley with 3.0-mm SutureTak anchors) or knotless (coreless No. 2 FiberWire interconnected between 3.9-mm knotless CorkScrew anchors) double mattress construct. The tendon was cycled between 10 and 100 N at 1 Hz for 100 cycles, followed by a single-cycle pull to failure at 33 mm/s. Cyclic displacement, load to clinical failure (5 mm), yield load, and mode of failure were recorded.

RESULTS

Neither construct demonstrated clinical failure under cyclic loading. Load to clinical failure was higher for the knotless repair than that of the knotted repair (788 ± 162 N vs 488 ± 227 N; P = .003). The yield load was higher for the knotless repair than that of the knotted repair (1,080 ± 298 N vs 591 ± 265 N; P = .008). The most common failure mode for the knotted repair was knot failure or tendon tearing, whereas the failure mode for the knotless repair was by anchor pull-out or tendon tear with no failures occurring via the interconnected suture construct mechanism.

CONCLUSIONS

In this biomechanical study comparing cyclic and ultimate loading for 2 double mattress remplissage repairs, the construct using interconnected, knotless sutures outperformed the knotted construct. No failure of the interconnected suture construct mechanism by slippage or breakage was observed in the knotless group.

CLINICAL RELEVANCE

The use of the interconnected knotless suture technique might improve the biomechanical strength of arthroscopic remplissage repairs in treating shoulder instability.

Editorial Commentary: What's Knot to Like? In the Biomechanics Laboratory, Knotless Shoulder Anchors Hold Their Own

Arthroscopic knot tying remains challenging, and the knots are a weak link for many repair constructs. Knotless strategies continue to evolve, and in some cases, these methods enhance biomechanical repair characteristics. The associated impact on clinical outcomes remains unknown.

Validation of the FAST Workstation as an Objective Evaluator of Hand-Tied Surgical Knots

INTRODUCTION

Hand-tying surgical knots is an important skill that is applicable across all surgical disciplines. Knot quality is traditionally assessed in the operating room by visual inspection, which is inherently subjective. With the increasing prevalence of simulation training, surgical trainees having access to objective feedback of their knot-tying skills are paramount for skill evaluation. Our study aimed to validate a mechanical suture loop security tester as an objective evaluation method of hand-tied surgical knot quality.

METHODS

Seventy-three subjects were recruited and categorized based on surgical expertise into one of the following three groups: medical students, surgical residents, and attending surgeons. They hand-tied five surgical knots consecutively using 0 Vicryl sutures. The knots were tested using the suture loop security workstation with 10 lbs of linear force for 10 seconds. Success of the suture loop was set at less than 3 mm of loop expansion. This protocol was based on previous research showing that 3 mm of loop expansion would represent clinical failure of the knot in vivo.

RESULTS

The students, residents, and attending surgeons tied a median of two, three, and four successful knots, respectively. Post hoc pairwise comparisons revealed that residents tied more successful knots than students (p < 0.001), and attending physicians tied more successful knots than students (p < 0.001). However, there was no statistically significant difference in the number of successes between residents and attending physicians (p = 0.24).

CONCLUSIONS

Using the mechanical loop security workstation demonstrates construct validity as a reliable objective evaluation tool of hand-tied surgical knots.

The effect of residency training on arthroscopic knot tying and knot stability: which knot is best tied by Orthopaedic surgery residents?

Background

The aim of this study is to evaluate which of three arthroscopic knots are most reliably taught to and executed by residents at varying levels of training.

Methods

Three arthroscopic knots, the Samsung Medical Center (SMC), the Weston, and the surgeon’s knot, were taught to 16 orthopaedic surgery residents. Each knot was tied in triplicate at two sessions 1 week apart. The knots were then biomechanically tested for strength. Corresponding knots tied by a sports medicine fellow served as the respective controls.

Results

Comparing all knots regardless of year of training, the SMC knot failed at significantly higher loads (237.2 ± 66.6 N) than the surgeon’s knot (203.7 ± 45.3 N, p = 0.049) and the Weston knot (193.5 ± 56.1 N, p = 0.013). No significant differences in knot strength were found when comparing knots tied by residents at different levels of training and when comparing residents to the sports medicine fellow. There was no difference in conditioning elongation between surgeon’s (p = 0.343), Weston (p = 0.486), or SMC knots (p = 0.200) tied by post-graduate year one and five residents.

Conclusions

We report the first study that evaluates the loop strength of an arthroscopically tied knot performed by orthopaedic surgery residents in various levels of training. In our cohort, the SMC knot required a higher load to failure, when compared to the Surgeon’s and Weston knot, after a simple arthroscopic knot tying curriculum. Based on these findings, he SMC knot should be considered as a part of future orthopaedic surgery resident arthroscopic training programs.

Knotless Fixation Is Stronger and Less Variable Than Knotted Constructs in Securing a Suture Loop

Background:

Historically, tendon-to-bone fixation has relied on knot tying. However, considerable variability exists in knot-tying strength among surgeons.

Purpose/Hypothesis:

The purpose of this study was to compare the biomechanical properties of knotted and knotless fixation and to evaluate variability among surgeons. The hypothesis was that knotless constructs would be stronger and have less variability as compared with knotted constructs.

Study Design:

Controlled laboratory study.

Methods:

A total of 34 orthopaedic surgeons participated in a laboratory study to compare knotted and knotless constructs, where 104 knotted constructs were performed with No. 2 suture, 21 knotless constructs with No. 2 suture (K2 group), and 79 knotless constructs with suture tape (KT group). Mechanical testing was performed to compare load at 3 mm of displacement, load to failure, and stiffness of each construct.

Results:

The mean load at 3 mm of displacement was greatest in the KT group, with significant differences among all 3 groups (P < .001). Load to failure was significantly greater in the KT group as compared with the K2 group and the knotted group (P < .001), but there was no difference between the K2 and knotted groups (P ≥ .999). Stiffness and displacement were also greatest in the KT group. Based on the F test, the variance in load to failure was significantly different between the knotted and knotless constructs, with the knotted group demonstrating greater variability (SD, 94 N) than the KT (SD, 38 N) and K2 (SD, 17 N) groups (P < .001).

Conclusion:

Knotless fixation with suture tape had improved biomechanical performance as compared with knots or knotless fixation with No. 2 suture. In addition, knotless fixation had less variability in biomechanical properties among multiple surgeons.

Clinical Relevance:

This study may be relevant for surgeons choosing between knotted and knotless constructs as well as for considerations in the design of rotator cuff repair constructs.

Triple-Loaded Suture Anchors Versus a Knotless Rip Stop Construct in a Single-Row Rotator Cuff Repair Model

PURPOSE

To compare the biomechanical properties of single-row repair with triple-loaded (TL) anchor repair versus a knotless rip stop (KRS) repair in a rotator cuff repair model.

METHODS

Rotator cuff tears were created in 8 cadaveric matched-pair specimens and repaired with a TL anchor or KRS construct. In the TL construct, anchors were placed in the greater tuberosity and then all suture limbs were passed through the rotator cuff as simple sutures and tied. In the KRS construct, a 2-mm suture tape was passed through the tendon in an inverted mattress fashion, and a free suture was passed medial to the suture tape to create a rip-stop. Then, the suture tape and free suture were secured with knotless anchors. Displacement was observed with video tracking after cyclic loading, and specimens were loaded to failure.

RESULTS

The mean load to failure was 438 ± 59 N in TL anchor repairs compared with 457 ± 110 N in KRS repairs (P = .582). The mean displacement with cyclic loading was 3.8 ± 1.6 mm in TL anchor repairs versus 4.3 ± 1.8 mm in the KRS group (P = .297). Mode of failure was consistent in both groups, with 6 of 8 failures in the TL anchor group and 7 of 8 failures in KRS group occurring from anchor pullout.

CONCLUSIONS

There is no statistical difference in load to failure and cyclic loading between TL anchor and KRS single-row repair techniques.

CLINICAL RELEVANCE

KRS repair technique may be an alternative method of repairing full-thickness supraspinatus tendon tears with a single-row construct.

Biomechanical Comparison of 3 Glenoid-Side Fixation Techniques for Superior Capsular Reconstruction

BACKGROUND

Superior capsular reconstruction (SCR) was recently introduced as a treatment for irreparable superior rotator cuff tears in younger patients. Purpose/Hypothesis: The purpose was to assess the biomechanical strength of 3 methods for fixation of the graft to the glenoid for SCR. It was hypothesized that a 4-anchor technique would provide greater load to failure than 3-anchor techniques.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-six cadaveric specimens were randomized into 3 groups of previously established glenoid-side graft fixation techniques: (1) three 3.5-mm knotless screw-in anchors, (2) three 3.0-mm knotless push-in anchors, and (3) a 4-anchor hybrid construct with two 3.0-mm knotted push-in anchors and two 2.9-mm knotless push-in anchors. The repairs were cyclically loaded at 0.5 Hz from 10 to 200 N, then pulled to failure. Elongation, stiffness, maximum load at failure, and mode of failure were recorded and calculated.

RESULTS

There were no significant differences in graft elongation or stiffness among the 3 techniques ( P > .37 and P > .26, respectively). Maximum load to failure was significantly greater in technique 1 (mean ± SD, 427.85 ± 119.70 N) than technique 3 (319.5 ± 57.60 N) ( P = 0.024). There were no significant differences in load to failure between techniques 1 and 2 or between techniques 2 and 3.

CONCLUSION

Glenoid-side graft fixation with 3 threaded 3.5-mm suture anchors showed a significant superior pull-out strength when compared with a 4-anchor hybrid technique and thus might be recommended in SCR for patients with irreparable superior rotator cuff tears to achieve maximum stability.

CLINICAL RELEVANCE

SCR presents a novel alternative for treatment of irreparable superior rotator cuff tears in younger patients. Glenoid fixation is essential to provide adequate fixation of the graft to prevent the humeral head from rising and to restore normal biomechanics.

Arthroscopic Double-Row Transosseous Equivalent Rotator Cuff Repair with a Knotless Self-Reinforcing Technique

BACKGROUND

Rotator cuff tears are a significant cause of shoulder morbidity. Surgical techniques for repair have evolved to optimize the biologic and mechanical variables critical to tendon healing. Double-row repairs have demonstrated superior biomechanical advantages to a single-row.

METHODS

The preferred technique for rotator cuff repair of the senior author was reviewed and described in a step by step fashion. The final construct is a knotless double row transosseous equivalent construct.

RESULTS

The described technique includes the advantages of a double-row construct while also offering self reinforcement, decreased risk of suture cut through, decreased risk of medial row overtensioning and tissue strangulation, improved vascularity, the efficiency of a knotless system, and no increased risk for subacromial impingement from the burden of suture knots.

CONCLUSION

Arthroscopic knotless double row rotator cuff repair is a safe and effective method to repair rotator cuff tears.

Validation of Improvement of Basic Competency in Arthroscopic Knot Tying Using a Bench Top Simulator in Orthopaedic Residency Education

PURPOSE

To validate basic competency in arthroscopic knot tying using a unique simulator device to compare the level of training needed for learning and tying the arthroscopic knot by evaluating the tensile properties of the arthroscopic knots.

METHODS

Three groups of surgeons of various experience levels (postgraduate year [PGY] 1, PGY 3, and experienced surgeons) tied 2 different arthroscopic knots (Tennessee Slider, considered easier, and Weston, considered more difficult) over a 10-week period. Each group went through 3 separate stages of knot tying: stage 1, tying 8 knots without cannula or knot pusher; stage 2, tying 12 knots with knot pusher; and stage 3, tying 20 knots with knot pusher through a cannula that simulates knot tying during surgery. A single load-to-failure test was performed and ultimate clinical failure loads were recorded. Time needed to tie each knot was also recorded.

RESULTS

At stages 1 and 2, the PGY 1 group had a significantly weak knot tensile strength (Tennessee Slider stage 1: 60 v 129 N, P = .001; Tennessee Slider stage 2: 69 v 132 N, P = .0029; Weston stage 1: 73 v 184 N, P = .0000; Weston stage 2: 125 v 173 N, P = .0045) and were slower (Weston: 56 v 30 seconds, P = .0010) than the experienced surgeon group for both knots. At stage 3, only the initial 2 weeks of Tennessee Slider showed a significant difference between groups 1 and 3 (week 6: 87 v 118 N, P = .0492; week 7: 89 v 126, P = .01485). Even though the Tennessee Slider knot is one of the easier arthroscopic knots to learn to tie, the results showed a slow trend of improvement in this knot-tying skill for group 1 after each stage.

CONCLUSIONS

The data validated an important learning effect in all trainees in arthroscopic knot tying over a 10-week period and showed that inexperienced trainees will be able to improve their knot-tying skill with training in 3 stages with a simulator environment.

CLINICAL RELEVANCE

The findings of this study indicated the importance of hands-on experience in performing arthroscopic knot tying, as determined by both knot performance and ultimate suture loop strength. In addition, each orthopaedic resident learned and developed his or her arthroscopic knot-tying skills and provided a foundation for his or her future practice in orthopaedic medicine.

Reverse Flipping Technique: An Alternate Approach to Tie Reversing Half-Hitches on Alternating Posts

Arthroscopic knot tying requires practice and attention to detail, especially tying the 3 reversing half-hitches on alternating posts (RHAPs) in a knot. Mistakes can occur that result in an unintentional tension (>10 N) applied to the wrapping suture limb, and by placing tension in the wrong limb, the previously "flipped" half-hitch is converted from a series of RHAPs into a series of identical half-hitches on the same post, thereby producing insecure knots or suture loops. This was hypothesized to be a source of knot failure by knot slippage. This error can be avoided by using a technique we describe as "reverse flipping," which purposely "flips" the half-hitch down at the main knot while tying the 3 RHAPs in a knot, and then the half-hitch is retightened using either a past-pointing or over-pointing technique. This way the surgeon can be absolutely sure that the half-hitch is tightened in the direction that it was intended to be placed, and can also prevent the unintentional tension applied to the wrapping suture limb that causes the half-hitch to "flip." However, caution should be used when tensioning the half-hitches; overtensioning (>40 N) during past-pointing or over-pointing could also potentially "flip" the previous half-hitch that has already been tightened and cause potential knot failure.

Performance Comparison of a Pretied Suture Knot With Three Conventional Arthroscopic Knots

PURPOSE

To compare the knot characteristics of a pretied suture knot with 3 of the most commonly used arthroscopic knots tied with various high-strength sutures.

METHODS

Three commonly used arthroscopic knots (surgeon's knot, Seoul Medical Center, and Duncan loop) tied with no. 2 high-strength sutures were compared with a pretied knot secured with either 1, 2, or 3 reversed half hitches (RHAPS). An orthopaedic sports medicine surgeon and fellow tied a total of 120 knots. All knot combinations were tested for strength, knot bulk, cyclic loop elongation, ultimate loop elongation, and ultimate strength.

RESULTS

All pretied configurations had statistically significant improved strength (P = .048, P ≤ .001, and P < .001) versus all other knot groups with mean ± standard deviation loads of 206.3 ± 37.5, 285.6 ± 68.6, and 357.6 ± 61.1 N, respectively. The pretied knot with 1, 2, or 3 RHAPs has significantly smaller volume than the arthroscopic knots in all suture materials. All pretied knot configurations demonstrated no significant difference in cyclic loop elongation compared with standard arthroscopic knots; however, they had a statistically significant lower ultimate loop elongation (P = .001 for each pretied knot configuration).

CONCLUSIONS

Compared with other commonly tied arthroscopic knots using no. 2 high-strength suture, the pretied knot with doubled no. 1 high-tensile-strength suture tied with 1, 2, or 3 RHAPs results in a statistically significantly improved strength. The pretied knot has an equivalent cyclic loop elongation and lower ultimate loop elongation with all RHAP configurations. The pretied knot with 2 or 3 RHAPs has a significantly higher ultimate strength than all combinations of arthroscopic knots excluding one. The pretied knot with 1, 2, or 3 RHAPs has significantly less knot volume than all other knots tested and offers a more reproducible knot.

CLINICAL RELEVANCE

The pre-tied knot offers equivalent or improved strength while having a smaller knot volume.

Objective Assessment of Knot-Tying Proficiency With the Fundamentals of Arthroscopic Surgery Training Program Workstation and Knot Tester

PURPOSE

To assess a new method for biomechanical assessment of arthroscopic knots and to establish proficiency benchmarks using the Fundamentals of Arthroscopic Surgery Training (FAST) Program workstation and knot tester.

METHODS

The first study group included 20 faculty at an Arthroscopy Association of North America resident arthroscopy course (19.9 ± 8.25 years in practice). The second group comprised 30 experienced surgeons attending an Arthroscopy Association of North America fall course (17.1 ± 19.3 years in practice). The training group included 44 postgraduate year 4 or 5 orthopaedic residents in a randomized, prospective study of proficiency-based training, with 3 subgroups: group A, standard training (n = 14); group B, workstation practice (n = 14); and group C, proficiency-based progression using the knot tester (n = 16). Each subject tied 5 arthroscopic knots backed up by 3 reversed hitches on alternating posts. Knots were tied under video control around a metal mandrel through a cannula within an opaque dome (FAST workstation). Each suture loop was stressed statically at 15 lb for 15 seconds. A calibrated sizer measured loop expansion. Knot failure was defined as 3 mm of loop expansion or greater.

RESULTS

In the faculty group, 24% of knots "failed" under load. Performance was inconsistent: 12 faculty had all knots pass, whereas 2 had all knots fail. In the second group of practicing surgeons, 21% of the knots failed under load. Overall, 56 of 250 knots (22%) tied by experienced surgeons failed. For the postgraduate year 4 or 5 residents, the aggregate knot failure rate was 26% for the 220 knots tied. Group C residents had an 11% knot failure rate (half the overall faculty rate, P = .013).

CONCLUSIONS

The FAST workstation and knot tester offer a simple and reproducible educational approach for enhancement of arthroscopic knot-tying skills. Our data suggest that there is significant room for improvement in the quality and consistency of these important arthroscopic skills, even for experienced arthroscopic surgeons.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Orthopaedic Residents Improve Confidence and Knot-Tying Speed With a Skills Course

PURPOSE

To determine the effect of a knot-tying module, within an arthroscopic training course, on resident speed, resident confidence, and biomechanical quality of arthroscopically tied knots.

METHODS

Sixty-four participants (8 postgraduate year [PGY]-3 and 8 PGY-4 orthopaedic residents annually for 4 years) were enrolled in a 5-day training course, which included a daily knot-tying module. Self-assessed confidence was obtained by pre-course (day 1) and post-course (day 5) questionnaire. Each participant tied 5 sequential knots using an arthroscopic knot-tying station. Time per knot was recorded in seconds. Knots were later preloaded, cycled, and tested for peak load to failure and displacement change. Mean peak load to failure, displacement change, speed, and confidence were compared before and after training.

RESULTS

The mean time to complete 5 knots was significantly faster after training (12.8 minutes before the course [day 1] v 9.39 minutes after the course [day 5]) (P < .0001). Confidence improved from pre-course (mean, 3.3) to post-course (mean, 7.8) questionnaires (P < .0001). No statistically significant difference was found between peak force for pre-course (mean, 136 N) and post-course (mean, 138 N) knots (P = .076). No statistically significant difference was detected in mean displacement change (mean, 3.51 mm before the course v 3.57 mm after the course) (P = .61). Comparison of PGY-3 and PGY-4 residents was significant only for a higher pre-course confidence in PGY-4 residents (P = .02).

CONCLUSIONS

Participation in an arthroscopic knot-tying module improves resident speed and confidence in tying arthroscopic knots. Our data did not show a significant change in peak load to failure or loop security with training. These findings suggest that participation in a knot-tying module improves efficiency regarding arthroscopic knot tying by residents.

CLINICAL RELEVANCE

Residents who practice arthroscopic knot tying 5 days per year as part of an arthroscopic training course may be more efficient in the operating room.